Posted on 05/05/2019 7:27:23 PM PDT by E. Pluribus Unum
AoA tells you the relative orientation of the aircraft with respect to the airflow. A gyroscopic detector tells you the absolution orientation of the aircraft in space without regard for the airflow direction. Those are two very different things.
I don’t believe that Boeing is in any danger of going out of business. I believe that they are going to struggle a lot until this 737 max issue is satisfactory resolved and put behind them. They may lose some aircraft orders in the process. I have always had a lot of respect for Boeing and have worked with them on numerous programs including ALCM, ABL and EKV.
Can you say ...DC-10 and L-1011.
Now cargo haulers. Not really safe enough for passengers.
The DC-10 was built by McDonnell-Douglas prior to merging with Boeing, the L-1011 is a Lockheed built aircraft. I don’t think there is many of either aircraft still in service. I’ve seen an occasional DC-10, I haven’t seen an L-1011 in quite awhile.
Boeing’s 737 MAX’s REAL problem.
“To handle a longer fuselage and more passengers, Boeing added larger, more powerful engines, but that required it to reposition them to maintain ground clearance. As a result, the 737 can pitch up under certain circumstances. Software, known as the Maneuvering Characteristics Augmentation System, was added to counteract that tendency.”
“But some aspects of the legacy 737 design are vintage headaches, such as the ground clearance designed to allow a staircase that’s now obsolete.” (”the Boeing 737-100 had folding metal stairs attached to the fuselage that passengers climbed to board before airports had jetways. “)
https://www.latimes.com/local/california/la-fi-boeing-max-design-20190315-story.html
Repositioning of the engines is a fatal redesign flaw. One they can’t take back. Everything they do after that are attempts at mitigating their fatal mistake.
Discussion in Boeing boardroom:
“What is the cause of this dangerous pitching up problem and how do we fix it?”
“The problem is we made the engines too big and moved them too far forward.”
“Well we can’t do anything about that NOW, what else can we do?”
If true, even worse.
L-1011 retired January 2019
DC-10 Likely gone in 2019
https://www.youtube.com/watch?v=6bpAIMfPsg0
“FedEx announced earlier this month that it would begin to retire a considerable portion of the older widebody aircraft in its fleet. The announcement from the express carrier came on the heels the completion of its phase out of the 727-200F, which ceased flying for the Memphis giant earlier this month after more than 30 years of service. Included in the accelerated retirements are the A310F and the MD-10-10F/-30F. Five MD-10-10Fs and an equal number of A310-200Fs were retired in May, while future retirements will be accelerated for 47 more MD-10-10Fs, 16 A310-200Fs, and 13 MD-10-30Fs.
This MD-10-10F, N365FE (msn: 46601), named “Joey” (nearly all FedEx airplanes are named after the children of employees) is the oldest widebody in FedEx’s fleet.
Delivered to United Airlines in July of 1971, “Joey” was the sixth DC-10 ever built and the second oldest active DC-10 in the world, with the original Orbis Flying Eye Hospital (line number 2) being the only older and still extant example of the type.”
https://cargofacts.com/reelin-in-the-years-fedex-md-10-10f/
Problem was there were no AOA gage display on the PFDs and no AOA Disagree alert. The only indication in the cockpit is the left stick shaker activation and the voice warning is yelling "Stall".
The proposed fix, in flight test, will fix the problem.
Here's what I don't understand...75° AoA is impossible to achieve in an airliner. At the speeds the aircraft was flying, 75° AoA would rip the wings off. Boeing could have easily included logic in the original MCAS software to disregard impossible AoA. Any AoA above 25° would be rejected and the other AoA sensor would be used.
Boeing made some stupid decisions in development and delivery of the MAX. I hope the guilty individuals are punished appropriately.
Correct...
However, in a computerized aircraft the GPS/IMU provides pitch and roll, G sensors provide G and yaw, pitot/static provide IAS/Altitude. With all of this information the FCC (Mission Computer in military aircraft) can calculate AoA.
IMHO, Boeing should have implemented this as a crosscheck to the AoA gauges.
True enough however; If they put MCAS in the MAX for a good reason then why not cross check the AOA or even multiple AOA's with the artificial horizon?
Here's another thought; if flying in autopilot the MCAS is disabled but of course the stabilizer trim is still very much active. I doubt the AP bases stab trm setting on any single instrument.
BTW we're pretty sure the 737MAX got the MCAS from the Airforce KC-46 as a quick off the shelf solution, but they somehow missed the fact that the KC-46 has three AOA's not just one.
