BMI Tests For Pilots: Avoiding The Issue





Body Mass Index Accuracy






Flight Fatigue










Suggested Further Reading

Center For Disease Control: “About BMI For Adults
Sept 13, 2011
November, 2013
Mayo Clinic: “Sleep Apnea
July 24, 2011
January 27, 2010
FAA: “Flightcrew Member Duty and Rest Requirements
December 21, 2011
The Sleep Foundation: “Sleep Studies
October 24, 1991
February 19, 2008 “Summary Of Pilot Medical Standards
February 26, 2007












KDAL ILS 13L 6 Degrees




IF = RIVET, Unknown MSL, 12.6nm from FAF



KDFW ILS 17L 6 degrees





Aerobatics Undefined










There Is Never* Too Much Airplane

* Let’s get the disclaimer out the way up front. When I say “never”, I’m not talking about your fringe elements. You know the guy who somehow managed to buy a functioning SR-71 for trips from Tamiami to Beale. Nor am I talking about the person who has 50 hours in a Cessna 152 and buys a P-51D because he’s “always wanted one”. I’m ruling these aircraft choices out because they are pretty rare. This article is meant for the pilot who wants to upgrade from a trainer to a faster/larger aircraft in the same class and category and is intimidated by the change in cruise speed or engine size.

Part 1: Speed

“Speed is relative. If he’s doing 600 and you’re doing 600 what’s the difference? Zero.”     ~ Brigadier General Robin Olds

When sitting around hangars, the talk occasionally brings up some guy who allegedly went from a Cherokee to an Arrow and got so far behind the airplane that he was just contacting departure at the same time he was beginning his initial descent to the destination. And the talk will progress to how complex the new airplane is and how much power it has, which inevitably leads to someone belting out “It’s the same old thing, it was waaaaaay too much airplane for him.” At which point I sigh and hold in what I really want to say.

What I really want to say is “That’s nonsense.” Simple and to the point. Sure there may be some truth in not taking someone who had an intro flight in a Skycatcher and suggesting that they do the rest of their training in a T-38. But the chances of that happening are very, very remote. It doesn’t help pilots to keep them in slow airplanes for hundreds of hours anymore than it helps to teach them how to fly in said T-38. How can I say this with a straight face? Go to the FARs and look at Part 23.49c which regulates stall speed for all single engine aircraft (we’re ignoring twins in this discussion). No aircraft can stall above 61 knots in landing configuration unless an equivalent level of safety is demonstrated with respect to occupant restraint. This stall speed important because it’s a benchmark for any certified single engine aircraft.

Example: Bill Generic wants to upgrade from a Cessna 172 to a Piper Saratoga. Aerodynamically, it’s not a huge leap. In terms of systems of course, it is a completely different aircraft and if Bill doesn’t get transition training, he has a few cotter pins loose. But once Bill finishes training and goes out on his first solo cross countries, he may end up blasting past intersections or call on the wrong frequency because he’s not keeping up mentally with his progress and there’s no instructor/mentor next to him to help coach. The easy way for Bill to fix all that is to simply pull the power back. No he won’t drop out of the sky. No he won’t be hanging on the edge of a stall. Since all singles are created equal in that they cannot exceed 61 knots Vso, it means you can cruise any single between 100 and 120 knots without any superhuman effort at all.

Will the faster airplane like loafing along so slowly? It may not handle exceptionally crisp and depending on how far back Bill has to pull back the power, the engine may start getting warm if he tries this at 2000 feet over Death Valley. But done with agreeable weather conditions, this is a great way for him to get used to progressively faster speeds. It may take 3 or more trips for he becomes comfortable spanning the gap between 110 and 170 knots. Or he may be fine after one leg of continuous increases in speed. But the important part is that he can adapt at his own pace. The throttle doesn’t control power, its controlling time.

