Posted on 05/20/2019 1:24:03 PM PDT by CondoleezzaProtege
Bjorn Fehrm, a Swedish pilot and aerospace engineer who is an analyst for Bainbridge Island-based Leeham.net, said the report assumes the accidents could have been avoided by “a really proficient pilot … on a good day.” But he said Boeing and Airbus cannot rely on the roughly 300,000 pilots flying worldwide having a good day and being perfectly trained for every emergency.
The veteran U.S. airline captain said that the American aviation community needs to avoid getting “too cocky about U.S. pilots being immune from mistakes.”
He said he’s spent a lot of time flying with local pilots in western China where the mountains are high and the flying is hazardous. I’d put them up against American airline pilots any day,” he said. “They are exceptional airmen.” And he criticized Boeing for designing an airplane in which a system triggered by a single sensor failure would present such challenges and require such a high-performance response from the pilots.
(Excerpt) Read more at moneymaven.io ...
Documentation about the computer-assisted trim settings to stabilize the upward pitching was lacking because the pilots weren't told about the automated leveling features to compensate for the forward placement of the engines.
The computer was trying to push the nose down and the pilots were trying to lift the nose back up during take-off. If this happened at 35,000 feet, they'd have time to look for the system configuration settings. Because it happened at 1,000 feet, they didn't have the time.
Ideally, they would have disabled it completely before taking off and re-engaged it at altitude, if they had known about it in advance.
-PJ
MCAS is not an autopilot system. MCAS is on when he autopilot is turned off (pilots are manually flying the aircraft) and the flaps are up.
“MCAS is not an autopilot system. MCAS is on when he autopilot is turned off”
I probably should have realized that. I say “autopilot” but it’s called a flight management system now, isn’t it?
I’ve read that there’s a switch to disable MCAS. Certainly it’s on the console and labeled. Wouldn’t you think all pilots would insist on knowing what it does?
Boeing calls theirs "Autopilot Flight Director System (AFDS)"
AFDS is a very complex system. I have found a CBT lesson for 737 NG AFDS. The lesson has 2 parts and is a total of 237 slides. I believe the 737 MAX would have the same AFDS. Here's the links:
I’ve read that there’s a switch to disable MCAS. Certainly it’s on the console and labeled.
MCAS cannot be disabled on its own. It is disabled by turning off 2 switches (located on the console) that disable the Speed Trim System (STS).
Wouldn’t you think all pilots would insist on knowing what it does?
The short answer is YES. Please refer to my earlier response #15:
During development and delivery of the 737 MAX Boeing decided that the pilots didn't need to know about MCAS. The 737 MAX had a procedure to handle runaway stab trim. MCAS malfunction would appear to the pilots as runaway stab trim.
That decision is going to cost Boeing a lot of money.
That’s exactly the way my instructor did it to me. :)
“MAX had a procedure to handle runaway stab trim”
I’m not an expert on piloting or the 737MAX.
Someone told me that with the two planes that crashed, the pilots were going through a step-by-step procedure to handle their situation, but the plane crashed before they got to the step that told them to disable MCAS.
It bothers me that MCAS failed in these two situations because the angle of attack sensor, which is a small airfoil protruding from the fuselage, was damaged, and that these angle of attack sensors are subject to being damaged by something like a bird hitting them.
Particularly bothersome is that Boeing had an extra-cost option to MCAS that would detect a wacky sensor. Very bad PR for this to be an extra cost option.
Here's a link to the preliminary report for the Ethiopian Air accident.
They initially performed the procedure for runaway trim. However, they were slow to identify the problem and by the time they disabled pitch trim, MCAS had put the aircraft into a dive that they could not recover from.
They deviated from the procedure and put pitch trim back on. They were then able to level the aircraft using the trim buttons on the yoke. When they stopped using the trim buttons, MCAS kicked back on and pitched the aircraft back into a dive.
They then tried to recover by pulling back on the column but did not have enough elevator authority to recover.
Particularly bothersome is that Boeing had an extra-cost option to MCAS that would detect a wacky sensor.
The extra cost options were AOA display on the PFDs and "AOA Disagree" warning message. These MAX options were standard on the 737 NG. Why Boeing took them out of the MAX and made them priced options is a huge question, still to be answered.
Below is a picture of the 737 NG, the version just prior to the MAX.
It appears to me that the MAX engines were raised less than 6 inches.
There are a lot of articles and threads on FR that discuss the flight control issue caused by mounting the engines higher.
I have not seen any article that adequately describes the flight control issue. Most of the articles blame additional lift created by the engine nacelles. Looking at the 2 pictures, the NG nacelles would also create additional lift. The only difference being nacelle placement.
IMHO, mounting the engines higher would cause minimal change in handling characteristics between the NG and the MAX. Any change in handling characteristics could be handled by the Elevator Feel Shift module.
