Pontifications: Pilots train for instrumentation mismatches

By Scott Hamilton

Nov. 5, 2018, © Leeham News: It was a week ago that Lion Air JT 610 crashed into the sea, just 13 minutes after takeoff.

The crash was the first involving the Boeing 737 MAX (in this case, the -8 model). The airplane was virtually new, having been delivered to the airline in August. Lion Air was not new to the 737, having flown the NG models for years.

Because the airplane crashed into the sea, recovery of the black boxes was not quick. The flight data recorder was recovered several days later but the cockpit voice recorder is still missing. The FDR data apparently has not yet been downloaded for a preliminary read. At least nothing has been made public, if it has.

Little information

Absent even a first-read of the FDR data, information about why the crash happened is sketchy.

We know the same airplane had airspeed mismatching the day before.

There was a report, but unconfirmed, there may have been an issue with the elevators, too. But until this is confirmed, I’m treating this as a rumor.

We know from Flighttracker24 JT 610 was at a lower altitude than normal at this point in the flight after departure, the altitude was erratic and so was the speed. Flighttracker also showed a virtually straight-down dive from 5,000 ft into the sea.

Bloomberg reported over the weekend it commissioned three experts to analyze the Flighttracker information. Each concluded, separately, that the plane was going +/- 600 mph on impact, with the nose-down attitude at least 45 degrees and maybe more.

So far, that’s about it.


Supposedly, Lion Air maintenance personnel fixed the airspeed mismatch issue from the day before, but this is unclear. Nothing definitive has pointed to the cause of the mismatch.

It could be faulty instrumentation.

It could be a fault with the pitot tubes that measures airspeed. This has happened before.

There were two Boeing 757 accidents traced to pitot tube malfunctions. Birgenair flight 301 sat on the ground for two days in Puerto Rico without the tubes covered. In this short time, mud wasps built a nest in the tubes. The walk-around didn’t detect this.

A speed mismatch was detected on the takeoff roll, but the pilot continued. As the airplane climbed through 4,700 feet, things began to go wrong, with the airspeed instrumentation mismatch between the pilot and captain and erratic airspeed indications appearing. (When I read the altitude in this accident summary and compared it with Lion Air’s altitude, the similarity was chilling.) The auto-pilot disengaged.

Events led to a stall and engine flame out and the airplane crashed, killing—get this—189 people on board, the same number as JT 610.

Eight months later, while Birgenair was still under investigation, Aeroperu Flight 603 crashed shortly after takeoff from Lima.

The cause was determined to be the failure of the ground crew to remove tape from the static ports that fed the airspeed and altitude to the cockpit instruments. The flight was at night and with no visual reference, the crew lost control and crashed.

Then there is Air France 447, an Airbus A330, that crashed June 1, 2009, in the South Atlantic. The pitot tubes collected ice at cruising altitude, causing airspeed mismatch instrumentation. The crew became confused, stalled the airplane and it pancaked into the Atlantic at high speed.

Training for mismatches

Pilots are supposed to be trained for deal with airspeed and altitude mismatches. A Delta Air Lines Boeing 767 aborted a takeoff at New York’s JFK on the takeoff roll when airspeed mismatch occurred. (Ironically, during a long taxi period to cool overheated brakes, the make gear nevertheless caught fire and an emergency evacuation on the taxiway was necessary.)

Without visual reference (such as with the Aeroperu flight), things become more difficult.

Still, a pilot for a US 737 operator emailed me and said instrument mismatch “is why we work on unreliable instrument scenarios in training.”

And, as another remarked, JT 610 was in broad daylight. Looking out the windows would have been useful.

Unanswered questions

There are very few answers and there are hundreds of questions.

We don’t know what was happening to the airplane. We don’t even truly know if this was instrumentation or something else.

We don’t know what was happening the in cockpit. We know the pilot radioed he wanted to return to the airport. Other than this, what was being said between the pilots, what were they seeing, hearing or thinking out loud?

The FDR will tell us what the airplane was doing, but as of this writing, we don’t have this information.

Did the pilots have a situation they couldn’t handle? Or did the pilots create a situation they couldn’t handle?

