When dealing with crosswinds and drift, I find the easiest way to understand the concept is to imagine a fast flowing river of water.

If you tried to swim straight across a fast river you will end up downstream.

You don't "feel" the current.

You just keep swimming and the current carries you.

Any time you have wind it is like a river of air flowing over the earth.

Traveling through a river of air is exactly like traveling through a river of water.

You don't go where you are pointed, you go where the current carries you, plus the direction you are swimming.

The main reason is that you are, in fact, flying straight through the air, and the air is moving sideways.

So the plane isn't really being pushed sideways or anything, it's just flying straight through something that is moving...

As a simple example, if you are flying north at 150knots (the red line below) and the wind is blowing east at 20 knots (the blue line), you are going to end up flying

just every so slightly North East at about 151knots (roughly).

But, to your plane, you're just traveling north at 150 knots, the wind is adding the last 1 knots.

The bottom line is that your plane flies in a straight line through the air mass, and the air mass moves as well.

You have to add these two velocities/directions together in order to find your true velocity/direction relative to the ground.

This is normally called a "vector" in the aviation world, and if you do a bit of study into those, I think you'll have a much easier time understanding those charts.

A change of reference frame may help to understand.

So you sit in the plane and fly as usual, the only effect of wind is drifting the ground in the direction where it comes from.

Headwind moves the ground forward, tailwind backwards.

Sidewind to the side, so you compensate not by applying continuous rudder, but just by pointing the nose slightly to the side.

As for your question about why no rudder is required, there are two methods for handling a crosswind.

One is "crabbing" and the other is "slipping."

When you crab, you point the nose of the airplane into the wind as described in the other answers and in your pictures.

This is an efficient way to deal with a crosswind over long distances, such as when cruising.

During landing, if you are still crabbing when the wheels touch down, it's very hard on the airplane and is called "side-loading" the landing gear.

Instead, a slip is used.

In a slip the ailerons are held towards the wind and the rudder is held away from the wind just enough to keep the nose from turning.

In this way the longitudinal axis of the airplane is still kept in line with your flight path, but some of your lift is being used to "pull" you up-wind and thus counteract the crosswind.

On most airplanes this is the method used right before touchdown.

On the final/short final phase, pilots have different preferences for crab or slip technique.

In general: as Jay Carr visualized with his interactive graphic, velocities (speeds) are vectors (this is rather physics than aviatic, but if pilots consider physics they tend to live longer).

Vectores have a value and a direction.

So you can visualizes them by an arrow (lenght visualizes the velocity).

Contrary to e.g. temperature which is a scalar measure, it has only a value but no direction.

So to add speeds you must consider values and directions.

Now to your questions ... ad Image 1)

The wind is blowing from the left.

If the aircraft would aim to the north ("heading north"), the cross wind would move it to the right, so it would pass the city more to its right (if map is oriented "north up" than it would pass the city east).

BUT, the pilot is smart: he compensates for the crosswind by pointing the aircraft's nose slightly "into the wind" (look, where the aircraft's noise is pointing to).

Durign his flight planning he might have calculated the "offset" comparing desired track and forecasted wind.

Once in the air he could also find out by applying a heading into the wind and check whether the aircraft moves along the desired track.

ad image 2)

the plane is sliding (well, it does not touch the ground) because its air speed (caused by the propulsion of the prop and being straight - visualized in the image by the wake vortices and its wing tips ) points to its noise (the prop is mounted without pivot), plus (plus in a sense of vector addition)

the wind from the left result here in a track following the railways.

ad image 3)

the wind from the left moves the whole air which surrounds the aircraft (a static wind, no gusts).

So the while the aircraft moves through this air mass, the air mass itself (and with it the aircraft)

moves along the wind direction.

So you do not need rudder to hold that direction (heading).

You only have to apply rudder to change the direction.

So the pilot did apply rudder for some seconds when he noted that he needs to compensate for the crosswind, just until the aircraft changed its direction from north to slighly north-north-west.

The author says "the aircraft does note feel the crosswind" -

yeah, due to its static effect you could not tell without any reference (to the ground, to your GPS or whatever navigation aid) that there is a wind at all.

To bring Wurzel's answer into the context: yes, if you want to land then you could use the same maneuver as shown in the 3 images (called crab, because this animal walks sideways), - or if you could fly straight along the runway direction but compensate for the crosswind by lowering the windward wing.

Hope it helpsHolger

Question: Apologies for multiple pictures but I thought they would depict my question more clearly than a lengthy description.  Image 1: Why does the aircraft still follow the straight path even if the wind is blowing from left to right?  Image 2: Why does it appear that the aircraft is sliding?  Image 3: Why is there no need to apply any rudder in the presence of a cross wind?

Why does the airplane not 'feel' the crosswind?

The main reason is that you are, in fact, flying straight through the air, and the air is moving sideways.

The airplane is flying in a straight line, while the air mass is moving sideways, thus creating the feeling that the airplane is being "pushed". You cannot feel the crosswind because a reference point is needed (ground, GPS, etc.) due to the static effect.

Because the airplane is flying in a straight line, while the air mass is moving sideways, thus creating the feeling that the airplane is being "pushed".


From a luxury round the world flight on several different models of aircraft on several different airlines, a traveler used the exact same sound meter at his seat in either business or first class to measure ambient noise level during cruise.

Here is a chart I made of his measurements, including carrier and age of aircraft.

As you can see, long haul aircraft are quieter than short.

Carrier and age of aircraft also seem to make a difference.

For this set of measurements, the b773 is 3db (or 25%)

louder than the a380.

As a passenger: In the forward bulkhead section of economy class (lower deck) there is almost no engine noise in the A380.

If you listen carefully, you can hear it.

I was actually surprised at how quiet it was that I didn't need my noise cancelling headphones.

In the upper deck, there is no engine noise to speak of.

In the forward section of the 777 (normally this is business class)

the noise is a loud but muffled (think of a speaker under a pillow), but not as loud as in the entire economy class cabin.

In economy class the noise is atrocious on the 777.

Note that both flights were on Emirates.

I can tell you that in economy, the 777 noise was, in my opinion, almost unbearable.

The A380 was almost silent.

I have been on both on long haul to the uk, and their is a world of difference in the noise levels.

Will never fly 777 again.

This is a very difficult question to answer, but lets assume that you're flying during cruise, eliminating as much airframe noise as possible (landing gear, flaps, slats and spoilers) then the position of you in the aircraft is of importance as well.

The further you go to the front the more silent your flight will be.

Since the A380 also has an upper deck this will be even more silent.

Then during the flight it is important to know if the crew is doing some catching up so flying faster than normal, this will indeed be more noisy.

So with this I can give you only my opinion and then overall the A380 is a bit more silent on board, further more I found it harder to notice that we were in fact flying than in the 777.

Every movement feels more dampened which contributes to the overall feel on board.

In business class

the 777 is more quiet than the 787 in business class when the crew is making up for lost time by flying at a higher speed.

To conclude: It greatly depends on your position in the aircraft, aft equals more noise Cruising speed, higher speed than normal equals more noise Engine type, airlines have for most the option to choose between 2 or 3 engine manufactures.

Personal perception, during the night you're maybe less tolerant to noise than during the day and during the night there is less noise from the cabin to muffle the engine noise.

In my recent travels, I have been lucky to get a host of aircrafts.

X 2 (9W)&(SIA), A330-300 X 2 (QANTAS), A350-900

X 1 (SIA), A380-800 X 2 (SIA) seated at various positions.

I must say that the A380-800 is a class apart!

take a bow Airbus!

I had always been partial to the Boeing, but the A380 had taken my heart away.

I was seated at the lower deck the 1st time I boarded an A380.

Honestly, I had no clue when the aircraft was at rotate speed and through out my 6 hours in it, I could virtually feel no sound at all.

Note that I was at the front aft of the economy section.

I could enjoy a great view of the Changi airport while the A380 banked almost 360 during a summer sunset.

I surprisingly found no difference between the noise levels of the 777-300ER & the A350-900 (shocked)

I was rather hoping to find the same db levels on the A350-900 as the A380-800 since conceptually it was a newer aircraft but was bitterly disappointed.

On my way back I was at the upper deck and re-lived that experience of a virtually noise free cabin!

Thank you Airbus and thank you Singapore Airlines.

My next would be an A380-800 on Qatar airways!

Looking forward to it already. -Nik

I have just returned B/Class from the UK and both the 380 and the 777 were used.

The 777 for 14 hrs and the 380 for 6hrs.

The difference between the two aircraft was amazing

the 380 noise levels are only a quarter of the 777, in the 380 ear plugs were not needed however in the 777 you did plus the audio head phones further reduced the noise in the 777 was unbearable and sleep was not at all possible.

Not a frequent flyer but

I've done quite a few SYD-LHR-SYD flights over the years (all economy).

No matter the carrier (SIA, BA, EK) the 777 regardless of model is my least favourite thing to fly on - the noise just does not stop

and it isn't a pleasant noise either.

Give me an A380 any day or night.

Question: I couldn't find any official comparison for noise level (dB) in Airbus A380 versus the Boeing 777 300 ER. Does anyone have some info about it? Which one is better in terms of acoustic isolation?

How do the cabin noise levels of the A380 and the 777 300 ER compare?

The A380 is far quieter than the Boeing 777, especially in economy class.

