Countries Restricting 737 MAX Flights After Second Crash

[Suvorov]

After 20 months on the tarmac that followed two fatal crashes, Boeing's troubled 737 Max airliner has been given the green light to resume passenger flights, the Federal Aviation Administration announced Wednesday.

Ironic. This time last year the biggest worry at my company was “where are we going to get the airplanes we need”? Now we are worried about furloughs and pay cuts. Our older airplanes that are coming up for heavy maintenance are going to be parked. While it will be nice to see the MAX finally back - the only thing it will be doing for us is burning less gas until the industry once again reaches a positive rate.

[peterb]

DALLAS — A Boeing pilot involved in testing the 737 Max jetliner was indicted Thursday by a federal grand jury on charges of deceiving safety regulators who were evaluating the plane, which was later involved in two deadly crashes.

The indictment accuses Mark A. Forkner of giving the Federal Aviation Administration false and incomplete information about an automated flight-control system that played a role in the crashes, which killed 346 people.

https://www.npr.org/2021/10/14/10461...x-mark-forkner

[Lon]

I just saw that Netflix has a show about this called Downfall. Didn’t watch it yet.

[ccmdfd]

I just saw that Netflix has a show about this called Downfall. Didn’t watch it yet.

Started watching it last night, finished it up this morning.

It's OK. I'm certainly not a fan of some of the mistakes Boeing made with this whole situation, but this movie came off as a major hit piece. Furthermore, any shows that portrays the US Congress as being the White Knight on the White Horse coming in to save the day puts me off.

I've seen some YouTube videos do better jobs of describing what actually led to the crashes.

[0ddl0t]

Watched the movie last night and then reread this entire thread this morning. PF is pretty lucky to have so many knowledgeable folks from so many different fields...

You also introduced head/tail winds in your question, and that leads to yet a third speed used in aviation: ground speed which is the actual speed of the aircraft not relative to the air mass that surrounds it but relative to the ground itself.

Ground speed is estimated as True Air Speed + wind (positive for tail wind, negative for head winds) and conclusively deduced from navigation. It can be as rudimentary as timing your passage over two known landmarks along a fixed course (not fixed heading, two different things) or as sophisticated as getting it from your GPS.

If the wind isn't exactly on your nose or tail, some trig needs to happen to calculate the wind vector that is on your nose/tail.

Does the Coriolis effect make much difference?

Interesting reading on changes to the size of the trim wheel and the stabilizer, as it evolved from the Classic to the NG. Requiring more muscle power to crank the manual trim wheel, and necessitating the invention of a roller coaster maneuver to unload the stab in order to retrim it manually. I’ll bet the passengers would love that maneuver.

https://www.moonofalabama.org/2019/0...g-737-ngs.html

Writer is a bit dramatic/hyperventilating at time, but the information is detailed and accurate. Boeing could have more problems going forward. Time will tell.

Random question after watching the crew struggle with the trim wheel in that article's video: if someone (or something) wedged itself against the manual trim wheels would it be overpowered by electric trim and/or MCAS?

[entropy]

The final item on the Runaway Stabilizer Trim Checklist is:

STABILIZER TRIM WHEEL—GRASP AND HOLD

Usually, this is best accomplished by reaching across the center pedestal and grasping the opposite side wheel. (There is one wheel on each side.) You get a better grip on it that way. It’s about 2” thick and 8” in diameter. You can physically hold it and thus stop the stabilizer from trimming.

This is AFTER you have accomplished the other memory recall items which include attempting to use the main electric trim to counter the movement, (via the thumb pickle switch) and selecting both Stabilizer Trim Cutout Switches to the “Cutout” position. These are (and always have been) located at the base of the throttle quadrant. They have been located in the same exact position since the 707 first rolled off the assembly line. The procedure is a Memory Recall Item and has been for nearly 60 years. MCAS is nothing more than a Speed Trim system on steroids. Speed trim has not only been a part of the 737s systems since the -700 but a similar system has been used in various airplanes and airliners dating back to the DC-9. In that application it was called “Mach Trim” but it’s basic function was the same...automatic trimming of the stabilizer.

Coriolis is one of those things you learn about, but in actuality, you never think about again.

[ccmdfd]

Maybe this is been brought up before and I have just missed it.

But back after these two crashes occurred, and then they discovered that it was due to repeated mcas activation dodue to a faulty sensor, did they ever run US pilots through this scenario in a simulator and see if the results were the same?

[0ddl0t]

Maybe this is been brought up before and I have just missed it.

But back after these two crashes occurred, and then they discovered that it was due to repeated mcas activation dodue to a faulty sensor, did they ever run US pilots through this scenario in a simulator and see if the results were the same?

They definitely ran through simulators to determine how much time the pilots had to respond correctly (something like 4 seconds). But we know the sensor was bad for the prior 4 Lion Air flights and that mcas for sure activated on the flight preceding fatal crash. That Indonesian crew responded appropriately.


Edit: 4 seconds was the typical response time, over 10 seconds was catastrophic:

“With pilot training to recognize the runaway and use
of teamwork, the failure was found Hazardous, which
is the same as the item C finding. A typical reaction
time was observed to be approximately 4 seconds. A
slow reaction time scenario (> 10 seconds) found the
failure to be catastrophic [10-9/hr] due to the inability
to arrest the airplane overspeed.”

https://www.incose.org/docs/default-...rsn=699b67c7_0