At this point we just don’t know.

30 Comments on “Pontifications: Pilots train for instrumentation mismatches

  1. Flightglobal reports that NTSB have downloaded 69 hours of data from the FDR including the last flight.

  2. “We don’t know what was happening to the airplane. We don’t even truly know if this was instrumentation or something else.”.

    But – get this – we’ll still speculate…

    • No speculation. Airspeed mismatch had been reported on previous flights. Pilots are trained to fly through instrumentation mismatch. Purely factual.

  3. There are real time wind models of the whole world and gps tracking. Perhaps we could make the cockpit a bit more idiot proof with a speed/altitude indicator which is independent of pitot tubes?

    • Altitude would be possible. Speed would not, unless you happen to the know the wind speed at every point on Earth. Ground speed is not relevant to an aircraft’s flight characteristics, except during takeoff and landing.

        • That is a huge misrepresentation of reality.

          It just a general view, it has no relevance to what is going on in any given locale other than a general movement of air.

      • Mike,
        While your reply is technically correct, JT 610 was at about 5,000 feet in good weather. The difference between ground speed and indicated would not be very great and if you just set the ground speed at 280 knots, you would be well within the envelope while you tried to figure out what was going on. Even at higher altitudes, the flight plan has wind forecasts that will keep you safe as long as there is not great wind shear.

  4. Granted, I retired from the 757/767 15 years ago, but at that time we got little training on erratic air data info.
    Yet ground speed info was available on the overhead panel from the inertial units and attitude info was available by looking out the windshield or at the attitude indicator.
    I wonder if they are training on that now.

    • Bob:

      The move has been to stop the repetitive stuff that gets tested each flight (like take offs and landings) and replace them with failures that tests a crews understanding of the underlying fundamental of ho9w the system on their aircraft works.

      How far Indonesia has gotten I don’t know.

      They have coined a phrase called startle reaction. If you know its coming you can cover it up, if you don’t then you fine out (and the idea is to deal with individuals in their areas of poor or disastrous reactions)

      Rarely is the issue non workable (the 737 Ruder issue and the Lauda Air Crash would be a couple that nothing would have saved them) – sadly Boeing fought both tooth and nail.

      Pilots have reported they never had any training on loss of pitot system at altitude and often were chastised if they touched the controls.

      And with it getting harder to find pilots, what is allowed to slip by is a good question.

      What I do see is that they put automation in charge until its suddenly taken away. People live on a Bell Curve of reactions and pilots are no different. Some handle it the way it should be, most have some lag and some cna’t handle it at all.

      AF447 is an example of ???? as the crew was very experienced and what would cause a pilot to think that the speed had suddenly gone to zero without a mountain in the way? Let alone pull full back on the controls.

      And if you are going to automate, why would you not have the airplane automatically revert to the poss of speed in that situation (5 deg up on the nose and 85% thrust5 as I recall) rather than just dumping it into the pilots laps?

      A 757 out of Ireland did the opposite, pilot lost his speeds and he put the nose down to get speed back. I believe he was in a decent at the time.

      Mostly none of this was given any thought as to a system. The tech guys came up with stuff, and gee, that is so cool we put it in. To me its like releasing chemical into the environment without testing them thoroughly first.

      They know some things like bells, whistles and horns get ignored (tuned out). When I started working our trucks had a clanger on the wheels. That just became background noise.

      Now we have horns, and warblers and flashing lights and they still get ignored.

      And there is no standardization. Boeing does it their way, Airbus does it different and both are approved (more related to Asiana Crash and the pilot used to auto throttle coming back in regardless of the mode he had it in)

      Humna being are pretty weird, there is a purported logic but when you break it down its just silos here and there without a real system.

      Then the system tried to catch up, maybe with aircraft they can but the tech world is changing so fast and their is a cumbersome process to get training to stay even.

    • Hello Bob Mauer,


      I wonder if they are training on that now.”

      See the 737 classic simulator training/demonstration video at the link below.

      In your day were there not memory items and quick reference checklists for “airspeed unreliable” of the type being practiced in the video?