The noise depends on many factors, like aft, cruising speed, higher speed than normal, engine type, etc. That said, the A380 clearly has much lower cabin noise levels; they are only 1/4  the noise levels of the 777. It is almost silent, there is no need for earplugs and it is not that noticeable that you are flying. On the other hand, the cabin noise of the 777 300 ER is often described as unbearable, making it almost impossible to sleep.

The A380 clearly has much lower cabin noise levels; they are only 1/4  the noise levels of the 777. It is almost silent, there is no need for earplugs and it is not that noticeable that you are flying. On the other hand, the cabin noise of the 777 300 ER is often described as unbearable, making it almost impossible to sleep.


It is mostly standardized procedures.

I take as example Amsterdam airport (AMS), but the following is applicable to most, if not all, major commercial airports.

Let's look at the departure charts , in particular

this one: as you can see, if an airplane is departing via that runway, it MUST follow one of the two specified paths to exit the airspace of the airport through the "ANDIK" waypoint.

It has different paths for the other exit waypoints, but they are similarly defined and limited in number.

In the link you will find similar charts for each of the runways.

Within restrictions due to factors like terrain, noise abatement over populated areas (as Dan's mentions in his answer ), areas restricted due to security and safety (over city centres, government and military installations, nuclear power plants and such) or used for other purposes (military operations, space launch and such), these routes are defined so they don't intersect (much).

This ensures arriving and departing aircraft

don't come close to each other, which greatly reduces the risk of collision and allows responsibility for different routes to be split among several controllers who can each handle their assigned routes mostly independently of the others.

Weather conditions and other factors will dictate which runways are used, but the runway will dictate how the airplane will exit the airport's airspace, after the appropriate exit waypoint has been selected (you generally would not use a waypoint on the north side if you have to go south).

So, to summarize: you have a limited amount of exit waypoints

you have

a limited amount of runways weather will restrict your choice (well, the airport's tower will do this for you) of runway

your destination will restrict your choice of exit waypoint for each runway-waypoint pair you will have one or two possible routes

This results in the kind of behaviour you have observed.

Aircraft are routed based on all manner of different things.

Just off the top of my head, here are some of the more common reasons: Standardised routing.

It's much easier for controllers to manage aircraft if everyone is following a similar route, and so there are generic routes defined.

This is especially true in and out of

airports - imagine

if dozens of planes were simply arriving in any direction they like, it would be very chaotic to deal with.

Noise Abatement.

Many areas have noise abatement procedures, where aircraft are either restricted from flying over or the number or flights is limited.

It's not uncommon for aircraft to have to fly around certain places.

Weather Avoidance.

For comfort and safety, aircraft will sometimes be routed around certain types of weather.

This isn't an answer, just an addition to @federico's answer.

The following image shows departing aircraft from international airports near my location, Düsseldorf (red) and Cologne (blue).

The data was recorded over 24h from flightradar24 and put on a map together with some beacons.

The dotted lines indicate the angles mentioned below.

Looking into the departure charts for Düsseldorf , one finds for take-offs to south-west this, in layman’s words:

Turn hard right and fly away from NOR at 0° Turn right to LMA (Roughly, there are more points not shown in the map, and more than one route), then depending on destination turn

left to 203° or 209°.

Turn left and fly to NOR at 174°, then turn left to GMH at 86° Finally, there's a chart showing all this together, though this is more about noise:

For cologne it's obvious that there are similar rules.

It's also clear that the flights from Düsseldorf to south-east are guided around Cologne by flying a little towards GMH first.

So, not an answer, just to show that aircraft fly as they are intended to do, though there are a few exemptions.

Just like you can't drive your car straight from point A to point B because there might not be a direct road between the points, aircraft can't necessarily fly from point A to point B because there might not be airways that directly connect the points.

Also, most traffic between major airports will follows established procedures.

These are either Standard Information Departure (SID) - for flights departing or Standard Terminal Arrival Route(s) (STAR or STARS), for flights arriving.

These standard departure and arrivals procedures are put in place based on the geography, weather or other restrictions at or near the airport and don't have to coincide with the flight's arrival or departure direction.

Just one clear answer why it is also done on short trips

(so not depending on the earths curvature that much): Airplanes have the allowance to fly on a flight level (FL), given in feet / 100 AND refering to an imaginary surface level where the standard pressure of 101325

Pa is located.

So FL 130 is 13000 feet above the level with 101325Pa ambient pressure.

Some turns are only allowed at that FL to avoid collisions with other airplanes.

Question: I have seen that flights will make a turn, after traveling some large distance (say after some kilometers), but that can be done before.    Why not flying directly like in  2 ?  I am not expecting a passenger flight to do like fighter jets and perform nearly vertical take-offs, or some other manoeuvrers.   Are these flights restricted to do so, or is there any reason to behave so? Or did I misunderstand something?

Why do some flights make turns shortly after takeoff?

There are a number of reasons why planes turn after take off. The ease of controlling traffic at the airport is one: aircraft take off in the same direction and then turn to follow their airway. Noise abatement is another issue, some areas cannot be flown over constantly. Planes also turn to avoid certain weather conditions.

The main reason is that there are some generic routes for pilots and standardized procedures to be followed. Also, similar to driving and roads, aircraft cannot reach a certain point from another if there doesn't exist an airway connecting them. Another reason is that in many regions there are noise abatement procedures in place, restricting the possible routes or number of flights. Finally, sometimes this happens to avoid certain types of weather.

Similar to driving and roads, aircraft cannot reach a certain point from another if there doesn't exist an airway connecting them.

In many regions there are noise abatement procedures in place, restricting the possible routes or number of flights.

Sometimes this happens to avoid certain types of weather.


Not likely.

Pilots wear headphones, so we cannot hear the idle prattle of the pax in the hold.

In any case, we don't take orders from passengers.

Think about that for a second: would you like it if aircraft pilots followed the instructions of a crazy screaming passenger?

What if there were TWO crazy screaming passengers giving contradictory commands?

Which one should we obey?

In any case, nowadays cockpit doors are closed during flight anyway.

Unless he’s shouting “cow on the runway”, I don’t even hear my copilot on finals as he mutters “too fast/slow”, “too high/low”, “left a bit”, etc., but I hear fine as we taxi

and he says “Coffee’s on me”.

No, but the passenger is likely to be arrested for causing such a disruption and face serious charges.

The authorities don't react kindly to that kind of crap in a post 9/11 world.

The chosen answer is correct so far, no doubt.

But in my eyes, it lacks some generality and an important point: While it is certainly true for a 737 that a pilot won't hear you and therefore take no action, I'd add that is can be true for smaller aircrafts when you hear the passenger as they may even can speak over the intercom (say a Cessna 172).

As a pilot, you have to decide, if you realize that it was a passenger screaming "go around", if you take action.

You train a lot of things as a pilot, one of the most important one is to make a go around as fast as possible if anyone screams it (normally co-pilot, flight student etc) and you do not think about whether it is right or not

(you assume he had a good reason) because there is no time, you better focus on the maneuver.

The conclusion is nearly the same as mentioned in other answers with the small addition that, if the pilot hears you, you may trigger it's trained reflexes and he will make a go-around.

If there is a legitimate need for a go-around like an emergency that the pilots can't see but the passenger can or landing at the wrong airport, then it might influence the pilots.

However, that might not happen because of the conditions described by @Tyler

Durden's answer.

aviation.stackexchange.com/users/12220/SMS von der Tann

Question: Sorry if this question is too stupid, but I wonder what would happen if a passenger on the first row just behind the cockpit (ie. on a 737) starts screaming "GO AROUND" when the plane is about to touch down. Can it confuse the pilots?

Can a passenger force a Go Around?

It is unlikely a pilot will make a go around because a passenger shouted it ou. Pilots wear headphones so they cannot hear the passengers. A passenger doing this may face serious charges. There could be a legitimate reason for doing this if the passenegr could see a safety issue that the pilot could not.

Since they wear headphones and generally do not listen to passengers, no, they would not go around. However, the passenger is likely to face legal trouble. There is only a small chance that the pilot will listen to them due to reflexes honed during training or if there is a legitimate reason, e.g. an emergency that isn't in the pilot's line of sight or it's the wrong airport.

Since they wear headphones and generally do not listen to passengers, no, they would not turn around. However, the passenger is likely to face legal trouble.

There is only a small chance that the pilot will listen to them due to reflexes honed during training.

Only if there is a legitimate reason, e.g. an emergency that isn't in the pilot's line of sight or it's the wrong airport.


As a private pilot, I have heard "Tally-ho" and other pseudo (British?)

military phrases used when talking to ATC.

I understand "Tally-ho" to be equivalent to "target(s) in sight" or "inbound" or even in some cases "affirmative", and that's the problem.

It is important to be clear and precise when communicating on the radio, however, the folks working at ATC seem to understand these phrases.

FAA:

I've read the AIM - Aeronautical Information Manual and Pilot's handbook of aeronautical knowlage

(Both available for free download from the FAA's website) and I don't remember seeing these phrases anywhere.

Other texts caution against using these colorful phrases instead of standard phraseology because problems stemming from varied interpretations.

It is important to be clear and precise when communicating on the radio.

I think the correct terminology is: "Traffic In Sight" and "Negative contact"

No, they aren't considered acceptable although you do hear them from time to time.

Neither term is in the P/CG and the AIM 4-2-1 says: Good phraseology enhances safety and is the mark of a professional pilot.

Jargon, chatter, and “CB” slang have no place in ATC communications.

The Pilot/Controller Glossary is the same glossary used in FAA Order JO 7110.65, Air Traffic Control.

