By now you’ve probably heard about the crash of Lion Air Flight 610. And you might have heard that there’s been speculation that the Boeing 737 Max crashed because the pilots were flummoxed by faulty readings on the plane’s instruments due to problems with the pitot-static system, which senses the plane’s altitude and airspeed. All 189 aboard the plane are presumed to have died in the crash, and recovery efforts are underway.
As you might remember, it was this system that contributed to the crash of Air France 447 in the Atlantic on June 1 of 2009 while at cruise on the way from Rio de Janeiro to Paris, killing all 228 people aboard. When a plane’s sensors give false or unreliable altitude or airspeed (or both) indications, the danger is that the pilots will try to do as they’re trained to do when systems are operating normally and stabilize the flight path by adjusting power and pitch. When the plane is getting bad or erratic altitude and airspeed information, it might be impossible, however, to do anything but make matters worse by attempting to hold the plane’s altitude and airspeed, because the pilots are chasing false indications without reliable cues. In the Air France 447 disaster, investigators believe that the pilots stalled a perfectly good-flying airplane into the sea because they couldn’t determine how fast it was going or at what altitude they were flying. Complicating their vain attempt was the fact that it was dark at the time, so they presumably had few or no outside visual cues. It was, for the record, about an hour past official sunrise in Jakarta when Lion Air 610 crashed into the sea. It is not known if the flight was in visual conditions or if it was being flown by reference to instruments solely due to cloud coverage.