      The usual approach in today’s airspeed unreliable checklists is to disengage auto-everything and fly conservative and safe pitch and power settings unless or until a reliable airspeed reading can be identified.


      • AP: That works at altitude in cruise.

        I don’t know what the drill is for lower level and departure.

        Some has to be situational based on terrain.

        I do know the AF447 should have just put it to 85% thrust and 5 degree up altitude and they would have been in the envelope (it does get pretty dicey between stall and over speed at 35k but even a stall is doing to drop you to where you are good – a stall is not as much an issue as over-speed in those circumstances)

        There is a massive change going on in upset training and the drills and what needs to be memorized.

        At issue to is overload as the new systems flash a bazillion messages and the key one you need is just speed lost.

        My flight instructor wanted to see a takeoff with no speed referee. He didn’t believe me when I told him I would hold it on the ground until we were bouncing good.

        After we bounced about 5 times he said ok, ok.

        Short of some crisis I would not have taken an airplane off the ground with no speedo.

        We did practice loss of multiple instruments and if you do the drill, its doable.

        • Hello TransWorld,

          Regarding: “AP: That works at altitude in cruise.

          I don’t know what the drill is for lower level and departure.”

          For the answer as to what happens at low level or departure, watch the video of the 737 simulator airspeed failure training session that I posted a link to above.

          Takeoff (rotation) occurs at 1 minute 45 seconds.
          Stick shaker activation occurs at 2 minutes 58 seconds.
          Left seat pilot calls out “I have no airspeed” at 3 minutes 8 seconds.
          Panel close up shows altitude of 8,520 feet at 3 minutes 11 seconds.
          Panel close up shows altitude of 8,460 feet and decreasing at 3 minutes 21 seconds.*

          Thus, the airspeed failure in the simulator video occurs about 1 minute and 13 seconds after takeoff, at an altitude of about 8,500 feet.

          According to the “airspeed unreliable” checklist closeup at about 5 minutes. The first 4 responses to unreliable airspeed for this aircraft, independent of phase of flight, should be as follows.

          1. Autopilot – Off.
          2.Auto Throttles – Off.
          3. Flight Directors – Both Off.
          4. Set pitch and power as follows.
          Flaps Extended: 10 degrees and 80% N1.
          Flaps Up: 4 degrees and 75% N1.

          *The right seat pilot has immediately pushed the nose down in response to the stall warning (erroneous in this case), unlike for instance, the pilot flying Air France 447 ever got around to doing during the first 28,000 feet of falling from 38,000 feet with his aircraft 30 degrees or more nose up with stall warnings sounding intermittently. To his credit, the pilot not flying tried to push the nose down at 35,000 feet, but because the aircraft was controlled by video game play sticks that do not resist movement or sound an alarm when the other pilot is making conflicting control movements, his attempt at stall recovery was “cancelled out” by the flying pilots nose up death grip (for him and 227 others) on his play stick.

          “In response to the stall, first officer Robert took over control and pushed his control stick forward to lower the nose and recover from the stall; as Bonin was still pulling his control stick back, the inputs cancelled each other out.”

          By the time the captain figured out what was going on, it was too late to recover.

          ‘First officer Robert responded with: “We’ve lost all control of the aeroplane, we don’t understand anything, we’ve tried everything” and then: “Climb climb climb climb”. When Bonin replied: “But I’ve been at maximum nose-up for a while!” captain Dubois realized Bonin was causing the stall, causing him to shout: “No no no, don’t climb!”

          The aircraft was now too low to recover from the stall. Shortly thereafter, the Ground proximity warning system sounded an alarm, warning the crew about the aircraft’s now imminent crash with the ocean. Bonin, realizing the situation was now hopeless, said: “Fuck! We’re going to crash! This can’t be true. But what’s happening?” The last CVR recording was captain Dubois saying: “[ten] degrees pitch attitude.”