SINCE this is from CNN, it must be assumed some error in reporting occurred, that the entire story was manufactured from the tiniest, misunderstood morsel of truth ...
re: “Bean counter about to be fed into the coffee grinder. “
Customer drives requirements, and ultimately the aircraft they desire, and purchase ...
Three authors of this article, and not one of them can get a simple detail right.
The AoA Indicator lets the pilots know the angle of attack of the aircraft, as displayed on their Flight Display.
Asshats.
But if the airline didn't buy the AOA Indicator option, there IS NO DISPLAY OF ANGLE OF ATTACK ON THE FLIGHT DISPLAY.
How exactly is the pilot supposed to know that the AoA sensor fluctuated from 11 degrees to 75 degrees if there is no display of that information?
And for the record, the display of angle of attack is not required for safe operation of the aircraft. Many aircraft do not display that information, yet still have AoA sensors and use that information to warn of impending stall by operating a 'stick shaker.'
The MAX has two AOA sensors as 'standard equipment.'
The FCCs (Flight Control Computers, where the MCAS software lives, along with all of the other computer flight software such as autopilot, automatic speed trim, etc.,) alternated between using the Left or Right AOA sensors for MCAS on every other system startup, so that only one AOA sensor was used for MCAS at a time.
The left AOA sensor was still used at all times by the left FCC, and the right AOA sensor was used at all times by the right FCC for warning of approach of stall, and to display AOA on the Flight Display if so equipped.
Sales guy: Let’s offer this critical information at a upgrade price and bury the details on how to recover the airplane in the manual as well.
Southwest Airlines ordered 280 Max 8s / 36 in service. Purchased the disagree alert option, and also installed an angle-of-attack indicator above the pilots’ heads. Following the Lion Air crash, the airline said it would place the sensor on the pilots’ main computer screens.
United Airlines ordered 137 Max 8s / 14 in service. Did not select the indicators or disagree light. The airline says that pilots use other data to fly the plane.
American Airlines ordered 100 Max 8s / 24 in service. Purchased both.
Boeing plans to make the disagree light standard moving forward. The company will also update the MCAS software; the changes will include combining data from both sensors, rather than just one as was originally the case. If the sensors disagree in the readings, the MCAS will be disabled. The AOA indicator will remain optional. New York Times, March 21, 2019.
And as I understand it, there is no option to buy the disagree indicator separately from the AOA display. If you bought the AOA display option, the AOA disagree display came along with it. The reasoning is that if you are giving the pilots information on their displays, it needs to be checked for reliability.
Boeing is now saying that the AOA disagree should have been included on all aircraft regardless of AOA display option, but that it didn't get implemented correctly.
Boeing's view was that the MCAS software would only be active during a very narrow and specific flight profile that most pilots would never activate it, hence the reason it wasn't made more prominent to the pilots.
However, AOA sensor failure and its effects on MCAS were not fully appreciated.
The correct procedure in case of any MCAS malfunction, including a failed AOA sensor, is to follow the "Runaway Stab Trim" emergency procedure. However, runaway stab trim rarely happens in earlier 737s, so pilots don't think of Runaway Stab Trim action items immediately.
MCAS made the odds of experiencing Runaway Stab Trim much more likely, however, and the procedure should have been stressed more than it already was.
Here's some little reported info:
Boeing signed a contract selling Boeing 737 MAX aircraft to launching customer Southwest Airlines. Media report that “Boeing had committed to paying Southwest Airlines $1 million per plane if the 737 MAX ended up requiring pilots to spend more time training on simulators.”.
I have no way to verify this information. However, if true, Boeing has 280 million reasons to cut corners. The marketing genius who agreed to this scheme should be fired.
Sounds like Southwest Airlines didn't want to buy any 737 Max Level D simulators.
Thanks.
“Runaway stab trim rarely happens in earlier 737s, so pilots don’t think of Runaway Stab Trim action items immediately.”
And given the ground proximity and MCAS commanding down pitch, pilots only have a few seconds to assess and act.
Having ONE AOA sensor feeding the FCC is a horrendous decision by Boeing especially when failure mode and effects leads straight to a crash. I’d be concerned about using only two AOA sensors to FCC. How can the system adjudicate which is correct and reject the faulty reading? Will the readings be compared to a separate inference of AOA such as the artificial horizon?
Process control plants frequently use “auctioneering” logic to determine which of three different and independently measured values to feed to the control system.
So... if one AoA is out is there a way of the crew choosing the other AoA to be looked to by the MCAS.
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