We recommend that it be studied and reviewed from time to time to sharpen your communication skills.

In other words, if it isn't in the P/CG then don't use it.

Of course in reality some pilots do use military terms for whatever reason (force of habit?)

but it's definitely discouraged.

Apart from anything else, many pilots have no military background (or are foreigners) and have no idea what these or other slang/military phrases might mean.

NO.Not an acceptable term.

As stated earlier by others - the term has no official recognition and would only serve to confuse.

Only a tiny (and rapidly diminishing) number across the globe appreciate its original 1930's context.

Some commonsense and logical

analysis:"Land

Ho" means "land in sight!"

"Tally" is another word for a score - or for a count of sorts.

It follows that somebody announcing "Tally Ho" is excitedly anticipating racking up a score.

This could be foxes or Messerschmitts.

Of course, this only makes sense in the context of a heart-felt outburst in the heat of the moment in old England - or a place influenced by old English culture.

Use of "Tally Ho" in civil aviation makes no sense at all.

How would you intend to "rack up" the score?

Tally Ho is believed to be based on a French expression from way back: https://en.wikipedia.org/wiki/Tally-ho

It is the nature of humanity to bend language out of shape...

What do you call an AERObatic machine designed by AEROnautical engineers?Not an AEROplane?

"No Joy" or "Tally-Ho" are not acceptable when talking on aviation bands.

Worse yet, they are not even true military terms.

While "Tally" does mean you have the enemy in sight, notice there is no "Ho" attached to it.

Since you are up there and NOT shooting at people you should use the term "Visual" when you can see the aircraft being referenced.

Visual is not only a military term, meaning you see a friendly but it is also used in civilian aviation and means EXACTLY the same thing.

But!

It's just easier to say, "Tower, traffic in sight."

Roger, Wilco (will comply) are great words that mean things.

I use them all the time.

Telling ATC

your fuel is "Bingo" will get you killed, declare an emergency instead.

Fly safe!

Blue skies!

"Tally Ho!" was adopted by US military pilots during WWII, from British fighter pilots.

Who in turn had adopted it from fox hunting.

The US pilots must have just liked the sound of it, although it was an official part of the lexicon of British pilots .

They used lots of other lovely quaint terms.

"Angels" for flight level, "Bogeys" for enemy aircraft.

And the Navy had a particular anti-submarine manoeuvre they called "Raspberry"!

Nothing like some jolly fun during a war old boy.

You still hear "Tally Ho" used by military pilots on both sides of the Atlantic, with the same meaning it had in WWII.

Question: I keep meaning to ask this question. I heard "Tally-ho" used for the first time by a pilot on Liveatc.net. I know these are pretty standard phrases in military aviation but I wondered if civil pilots use them. Are they acceptable under either FAA or ICAO standards? If not, what's the likelihood a controller will know what you mean?

Are "Tally-ho" and "no joy" acceptable ATC terms for civil operations?

"No Joy" and "Tally-Ho" are not considered acceptable when talking to the tower. Clear communication is vital. However, it seems these phrases are heard occasionally and the ATC understand them

The people working at ATC understand these phrases, but that does not mean they should be used. They are not acceptable, standard terms and have no place on aviation bands, they would only confuse.

The people working at ATC understand these phrases.


They do in fact exist, though they often use smaller helicopters.

A Google search on the term "heli taxi" yields thousands of results, and while a lot are probably irrelevant, the first few pages give hundreds of operators around the world, ranging from companies ferrying passengers between airports and major cities to companies servicing oil platforms at sea, islands too small to have airfields, etc.

Air Greenland is a good example of a company that uses helicopters in scheduled air traffic.

Unlike many of the other examples mentioned here, a large part of Air Greenland's helicopter operations take place as scheduled traffic, and not charter flights.

They operate the following: 2x Sikorsky S-61N with 19 seats 9x Eurocopter AS 350 with 5 seats 8x Bell 212 with 8 seats to and from multiple small cities and towns on the coast of Greenland.

The other answers demonstrate that there are several helicopter airlines, but I don't think that really answers the question.

Why aren't there more?

Simple economics.

Compared to other kinds of powered aircraft, helicopters are small, slow and expensive to run.

They do have the advantage that a helipad takes up much less space than a runway which means you could fly your helicopters right into the middle of the city, rather than to large airports in the suburbs or beyond.

However, helicopters are also very noisy, so that would be very unpopular with everybody else who used that part of the city.

This means that your heliport actually has to be out in the suburbs anyway, and you've just lost your only advantage.

All of this makes it very difficult to be a profitable helicopter airline.

All of the examples in the other answers are cases where special circumstances mean that helicopters can still work.

Taking people to oilrigs by air is much faster than by ship, but you can't land a fixed-wing plane on an oil rig.

Small, widely spaced communities might not be accessible by road and might not have the resources to maintain an airport, but might be willing to pay enough to support a helicopter service when it's their only option.

If you just want to transport "10–20 people a short distance", a bus is going to be almost as fast, much more comfortable and orders of magnitude cheaper in almost all non-special circumstances.

We do: Helijet International .

Helijet International is a helicopter airline and charter service based in Vancouver, British Columbia, Canada.

They operate regularly scheduled flights between: Vancouver Harbour Heliport and Victoria Harbour Heliport Vancouver Harbour Heliport and Nanaimo Harbour Heliport (Monday-Friday) Vancouver International Airport and Victoria Harbour Heliport(Monday-Friday, limited flights)

I'm sure there must be other services where the geography and economy can support it.

There are helicopter airlines.

Definition: airline is a company that transports people by air and in so doing

makes a profit (or tries to).

PHI , Bristow , and CHC are three of numerous companies who transport people to and from oil platforms as passengers, for a profit.

(At least, that's their aim).

Erickson Aviation operates a regular helicopter service from Nome, Alaska to Little Diomede Island, Alaska.

Little Diomede sometimes makes it onto lists of the most remote towns in the USA and is more or less a small rock in the middle of the Bering Strait with a fishing village on it.

New York Airways used to operate a helicopter taxi service until they closed in 1979.

They operated a number of helicopters, including the tandem rotor BV107-II.

If you ever watch the Clint Eastwood film Coogan's Bluff (1968), you'll see at least two of them operating off the Pan-Am building.

New York Airways

The helicopter option is popular with Hong Kong's high rollers, looking to hit the tables in Macau.

In the UK, British International Helicopters (formerly British Airways Helicopters ) is a helicopter airline, although they do not currently fly any regular public routes.

BIH fly for offshore (e.g. North Sea oil) and defence industries.

They also offer training and sightseeing tours from London (Redhill) and Coventry.

BIH operated a regular Sikorsky S-61 service from Penzance Heliport to St Mary's Airport and Tresco Heliport on the Isles of Scilly from 1964 until 2012, when Penzance Heliport was sold to the supermarket Tesco.

There are plans to reinstate the service if a suitable new site can be found.

BIH jointly operated the Airlink shuttle service between Gatwick and Heathrow between 1978 and 1986.

The service ended because its licence was revoked after the M25 motorway had been completed.

Question: Just a curious thought. Why isn't there any helicopter airline? Airlines that operate large helicopters that can transport 10 or 20 people a short distance?

Why don't we have helicopter airlines?

Helicopter airlines do exist. Some examples include Air Greenland, New York Airways. However, helicopters are small, slow, expensive and noisy which explains why they are not used more widely.

In fact, there exist many helicopter airlines like Helijet, Erickson Aviation, British International Helicopters, Air Greenland and, formerly, New York Airways. They mainly connect remote locations and service oil and defense industries or high profile customers, although their helicopters are usually smaller. They are not so common because it is not profitable and helicopters make a lot of noise, so they are not preferred.

They are not so common because it is not profitable.

Helicopters make a lot of noise, so they are not preferred.


Strictly speaking, there is no need to set a particular angle of incidence-

the wing will decide that for itself depending on the conditions (speed, weight, altitude etc.).

What we are deciding is the The mounting angle, which is set for various reasons and is not variable in flight (except for some rare cases) including: Mostly this is set so that the fuselage is (nearly) horizontal during cruise.

This is especially important for airliners- DC-10, especially flew at a pronounced nose high attitude requiring the cabin crew to walk uphill.

Setting the wing at an incidence helps improve the visibility- this is important especially for carrier aircraft, where the pilot requires good visibility and also higher angle of attack (for keeping t/o and approach speeds low).

Setting the wing at an angle helps in keeping the drag low for the given lift.

Having the wings at an angle and fuselage horizontal means that the drag is minimized, while the wing has the required angle of attack.

Though the angle of incidence is usually fixed, it can be varied in response to specific requirements.

A good example is the Vought F-8 Crusader , which allowed the wings to be pivoted 7° out of the fuselage on takeoff and landing, resulting in a high angle of attack -- reducing the approach and take-off speed -- while keeping the fuselage level and giving the pilot a good forward field of view.

F-8 Crusader with the wing pivoted up during landing.

By USN - U.S. DefenseImagery photo VIRIN: DN-SC-88-06695, Public Domain, Link

Another example is the Martin XB-51 which had a variable incidence wing to reduce the takeoff run.

The wing will pick the angle of attack that is appropriate for the given speed, air density and the needed lift.

If it is too high, the aircraft will accelerate upwards which will reduce the angle of attack, and vice versa.

The wing's angle of incidence will then define the angle at which the fuselage sits during flight.