The ability to control time means that while doing transition training and even afterwards, a pilot can get used to the checklist items and internalize procedures. Your aircraft upgrade may have a turbocharger or oxygen system or cowl flaps or even extra fuel tanks. More time gives you a cushion for making sure these systems are working the way they should and that you understand why they’re doing what they’re doing. Waypoints passing too quickly and your map (some of us aren’t totally paperless yet) can’t get turned to the proper side fast enough? Pull back the throttle/time controller and slow things down.

Landing and approaches are another place where the 61 knot rule levels the playing field.  Surely you practiced rectangular patterns at altitude, so making the base and final turns shouldn’t be an issue but all the same, give yourself more time in the form of a slightly wider and longer pattern. On downwind, fly whatever was recommended but 90-100 knots is a safe range (1.47 to 1.63 times Vso) where you have some wiggle room in case your aircraft bleeds speed quickly when flaps or gear come down. If that happens, use the time controller in reverse…push the throttle up so that the bleed rate slows and you have more time to adapt to the aircraft’s idiosyncracies. The standard 1.3 Vso approach speed for the 61 knot aircraft comes out to 79 knots (just say 80). Flying final at 80 knots is an easy and safe target if for some reason everything the instructor taught in transition leaked out of your ears. If you’re being vectored for an approach and the controller wants you to hold 170 knots to the marker and you aren’t comfortable doing that yet, tell them you are unable. They don’t need to know why and if they do ask, mention something about monitoring a fluctuating sonidecimeter indexer. By the time they figure out you’re full of it, you’ll be making the second turnoff.

Part 2: Power

Power is relative too. In my view, too much is made of horsepower being the primary indicator of performance. The FAA categorizes any aircraft with over 200hp as high performance. Because of this, you will often hear the same people who griped about “too much airplane” complaining that a certain airplane had way too much power. While there are cases when this is true, 90% of the time you can never have too much power. High performance is what you make of it, what you wish to measure and what you’re used to.

For a real life example, take a Rockwell Commander 114 and a Pitts S-2C. Both use a 540 cubic inch, 260hp engine and both are technically high performance, but that’s where the similarities end. The Pitts can fit 2 people very snugly and climb at 2900 fpm. The Commander can fit 4 in leather-bound comfort and climb at just under 1100 fpm. The Commander has a 1000nm long-range cruise while the Pitts is limited to 247nm. We could go on and on but the point is that power gives you radically different performance based on what you want to do with it. The Commander is intended to carry people places, the Pitts is made to go up, have some fun and come back within a relatively short time. Which one is high performance? Depends on what you want to do. Flying an advanced aerobatic sequence complete with a pull-push-pull humpty and snap rolls on a 45 downline? The Commander is going to be a letdown. Need to take 3 people nonstop from Teterboro to Nashville in IFR conditions? The Pitts would not be a good choice. What if payload is the determining factor in what you count as high-performance?  Looking at a much larger aircraft, the Cessna Caravan, has 675 shaft hp from its turboprop engine, but because of its rugged design the aircraft max cruises at 186 knots. By comparison the Cirrus SR22T has less than half the power (315hp) but max cruises at 214 knots. But while the Cirrus can only hold 4 people, the Caravan can carry up to 14. If lifting payload is the performance factor your type of flying depends on, the Caravan is the clear winner. And what about your own experience? What you have flown in the past and what you are flying currently has a lot to do with this perception. If you had a PC-12 and are downgrading to a Commander, you may not consider it to be high performance by comparison. If you are coming from an MX-2, then maybe the Pitts isn’t such a wild ride. But if you’re upgrading from a Diamond DA20, you’re most likely going to be wowed by either aircraft. Performance is just as relative as power.

