Preliminary accident investigation results of the Boeing 737 crash of the Turkish Airlines that killed 9 were released yesterday. According to the report a failing radar altimeter caused the plane flying on autopilot and auto throttle to enter the landing sequence too early and to slow to stall speed in 600ft above the ground. When the pilots discovered the error it was too late to recover from the stall and the plane crashed a short distance before the runway. (Jet engines need a couple of seconds (an eternity when you need power) to spool up to power, very different from combustion engines).
What went wrong was that the pilots failed to properly monitor and second guess the full automatic system. The warning light for the failed radar altimeter was ignored and its implications for the approach not understood in time.
Automation is great, but if it makes the pilots complacent it’s dangerous. If automation works 99.9999% of the time, second guessing the computer becomes a boring task – you can get away with negligence many times. Had the pilot hand flown the approach in first place, this particular accident wouldn’t have happened, as he would have noticed the altitude error on time and would not have stalled the airplane while hand flying. Of course, statistically speaking, hand flying the approach is the less safe procedure compared to an auto approach.
So how could you prevent such an accident? First, crew coordination has failed. One of the pilots should have noticed the warning and disabled the auto approach. But beyond that there’s something lacking in the man/machine interface. The human mind needs to get challenged more often to stay engaged. So maybe a random simulated malfunction that requires pilot interaction with the system could cure the lack of attention that grows with time.
I don’t claim to have all the answers, but an accident like this is tragic and warrants thoughts on procedural change. The accident triggered Boeing to issue the following statement to the operators of the 6000 737 in the fleets: “…to carefully monitor primary flight instruments during critical phases of flight.” – Really?! Now that’s something new.
Fortunately I know the big airlines are paying people to do exactly that kind of accident analysis and implement the results in their daily procedures. One more reason to fly with a well reputed airline that trains their crews well and doesn’t cheap out on maintenance. Lufthansa , anyone?
I thought we flew Lufthansa for the free wine 😉
Having been inside a Boeing cockpit, we can full appreciate how many panel lights pilots are constantly staring at. More than stimulating pilots with false warnings (which might lead to the crying wolf problem and a real warning won’t be dealt with immediately), perhaps they need loud alerts for each warning which makes them stand out. Or even verbal ones that say “altimeter malfunction”, for example. Or really annoying ones like the seat belt warning on my car. It is pathetic that Boeing has to issue a statement for something that every pilot must do in good conscience.