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In fact, ALL people divide safe and unsafe as black and white. Is flying in an aircraft "safe"? Is driving a car "safe"? These are not absolutes. |
Fly Aiprt
Originally Posted by Fly Aiprt
(Post 10481456)
One must remember that the 737 was a "certified" aircraft, and so was supposed to be trimmable at any speed within the flight envelope.
So there is nothing wrong with leaving full thrust with a stickshaker alarm at takeoff. Duly warned and briefed pilots experienced great difficulties in the sim when confronted with the same scenario. Even though nothing was at stakes, they say they had their hands full with dealing with the recovery and fighting tunnel vision. What with a real unexpected alarm in a real aiplane with no previous briefing ? And remember, the "certified" 737 was supposed to be hand trimmable at the time. Only now do we know Boeing "autocertified" their airplanes, and there are suspicions of trim difficulties on the MAX as well as the NG. |
https://www.wsj.com/articles/boeing-...ys-11559117714
Boeing 737 MAX Could Stay Grounded for at Least Two Months, Trade Group Says IATA boss says the impact of the global suspension of MAX flights on airlines has been significant By Robert Wall and Na-young Kim May 29, 2019 4:15 a.m. ET The boss of the airline industry’s largest trade group Wednesday said the Boeing BA -0.01% 737 MAX fleet could remain grounded for another two months or more in the wake of two crashes. IATA Director General Alexandre de Juniac said the timing on the MAX’s return to service was up to regulators, but airlines were bracing for 10 to 12 more weeks of delay before the plane can resume commercial service. The U.S. Federal Aviation Administration last week hosted foreign regulators to discuss the process of clearing the MAX to commercial service after the grounding that followed the March 10 crash of one of the planes in Ethiopia. It was the second MAX crash in less than five months. “We have to maintain an alignment between those authorities. Hopefully an alignment in terms of schedule,” Mr. de Juniac told reporters. Boeing has been working on a fix to the flight-control flaw implicated in both crashes, but hasn’t submitted the formal submission to the FAA as it responds to questions from regulators. He said the impact of the grounding on airlines was significant, though IATA doesn’t yet have a figure for the financial hit from canceled flights, higher costs and lower sales. If the plane remains grounded for another three months, it would hit airlines for the bulk of their summer flying, the busiest travel period for most MAX operators. Mr. de Juniac said it was unfortunate that the FAA meeting last week didn’t spell out a timeline for the MAX’s return to flight. IATA on the same day held a meeting of 23 airlines that have the MAX in their fleet or on order. Boeing and the FAA provided information to the carriers at the event. Mr. de Juniac said carriers are hopeful that regulators will “find a reasonable time frame” to safely return the MAX to the sky. Mr. de Juniac said a meeting between airlines, Boeing and regulators is likely to be held in five to seven weeks to prepare for a smooth MAX return to service. “We need to restore confidence in our industry,” he said, both related to the MAX and the certification process for planes more widely. IATA members are gathering for their annual meeting, which starts Sunday, against a backdrop of global trade tensions and uncertainty over Britain’s exit from the European Union, which have dented demand for air travel. Air freight demand in April fell 4.7% compared with a year earlier, continuing a slump in demand that began in January, IATA said. The Trump administration this summer plans to impose higher tariffs on numerous goods made in China, denting freight demand. The airline industry is only one of several to feel the sting. Danish shipping giant A.P. Moeller-Maersk AS last week reported a first-quarter loss and warned that rising trade tensions between the U.S. and China could cut container growth by up to a third this year. Write to Robert Wall at [email protected] |
Originally Posted by Fly Aiprt
(Post 10481456)
One must remember that the 737 was a "certified" aircraft, and so was supposed to be trimmable at any speed within the flight envelope.
