9 ms·

Pilots offer insights on Boeing 737 crashes

78 points by internalfx 8y ago

fuckyah 8y ago
TLDR: "[...]it’s not the airplane so much as whether or not the manual properly describes what’s going on."
scriptkiddy 8y ago
I was waiting to hear something like this. Generally speaking, Airline pilots who actually flew the plane are one of the best sources to consult when it comes to determining any possible safety malfunction of an aircraft. One thing to note is the mention of a "Runaway Trim Checklist". When piloting an airliner, there is a checklist for almost everything. Sometimes there are multiple checklists with branching paths. Most emergency/malfunction checklists involve what are called "memory items". These are checklist steps that the pilot must remember in order to react quickly to any possible problem. After the memory items are completed, the pilots will break out the checklist binder and follow the checklist procedure that comes after the memory items. Every procedure the pilots undergo has passenger safety as it's #1 concern. Pilots are free to make whatever decision they deem necessary to ensure the safety of their passengers, even at the detriment of the airline's bottom line. They are free to make these decisions without question, even if the problem seems small. I believe it's important to note the above information whenever we look at these horrible accidents and try to reason about them. Often, pilots are the first line of defense against failures. Most aircraft have 2-3 redundant systems for almost every control and feature. Pilots need to understand and know how to work with and around these systems in order to react to emergency situations. That's why I think the MCAS isn't really to blame here as much as Boeing is to blame for not properly documenting it's operation in their manuals.
- tim333 8y ago
  >That's why I think the MCAS isn't really to blame here as much as Boeing is to blame for not properly documenting... I pretty sure the Ethiopian pilots would have been aware of the Lion Air crash and MCAS issues. The fact they still crashed suggests there's more to it.
  - dragontamer 8y ago
    I think a wait-and-see approach is best (now that the planes are grounded). The black-box of the Ethiopian crash surely has the voice-recordings of the cockpit. So we'll be able to hear what the pilots were saying as the crash went down... we just gotta wait for the data. No point speculating when hard data is just around the corner. With the planes being grounded, there shouldn't be any safety issues if we wait.
- outworlder 8y ago
  > One thing to note is the mention of a "Runaway Trim Checklist". The pilots may not have recognized (in time) that it was a runaway trim issue. Many such issues involve trim being continuously applied. The trim wheel spins wildly. MCAS will trim in increments of 10s. So it will trim, pause, trim some more, pause. This may have confused the pilots. And they don't have much time to begin with – MCAS engages with autopilot off and flaps retracted. Most takeoffs have at least minimum flaps, so the plane will fly fine and then start misbehaving while still relatively close to the ground. > Most aircraft have 2-3 redundant systems for almost every control and feature. Yes. MAX 8 has two AOA sensors. Only one needs to misbehave for this issue to happen. But even with two, it is difficult to know which one is fault (for a machine). With three, it would be possible to tell. In any case, all of this is still speculation.
  - losvedir 8y ago
    > MCAS will trim in increments of 10s. So it will trim, pause, trim some more, pause. No, not quite. By itself MCAS will only trim once, I believe. But if it's interrupted by a pilot manually trimming, then it will stop, wait 5 seconds, and then try to do its 10 second trim again. The characteristic up-down pattern from the Lion Air flight I think was from the latter scenario of MCAS starting to trim, the pilot manually trimming back (disabling MCAS for 5 seconds) and then it activating again. > Yes. MAX 8 has two AOA sensors. But I think the MCAS system only gets its input from one! (And it switches each flight.) If true, that's just appallingly bad.
    - outworlder 8y ago
      > No, not quite. By itself MCAS will only trim once, I believe. Under normal operation, that seems to be the case. But note that we are operating with the assumption that the AoA sensor is faulty. So it may still think the plane is in a bad attitude. > But I think the MCAS system only gets its input from one! (And it switches each flight.) If true, that's just appallingly bad. As far as public information goes, that's correct.
