The Lev

What you are hearing is highly misleading. The story being circulated (if we are thinking of the same one) is that the pilots were not trained on a 737MAX simulator. This is almost certainly true as very few MAX simulators have been delivered. They were however training on a 737NG simulator. AFAIK Boeing and FAA maintain that the MAX and NG retain the same type rating and are similar enough not to reqiure pilot training on a dedicated MAX simulator in order to fly the aircraft.

One can quibble as to whether you agree with what the manufacturer and regulator have allowed, but it's not fair to blame the pilots and airline for following the rules.

lsquare

You mean at SFO? LMAO!

CZAMFlyer

The attitude indicator displays pitch and roll but not AoA information.

ffsim

I'll say this as someone who would fly on an AC 7M8 tomorrow: the fact that Boeing intentionally did not disclose the existence of MCAS is completely inexcusable, regardless of any pilot's (highly debatable) inability to fly the plane.

The Lev

Very interesting article on why the Lion Air and Ethiopian aircraft crashed..."MCAS didn’t crash the aircraft, Blowback did.

This week a poster in the Professional Pilot’s forum revealed the Boeing 737 has a blowback elevator problem at high dynamic pressures (thanks Dominic Gates of the Seattle Times for pointing me to this post). Now the penny dropped.

I know all about blowback problems of elevators. It was the most dangerous shortcoming of the fighter I flew, the SAAB J35 Draken. Even more dangerous than its famous “Super stall”, a Pugachev Cobra like deep stall behavior the aircraft would only exit from if you “rock it out” of the stall (more on this some other time). While “Super stall” is scary, Blowback is deadly.

Blowback means the elevator is gradually blown back to lower and lower elevation angles by the pressure of the air as the speed increases. The hydraulic actuators can’t overcome the force of the air and gradually back down if the force of the air grows too strong
<snip>
he JT610 crew knew nothing about MCAS and a potential blowback problem. The ET302 crew knew about the MCAS problem but not about the danger of flying to fast while sorting MCAS.

I have checked with longtime pilots of the 737. They have not heard of a Blowback problem when flying at elevated speeds at low altitude. And before MCAS there was no reason to, it was beyond normal flying practice.."

https://leehamnews.com/2019/03/22/bj...-crash-part-2/

yulred

Stranger

Thoughtful comment on Boeing's situation: https://www.flightglobal.com/news/ar...boeing-456821/

Mikey Mike Mike

I know that Air Canada will muddle through this like the other carriers. I think the effect with AC has been more profound given the max generally operating the trans canada / west coast US - esp from Montreal and the niche LH routes like Halifax and St Johns to London.
The longer impact for AC will be how many regular PAX (in the short term at least) will be happy to fly on a max when they do take to the sky again. Personally, I will - but not immediately as I'd want to see a good year accident free.
The other heroes of the moment for AC are the 6 x 767s and the E190 fleet who will soldier on for longer than expected

CZAMFlyer

It's nuts to think that a single accident-free year is enough to create a sense of satisfaction amongst the public. We all have our varying levels of comfort based upon knowledge, experience, playing-the-odds or blissful ignorance, but I think enough negative global attention has been drawn towards this type that it will become a toxic asset for many airlines. Never loved by the passenger to begin with (at least not within this forum), I can't imagine many people will be eager to queue up to ride the Max if/when it returns to service.

I'd want to see an accident-free period massed by the global fleet measuring in the millions of hours. Given that the 350 current Maxes in service would likely accrue in excess of 1 million hours of flight per year, let's see if they can string together a half-decade free of non-mechanical related accidents.

It might be too late for some - I bet some airlines are drawing up plans to defer/cancel their Max orders or shed their existing frames. Boeing will lose billions of dollars with this issue in lost orders, imposed penalties, family compensation and perhaps most importantly in the long-term: will lose customer trust.


(this probably needs to go to the main 737 Max thread...sorry)

bimmerdriver

WRT the part in bold, with all due respect, it's complete nonsense. When an aircraft enters a stall, the pilot should be able to get out of the stall by changing the trim (i.e., pushing the nose down, which is exactly what MCAS is supposed to assist with). In fact, I think your statement is the opposite of the reality. If an airplane was designed that could not be controlled out of a stall by changing the trim, that would be a problem. Such an airplane should have an ejection seat and it should not carry passengers.

As for calling MCAS a "gimmick", that's also nonsense. MCAS is part of the 737 MAX flight control system. The purpose of the flight control system is pretty obvious. It's to control the flight. The specific purpose MCAS has as part of the flight control system was to make the 737 MAX stall in the same predictable manner as the other 737 models. There are very few modern airplanes that don't have a flight control system that intervenes in some way or another to make the airplane behave in a safe and predicable manner. Aircraft manufacturers routinely use the flight control system to minimize the amount of relearning that pilots must do when they switch from one type to another type. This is not a "gimmick". This is how Boeing (e.g., 757/767, 787/777) and Airbus (A31X/32X) get cross-type certification. In theory and normally in practice, there is nothing wrong with this.

The problem in this case is not that Boeing put MCAS on the 737 MAX, it's that MCAS seems to be not very well designed, with respect to the number of AoA sensors it uses and also with respect to how it accomplishes its purpose(s) and Boeing seems to have not done a very good job of communication the role of MCAS to the pilots. I suspect that the airlines had something to do with the latter, as well.

After all of this is said and done, the 737 MAX will still have MCAS, but it will work differently, be more reliable / predictable and pilots will be properly informed on its correct operation.

Stranger

RatherBeInYOW

Lol!

bimmerdriver

You're confusing trim and trim tabs. Here is a good reference: 737 MAX - MCAS.

If you want to hear about the 737 MAX from an airline pilot's perspective, here is great video: Juan Brown, the presenter flies in the right seat of the 777 for AA. He has other very informative videos about the 737 MAX, the 777 and many other related topics.

Also, trim tabs are used in both manual and autopilot flight. In manual flight, using trim tabs allow the pilot to maintain the desired attitude without having to apply constant pressure on the yoke / stick. In autopilot flight using trim tabs prevent the attitude from changing abruptly when the autopilot is disengaged.

WildcatYXU

Trim tabs? No, there are no trim tabs on transport category aircraft. At least not at the current ones. The entire horizontal stabilizer is moving when the aircraft is trimmed.

bimmerdriver

If you're really wanting to know how stabilizer trim works on a 737, here is a great reference: Stabilizer Trim

tl;dr, it's complicated.