Perhaps the regs should focus on acceleration, climb rate and cruise speed instead of power for a definition of high-performance. This is probably what the FAA intended people to focus on all along but we ended up getting fixated on the semantics of 200 vs 201 hp. Here is an example of why horsepower can be a dead-end. Take an airplane with a pretty anemic power to weight ratio of 16 to 1, meaning there are 16 pounds of aircraft per horsepower. With a 100hp engine, this fictional airplane will weigh 1600 pounds. But what happens when we scale everything up by a factor of 3? The horsepower explodes to 300…definitely high performance by federal standards. But the weight also balloons to 4800 pounds. And in case you didn’t notice, the power to weight didn’t change either which means acceleration and climb is going to be pretty similar (provided the wing loading remained constant). Glancing back at our earlier examples, we’ll compare the difference in power loading for the Commander and Pitts. The Commander has a 12.5lb/hp loading while the Pitts has 6.6lbs/hp. That’s a massive difference in the amount of weight each horsepower has to work with and why the performance figures are so radically different for the same horsepower engine.

Part 3: The Moral

Yes, upgrading in aircraft will take time and money. Get transition training, talk to pilots and owners of the same aircraft first. Learn the little quirks that aren’t written in the operating manual. Study the systems and know little things like how to start the engine. Nothing makes a passenger reevaluate their friendship with you like watching you fumbling around with throttles, mixture knobs and primers on the ramp and saying “It normally doesn’t do this.” Things like starting the engine are and knowing how the fuel system works are pure study items. The things that you can’t learn from a book are your own comfort zones. The only way to learn that is by actually doing it in increments.

Hearing people repeat over and over how hard it is to keep up with fast airplanes and how so much horsepower will ball you up like a Bf109 in a crosswind does not boost confidence. But remember that they’re just repeating what they’ve heard. If flying high performance aircraft was so hard, nobody but astronauts would be doing it and the last time I looked, there’s plenty of non-astronauts in Meridians, Stationairs, Bonanzas and the like. It will just take a little getting used to. Be kind to yourself and don’t expect to go full-tilt right out the gate. Remember, nobody goes 220mph out of turn 4 at Talladega their first time in a race car either.

Virtual VFR and Pilot Safety

Don’t Worry, There Won’t Be Any J-3s On An ILS To Minimums

 Original date: August 2, 2011

"I'm sorry sir, these flat panel displays are for airliners only. Have fun with your morse code identifiers."

Warning: This blog is filled with aviation terminology that may be objectionable to land-locked readers.

This all started after reading Mac McClellan’s blog on head-up displays in light aircraft. I posted a response and one of my friends who happens to be an airline captain saw it and responded to my response (don’t you love the internet?). We’ve been going back and forth about the benefits of advanced technology for general aviation aircraft. Specifically, it was about synthetic vision and how it could create Virtual VFR regardless of weather conditions. His stance is that GA pilots don’t need super advanced instruments and information systems because it will make pilots fly into conditions they shouldn’t be in. My stance is that it will make those who take the time to learn how to use it much safer.

The sticking point in any field is that new technology that makes things easier is often seen as a crutch by those who did without for the majority of their lives. When GPS began showing up in aircraft, people said “What will you do if it all fails?” I would then point to their stack of navcoms, adf and loran receivers and ask them the same question. Stuff fails no matter how high tech or low tech it is. Dealing with failures is the burden of the pilot. The mean time between failures with modern electronics far surpasses any analog, transistor or vacuum tube based system that bore the generic label “computerized” in previous decades. Automatically that is a huge benefit not just for safety but for life cycle operating costs.

The other problem brought up during the initial GPS revolution was that people would forget how to navigate or look for other aircraft. That is a problem, not so much of the GPS but of people not knowing how to divide attention, especially in busy airspace. I remember several times with my instructor when we’d spot an airplane (or worse, get bounced from behind) I’d say “Did he even see us?”. To which Marty would always have a witty comeback like “Why don’t you get out and ask him. Think it’ll make a difference?”. I have no idea why the overtakers didn’t see us but a distraction is a distraction. I don’t care if its GPS, an ADF or some poor soul with headphones on listening for “dah-dit dah-dit” on the four course.

