MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
Join Date: Mar 2015
Location: antipodies
Posts: 75
Likes: 0
Received 0 Likes
on
0 Posts
I realized how confusing the situation would have been for the Ethiopian captain after working on my comment comparing the differences between the pressure altitudes computed on the left side and the right side.
The broken AOA indicator messed up the computed pressure altitude on the captain side so severely that it was showing the aircraft much lower than it actually was, more than 1000 feet lower as the speed increased, reaching almost 3000 feet difference during the final dive. At some point after the MCAS activation the aircraft was slightly climbing, but the captain pressure altitude was showing the aircraft as failing to climb, despite the increasing speed. Also the indicated airspeed was lower on the left side than on the right side by up to 25 knots.
So overall the instruments were presenting to the captain a situation much worse than it actually was. It's not the same thing if you are at 1500 feet, you lose 250 feet of altitude, and then the aircraft slowly starts climbing, compared with what the captain was actually seeing: being at around 950 feet and losing 450 feet of altitude, then the aircraft not climbing at all, despite the increasing speed.
With that in mind, even ignoring other factors, it becomes more understandable why the captain didn't reduce thrust. And I think determining quickly which side had the unreliable airspeed and altitude information, and using the information from the other side, is one thing that could have prevented the accident.
The broken AOA indicator messed up the computed pressure altitude on the captain side so severely that it was showing the aircraft much lower than it actually was, more than 1000 feet lower as the speed increased, reaching almost 3000 feet difference during the final dive. At some point after the MCAS activation the aircraft was slightly climbing, but the captain pressure altitude was showing the aircraft as failing to climb, despite the increasing speed. Also the indicated airspeed was lower on the left side than on the right side by up to 25 knots.
So overall the instruments were presenting to the captain a situation much worse than it actually was. It's not the same thing if you are at 1500 feet, you lose 250 feet of altitude, and then the aircraft slowly starts climbing, compared with what the captain was actually seeing: being at around 950 feet and losing 450 feet of altitude, then the aircraft not climbing at all, despite the increasing speed.
With that in mind, even ignoring other factors, it becomes more understandable why the captain didn't reduce thrust. And I think determining quickly which side had the unreliable airspeed and altitude information, and using the information from the other side, is one thing that could have prevented the accident.
Join Date: Dec 2018
Location: 8th floor
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
There might be a confusion here between the Ethiopian accident and the Indonesian Lion air accident, where the FDR traces suggest the captain handed control to the FO before the crash.
Join Date: Jun 2019
Location: VA
Posts: 210
Likes: 0
Received 0 Likes
on
0 Posts
Once the flaps are retracted, the AOA malfunction triggers MCAS which then looks like a Runaway Stab Trim problem. As previously discussed, the aircraft was controllable if the flying pilot was using aggressive electric trim inputs (first Lion Air flight Captain and First Officer, Captain of the second Lion Air flight) and not so much if the primary response was with elevator (second Lion Air First Officer, Ethiopian Captain). Setting aside the issue of the delay or inability to connect the malfunction with the Runaway Stab Trim NNC, an open question is why three of the flying pilots were able to maintain aircraft control and two were not. This outcome is possibly related to training issues, automation policy (comfort with hand-flying, etc.).
BTW, reference some previous comments about stopping the moving trim wheel manually, 1) not really a problem given proper technique, and 2) I know of no historical case where this actually became necessary.
Simple questions. How many of you would retract the flaps when a stall warning is sounding off? Why would you do something which will raise the stall speed? Surely, the best thing to do would be to maintain the configuration and fly pitch and power while you try to sort out the multiple warnings.
Join Date: Jun 2019
Location: VA
Posts: 210
Likes: 0
Received 0 Likes
on
0 Posts
Simple questions. How many of you would retract the flaps when a stall warning is sounding off? Why would you do something which will raise the stall speed? Surely, the best thing to do would be to maintain the configuration and fly pitch and power while you try to sort out the multiple warnings.
I found it very interesting just after MCAS activated during the second Lion Air flight, the crew actually extended the flaps after having retracted them. The MCAS input stopped, although the stick shaker was still going. After a short time they retracted them again setting the stage for MCAS again. I would really love to know what they were thinking. Perhaps we will find out when the full CVR transcript is published with the final report.
I've mentioned before that the FCOM states quite clearly that the manufacturer cannot write a procedure for every possible set of circumstances, but some airlines give this concept very little consideration. If one's training and background includes a "big picture" emphasis, then I suspect then that there would be some hesitation to retract flaps with an active stall warning. If one's training emphasized following the written procedure without modification, then the flaps are probably going to come up - as we saw in all three of the incident/accident flights.
