Originally Posted by
yoko1
I think the crew of the penultimate Lion Air 610 flight did a great job handling this emergency, particularly since at this point no one outside of Boeing had ever heard of MCAS. They dealt with the immediate stick shaker, recognize the plane was flying and not stalling, and identified the IAS DISAGREE problem early on. They were rightfully taken surprise by the MCAS event, but they kept the plane flying, both the Captain and FO in turn, while they tried to sort out the problem. They used the resources available to get the malfunction contained and eventually landed safely. Good job all round.
We can look at their performance and see it follows a pretty standard three-step approach to dealing with any aircraft emergency. Different airlines/flying organizations may express this process in different ways, but the version I prefer goes like this:
1. Maintain aircraft control
2. Evaluate the situation and take appropriate action
3. Land as soon as conditions permit
While each step is critical in its own right, it is important to note that you can’t get to Steps 2 or 3 without first getting through the critical Step 1. You can actually make mistakes or fail to complete Step 2 and still get through the situation. Step 3 is, of course, mandatory for successful completion.
Now, personally I don't feel the need to criticize the previous Lion Air crew for their initial response to the emergency. As you said they saved the aircraft from a malfunctioning system they didn't even know existed, so we can cut them a lot of slack. However, if they did crash, many people would be very quick to point out their "mistakes":
- attempting to engage the autopilot twice with the stick shaker active and unreliable air speed and ALT disagree;
- some posters previously said that retracting flaps early in this situation is not a great idea either;
- fighting with MCAS for about 5 minutes before using the cutout switches;
- temporarily re-enabling electric trim 5 minutes later.
However I do have some actual criticism about their later actions during and after the flight:
- "Step 3 is, of course, mandatory" - then it's funny they skipped that step. Instead of landing "as soon as conditions permit" they kept flying to the destination, with the stick shaker active for over 90 minutes (unless they pulled its circuit breaker). In my opinion flying to the destination in a bird that was clearly very sick and repeatedly tried to kill them was not wise. Yes, "land as soon as possible" was missing from the checklists for the problems they experienced, but still, unless they were afraid their airline would punish them for not continuing the flight, I don't understand why they continued their flight to the destination. In my opinion they subjected their passengers to unnecessary risk.
- Post flight they reported: "Airspeed unreliable and ALT disagree shown after takeoff, STS also running to the wrong direction, suspected because of speed difference, identified that CAPT instrument was unreliable and handover control to FO. Continue NNC of Airspeed Unreliable and ALT disagree. Decide to continue flying to CGK at FL280, landed safely runway 25L.". They made no mention in their report that they had the stick shaker active for the entire flight, or that they had to use the cutout switches and had to trim manually with the trim wheels for most of the flight.
Including that additional information in their report could have given the technicians a chance to find the real problem, or at least it could have given the next crew enough information to be able to deal with the problem successfully. I find it very strange that they didn't include that in their report.
To conclude, sorry, but I can't agree that this was a great job.