What a proper angle is depends on the aircraft: On transport airplanes, it makes sense to have a horizontal floor during cruise so the flight attendants don't have to push their carts uphill .

This will result in a slightly positive incidence angle.

On high performance airplanes the incidence is set to optimise the lift to drag ratio.

On aerobatic airplanes it is set to zero

so the aircraft can be inverted without elevator input .

On crop dusters, it might be important to give the pilot the best possible view

so he/

she can fly safely while manoeuvring close to the ground.

The next important detail is the height of the tail surface relative to the wing's vortex sheet.

If the tail is too far above, it will sink into the wing's wake during stall and become less effective.

A deep stall stability condition might be the consequence.

Only by defining the angle of incidence can the airplane be built and operated as designed.

My understanding is this.

One of the design consideration of fuselage design is to avoid flow separation.

And another important thing is that usual looking fuselage is not very efficient at providing lift because both above cases produce huge amount of drag.

So it is important to avoid the fuselage from separating flow and non-lifting/less lifting in normal configuration in cruse condition.

To do so its important to keep the fuselage nearly horizontal Secondly to produce max L/D or nearly max

L/D wing has to operate in some positive AoA. This can be achieved by introducing this incidence angle.

Let us denote $\delta_{wing}$ the incidence of the wing.

For moderate values of the angle of attack of the airplane $AoA$ the lift coefficient of the wing has a linear behavior :$$Cl_{wing}=\frac{dCl_{wing}}{dAoA}(AoA+\delta_{wing}-AoA_0)$$Where $AoA_{0}$ is the value of $AoA+\delta_{wing}$ for which the lift coefficient is zero.

$AoA_0$ is a constant.

Basically the incidence of the wing increases the effective angle of attack of the overall wing.

You understand that lift is generated by the action of the wing pushing air molecules down as it moves forward, requiring an angle of attack to the air passing under the wing?

So if you don't tilt the wing with respect to the body of the aircraft, then to get the angle of attack required to generate lift, you would need to tilt the body as well, greatly increasing the (non-lift generating) surface area and so greatly increasing the drag.

Angle of incidence is required to generate lift if the roll axis is parallel to the airflow.

Otherwise the fuselage would also be required to present AoA in order to generate lift.

The wing's AoA =

AoA of roll axis + angle of incidence and AoA is the primary creator of lift, not the shape of the wing, contrary to popular belief.

Otherwise how could planes fly inverted?

Question: I know that the angle of incidence is the  angle between the chord line of the wing and the longitudinal axis of the fuselage.  I know that it doesn't change in flight because it is fixed.   And usually, there is a positive angle of incidence on airplanes, which means that the wing kinda looks like this:    credits:  Naval Aviation Schools Command aerostudentguide(dot)pdf  My question is, why is there a need to incline the wing like that? Why is there a need for Angle of Incidence?

What is the reason of having an Angle of Incidence on an airplane?

There is no need to set a particular angle of incidence, However, the angle of incidence mimimises drag. It also generates lift. If the wings were not at angle, the body would have to be tilted which would increase drag. The angle of incidence must be defined to allow the plane to operate as designed.

Strictly speaking, a certain angle of incidence is not needed. However, the angle of incidence helps with visibility. In addition, setting the aircraft wings at an angle of incidence helps with the lift, minimizing the drag and acquiring the correct angle of attack, and it also determines the angle of the fuselage. In general terms, the definition of the angle of incidence makes the aircraft operate as intended.

The angle of incidence helps with visibility.

Setting the aircraft wings at an angle of incidence helps with the lift, minimizing the drag and acquiring the correct angle of attack.

It determines the angle of the fuselage.

The definition of the angle of incidence makes the aircraft operate as intended.


FORTRAN is not used much that I'm aware of in aviation , but it is significantly used in aeronautical engineering .

I work with people that use Mark Drela's 'xfoil', 'xrotor' and 'aswing' programs on a daily basis for the design and analysis of airfoils, propellers and aerostructures.

And I've used the 'CHARM' model of rotorcraft dynamics.

All of these are written in FORTRAN and you often need to know the language to debug them or integrate them into other programs e.g. for global design optimization.

Fokker Services and DynamicSource AB have jointly developed an iOS Application to run FORTRAN Take Off and Landing SCAP (Standard Computerised Airplane Performance)

modules on the Apple iPad®.

The app allows an operator to make the performance calculations shortly before take-off and therefore allows the opportunity to incorporate last minute changes with respect to aircraft loading and runway conditions.

OEM take-off and landing performance calculation modules are complying with the IATA SCAP interface specification.

They are written in Fortran.

Normally Fortran programs do not run on iPad® , but the software engineers from DynamicSource AB managed to make this possible.

The OEM-supplied SCAP module is combined with a calling program and an airport/obstacle database.

Via a user-friendly Graphical User Interface (GUI) relevant data like aircraft-weight, wind, and runway condition are fed into the app.

Within seconds the take-off and landing data like V1, V2 and flap setting are presented on the screen of the iPad

Fortran at 59 Notes for "Fortran at 59

FORTRAN is still in active use for AT LEAST the following reasons, not all of which I have seen spelled out here:

FORTRAN has a huge legacy base of code that just works and has stood the test of time.

Sure, you can pipe the source through a FORTRAN-to-C converter (which is how some modern FORTRAN compilers actually work behind the scenes), but then you largely ruin any self-documenting nature of the code -- which for many programs and algorithms is the only documentation that exists or is complete and reliable.

The syntax and control flow of FORTRAN is relatively simple compared to many modern languages and thus can be used as the "lingua franca" for distributing calculation algorithms that demonstrably work.

As a corollary to the immediately preceding point, the fact that FORTRAN is a relatively "dead" language that will not be revised can be seen as a good thing.

If you publish a scientific finding, and include the FORTRAN source of the algorithms used to extract the critical data and perform the analyses that support the finding, there is no question that in 50 or even 100 years, scientists and researchers will still be able to run your code somewhere.

Can the same claim really be made for something like MATLAB?

I think not.

You'd be crazy, of course, to try and write a GUI framework or really anything beyond pure number-crunching code in FORTRAN.

But what it does, it still does very well.

Yes, Fortran is still being used.

However, don't get too worried if you find your class less than exciting: Most Aerospace engineers don't do much (if any) computer programming.

However, if you intend to go on to graduate school, pay attention in you Fortran class!I think your first priority (regardless of your grad school plans) should be Matlab.

Everyone uses it today, especially if you publish.

The power of Matlab (and Mathematica) is in their ability to do algebraic equation simplification and producing pretty (publish ready) output.

Mathematica used to be the king of the hill in this area, but Matlab has pretty much pushed them out (although Mathematica is seeing resurgence due to the free Raspberry pi version).

These are both great tools, but if you need to crunch big data, the tools of choice in Aerospace are Fortran or c/c++.Fortran is preferable when dealing with complex numbers and has many built-in vector, matrix, and mathematical functions.

However, it falls short when trying to deal with pointers or interfacing with low level operating system functions (where c shines).

But, only a small percentage of Aerospace engineers write code in these languages.

Most of the Fortran at Boeing runs on their massively parallel machines performing electromagnetics and fluid dynamics calculations in research areas.

The c languages are primarily used in embedded systems (avionics).My recommendation: You should be proficient in Matlab but know you way around (be able to read and understand) both Fortran and c...

My current employer in the flight simulation industry still uses it on new work.

We are trying to move away from it, but its simply not possible (or sensible) to do 100% when we have a lot of fully-debugged reusable code written in it, and we still occasionally get flight models from vendors that employ it.

(That right there is your big huge clue that yes, the Aviation industry is still using it)

I believe most other major players in the flight simulation business are in the same boat.

Even when we do move away from it, its mostly to other non-VM procedural compiled languages like C++, which I suspect a lot of college students also consider "old languages" these days.

Even if we could get rid of Fortran in all our new jobs, we have a lot of delivered systems that use it, and those periodically need bug fixes or upgrades (obsolescent hardware replacement efforts, etc.).

So we would still have to support Fortran for another couple of decades.

I've been told directly by a director of UAV development for the U.S. that Fortran is still used in their UAVs.

Question: I am an aeronautical engineering student at Istanbul Technical University and our course plan includes Fortran as a programming language. I have some doubts about that because Fortran is an old language.  Is Fortran still being used in aviation?

Is the Fortran language still being used in aviation?

FORTRAN is not used much in aviation but it is used in the aeronautical industry.

Yes, FORTRAN is still being used, mainly in aeronautical engineering, in the flight simulation industry and in UAVs.


Usually not.

It depends on various factors, most importantly the available fuel.

If the pilot decides that enough fuel is available even after accounting for the extra drag due to extended landing gear, he can decide to continue, though this will rarely be the case as the drag penalty is too high and the aircraft speed is limited.

A case in point is the Hapag-Lloyd Flight 3378 , which crash landed due to fuel starvation caused by the extended landing gear (which was kept that way as a precaution).

The pilot was criticized for his decision to keep on flying instead of diverting to another airfield, and given a suspended prison sentence .

Unless it's a (very) short hop with sufficient fuel onboard and anticipated maintenance services at the destination airport, no.

As mentioned above extended gear restricts speed and increases parasite drag on the airframe.

The most likely scenario would be to report this to ATC, thence divert to a hold to either dump or burn off your excess gas until you're below the maximum landing weight, thence return to the departure airport or divert to an alternate.

A flight can continue, there's no regulations to prevent it

, it's the judgement of the pilot in command.

