Most likely yes, it would have made a safe return. The reason I am saying most likely is that the Ethiopian pilots are reported to have followed the Boeing guidelines for disabling MCAS however as you stated, they left other aspects of the flight uncontrolled which complicated the situation to the point of fatality.There are a number of questions that come out of this:
- Did the jump seat pilot correctly diagnose the issue or did he get lucky? I say lucky because remember at this stage Boeing had not made the presence of MCAS widely known.
- If that 3rd pilot had been one of the regular crew that day and there had not been a third pilot present would he have made the same decision or would he have become overwhelmed as with the other crews?
[li]
The Ethiopian pilots were in Visual Metrological Conditions, meaning they didn't have the extra burden of trying to keep the airplane upright in clouds with no visual cues. So the
Other Apspects of the flight following the Trim Disconnect would have been to reduce the thrust and return to the airport. Or as they say in the Business - Fly the Plane -.Unfortunately many of these
3rd world airlines put pilots into the plane with very low hours and little hands on flying experience. A good example is the 350hr Right seater on the Ethiopian flight. Mind you, that the average flight student at least here in the U.S. - just to get your Private Pilot license is around 70hrs. Although the FAA allows you to get it in as little as 40hrs. More than 1/2 those hours are with an instructor. To get your commercial license is around 250hr total time, and less if you attend a Part 141 school. Thats 250 to 350 hours total time spread out over 2+ years to attain such time. So, consider how much experience the right seat pilot could have really had and put that into perspective.
With the engines set to takeoff power during the entire event - it is a good indication the crew quickly became overwhelmed. Although they initially performed the runaway trim procedure correctly following the recommended procedure. They spent less than 6 seconds trying secondary trim, and then re-activated the Primary Trim. That is not in ANY manual.
There are two trim wheels sitting next to each pilots Knees the size of a dinner plate blackish brown in color with a big 1" white stripe painted on them. It moves anytime the plane is being trimmed. You wont miss it.
When it moves uncommanded, the "Memory" (Immediate action)(No Looking it up in the Emergency Checklist) item for every aircraft is to disable the Primary Trim. Every Pilot is tought this, trained in class on this, given an oral exam on this, and trained in the simulator. It doesn't get overlooked. If it is, then that's on the Airline training department, not the manufacturer.
You say
"Lucky" - I say the 3rd pilot studied his manual and
offered the proper advice because that is what he was trained to do. It doesn't matter whether the trim malfunctioned or MCAS activated it. The deciding factor is if it moved without pilot or autopilot input.
Since the pilot deactivated the autopilot and was hand flying and getting uncommanded trim, its obvious he recognized a trim problem countering with opposite trim. What isn't obvious is why he waited so long to deactivate the trim - again more than likely he was overwhelmed and input overloaded.
The Ethiopian 350hr right seater was reading through the Emergency checklist taking up valuable "Minutes" on items that should have been quickly looked up and some by memory. This is a strong indication of a lack of thorough training, lack of experience, and a strong indication about the airlines culture as it relates to safety and desire to make money. Having a 350hrs total time person in a jet with sophisticated systems when compared to your Cessna 172 in an emergency situation is about as helpful as 5 year old sitting in a puddle of spilled milk while you try to clean it up.
BOEING handled the entire MCAS situation completely wrong, should be going through what they are going through, and is paying the price - as they should.
And while the Pilots made mistakes in their handling of the events no matter what % it contributed, in your 8 Bullet Points, I did not see anything put onto the airlines themselves, there lack of maintenance and safety processes, or their governing body which should oversee such actions, which BTW owns the airline. The Airlines and their respective Governments are as much a party to these accidents as the manufacturer and they clearly put the desire to make Money over Safety.