The B737 is not alone in being able to be put into a severe out of trim case, but the fact that a condition can arise where the trim cannot function at all as a result of the error is a serious lack of certification shortfall in the protections provided by certification. The only part of the regs that the MCAS appears to be actually non compliant with is related to stability augmentation systems. The trim case it may well have been compliant, the rules themselves were deficient in this case, and appear to be in any case where a condition may arise where the stabiliser can only be returned to function by undergoing special procedures that were not generally taught or discussed, could require a breach of the single crew on the controls policy, and would exceed the control input force requirement of certification. That latter item is a possible breach. The OEM and the industry have had an expensive lesson on the real world behaviour of the worlds favourite jet transport, and as always the industry will learn from the wreckage and reinforce rules as a result. This particular deficiency is going to be more than a minor matter, personally, I would think that there is some serious issues raised in how to ensure trim is always able to be controlled. watch out for some T tabs on elevator TE in the near future etc... Perhaps nothing gets fixed. |
Airworthiness
JSP 553 is not the only definitive statement regarding aeronautical products and reflects the USA Military and CFR14 FAR interpretations. This is a good definition, however Nations signatory to the ICAO Convention and in particular Annex 8 have jurisdiction concerning the interpretation and this is reflected in the National Regulatory Organisational standards. Whilst acceptance of Aeronautical Product certification standards between many but not all nations is to date convention this MAX 8 situation indicates that this may not hold true for the future. EASA have made it quite clear that automatic acceptance of FAA MAX 8 changes will not happen. This may have implications wrt the ICAO Convention not least as it also may affect Annex 13 and its interpretation. |
Originally Posted by cessnapete
(Post 10481940)
“Nothing wrong with leaving full power on”. Why would a competent crew ever do that? With speed whistling through 250/300 kts you are obviously not stalling. ( easily confirmed by GS readout). Reduce power, pitch and power ( covered in your Type Rating) if ASI indications unreliable. Partial flap as required, no automatics due erroneous Stick Shaker, and manually fly a return circuit to land. Now, in the real airplane at takeoff, why would a crew reduce thrust while battling with a persistent stickshaker (it makes noise, no whistling sound) and lots of most distracting alarms, instead of climbing away to sort things out ? Even just in a sim, warned and briefed crews had their hands full doing the correct thing, which implied resorting to the roller-coaster maneuver. And just got away by a small margin that the real crew in the real event didn't have. And BTW, it appears that no flight sim to date reflects the real airplane... So...I must admit that I'd not be so affirmative... |
Originally Posted by fdr
(Post 10481965)
that the 737 was a "certified" aircraft, and so was supposed to be trimmable at any speed within the flight envelope. Was meaning "the trim was supposed to be moveable"... |
fdr #44, Interesting views, no disagreement. ‘This particular deficiency is going to be more than a minor matter …’ It might be premature to discuss specific solutions for a deficiency which as yet is not clearly understood (at least publicly). Elevator effectiveness, yes; but also in normal operation consider the combined horizontal tail surfaces - trim drag. What do you imply with TE tabs; corrective effect must overcome the failed trim condition, but not detract from normal operation. Alternative thoughts could question why it was necessary to increase the tail area, yet retain the same size elevator. More trim range required whilst the pitch control appeared to be adequate. The obvious longer, heavier, cg, arguments apply, but pitching moment with varying thrust levels could add another dimension. Another question is why the trim range was chosen (horiz stab angles), is this relatively large, what are the limiting aerodynamic conditions; high, low speed, configuration, cg, thrust. Have these changed with the evolving variants. Background ref; https://www.satcom.guru/2019/04/stab...and-range.html |
Originally Posted by Zeffy
(Post 10481947)
IATA Director General Alexandre de Juniac said the timing on the MAX’s return to service was up to regulators, but airlines were bracing for 10 to 12 more weeks of delay before the plane can resume commercial service.
“We have to maintain an alignment between those authorities. Hopefully an alignment in terms of schedule,” Mr. de Juniac told reporters. Mr. de Juniac said it was unfortunate that the FAA meeting last week didn’t spell out a timeline for the MAX’s return to flight. Mr. de Juniac said a meeting between airlines, Boeing and regulators is likely to be held in five to seven weeks to prepare for a smooth MAX return to service. “We need to restore confidence in our industry,” he said, both related to the MAX and the certification process for planes more widely. And he thinks rushing an investigation of this magnitude and "alligning" it to a schedule will "restore confidence in [his] industry"?! I think, IATA needs a new CEO. |
Originally Posted by ProPax
(Post 10482087)
Daniel Elwell says that 737MAX investigation "will be driven by safety and not by schedule". Whereas the French socialist who went to the same school as the recent French president Francois Hollande, a school where Jean-Paul Sartre, no less, was a teacher once, says that MAX investigation should reach an "allignment" (whatever that is) "in terms of schedule" because - OMG!!! - summer schedule is in danger.