In most cases the drag penalty will mean the flight will run out of fuel short of its destination, but a flight could theoretically continue.

If the airplane has a short hop, plenty of fuel and the emergency facilities at the destination are better than the originating airport then continuing to the destination may be the best choice.

That would be very rare though, usually a flight would divert to a much closer airport or return to the field it took off from depending on the emergency facilities available.

Another factor would be the facilities available at the origin/dest/enroute airports.

For landing gear issues a gear-swing may be required and that would require aircraft jacks/stands.

Example, I worked in an airline which operated a short sector from KUL-CGK vv.

On departure KUL the landing gear would not retract.

The pilots discussed this with MCC (maintenance control) and decision was made to divert to SIN where there was full capability for any landing-gear work.

Basically, an aircraft with its gear down is still safe, it will not fly as fast nor as far as planned but it is not a 'land immediately' situation.

Gear down invokes two penalties: increased drag and reduced speed.

On modern airliners, gear down can add up to 50% more drag, so that's not an inconsequential number.

Also, the landing gear doors being open, or even partially open in the case of airliners that have some streamlining of gear in the down position, limits the maximum speed to a very low number, beyond which the doors will be torn off by the slipstream, possibly doing some nasty damage to the aircraft in the process.

That also limits the pilot's options in an emergency situation, like needing to descend quickly, or accelerate to avoid a dangerous condition, like stalling.

Finally, one has to ask... if the gear fails to retract, what else is wrong?

Maybe nothing, maybe something.

Could be a bad switch, could be a hydraulic leak that might also affect the flight controls, could be a piece of metal digging into the wiring harness that might later affect critical systems or start a fire.

For sure, the aircraft has a problem that's out of the ordinary.

In the end, it's up to the pilot to make the call, but a failure of the gear to retract on a commercial airliner usually means getting the plane landed as soon as practical...

i.e. dumping enough fuel to get down to a safe landing weight and getting clearance.

It's a lot easier to change planes or find and fix the problem, than to lose the aircraft and its passengers.

This happened to me while working as a flight attendant some years ago.

On a late night flight from Columbus to Cincinnati the pilots left the gear down because they saw a cockpit indication after take off that left them concerned that if they retracted the gear, they might not be able to get them back down and locked safely.

The flight was low and slow, but otherwise unremarkable.

We had a maintenance facility in Cincinnati

so they wanted the plane on the ground there as opposed to returning to Columbus where there was no maintenance support.

If an airplane can land and take off with the gear extended, it's certainly air worthy for a short flight with gear extended.

Low and slow would be a given, but otherwise there shouldn't be any problem.

If the gears failed to retract after take off, an aircraft could carry on with its flight, but with limitations to its airspeed, cruising altitude and ATC (Air Traffic Control) would need to be informed of decreased cruising speeds and altitudes.

The flight time may also be affected as increased drag from the landing gear will mean the amount of fuel may not be enough to reach the flight destination.

But due the fact that most airline routes are quite far, most wouldn't be able to be completed if the gears refused to retract.

It depends on circumstances if pilot have sufficient fuel, to counter increased parasite drag due to landing gear, for endurance and flight is important (due to any prospect like reputation of airlines or emergency flights etc.)

than they continues their flight.

In such cases pilot must have to inform ATC for their low cruise speed and altitude.

But generally airlines do not prefer to fly with extended landing gears and used to divert to nearby airstrip.

because this also restrict the airspeed and it causes delay in schedule, but there is no regulation on this.

Although not a general FAA regulations, some aircraft type certifications restrict their max airspeed with gear down.

That will also restrict their service ceiling, probably so much that the original flight plan can't be flown.

Question: So after take-off, due to any reason, the landing gear does not re-tract, is there any standard procedure to be followed? Or can the airline continue with its flight?  Also, I would like to know any FAA regulation on the same (if any), which deals as to the procedure to be followed in such situations.

Can a commercial airline continue its flight if its landing gear fails to retract after take-off?

Planes do not usually continue their flight if the landing gear fails to retract. There are several reasons for this. Firstly, the landing gear increases drag and hence fuel consumption. Second, there may not be maintenance services at the destination. Theoretically, it is possible to continue but in practice it rarely happens, unless the flight is just a short hop.

It depends on many things, mainly the available fuel after taking into consideration the additional drag and the facilities at the airport they are headed to. If the aircraft can land and take off under these circumstances, it should be able to complete the flight, albeit flying lower and more slowly. As far as regulations are concerned, there are certain limitations in cruising speed and altitude and ATC should be informed. However, airlines usually do not prefer to fly under these circumstances and will land as soon as possible.

Usually not, airlines do not prefer to fly under these circumstances and will land as soon as possible.


(Source: wikimedia.org )

Guiding is called progressive taxi and can be requested.

A follow-me car can also be used to guide the plane.

In some airports the follow-me car is mandatory , along with its fees.

In most cases the pilots use charts.

Either paper or electronic.

Some electronic charts offer a moving map feature, whereby the crew can see their position on the map.

Lastly, there's the new follow-the-greens ( video link ), in which the ATC programs the taxi route and the crew are then guided by smart green lights.

Follow-the-greens cockpit video / ATC audio in Singapore Changi can be seen here .

In all cases, except for follow-the-greens, the route is given.

It's worth mentioning that the taxiways are marked by signs as well.

Coming soon by 2020 is the taxi route display for pilots , in which the cockpit displays draw the taxi route via ATC datalink.

See possible interface here (Boeing).

Almost always pilots use a chart, ie a map which shows the airport from the air.

Runways are numbered according to their magnetic bearing (runway 22 is roughly aligned to 220 degrees magnetic for example) while taxiways are lettered.

As an example see the chart for La Guardia.

A pilot would be given a taxi clearance which gives an end destination and a set of taxiways to take in the order they should be taken.

For example, a pilot parked near the fire station might be given a taxi clearance like "US123 taxi to runway 31 via Foxtrot, Alpha, Lima, Bravo and Zulu.

" The pilot would look at the map and see the paths to take. While taxiing there are signs on the ground which assist the pilot in navigating the taxiways.

Some give directions, some indicate places where ATC have to clear a crossing.

Occasionally a pilot will need additional guidance in which case they can ask for a progressive taxi, where ATC will guide them through the airport, but this is rare as it is very labor intensive for ATC.

There are also vehicles with "Follow Me" signs and lights which can be sent as well (these vehicles need clearances too).

It is good practice for pilots to study the ground plan for any airport they plan to visit

so they know what to expect when they get there, and have the plans available in the cockpit.

'follow-me' cars, and progressive taxi can be used, but at a towered airport, ground control will give you that with your taxi clearance.

"United 2133, Laguardia Ground, taxi from the commercial ramp to runway four using taxiway alpha, echo, and bravo."

Using a taxiway diagram from the A/FD, you would locate your position on the plate, the taxiways in question and from there determine the route you will take.

In this case you'll turn left from the ramp heading northwest on taxiway A, then take a right on taxiway

E, then take a left on taxiway

B.

If you are unfamiliar with the airport, you can then request a progressive taxi.

"LaGuardia Ground, Beech 2375 X-Ray, Unfamiliar with the airport layout.

Request progressive taxi.

NOTE:

This will annoy controllers at busy airports if you habitually do this as it is expected that you have this information ready at hand before you call ground requesting a taxi clearance.

The 'follow me' vehicles are usually used for quickly routing VIP or special use aircraft to a section of the ramp e.g. Trump's 757 to a section of the ramp cordoned off for a campaign rally, etc.

Very often, the instruction is in the form "Taxi to holding point RWY 24 via H, L, cross RWY 13,

K, B." The letters are the names of the taxiways.

The pilot then looks into the airport chart and follows exactly as instructed.

You must hold short before crossing runways, unless they are used as taxiways.

It is easier when the instruction is followed by "Follow the follow-me car.

", then you just follow the car.

They have the charts in the cockpit, either in electronic or in printed format.

As an example, see page 83 of this pdf , showing the charts for Amsterdam's airport (AMS/EHAM).

ATC will not only tell them to which runway to go, but also which taxiway(s) to use to go there.

In pilot training, it is taught to have a diagram of the airport and to study it before flight.

The tower is usually willing and able to help (as described in other answers: progressive taxi) but depending what airport you're at, you may have to act like the pilot in command and know what ATC is talking about.

You'd need to know where to taxi and you'd need to do it fast.

Having the diagram of the airport is necessary but you also need to know it.

Sometimes taxi instructions change midway through taxiing.

You get the point.

The bottom line: pilot in command has to know where and when to taxi.

The rest of it is nice-to-haves.

Question: When the aircraft is readying to taxi, the ATC asks them to proceed to some runway number, say runway 09. In big airports, how do the pilots identify the correct path to their runway?  Does the ATC guide them? Or do they get a map of an airport chart?

How do pilots identify the taxi path to the runway?

Pilots have charts in the cockpit showing the airport with taxiways marked. They are also marked on the ground. Some help is also available from the tower, this is called progressive taxi. Professional pilots know to study maps of an airport before a flight to get to know the lay out. Pilots will be given information about the destination before the flight so they can plan their route and taxiways to use.

Usually, the pilots use charts, either digital or in print, and follow the taxi clearance given based on these resources. However, apart from having the relevant chart, the most important thing is for the pilot to be able to tell where and when to taxi. "Follow-me" cars are often used to guide the aircraft and guiding from the tower (progressive taxi) can be requested, but may not be available. There is also signage marking the taxiways.