” However, they were slow to identify the problem “
Uh oh. It’s time for me to just sit back and watch how this plays out.
Having a bad design that pilots did not overcome is not pilot error. I’m a pilot and an aerospace engineer.
No, they could not have. Not that low to the ground and not fast enough. Elevator trim is trim not maneuvering.
“Engineers inside Boeing would never not point out the software system had a single point of failure to their superiors.”
Wanna bet? Especially since those that wrote the software we’re most likely offshore.
HJ has no idea what she’s saying. She just spouts false Internet phrases like she’s an expert.
THEY had an opportunity. Go back and look closely at the timeline.
No porpoise maneuver, but brute force on the trim wheel, or, leaving the electrics on and trimming electrically.
They did neither.
Nicely outlined. But LOL: Really driving home my prior point that autopilot (and manual flight, by consequence) are terms which have no bearing when referencing modern commercial aircraft.
The decision to not include AOA Disagree (an option) on the subject aircraft will also prove to be an expensive mistake. But I’m not sure how much of a difference it would have made under the circumstances.
At a minimum, had the pilots of the (saved) Lion Air flight reported their malfunction, that plane might have been routed for maintenance rather than scheduled the next day for its fatal flight...
Agree. Autopilot and manual flight do not adequately describe what the pilots are actually doing. In almost all cases, manual flight means the pilots are providing inputs to the primary flight controls through the yoke & column. Auto-throttles take care of airspeed and the Speed Trim System takes care of pitch trim.
The decision to not include AOA Disagree (an option) on the subject aircraft will also prove to be an expensive mistake.
This decision has me stumped. I believe it is related to keeping "differences training" as CBT vs Level D simulator sortie. I would really like to get a copy of the differences training CBT and see if AOA disagree being removed is even covered.
But I’m not sure how much of a difference it would have made under the circumstances.
I believe both crashes would have been avoided and here's why:
This goes to training. If AOA disagree and AOA gages are displayed on the PFD, then Boeing would have to provide a checklist procedure to follow when the AOA disagree message is displayed. Training would be required in a Level D simulator, and the pilots would have known what to do.
At a minimum, had the pilots of the (saved) Lion Air flight reported their malfunction, that plane might have been routed for maintenance rather than scheduled the next day for its fatal flight...
Here's the info regarding the Lion Air prior flight (bolding is mine, my comments in red):
"On 28 October 2018, a Boeing 737-8 (MAX) aircraft registered PK-LQP was being operated by PT. Lion Mentari Airlines (Lion Air) as a scheduled passenger flight from I Gusti Ngurah Rai International Airport (WADD), Denpasar to Jakarta as LNI043. During pre-flight check, the PIC discussed with the engineer of the maintenance actions that had been performed including replacement of the AoA sensor and had been tested accordingly.
The aircraft departed at 1420 UTC (2220 LT) at night time, the DFDR showed the stick shaker activated during the rotation and remained active throughout the flight. About 400 feet, the PIC noticed on the PFD the IAS DISAGREE warning appeared. The PIC handed over control to the SIC and cross checked the PFDs with the standby instrument and determined that the left PFD had the problem. The PIC noticed the aircraft was automatically trimming AND. The PIC moved the STAB TRIM switches to CUT OUT and the SIC continued the flight with manual trim without auto-pilot until the end of the flight. AND trimming indicates AOA malfunction. PIC quickly recognized the problem and moved the STAB TRIM switches to CUT OUT. SIC continued flight with manual trim. PIC did not relate the AND trimming to AOA malfunction and did not inform engineer. If 'AOA disagree' were installed, then the PIC would have informed the engineer and maintenance would have been performed on the AOA sensors.
The PIC declared “PAN PAN” to the Denpasar Approach controller due to instrument failure and requested to maintain runway heading. The PIC performed three Non-Normal Checklists and none contained the instruction “Plan to land at the nearest suitable airport”.
The remainder of the flight was uneventful and the aircraft landed Jakarta about 1556 UTC. After parking, the PIC informed the engineer about the aircraft problem and entered IAS and ALT Disagree and FEEL DIFF PRESS problem on the AFML. Unfortunately, the engineer was unaware of the AOA malfunction.
The engineer performed flushing the left Pitot Air Data Module (ADM) and static ADM to rectify the IAS and ALT disagree followed by operation test on ground and found satisfied. The Feel Differential Pressure was rectified by performed cleaned electrical connector plug of elevator feel computer. The test on ground found the problem had been solved."
This post is long enough...All in all, a sad sequence of events.
Nicely done. Gives one a warm fuzzy feeling about flying commercial. /s
Boeing is a democrat company where everyone passes the buck and no one is accountable anymore.
“many pilots would have landed the plane safely. “
Are your stating that many pilots have had MCAS issues low to the ground?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.