Join Date: Mar 2019
Location: On the Ground
Posts: 155
Likes: 0
Received 0 Likes
on
0 Posts
You know that MCAS only works with the flaps up...they most certainly did not. With everything else going on, I doubt they ever made the connection.
"Hey look! Some system that we don't know exists quits doing some function that we don't understand when we put the flaps down! At least for the moment. Wish that stick shaker would quit, though."
"Hey look! Some system that we don't know exists quits doing some function that we don't understand when we put the flaps down! At least for the moment. Wish that stick shaker would quit, though."
If you've extended the flaps due to a stall warning then the instinct will be to raise them once out of that condition unless you are following a procedure which specifically tells you to leave them extended. Had the crews been aware of the MCAS and there been a laid down procedure to deal with its possible faults then they might have only had unreliable airspeed to cope with, rather than fighting an unknown system which was trying to spear them into the ground.
Unreliable airspeed has been known about for years, crews are trained in the simulator and there is a procedure to follow in the QRH. The crew of the Malaysia Airlines A330 in Brisbane last year which experienced unreliable airspeed were able to get back on the ground safely.
Unreliable airspeed has been known about for years, crews are trained in the simulator and there is a procedure to follow in the QRH. The crew of the Malaysia Airlines A330 in Brisbane last year which experienced unreliable airspeed were able to get back on the ground safely.
Join Date: Jun 2019
Location: VA
Posts: 210
Likes: 0
Received 0 Likes
on
0 Posts
You know that MCAS only works with the flaps up...they most certainly did not. With everything else going on, I doubt they ever made the connection.
"Hey look! Some system that we don't know exists quits doing some function that we don't understand when we put the flaps down! At least for the moment. Wish that stick shaker would quit, though."
"Hey look! Some system that we don't know exists quits doing some function that we don't understand when we put the flaps down! At least for the moment. Wish that stick shaker would quit, though."
High level observation and the ability to correlate an aircraft manouvre to a previous configuration is what test pilots do. They have extensive education, experience and training in order to test new aeroplanes. The average line pilot is simply not equipped to deal with an out of the box situation that has been built into the aircraft.
Join Date: Jun 2019
Location: VA
Posts: 210
Likes: 0
Received 0 Likes
on
0 Posts
Unreliable airspeed has been known about for years, crews are trained in the simulator and there is a procedure to follow in the QRH. The crew of the Malaysia Airlines A330 in Brisbane last year which experienced unreliable airspeed were able to get back on the ground safely.
Der Spiegel
Renowned German publication, Der Spiegel, has produced a through piece of journalism on Boeing and the 737. It paints a picture of Boeing so damaging, it makes one consider the future viability of the company. It's the underhand way they're doing business, where their actions are 180 degrees opposite to their rhetoric, that's really scary.
It's in 3 pieces, the first piece is here https://www.spiegel.de/international...a-1282869.html
It also paints a scathing image of the collusion between the FAA and Boeing, to the point where FAA has completely lost all creditability, and makes you wonder what will happen in the rest of the world when the FAA, once again, rubber stamps the Max and clears it for a return to service.
Renowned German publication, Der Spiegel, has produced a through piece of journalism on Boeing and the 737. It paints a picture of Boeing so damaging, it makes one consider the future viability of the company. It's the underhand way they're doing business, where their actions are 180 degrees opposite to their rhetoric, that's really scary.
It's in 3 pieces, the first piece is here https://www.spiegel.de/international...a-1282869.html
It also paints a scathing image of the collusion between the FAA and Boeing, to the point where FAA has completely lost all creditability, and makes you wonder what will happen in the rest of the world when the FAA, once again, rubber stamps the Max and clears it for a return to service.
Join Date: Jun 2019
Location: VA
Posts: 210
Likes: 0
Received 0 Likes
on
0 Posts
High level observation and the ability to correlate an aircraft manouvre to a previous configuration is what test pilots do. They have extensive education, experience and training in order to test new aeroplanes. The average line pilot is simply not equipped to deal with an out of the box situation that has been built into the aircraft.
Join Date: Jul 2002
Location: Ireland
Posts: 596
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Apr 2008
Location: Paris
Age: 74
Posts: 275
Likes: 0
Received 0 Likes
on
0 Posts
Der Spiegel
Renowned German publication, Der Spiegel, has produced a through piece of journalism on Boeing and the 737. It paints a picture of Boeing so damaging, it makes one consider the future viability of the company. It's the underhand way they're doing business, where their actions are 180 degrees opposite to their rhetoric, that's really scary.