Guiding from the tower can be requested, but may not be available.

"Follow-me" cars are often used to guide the aircraft.

Apart from having the relevant chart, the most important thing is for the pilot to be able to tell where and when to taxi.


Can a wide body airliner land with a full fuel tank?

Yes!

But it is safer to land an aircraft below its published MLW.

Wikipedia has the relevant specifications for the B777 and the A330 Using the B777-200 as an example.

Maximum take off weight: 545,000 lb / 247,200 kg Maximum landing weight: 445,000 lb / 201,840 kg

So this particular aircraft may have to drop roughly 46,000 Kg of weight if taking off at its maximum before it can land safely.

That's not to say it's impossible to land without doing so, but it's certainly not advisable.

When an emergency presents itself, what is "advisable" is getting on the ground as quickly as possible , and if that means landing overweight then so be it.

There have been plenty of times when an overweight landing has caused no damage - and even if the aircraft is damaged by an overweight emergency landing, that's still often a better outcome for the people on board than would be the case if the aircraft waited to get below its MLW before landing.

However, with that said, just because you are taking off with a full load of fuel it does not imply that you must be at MTOW.

You could be taking off with a full load of fuel but no cargo/passengers, in which case it is entirely possible that you may be below MLW.

And in which case the answer would be yes

, it's entirely possible to land with full fuel tanks.

They can land safely with full tanks but they will need the gear checked before they can take off again.

It's not unheard of, if you search for "overweight" on avherald

you can see a list of them

They will be marked as A38* or B77

For example this flight landed with a weight of 523t while the max landing weight of that aircraft is 394t.

If possible they will prefer to dump fuel or stay in the air to burn it off.

If there's a serious time-sensitive emergency, landing overweight is likely to be a far better plan than waiting around while burning off or jettisoning fuel.

As others have noted, an inspection, which involves time and money, is required after an overweight landing, as it stresses components, but aircraft are designed with structural tolerances to allow such a landing when necessary.

You might be interested in reading this Boeing AERO article (from 2007) on factors to consider when deciding whether to land overweight or to delay landing until below maximum landing weight: Landing overweight and fuel jettisoning are both considered safe procedures: There are no accidents on record attributed to either cause.

In the preamble to Amendment 25-18 to FAR Part 25, relative to fuel jettison, the FAA stated, “There has been no adverse service experience with airplanes certificated under Part 25 involved in overweight landings.”

Furthermore, service experience indicates that damage due to overweight landing is extremely rare.

Obviously, landing at weights above the maximum design landing weight reduces the normal performance margins.

An overweight landing with an engine inoperative or a system failure may be less desirable than landing below maximum landing weight.

Yet, delaying the landing with a malfunctioning system or engine failure in order to reduce weight or jettison fuel may expose the airplane to additional system deterioration that can make the situation worse.

The pilot in command is in the best position to assess all relevant factors and determine the best course of action.

Ultimately, it's a judgement call where the crew needs to assess the severity of the emergency, the likelihood of the situation to get worse, available runway length, and all other available information to decide whether an overweight landing is the best course of action.

Not a general answer, but in the book Flight Testing of the A380 by Claude Lelaie 1 , the main test pilot of that aircraft, he clearly states that during the test period, they landed the aircraft several times well over the MLW without any problems.

But, of course, these were test pilots...

The MLW is designed as a general limit that ensures that safe landing will be possible whatever the weather, runway length... and pilot performance!

I assume this must be the same for all contemporary airliners.

1 amazon.fr link (French), amazon.com link (English).

Yes, you can safely land with full fuel.

There are many Boeing 767 and Airbus A300, A310, and A330 that no not have fuel dumping capability.

They just land overweight in case of an emergency and then do an overweight landing inspection.

I recall watching a documentary on the development of one of the newer larger jets - either B777 or A380 in which extreme braking tests were performed as part of the certification process.

The test was to evaluate gear/brake performance for either a rejected takeoff at MTOW or overweight landing, using brakes only (no thrust reversers).

Heat accumulated in the brakes transferred to the tires (not unexpectedly), either initiating fires or at least overheating them to the point that several burst.

Part of the test protocol was that firefighting had to stand by for several minutes before engaging the fires in order to represent a typical response time.

It demonstrated that although the aircraft could stop safely and the brakes had the capacity to do so, the amount of heat produced was almost certain to cause damage and posed a significant fire risk.

Question: Can a commercial double-aisle jet aircraft (e.g., 777, A330) land safely with a full fuel tank (minus the fuel spent on taxing and takeoff)? Has that ever happened?

Can a wide body airliner land safely with a full fuel tank?

Aircrafts can land with full fuel. Landing overweight is generally better than waiting around for the fuel level to drop or jettisoning fuel. However, it is obviously safer to land a plane below its published MLW.

It is safer to land an airplane below its MLW but if the circumstances call for it, it can land safely but will need to be gear checked after. It is often preferable to make an overweight landing than waiting for the fuel levels to drop.

Yes, if the circumstances call for it, it can land safely but will need to be gear checked after. It is often preferable to make an overweight landing than waiting for the fuel levels to drop.

It is safer to land an airplane below its MLW.


Yes, there are.

The Boeing B-17 FLying Fortress is one example of an aircraft designed with a retractable tailwheel.

Source: USAAF via Wikimedia , Public Domain (USGOV-PD)

Another example would be the Vought F4U Corsair : Source:

Wikimedia , cc-by-sa-2.0 Doubtless

there are also other examples of aircraft similarly equipped with retractable tailwheels.

Concorde!

Actually a "bumper"

.Obviously it was there to protect against over-rotation on takeoff, but the relevant item on the checklist was four greens, not three.

As others have mentioned, yes.

Later in World War 2, speed and range became more important than weight and mechanical complexity; an extended tail wheel may be mechanically simpler to build, but adds quite a large amount of drag, affecting range and speed.

There are too many examples to list with links/

photos of them all, but a short list of examples include: Mitsubishi Zero.

P-51 Mustang.

P-40 Thunderbolt.

Later marks of the Supermarine Spitfire (around the MkVIII

from memory; I spent 6 years working on a MkV restoration).

Some models of Messerschmitt BF.109.

The F models were 'cleaned up' aerodynamically with retracting tail wheels, while the subsequent G models had a fixed wheel due to a bigger tyre for better ground handling, which didn't retract as on the F models.

Later G and K models again used a retracting wheel to lessen the drag.

Notable for being an oddball in that it's a jet tail dragger and also equipped for aircraft carrier landings would be the Supermarine Attacker .

There's an in-flight photo with the wheels up here .

In addition to the military fighters listed above numerous civilian airplanes with conventional landing gear had retractable tailwheel, including the Beech Staggerwing, the Boeing 307, the Curtis C-46 and many others.

the friedrich models, earlier gustav models of the 109 and kurfurst had retractable gear

The Bf-109E-4's did not have retractable tailwheel, but the Friedrich which came after the E did have retractable tailwheel.

The G had a larger tailwheel to improve the on ground handling that was difficult because of the narrow track undercarriage.

This made the tailwheel unretractable.

The P-51s, many variants of spitfires, Fw-190, many P-47s, the P-36s, (which were not in service with the US but were with the French), most Yakolev fighters as mentioned above, the F4U, the Zero, the Ki-84 and many others.

The Stuka had no retractable landing gear but part of the reason was that the huge landing gear was used to reduce the airspeed in a dive.

In conclusion, most fighters and many aircraft of WWII had retractable tailwheels.

A few more examples are the Soviet Tu-2 front line bomber (fully retractable) and the Il-10 attacker (partially retractable, i.e.: it folded into the fuselage but did not have a fairing).

Tu-2, note the tailwheel bay doors: Il-10, note the folded tailwheel:

Question: This comes from a slightly related question about  drag from landing gear .  A tail-dragger is the old-school layout of aircraft, particularly WW2-era fighters. It's also known as  Conventional Landing Gear .  The first two landing gear is usually retractable, but the tail wheel is not.  At least, I have never seen such a configuration with a retractable tail wheel. Has there ever been one?  Note: question excludes now more common tri-cycles.

Has there ever been a tail-dragger with retractable tail-gear?

There are a number of examples of a tail dragger with a retractable tail gear. One of these was Concorde. Many WWII planes had this feature as do many other fighter planes. Moreover many civilian planes had this feature in the past.

Yes, there exist many models with retractable tail-gear: the Boeing B-17 FLying Fortress, the Concorde, the Beech Staggerwing, the Boeing 307, the Curtis C-46,  the friedrich models, earlier gustav models of the 109 and kurfurst, the P-51s, many variants of spitfires, Fw-190, many P-47s, the P-36s, most Yakolev fighters, the F4U, the Zero, the Ki-84, the Soviet  Tu-2  front line bomber, the  Il-10  attacker (partially retractable) and many more.


consider if you Google a flight number you can see the flight status, imagine if the number was from a past crash, you might for a moment think the one you're looking up had crashed

Retiring flight numbers after crash is mainly done to prevent the flight evoking negative emotions among future passengers.

You don't want the flight number to conjure up images of crash while booking tickets, especially in when you type the flight number and google shows up the wreckage just below the flight data.

Also, it would be quite insensitive, with friends and relatives being reminded of their loved ones every time they hear about the flight.

However, it is not necessary that the airlines have to retire the flight numbers because of a crash.

A number of them are being used, a few examples being: Air Canada Flight 797 Delta Airlines Flight 723 Air Asiana Flight 214

You answered your own question, they retire numbers because of the emotional context.