    - linuxftw 8y ago
      > No, not quite. By itself MCAS will only trim once, I believe. Unfortunately, we don't know this is actually true. Certainly, it's what Boeing wants us to believe, that their software is perfect in this regard. Might be completely broken. Where's the independent verification. And, allegedly, it's only supposed to trim just a little bit at each increment. If you look at the accounts, there are roller coaster-like drops. Seems to me it started nosing down really hard.
- sandworm101 8y ago
  >>> Pilots need to understand and know how to work with and around these systems There is a problem with the "working around" some systems. While there are definitely some situations where a pilot should bypass something, one must also look at the situations where that would be a mistake. Some systems cannot be bypassed because the chance of a pilot bypassing them in error is far greater than he or she actually needing to. For instance, asymmetric flaps. One can contrive a situation where the ability to alter flap setting asymmetrically might save an otherwise doomed aircraft (multiple control surface failures) but the risk of misusing that ability far outweighs the benefit. This anti-stall system may well have crashed these aircraft, but are there any situations where is saved an aircraft? Perhaps someone calculated that the risk of allowing pilots to bypass it outweighed the risk of it malfunctioning. Perhaps that judgement call was incorrect in this case, but I wouldn't say that pilots should always be in a position to bypass every system.
- cjbprime 8y ago
  > Most aircraft have 2-3 redundant systems for almost every control and feature. The 737 MAX only uses one AoA vane when deciding whether to lower the nose, so this just isn't true in the situation we're talking about.
- tmd83 8y ago
  At least before Lion crash it sounded like the lack of documentation or training at least wasn't exactly a mistake but a purely business decision to make it appear like the regular 737.
jahewson 8y ago
How hard is it to flip through a binder while fighting against the trim system by putting significant force onto the stick and overriding the trim system every 10 seconds? Seems excessively challenging.
- capnrefsmmat 8y ago
  This is why there are two pilots, and techniques like Crew Resource Management dictate that one pilot be solely responsible for flying the plane while the other pilot attempts to resolve the problem. There were a number of incidents in the 1970s where pilots got so distracted solving a problem that they let the plane crash (by running out of fuel, or by gradually descending into the ground, or several other things), so training tries to explicitly account for this problem by ensuring the pilots are very clear about who is responsible for flying and who is solving the problem, and that they clearly communicate the steps they are taking to each other.
  - kayfox 8y ago
    Two examples of crashes due to the lack of CRM: https://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401 https://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401 https://en.wikipedia.org/wiki/United_Airlines_Flight_173 https://en.wikipedia.org/wiki/United_Airlines_Flight_173 One example of CRM success: https://en.wikipedia.org/wiki/United_Airlines_Flight_232 https://en.wikipedia.org/wiki/United_Airlines_Flight_232
- ralph84 8y ago
  The pilot flying (PF) controls the aircraft while the pilot monitoring (PM) calls out the checklist items. It's very manageable with an experienced crew. But apparently the first officer in the Ethiopian crash only had 200 hours of experience, so it will be interesting to see if his inexperience was a contributing factor.
  - dragontamer 8y ago
    But the captain had 8000 hours of experience. But I agree, maybe the less-experienced pilot was a contributing factor. The black box recording should provide insight if there were any cockpit squabbles...
burlesona 8y ago
Money quote is as the end, from a Max pilot: “Tecce did not fault the FAA for taking a wait-and-see approach. “A lot of people throwing a lot of rocks at the FAA. Since 2010 we’ve had one aviation fatality” in the United States. “Our safety record is astonishing,” he said. “I don’t think there’s anything wrong with the airplane. If you talk to the pilots who fly them, they’ll tell you it’s not the airplane so much as whether or not the manual properly describes what’s going on.”” Seems more and more consensus is forming around this idea, that the MCAS system generally did what it was supposed to do, _and_ has an appropriate safety cutoff for the pilot if needed, but that Boeing did not focus a lot of attention on this new system in their training/documentation when in fact they needed to.