It's in 3 pieces, the first piece is here https://www.spiegel.de/international...a-1282869.html
It also paints a scathing image of the collusion between the FAA and Boeing, to the point where FAA has completely lost all creditability, and makes you wonder what will happen in the rest of the world when the FAA, once again, rubber stamps the Max and clears it for a return to service.
Renowned German publication, Der Spiegel, has produced a through piece of journalism on Boeing and the 737. It paints a picture of Boeing so damaging, it makes one consider the future viability of the company. It's the underhand way they're doing business, where their actions are 180 degrees opposite to their rhetoric, that's really scary.
It's in 3 pieces, the first piece is here https://www.spiegel.de/international...a-1282869.html
It also paints a scathing image of the collusion between the FAA and Boeing, to the point where FAA has completely lost all creditability, and makes you wonder what will happen in the rest of the world when the FAA, once again, rubber stamps the Max and clears it for a return to service.
Edmund
Join Date: Jul 2007
Location: the City by the Bay
Posts: 547
Likes: 0
Received 0 Likes
on
0 Posts
If the Max is not fit to fly (which it isn't in it's current form as is obvious) and can not be made to fly safely (which currently is very much in doubt) then it must be put away. Boeing may face bankruptcy without the MAX (from which it CAN recover) but should the MAX have one more crash Boeing will face extinction.
Thread Starter
Join Date: Apr 2015
Location: Under the radar, over the rainbow
Posts: 788
Likes: 0
Received 0 Likes
on
0 Posts
That said, I agree that it would be reasonable to wonder about Boeing's future viability -- if not for the fact that it's nearly impossible to believe that the government of the US, and the business and financial sectors together, won't do absolutely everything possible to maintain B as a going concern and world leader in aircraft manufacture.
Join Date: Jul 2002
Location: Ireland
Posts: 596
Likes: 0
Received 0 Likes
on
0 Posts
The only way the US government and financial sectors would be able to stop Boeing from going under after another crash, would be to so heavily subsidise its products, that airlines have no choice but to buy them. Boeing would then be effectively a state-aided nationalised company in all but name.
Thread Starter
Join Date: Apr 2015
Location: Under the radar, over the rainbow
Posts: 788
Likes: 0
Received 0 Likes
on
0 Posts
The problem with an international business like aviation is that you can’t make people buy your aircraft, especially if there are safety concerns. Even if the idiot Trump threatens to economically punish any country which doesn’t buy from Boeing, I doubt that many would, when their citizen’s lives are at risk.
The idiot Trump won't be around forever and, in any event, you are quite right that his threats wouldn't work to convince purchasers. Whatever happens, Boeing's commercial aircraft business depends upon the world believing that, going forward, its products are safe. I think that's an achievable goal, although it's going to require a significant change in corporate culture.
The only way the US government and financial sectors would be able to stop Boeing from going under after another crash, would be to so heavily subsidise its products, that airlines have no choice but to buy them. Boeing would then be effectively a state-aided nationalised company in all but name.
Join Date: Dec 2018
Location: 8th floor
Posts: 0
Likes: 0
Received 0 Likes
on
0 Posts
The article from Der Spiegel pointed out something interesting: with all the outsourcing Boeing did for component manufacturing, it should now be easier for new aircraft manufacturers to emerge, since they could use the same component suppliers Boeing does. So in their rush to increase profits as much as possible, they may have jeopardized their future market share. Basically killing the goose laying the golden eggs. I'm not familiar with the situation on the Airbus side, do they have similar levels of outsourcing?
From Der Spiegel:
From Der Spiegel:
And this all comes at a time when the Airbus-Boeing duopoly has been developing cracks. The two may still be the world's undisputed aerospace leaders, but companies in China, Russia and Japan are in the process of grabbing a bigger piece of the pie. Furthermore, it has become easier to build airplanes because a highly specialized global market of suppliers has developed that can deliver almost any part in the desired quality at the desired moment in time. The times when airplane construction was a calling card of unattainable technological excellence are coming to an end. Things are becoming more difficult, especially for Boeing.
Join Date: Jul 2002
Location: Ireland
Posts: 596
Likes: 0
Received 0 Likes
on
0 Posts
The article from Der Spiegel pointed out something interesting: with all the outsourcing Boeing did for component manufacturing, it should now be easier for new aircraft manufacturers to emerge, since they could use the same component suppliers Boeing does. So in their rush to increase profits as much as possible, they may have jeopardized their future market share. Basically killing the goose laying the golden eggs. I'm not familiar with the situation on the Airbus side, do they have similar levels of outsourcing?
I assume Boeing do the same but at the moment, nothing at Boeing would surprise me.