          • Strangely, in the 737 simulator video that I posted a link to above, in the panel close up at 3 minutes 11 seconds, three seconds after the left seat pilot calls out ‘I have no (or low?) airspeed”, the left airspeed indicator and left flight director speed window are both showing 279 knots. The flight planing charts in a late 1990’s US Air 737-300/400 pilot’s handbook that I have are based on climb at 250 knots IAS below 10,000 feet, 300 knots IAS from 10,000 to 20,000 feet, and .70 mach above 20,000 feet, thus for a US Air 737 classic pilot in that era, 279 knots would not be an unusually low climb speed at 8,500 feet.

            Later, when the pilots are comparing their airspeed readings to those expected for a particular pitch and power setting, they decide that the airspeed readings are about 20 knots high.

      • AP_Robert,
        Well, I have not cracked a book in 15 years but my memory is that we didn’t receive any training on unreliable airspeed other than to review a chart in the QRH for loss of radome and that chart just had pitch & power settings for different altitudes.
        I would be the first to admit that my recollection after 15 years may not be or is not accurate.

  5. One of the hardest system to work on and get right are the pitot static system.

    While very reliable when they work, when they go wrong they are awful things to work on.

  6. This DailyMail story says one of the black boxes appears degraded and requires extra care in handling for data extraction, and the other box is still in the mud, and they know where it is, but due to circumstances it has not been hauled up yet.

  7. Modern technology must be able to allow us to sense wind speed and altitude without pitot tubes! Unfortunately, when conflicting data is introduced to flight computers and flight envelope protection is lost, we find out the hard way which airlines have properly trained their pilots.

    • Wind speed is not the issue, aircraft speed relative to the atmosphere is.

      Certainly GPS can give you both air speed and altitude.

      Altitude separation is critical and that is set by altimeter adjusmtnes to the local pressure so all are playing on the same point of reference (I don’t know what they use for over ocean flights)

      Update capability is critical, airspeed and altitude have to be near instantaneous.

      Your backup instrument (or which you shift to) has to be reaonly accurate.

      Small air craft use a vacuum system and electrically powered instruments so there is not sole failure source and you can derive whats going on with an altnervie instruments or instrument.

      You want your most relive and accurate instrument as primary.

      There is nothing complex about a pitot static system. It is a tough one when it has problems to trouble shoot and ID the problem.

  8. The question to be answered is : apart from pilot training, what is the necessary software/hardware control correction to prevent one pitot tube error from turning off flight envelope protection and possibly causing conflicting overspeed and stall warnings

  9. The Max did add FBW spoilers, which is quite interesting given the weird flight profiles which the LionAir jets experienced. Is the new FBW control software flawed, causing the strange elevation fluctuations?

    • You are back to speculating. As noted the flight profile is an almost exact match for previous Pitot Static system issues.

      The system is reliably reported to have had problems.

      Reports are out now to that affect but I have not seen the source yet.

  10. There is a lot of faldera about the CVR which in my view is about useless.

    What would be useful is a Cockpit video, that would show exactly what the pilots DID not what they were talking about.

    In this link the CV clearly showed what the Co Pilot did


    We had a recetn Airbus Helicopeter crash off the Gulf Coast of Alaska.

    CV showed the pilot decided to do an auto rotate (at an altitude that is below the allowance for it to work which the DR showed they were at).

    We don’t have to know what he said, just what he did.

    CV clearly shows that. Its the one remaining battle that needs to be corrected ASAP.

    We all are monitored at work, Pilots seem to think (or the union) that they should be exempt.

    As a non current pilot, I can tell you we are not gods. The best of us are very good and professional technicians and the worst are dangerous.

    I would assess myself as in between. I had one incident that should have killed me and one dumb stunt into a muddy field that should not have happened.

    I certainly did learn from both! The worst are the ones who won’t and or can’t learn at all, either though stupidity or sheer arrogance.

    There are a few rare pilots who are gifted with amazing feel. I was not anywhere near that class.

  11. If it’s a Boeing ,I ain’t going,at least until tomorrow. Apparently Boeing has just announced that it is just about to announce a safety bulletin. What if there’s an accident in the meantime?
    Logically the aircraft should be grounded.

    • Angle of attack (AOA) sensor was replaced before fatal flight, but according to the latest news, it may have acerbated or masked what may have been a related problem with others sensors or flight control.

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