PPRuNe Forums - View Single Post - MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
Old 18th Aug 2019, 15:07
  #1883 (permalink)  
Tomaski
 
Join Date: Jun 2019
Location: VA
Posts: 210
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by boofhead
Here's a novel idea. I doubt it has been considered by too many people, including pilots on this forum:

If you experience low oil pressure you should follow the QRH procedures for low oil pressure. If you experience an engine failure at or after V1, you should follow the QRH procedures for engine failure after V1. If you experience a runway stab trim you should follow the QRH procedures for a runaway stab trim. And so on.

Pretty radical, isn't it?

Note that the MCAS failure presents itself as a runway stab trim so that would mean that, wait for it! You should follow the QRH procedures for runway stab trim! Amazing, yes?

Boof,


I’m going to disagree with you here, but probably not for the reasons you think. One of my ongoing concerns with the current state of pilot training and management is that there has been far too much emphasis on executing written procedures and strictly complying with company policies and far too little on basic aircraft management (with and without the automation) while maintaining a “big picture” of what is going on without necessarily looking it up in a manual. Training itself has become so compressed and scripted that there is little room for critical thinking. At some airlines, pilot discretion exists in name only. In some cases, training and operational management has adopted so much of a paint-by-numbers philosophy that some pilots are no longer able to color outside the lines.

To illustrate, here is one of my favorite all-time aviation-related cartoons:




Here we have too much reliance on the literal word, not enough seeing the big picture. Funny in this context, not so much in real life.

For every airliner I have flown, somewhere in the preamble to the non-normals section (we used to call them “emergencies, and then “abnormals”, but I digress) there is a statement to the effect that while the manufacture has made a good faith attempt to create procedures for possible malfunctions, it is simply not possible to anticipate every possible failure or combination of failures in which case the pilots are expected to exercise good judgement. This is a very critical concept that is frequently disregarded in both training philosophy and overall company culture. The “good judgement” pilots are expected to exercise in unusual situations can be trained out of them by company policies that emphasize strict adherence to procedures (even when they may not apply), maximum use of automation that leads to loss of hand flying skills, and top-heavy or authoritarian management that discourages adaptive decision making.

Consider what we know of the first Lion Air accident (the ones that survived). The crew reported confusion regarding which procedure to apply because the MCAS failure did not match a classic runaway trim. Much has been made of the word “continuously” in the description section of this NNC. For my part, 9 seconds of continuous operation is “continuous” enough, but I could see how others would see it differently. However, this discussion itself has too much focus on the literal words, not enough on the big picture.

After the crew had turned off the trim and stabilized the aircraft, they then did two peculiar things. First, they did not disable the erroneous stick shaker even though the circuit breaker was in easy reach. Why would they not get rid of such an obvious distraction that increased the risk of further crew errors? Because there was no written procedure to do so. Too much literal interpretation, not enough big picture.

Next, despite having a malfunctioning AOA vane (which itself compromises a number of other aircraft systems like flight instruments, autothrottles, autopilot, etc), no electric trim, and probably quite a few distressed passengers, the crew elects to continue to the scheduled destination hundreds of miles away. Why? As the preliminary report cogently stated, neither the Airspeed Unreliable or Runaway Stab checklists direct the crew to land at the nearest suitable airport. In absence of some piece of paper that instructed them to get the aircraft on the ground now, they apparently felt they had no choice but to continue the flight - with an active stick shaker all the way.

We see strong desire to identify and execute a written procedure repeated in the second Lion Air flight. The Captain initially was able to stabilize the aircraft and flew around for several minutes while the FO looked through the QRH for an appropriate procedure. This is important. The aircraft was relatively stable and not in danger of crashing because the Captain was, quite appropriately, using aggressive electric stab trim inputs to counter MCAS despite the lack of any existing guidance that this is what he needed to do.

The First Officer stated that he could not find an appropriate procedure in the QRH. We can set aside for the moment the discussion whether either pilot should have connected the MCAS malfunction with the Runaway Stab procedure. The Captain, who so far was maintaining aircraft control, then hands the aircraft over to the First Officer so the Captain can then go look for an appropriate procedure in the QRH. Within seconds of this transfer of aircraft control, we see an immediate deterioration in the aircraft state due largely to inadequate electric stab trim inputs and the aircraft crashed within about a minute. Why the First Officer was not able to maintain aircraft control in the same manner as the Captain is an open question, but what is key to me is that this crew seemed to place such importance on finding a written procedure that precisely fit their situation that they sacrificed aircraft control in that pursuit.

Given what we know of these accidents, Boeing obviously needs to build a better aircraft and everyone in the chain needs to look at and revise the written guidance given to the air crews. However, I think the evidence also shows that there is more going on than just a need for “better” procedures and better adherence to those procedures.

Last edited by Tomaski; 18th Aug 2019 at 18:23.
Tomaski is offline