Some people think that using such a number again shows a lack of sensitivity to the dead and their families, others might think that getting on a flight with the same number would be bad luck.

It's irrational, but many people would feel uncomfortable getting on a flight with the same number.

It's also done for calming passenger superstitions about such things as well.

Kind of the same reason that many skyscrapers do not have or list a 13th floor or nobody would board a flight listed as "United 666" or that left handed people are possessed by demons, etc.

You would like to believe modern people would not be influenced by such nonsense, yet how many people did you see reading horoscopes on the train on your way to work this morning?

I am a retired airline employee, the reason for retiring a flight number is for the respect of any fatalities.

No other secret reason.

(At least the “original” Airlines)

it was ALL ABOUT RESPECT AND NOTHING ELSE.

Question: Perhaps it seems obvious, but I couldn't find a plausible reason why they do so other than that it evokes negative emotions among passengers and crew. Could there be other reasons to do so?  For example,  flight number MH370  was retired as a "mark of respect" for the passengers and crew.   And out of interest, is there any case where an airline company reused a retired number for any reason or in certain circumstances?

Why do airlines retire the flight number after a crash?

Flight numbers are usually retired after a crash out of respect for the dead and also because passengers in the future may be reluctant to take a flight with tha same number as a crashed plane. There are a few examples of where flight number are still being used after a crash, for example Air Canada Flight 797  Delta Airlines Flight 723  Air Asiana Flight 214 .

The main reason flight numbers are retired is out of respect for the victims and their relatives, in order to calm the superstitions of the passengers and to avoid the negative context that inevitably comes with a crashed flight. Also, they are often retired to avoid confusion when looking up the flight number. However, there are some flight numbers of crushed flights still in use.

They are often retired to avoid confusion when looking up the flight number.

There are some flight numbers of crushed flights still in use.


There are actually two separate coding systems in play here.

IATA (International Air Transport Association) codes are 3 letters and are used for commercial bookings etc.

They are assigned only to commercial airports throughout the world.

ORD is the IATA code for Chicago O'Hare.

Pilots and ATC use the four letter ICAO (International Civil Aviation Authority) codes, which are assigned to every public-accessible airfield in the world.

These are systematically allocated with the first one or two letters indicating the country.

K is used as the first letter of airfields in the continental US (with separate codes for Alaska, Hawaii & territories in the Pacific/Caribbean matching regional standards).

Commercial airports in the continental US tend to have the two codes in matching pairs such as ORD/KORD, LAX/KLAX etc

but this is not the case in other countries.

Manchester, UK has IATA code MAN but ICAO code EGCC.

Meanwhile smaller airfields in the US may only have an ICAO code, where the corresponding IATA code (minus the K) could belong to an international airport elsewhere in the world (for instance KPRG is Edgar County Airport, Illinois and PRG is Prague Václav Havel Airport, Czech Rep.).

Finally, the very smallest airfields in the US (typically private/restricted access fields, in any case not large enough to warrant an ICAO code) are given a 3- or 4-character code by the FAA which extends the ICAO system by allowing digits as well as letters.

Small public fields have a 3 character code (eg 9S2 or C97) while private fields have 4 characters which typically include the state abbreviation eg TX05.

For more details of the exact determination of which code type a US airfield is assigned by the FAA, see reirab's excellent self-answered question: How does the FAA determine which format of location identifier to assign to an airport?

The other answers have lots of excellent context & background info, but to give the direct answer to the direct question, *no, you don't use the "K" * with ATC under normal circumstances.

The (rare) exception will be when it is necessary for some reason, but that is almost never.

In voice communication, "direct Midland VOR" or "direct Midland airport" are used, rather than "direct MAF" or "direct KMAF".

Obviously, printed NOTAMS and flight planning work differently.

If you were to be cleared "direct MAF" (which is both the 3-letter FAA ID for Midland, and also the non-colocated VOR), it would be appropriate to query "is that the airport or the VOR?

" if you aren't sure.

(If you are navigating VOR to VOR to MAF & beyond, you could safely assume the VOR; if your destination is Midland, asking the controller would be appropriate.)

But when asking you to "say destination," it's understood you're landing at the airport rather than the navaid out in the field!

The "K prefixed" and the "non-K prefixed" codes are actually different designation systems.

The former is used by ICAO and the latter by IATA , and each have specific use cases by different authorities.

Not all airports in the world have their ICAO and IATA codes differentiated by leading K (an airport might not even have both).

This is usually holds true only to the larger airports and only in the US.

In case of airports in the rest of the world this is not true: some airports' ICAO and IATA codes are totally different from each other, while others' do bear some varying degree of similarity.

You can get an idea by looking at these lists: https://en.wikipedia.org/wiki/List_of_airports_by_IATA_and_ICAO_code http://www.flugzeuginfo.net/table_airportcodes_country-location_en.php

Usually, yes, and in particular when using the airport for position reporting.

Sometimes there will be a VOR or VORTAC which uses the same three letter identifier nearby but collocated on the airport so it can cause confusion for a controller.

When programming your GPS or FMS you need to distinguish between airports and VORs e.g. KLAX is an airport and LAX is a VOR on the airport.

But controllers rarely say the letters and instead use the names for airports and VORs.

It is usually clear from the context and the destination that the pilot has filed.

A typical clearance from my airport might be Crepe Three departure, Morro Bay transition, San Marcus then as filed.

The pilot knows to follow the CREPE3 departure which terminates at MQO and then direct to FLW and from there whatever was filed.

When asking for VFR flight following, pilots usually just give the name of the destination airport unless there are multiple airports in the same city.

For example, Bakersfield has two airports so to make sure the controller knows where you want to go you would give the identifier, either BFL or L45.

Also, if you are going to a small airport outside of the local area the controller may not have heard of it and will ask for the identifier.

I don’t recall hearing anyone say the identifier with a K when talking on the radio.

But that’s not necessarily something I’d

notice.

You might want to listen to some of the clearance delivery channels on LiveATC to get a feel for how pilots and ATC communicate routes.

In my experience, you usually use the NAME of the airport (or navaid).

Center controllers are well familiar with their AOR (and usually adjacent ones just by experience).

Now for longer VFR flights where you may be crossing multiple centers, they may not recognize the named airport, so giving them the identifier can be helpful.

This is not an issue for IFR where they already have your full plan.

Finally, a 'little secret' is that the name an airport is called locally is often different than the name in your AFD.

For example, Lewis A Jackson Regional Airport (I19) in Xenia Ohio is "Greene County" (not "Jackson Regional").

Calling the FBO on the phone before flight will uncover that, or listening on the radio as you approach.

If unsure, go ahead and append the identifier to the name you guess it should be called.

Yeah, you're chewing bandwidth, but that's more efficient than the back and forth and better than a mistaken ID.

Question: I'm a new student, and I see the US airport codes on charts with the K prefix, e.g. KORD for Chicago O'Hare.  I have always seen on commercial flight booking sites, only the last three, letters such as "ORD" are displayed.  Are pilots meant to pronounce the full code or just the letters after the prefix, assuming the K prefix, when talking with ATC?

Do you say prefix K for airport codes in the US when talking with ATC?

Apparently there is some debate about whether K is used whentalking to ATC in the US. It is, nevertheless, considered acceptable to use it.

When talking on the radio, the "K" is not used under normal circumstances. However, some would argue that you should usually use it when reporting position. Another opinion is that most often, the name of the airport is used. In any case, if in doubt, append the identifier to the name of the airport.

You usually use it when reporting position.

Most often the name of the airport is used.

If in doubt, append the identifier to the name of the airport.


It depends how you define the airport.

I don't think your Google Maps method is sound, however; it depicts built-up areas, not the airport boundary.

You couldn't draw the same map around LAX , say.

The standard for measuring the area of an airport appears to be the total land owned by the airport.

And jet age airports, with their expansive noise buffers and office park reservations, tend to take as much as they can get.

DEN is reckoned the largest airport in the U.S., at 33,531 acres (~136 km²), though only a fraction of this is developed.

The numbers for total land are easy to find, the numbers for improved land less so, but I found an informative Globe and Mail article about Montreal-Mirabel.

When originally created, the land seized for the airport was larger than the city of Montreal itself— around 97,000 acres (~392.5 km²).

The article notes that the airport perimeter itself was only about 5,200 acres (~21 km²).

Still, it's the former number that is commonly bandied about, and the measure by which Mirabel was considered the largest airport in the world.

According to Kable , a London-based business information firm, King Khaled International Airport covered an area of 225 km² when it opened in 1983.

In 1999 it was surpassed by King Fahd International Airport , which occupies 776 km².

This is roughly the figure given by the 2013 Guinness Book of World Records .

It might help to have citations for the claims you mention - perhaps there's missing context.

That said, you're right.

The comparisons sound utterly false, based on Google Maps' measurement tool: Click to embiggen the images, but they're not remotely close: Bahrain's total area is around 700km²; OERK airport

according to Google measures closer to 37km².

It's not even necessary to closely follow the Bahrain coastline to get a precise figure, the numbers are so far off.

That said, Wikipedia has an uncited claim that: The airport occupies an area of 375 square kilometres (93,000 acres).

It seems likely but not guaranteed that this could be due an omitted decimal (37.5km², not 375km²) or to unscrupulous edits.

Even so: if it were 375km², it would only be larger than the administrative center of Paris (105km²) ; it would remain smaller than Bahrain.

EDIT: that seems likely.

