User Interfaces, Boeing, Airbus, and the 737 Max 8

The crash of Ethiopian Airlines Flight 302 is a heartbreaking tragedy, and especially outrageous if it turns out that the pilots fought their own computer for control of the airplane. And of course the crash has prompted another round of hand-wringing over whether planes are just too complicated to fly.

There is a very long history of concern over the complexity of flying machines. In fact it’s why the venerated checklist exists, as described fantastically in Atul Gawande’s Checklist Manifesto.

But planes and other devices have gotten ever more complex to fly. And at the same time, we have grown less tolerant of human mistakes, which are still the cause of most crashes.

The major airlines, Boeing and Airbus, have developed different approaches to solving the problems of airplane safety. I won’t go into the details here, but they basically come down to whether you trust the pilot or the automation more. You can find plenty of examples of problems in both.

But in a number of the most recent incidents, pilots have had difficulty switching control from the automation. As pilot Mac McClellan writes, pilots have always been required to identify a flight automation failure and then disable it:

What’s critical to the current, mostly uninformed discussion is that the 737 MAX system is not triply redundant. In other words, it can be expected to fail more frequently than one in a billion flights, which is the certification standard for flight critical systems and structures.

. . . . .

Though the pitch system in the MAX is somewhat new, the pilot actions after a failure are exactly the same as would be for a runaway trim in any 737 built since the 1960s. As pilots we really don’t need to know why the trim is running away, but we must know, and practice, how to disable it.

. . . . .

But airline accidents have become so rare I’m not sure what is still acceptable to the flying public. When Boeing says truthfully and accurately that pilots need only do what they have been trained to do for decades when a system fails, is that enough to satisfy the flying public and the media frenzy?

I’m not sure. But I am sure the future belongs to FBW [fly-by-wire] and that saying pilots need more training and better skills is no longer enough. The flying public wants to get home safely no matter who is allowed to be at the controls.

Can Boeing Trust Pilots?

For a long time, Boeing has argued that pilots need ultimate control of the aircraft. And they have relied on pilots to intervene when fight automation is not triply redundant. Airbus, on the other hand, has argued that pilots make too many mistakes and that computers should prevent pilots from making unsafe maneuvers.

The lesson of this incident may ultimately be that we cannot allow computers to make mistakes because we cannot rely on pilots to fix them. And if we succeed in not allowing computers to make mistakes, do we need pilots?