- cjbprime 8y ago
  The entire world focused attention on the new system after the Lion Air crash, and it was not enough to stop the Ethiopian Airlines crash from happening. The FAA thinks it's likely that the crashes are related.
  - linuxftw 8y ago
    I don't think they had the altitude to recover, if it was even a recoverable MCAS issue to begin with.
    - cjbprime 8y ago
      I think they did -- it looks like it took six minutes from the first distress call claiming a control issue (at 7000ft) to impact, and they stayed at around 7000ft for much of those six minutes.
      - linuxftw 8y ago
        You're confused as the information is not widely available. That's 7k ft about sea level. From [1]: > The aircraft climbed very slowly and only to about 1,000ft above ground before crashing. https://leehamnews.com/2019/03/15/bjorns-corner-the-ethiopian-airlines-flight-302-crash/ https://leehamnews.com/2019/03/15/bjorns-corner-the-ethiopia...
antirez 8y ago
It almost looks like if it was an error to call this plane 737 MAX instead of, let's say, 738, to communicate that it's quite a different plane because of aerodynamic differences and electronic systems to require a training for the pilots. Aircraft semaver.
- cjbprime 8y ago
  Boeing fought extremely hard to avoid doing this because it would introduce new costs in certification and new requirements for pilot training. It wasn't accidental.
  - antirez 8y ago
    Oh interesting, thanks for the background info.
  - SketchySeaBeast 8y ago
    I blows my mind that a naming convention can be used to determine the similarities between vehicles. "I don't need a licence as this isn't a bus, it's clearly a tricycle, look on the side."
    - cjbprime 8y ago
      I think it does actually reuse the >50 year-old 737 airframe design, as a condition of continuing the same type rating. Just.. not much else.
      - ams6110 8y ago
        Yes it's the same basic design, but you might be hard pressed to believe it. Notice especially the engines. Original 737: https://en.wikipedia.org/wiki/Boeing_737#/media/File:D-ABEA_B737-130_Lufthansa_MAN_31JUL72_(6141699137).jpg https://en.wikipedia.org/wiki/Boeing_737#/media/File:D-ABEA_... Max: https://en.wikipedia.org/wiki/Boeing_737_MAX#/media/File:HS-LSI_(44161228802).jpg https://en.wikipedia.org/wiki/Boeing_737_MAX#/media/File:HS-... The fuselage, tail, wings and control systems are close enough to the original type to stay certified.
United857 8y ago
Refreshingly good analysis of the 737MAX from the pilot's perspective. Most are focusing on the flaws of the plane (which I'm not discounting) but pilot training is also a big part in recovering from unexpected situations, overriding MCAS or automation in general when things go south, and hand-flying the airplane. The two crashes happened in developing countries, Indonesia and Ethiopia, with local crew. While I don't know the specifics here, often times local airline pilots in developing countries (i.e. no pool of experienced general aviation or military pilots to recruit from) are trained ab initio to have a high reliance on automation, not so much hand-flying the jet. That's how you get, e.g. a first officer with 200 hours. I do believe that the US civil and military pilot training pipelines, flawed as they are, teach hand-flying and build up experience, and these crashes would be very unlikely to happen with a US carrier and crew.
- vkou 8y ago
  The Lion Air pilot had 6,000 hours of flight experience, and the co-pilot had 5,000 hours of flight experience. Also, these same airline pilots in developing countries have managed to fly the older 737 models just fine, for decades...
  - kayfox 8y ago
    Did Ethiopian manage to fly 737s just fine? https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_409 https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_409
    - mimixco 8y ago
      Another sad example. All lives lost on that 737, too.