Back in 2013 an anonymous user added that its area was 300km² and the airport's size has, at least in print, steadily increased since then.

I imagine if you did some more forensics you'd find that this is all random IPs.

Not a complete answer, but possible airports limits, based on zoning data, may be these one: Source Other clues may be discovered in the same page.

The cadastral information is handled by MOMRA .

The company that surveyed this area may be Twozan .

This is a "community answer", so feel free to improve it.

The King Khalid International Airport (234 km^2) is larger than Paris proper (160.0 km^2).

The King Khalid International Airport is not larger than Bahrain (762.8 km^2).

To arrive at this answer I used some data from various sources.

Mostly non-official but dependable sources as I do not have the language skills to navigate Arabic websites.

I pulled street data from OpenStreetMap and using the very good find by the community wiki response georeferenced the future land use map with points using the polyline data.

Georeferencing is used to correctly orientate and scale raster images to geographical locations.

I then created a new feature using the rubbersheeted/georeferenced land use map to draw the rough outline of the land that could be used for airport activities; this is the land dedicated to airport use not necessarily the actual size of the facilities.

This should give us a rough idea of the size and shape of the airport.

234 square kilometres.

Using data of the administrative districts for Paris, I summed the area of the 80 districts for Paris proper. 160.0 square kilometres.

Using ESRI's shapefile for world nations, I found the area of Bahrain.

762.8 square kilometres.

If you enjoy maps, come on over to the https://gis.stackexchange.com/ .

It is probably the closest to pure geography on SE yet.

It really depends on how you define 'big.'

In terms of size of the terminal and movement areas, it's not very big at all for an international airport.

Even medium-sized passenger airports in the U.S. are commonly larger than Riyadh's airport.

It has only 2 parallel runways and 24 boarding bridges.

By comparison, the medium-sized airport I usually fly out of in the U.S. has 36 boarding bridges, 3 parallel runways, and an additional crosswind runway.

The busiest airport - Atlanta International - has over 200 boarding bridges and 5 parallel runways in simultaneous use.

In terms of land area, especially land area owned by the airport rather than just what it actually uses , it is indeed quite a bit of land, though that's not necessarily unusual, especially for newer airports built in places with a significant amount of available land.

Airports generally like to buy up as much land as feasible in order to have room for future expansion.

Many of today's large airports are now space-constrained as the cities they serve have built up around them since the airport was originally built.

Airports that can try to buy up land that they might possibly need in the future in order to prevent running out of space to expand.

In terms of passengers per year, Riyadh's airport is relatively large, but nowhere close to the world's largest hub airports.

In 2015, Riyadh served 22.5 million passengers .

By comparison, Atlanta had 101.5 million.

The 50th-ranked airport was Minneapolis/St.

Paul International at 36.6 million.

So, by passenger traffic, Riyadh is probably somewhere around 100th worldwide, though exact rankings below 50th aren't made public by ACI .

Question: Apologies in advance if this is in the wrong place, there isn't a geography StackExchange so this was the next best option I could find.  I've read multiple things about the huge size of  King Khalid Internaional Airport (IATA: RUH, ICAO: OERK)  in Riyadh, one source said it was bigger than Paris and others have said it's larger than the entire country of Bahrain.  Judging from Google Maps, it really isn't particularly big. What's the deal with that?

Is King Khalid International Airport in Riyadh actually very big?

In terms of the land owned, King Khalid Airport is quite big. However, in terms of the terminal size and movement areas it is not very big at all.  Bahrain airport is bigger. In terms of passengers, the airport is quite large but does not compare with really large airports.

It all depends on the definition of the size of the airport, which is usually all the land owned by it. As far as the land area of King Khaled airport is concerned, it is indeed quite big at 225 km², though not bigger than Bahrain and not one of the biggest international airports. In terms of passenger traffic, it holds the 100th place worldwide.


The LearAvia LearFan 2100 used two separate PT-6B to drive a single pusher propeller through a common gearbox.

LearFan 2100 in flight (picture source )

If you want to know why its official first flight date is December 32, 1980, read here .

LearFan 2100 engine arrangement (picture source )

This engine arrangement was the LearFan's eventual undoing when the FAA denied it a proper certification because of concerns that the single gearbox constituted a single point of failure.

Well multi engine helicopters like the Bell 430 or the Westland EH101 do it all the time.

I don't recall any current production fixed wing aircraft using multiple engines to drive a single propeller, but the ill fated LearAvia LearFan used this propulsion arrangement, using two PT-6 engines to drive a gearbox connected to a pusher prop.

Yes, see Soloy's Dual-Pac concept.

Image courtesy of Soloy

The Soloy Pathfinder 21 is powered by the Dual Pac

It is essentially an extended and redesigned Cessna 208 with exactly what you describe: two PT6 engines geared to one prop hub.

I understand that the project has not progressed beyond the prototype built.

Image courtesy of Soloy

The Dual-Pac was also tested on a DeHaviland DHC3 Otter platform: Image courtesy of Soloy Quoting from the Dual-Pac page :

Soloy Dual Pac – Twin Engine reliability with single propeller symmetry.

The Dual-Pac was designed, patented and Certified by Soloy to safely combine the output of two independently operating Pratt Whitney PT6D-114A engines for a single propeller output.

The system was developed with extreme redundancy so that single engine operation is not only safe, but able to be done intentionally under certain conditions.

The Ayres LM200

Loadmaster was a similar design concept, though a clean sheet design using a different powerplant and also ultimately unsuccessful for economic reasons. See also the rotorcraft applications of the P&WC PT6T Twin-Pac , such as those that Carlo Felicione mentions.

Well, there is the Armstrong Siddeley Double Mamba engine.

It powered the Fairey Gannet

It wasn't a true single prop, but rather a contra-rotating prop (which amaze me).

Found a few more, some being single contra-rotating, others......multi-multi-engine? Aircraft powered by the Allison T40

There is one example of the twin turbine to single shaft Allison T40 powering a single propeller aircraft...

the Republic XF-84H

The thing was apparently as loud as the Tu-95, due to having a prop that spun at supersonic speeds on its outer edges.

And the prop created a continuous visible shockwave..

Personally, I am not sure if you would classify this as an aircraft, or more of a shock/awe weapon.

A similar concept was adopted on a bomber used by the German Luftwaffe in WWII.

The bomber, named Heinkel 177

"Greif" was a four engine but had just two propellers since a pair of engines was mechanically coupled in each of the two nacelles.

However coupling mechanically two engines on a single propeller revealed as a source of troubles (e.g. overheating occurred frequently on the rear engines) and the design proved to be unsuccessful.

This probably explains why it has not been used any more since then.

Depending on how strict you are about "single rotor"

The AH-64 Apache has 2 engines and one main rotor.

From Wikipedia "American four-blade, twin-turboshaft attack helicopter"

Kamov Ka-26 (1969, 816 built) is powered by two 325 hp (239 kW)

Vedeneyev M-14V-26 radial piston engines mounted in off-board nacelles, connected by a transverse shaft which drives the co-axial rotors.

According to Wikipedia , the reciprocating engines, although more responsive than modern turboshafts, are relatively maintenance intensive.

The Ka-26 is underpowered with its two radial engines, especially when used in cropdusting role, where excess payload is common.

No other helicopter exists in the world that runs at constant 95% engine power for most of its flight regime.

This leaves the pilot with little power reserve for emergencies.

Due to frequent overloads, the interconnect shaft which joins the two engines is prone to breakage and requires frequent inspection.

NOTE

An edit to the question makes this answer nonresponsive.

The Fairey Rotodyne probably counts, depending on your definition of "single rotor".

In level flight it was essentially an autogyro, driven by twin turboprops on short wings, deriving a fraction of its lift from these and the rest from the undriven rotor.

To achieve vertical takeoff and landing, the rotors were spun by tip jets, fed from bleed air from the turboprops, augmented by fuel burnt in the tip jets.

Although it seems to have been technically successful both in lifting capability and speed records for rotorcraft, the tip jets made it unacceptably noisy at takeoff and low altitude, precisely where noise was most objectionable.

I wonder if bleed air alone could work nowadays (given higher pressure ratio turbines) to reduce the tip jet noise.

The CH-53 uses 2 jet engines to power one rotating wing.

Question: Has a fixed-wing aircraft ever been conceived, prototyped or built that features multiple turbines powering a single propeller? The concept of a twin-engine aircraft with a single propeller is intriguing to me. Picturing something like a Pilatus PC-12 with two engines under the hood and a single prop might have some advantages. I come from a fixed-wing background and know little about helicopters, but if something exists I suspect it is a rotor wing.

Has a fixed-wing aircraft ever been built that featured multiple turbines powering a single propeller?

A number of planes with multiple engines and a single propeller have ben built. These include LearAvia LearFan and  Republic XF-84H  . There are also helicopters with multiple engines. There do not seem to be planes currently built in this design.

The LearAvia LearFan 2100 used this type of setup. Also, there are many multi-engine helicopters like this, like the Bell 430 or the Westland EH101. On another note, there is Soloy's Dual-Pac  concept and as far as engines are concerned, the  Armstrong Siddeley Double Mamba is a good example. Other examples are the Republic XF-84H , the AH-64 Apache, the  Fairey Rotodyne, the  CH-53, although their classification may depend on the definition of "single rotor".

There are many multi-engine helicopters like this, like the Bell 430 or the Westland EH101

As far as engines are concerned, the  Armstrong Siddeley Double Mamba is a good example.