And he thinks rushing an investigation of this magnitude and "alligning" it to a schedule will "restore confidence in [his] industry"?! Didn't it occur to you that both may be wrong^^?
Originally Posted by ProPax
(Post 10482087)
I think, IATA needs a new CEO.
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Originally Posted by Fly Aiprt
(Post 10482111)
What's IATA to do?
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What do they usually do? |
I'm afraid that reading the Wikipedia article will not enlighten you.
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Originally Posted by ProPax
(Post 10482186)
But what does IATA do? I'm seriously asking this question. I have NO idea. I'm sure there is an article in Wikipedia that will give me the official blurb, but what actual function do they perform, does anyone know?
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Certification is a binary process denoting an acceptable level of risk. Safety or risk is inherently not binary but is subject to the exercise of judgment to arrive at a compromise that can be certified. Not sure what the pregnancy argument is about but clearly no system is absolutely safe but when you are pregnant you are absolutely.
MCAS is popularly considered to have introduced an unnecessary level of risk that should not have been certified. It is probable that the aircraft would have been safer without MCAS and the pilots were responsible for potential pitch up conditions due to the new engine locations. The investigation will have to resolve these suppositions and whether there were fundamental irregularities with the design and certification process. Quite rightly the focus must be on whether the design and certification was appropriate. Consideration of pilot performance are of course relevant, but are not the primary cause of the accidents and are not capable of obvious remedial action. There will always be pilots of varying ability. It is far from certain that the situation that they found themselves would have been recoverable by average pilots... more information is required to establish what the pilots actually did at all stages of the flights. Based on the limited information, it appears to me that MCAS introduced an unacceptable level of risk and those risks were known to Boeing and possibly the FAA. It is not a good situation for public confidence in safety. |
MAX needs MCAS for FAR 25 compliance
Originally Posted by hans brinker
(Post 10478960)
It is about time. There is no difference between the NG and the MAX in manual trim, so if the pilots were unable to manually trim in the last crash, they wouldn't have been able to trim in any of the 6500 B737s flying.
The entire point of the introduction of MCAS is that the 737 MAX without MCAS responds to pitch control inputs differently to earlier models. In particular, runaway pitch-up is possible. Without MCAS, the 737MAX would fail to meet FAR 25 requirements for controllability in manual flight. In another thread
Originally Posted by gums
I like "25.203 Stall characteristics", as it may provide a clue why MCAS was incorporated. The first paragraph requires:
No abnormal nose-up pitching may occur. The longitudinal control force must be positive up to and throughout the stall. |
It is probable that the aircraft would have been safer without MCAS and the pilots were responsible for potential pitch up conditions due to the new engine locations. |
Originally Posted by ProPax
(Post 10482186)
ICAO issues and enforces the rules of international aviation, such as the freedoms of airspace. But what does IATA do? I'm seriously asking this question. I have NO idea.
Their relevance to the situation is in the forward planning of schedules and making reservations, where the aircraft provision and schedules are currently substantially disorganised by the grounding, such that carriers currently are unsure what capacity they may have available for the season ahead. It now looks likely the Max is going to be grounded right through the summer peak period, and carriers affected are going to be facing up to different timetables, and offering different fare structures through their yield management plans, to what they might have hoped. |
As others have noted, absolute safety is a myth - nothing in life is completely safe.
For certification purposes, there is a definition of safe: The probability of a catastrophic outcome is ~ 10-9/flight hour (or less - less is always better). The miss was that no one at Boeing or the FAA (or EASA) identified MCAS as being a flight critical system that needed to meet that 10-9 requirement. I'm not privy to everything the 'fix' entails, but 10-9/hr. is the standard it will need to meet to be determined safe. |
I don't think the MAX will be flying in Europe any time soon, there is a very nasty trade war brewing. The WTO has found that Airbus has been illegally subsidized by the government and so the US will be able to impose tariffs. Boeing is also illegally subsidized but the case is not as far along so there is going to be five or six months of one-sided tariffs (affecting cheese makers, etc.) over airplanes. It is a little hard to see that the European regulators are going to cut Boeing much slack, I imagine a "work to rule" type situation and they have plenty of ammunition. I don't know how many airlines will be affected; I do know that Sunwings in Canada is already cancelling flights and blaming Boeing (although they are affected by a different trade war.)
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