  - ralph84 8y ago
    To say Lion Air in particular has been flying 737s just fine simply doesn't agree with the facts. https://en.wikipedia.org/wiki/Lion_Air#Incidents_and_accidents https://en.wikipedia.org/wiki/Lion_Air#Incidents_and_acciden...
hencq 8y ago
It seems like there's a never ending barrage of 'news' around this. All of this is speculation at this point though. Investigation takes time, which is almost unusual in a time of minute by minute updates on absolutely everything. I would not be surprised if the cause ends up being more complicated than the currently suggested causes. There's definitely a lot to suggest that the cause of the Ethiopian and Lion Air crashes is the same, but the current explanation seems overly simplistic. The failure modes in the leading theory for the Lion Air crash were a broken AOA sensor causing the MCAS to kick in erroneously, combined with the pilots not reacting properly to a runaway trim situation. From what I understand, while MCAS is new, the process for reacting to runaway trim is not new to the 737 Max. This is probably also why the FAA and airlines like Southwest were confident their pilots would handle this situation correctly. For the cause of the Ethiopian crash to be the same, the pilots would also need to be unfamiliar with the runaway trim process. This seems unlikely though after the Lion Air crash since it put so much attention on that scenario. That suggests to me there might at least be other contributing factors to both these crashes. I think we just need to wait and see what the investigations of both these crashes find.
- linuxftw 8y ago
  > This is probably also why the FAA and airlines like Southwest were confident their pilots would handle this situation correctly. It's interesting to note that American Airlines released a statement that they have not observed any MCAS related malfunctions in any of their fleet data. In particular, there is only one account of (alleged) MCAS malfunction (possibly due to a faulty AoA sensor, which was subsequently replaced... hmmm.... new part still didn't fix it?) where the plane wasn't destroyed. And that account notes several drops in altitude before being able to stabilize. So, you better hope MCAS malfunctions at 8k feet about ground instead of 800.
gscott 8y ago
The important part of the article ---------- “When Boeing built the MAX, in order to increase fuel efficiency, they went with a different engine, explained Fred Tecce, a commercial aviation expert. “Because the 737 sits pretty low on its landing gear, [Boeing] had to move the engines up a little bit and move them forward a little bit” on the MAX versions. “In order to compensate, they extended the nose gear by eight to 12 inches" and repositioned the engines which "affected the airplane’s pitch characteristics and center of gravity.” Tecce concurred that control inputs and the resulting pitch changes were challenges that had to be overcome in the latest version of the world’s best-selling aircraft. “In order to compensate for what the engineers perceived to be an issue with respect to pitch, they added this MCAS system that operates when the autopilot is off and the angle of attack exceeds certain limitations and when the airplane is banked pretty steeply.” He said the technology runs the stabilizer pitch down for several seconds and it “reassesses and will start again until it believes the airplane has reached a safe angle of attack, and it operates without the pilots knowing [about it].” Tecce noted that in the case of the Lion Air Boeing 737 MAX crash, “now the airplane is pitching down and actually moving the control wheel will not stop that system. If the pilot uses the trim system on the yoke, the [MCAS] system will stop" but "if the airplane isn’t in the proper attitude it will reactivate,” Tecce said, further forcing the aircraft downward if pilots fail to recognize the situation and take proper corrective action. A pilot familiar with the system pointed out that recognizing this scenario was crucial to determine if there was a problem that warranted activating the trim cutoff switches. Additionally, if the autopilot is engaged, activating a yoke trim switch disconnects the autopilot and gives full control back to the pilot immediately. Tecce did not fault the FAA for taking a wait-and-see approach. “A lot of people throwing a lot of rocks at the FAA. Since 2010 we’ve had one aviation fatality” in the United States. “Our safety record is astonishing,” he said. “I don’t think there’s anything wrong with the airplane. If you talk to the pilots who fly them, they’ll tell you it’s not the airplane so much as whether or not the manual properly describes what’s going on.”
tim333 8y ago
There is some evidence that doesn't fit with the faulty angle of attack sensor triggering MCAS hypothesis. With the LionAir crash, they thought there was an a problem with the AoA sensor and replaced it but problems continued. On the flight before the fatal one and "Passengers in the cabin reported heavy shaking and a smell of burnt rubber inside the cabin." (wikipedia) " The plane floor is hot. During the flight, it's never been like that" (https://news.detik.com/berita/d-4278530/kesaksian-penumpang-soal-masalah-di-lion-air-denpasar-jakarta https://news.detik.com/berita/d-4278530/kesaksian-penumpang-...) also "erroneous airspeed indications were still present" Then with the Ethiopian flight several witnesses reported smoke and a weird sound from the plane. Also the pilots were aware of the Lionair crash and MCAS issues. I guess they'll figure it eventually.