Flying in a general aviation aircraft, regardless of what we tell passengers is a more risky activity than driving on average. However the risks can be adjusted based on a pilot’s skill, comfort level and aircraft capability. Maybe a particular pilot doesn’t like flying in clouds, flies only for pleasure and operates an aircraft equipped with VFR only steam gauges. However this pilot wants to upgrade to a 3 tube EFIS system combined with a HUD. Should we deny them advanced navigation and weather information based on the assumption that he is going to suddenly start flying between level 5 thunderstorms? Should information-dense systems be the sole domain of the turbine fleet and business jets? If the light airplane pilot wants to fly a 300nm trip, is it fair to make them use less capable avionics, ostensibly to keep them out of trouble?  

There's a lot of information, but how easy is it to interpret under stress?"

Being able to navigate a couple hundred miles through a high-pressure system without super-duper graphics and satellite weather should not be too difficult for any pilot. A basic GPS or (gasp) a stack of VOR receivers can get you just about anywhere in the United States. But the cushion of safety for those who choose to learn everything that their super-duper system can do for them is undeniable. The objective for VFR pilots is to use extra information to stay away from weather (terrain shouldn’t be a problem since if they’re VFR they should be able to see it). To say they don’t need it because they’ll start flying into frontal systems is like saying that airline pilots shouldn’t have terrain avoidance systems because they’ll see where the ground is and fly into it.

IFR flight on the other hand is a more difficult situation because there are so many variables in the types of aircraft, the types of missions, and the weather conditions at any given place or time. There may be the person in the Cirrus who is cruising at 11,000 feet on top of a cloud layer and wants to know the exact position of the hills hidden beneath those clouds. Sure he can use an IFR chart and know that by staying above the MEA he’ll be fine but let’s use the favorite example of instructors: What if the engine quit? Synthetic vision cannot dead stick an airplane onto an open farmer’s field automatically, but it does give the pilot far more information in an emergency situation with regards to wind direction, terrain location, obstructions, etc.

Take a single-pilot King Air on an ILS on a scuzzy day. The pilot has approach charts that show what the decision height is, how far from the touchdown zone that will be, what the missed approach procedure is, etc. And since the pilot is IFR rated and trains in a simulator at least once a year, it should be no big deal. However, if there is a distraction, or a problem with the aircraft, a small mistake could be made. To the delight of lawyers everywhere, I will be completely honest: pilots do make mistakes (if you don’t believe me, ask the NTSB). The majority of accidents are not one massive brain-fart but a series of smaller errors that compounded until the snowball became an avalanche. By providing easy to interpret data, the pilot’s mind is freed to deal with any other issues that arise during times when the mind is approaching task-saturation. So now while dealing with a generator problem, a sick passenger, or just an unfamiliar approach, the pilot is able to see the image of where the runway should be and cross-reference that with the standard charts and data. This removes all doubt as to the aircraft’s location and where it will be in the next 15 to 30 seconds. Breaking the links in the accident chain should be reason enough for encouraging use of such equipment.

Information-rich technology is not for every style of flying. I admit, it would be odd to fly a Stearman with a HUD. And a Cessna 152 that is only used for $200 dollar hamburger runs (inflation hurts, doesn’t it) would not need an extensive weather suite and electronic IFR charts loaded into the system. Am I in favor of putting EFIS and HUDs in everything from 

Open cockpit EFIS

light sport to piston twins? Honestly it doesn’t matter what I think. If the pilot/operator feels that the technology will be a benefit to their type of flying, then full support should be offered for getting that equipment into their cockpits. I was in Woody Saland’s hangar a while back and was intrigued by the fact that his AirCam had synthetic vision EFIS, EICAS and an autopilot. Why would anyone want so much technology in an open cockpit airplane? Then it hit me: To make the task of converting numbers, radials and performance figures into an instantly interpretable view of what your aircraft is doing. With so much of your mental capacity relieved of that repetitive task, you can actually enjoy the act of flying.