cmurf 8y ago
Not in any discussion I've read so far: what is the stall behavior of 737NG compared to 737MAX when MCAS is disabled via STAB TRIM set to cutoff? We don't know, but will eventually find out, whether either plane was flying during the final descent to crash. By that I mean, was the wing producing any lift (dive to crash), or was the wing stalled (stall to crash) or some combination of both and in which order? And the stall behavior very well may become highly relevant. It's a whole lot of ifs, a lot of questions, and not many answers.

78 points by internalfx 8y ago

TLDR: "[...]it’s not the airplane so much as whether or not the manual properly describes what’s going on."

I was waiting to hear something like this. Generally speaking, Airline pilots who actually flew the plane are one of the best sources to consult when it comes to determining any possible safety malfunction of an aircraft. One thing to note is the mention of a "Runaway Trim Checklist". When piloting an airliner, there is a checklist for almost everything. Sometimes there are multiple checklists with branching paths. Most emergency/malfunction checklists involve what are called "memory items". These are checklist steps that the pilot must remember in order to react quickly to any possible problem. After the memory items are completed, the pilots will break out the checklist binder and follow the checklist procedure that comes after the memory items. Every procedure the pilots undergo has passenger safety as it's #1 concern. Pilots are free to make whatever decision they deem necessary to ensure the safety of their passengers, even at the detriment of the airline's bottom line. They are free to make these decisions without question, even if the problem seems small. I believe it's important to note the above information whenever we look at these horrible accidents and try to reason about them. Often, pilots are the first line of defense against failures. Most aircraft have 2-3 redundant systems for almost every control and feature. Pilots need to understand and know how to work with and around these systems in order to react to emergency situations. That's why I think the MCAS isn't really to blame here as much as Boeing is to blame for not properly documenting it's operation in their manuals.

tim333 8y ago
>That's why I think the MCAS isn't really to blame here as much as Boeing is to blame for not properly documenting... I pretty sure the Ethiopian pilots would have been aware of the Lion Air crash and MCAS issues. The fact they still crashed suggests there's more to it.
- dragontamer 8y ago
  I think a wait-and-see approach is best (now that the planes are grounded). The black-box of the Ethiopian crash surely has the voice-recordings of the cockpit. So we'll be able to hear what the pilots were saying as the crash went down... we just gotta wait for the data. No point speculating when hard data is just around the corner. With the planes being grounded, there shouldn't be any safety issues if we wait.
outworlder 8y ago
> One thing to note is the mention of a "Runaway Trim Checklist". The pilots may not have recognized (in time) that it was a runaway trim issue. Many such issues involve trim being continuously applied. The trim wheel spins wildly. MCAS will trim in increments of 10s. So it will trim, pause, trim some more, pause. This may have confused the pilots. And they don't have much time to begin with – MCAS engages with autopilot off and flaps retracted. Most takeoffs have at least minimum flaps, so the plane will fly fine and then start misbehaving while still relatively close to the ground. > Most aircraft have 2-3 redundant systems for almost every control and feature. Yes. MAX 8 has two AOA sensors. Only one needs to misbehave for this issue to happen. But even with two, it is difficult to know which one is fault (for a machine). With three, it would be possible to tell. In any case, all of this is still speculation.
- losvedir 8y ago
  > MCAS will trim in increments of 10s. So it will trim, pause, trim some more, pause. No, not quite. By itself MCAS will only trim once, I believe. But if it's interrupted by a pilot manually trimming, then it will stop, wait 5 seconds, and then try to do its 10 second trim again. The characteristic up-down pattern from the Lion Air flight I think was from the latter scenario of MCAS starting to trim, the pilot manually trimming back (disabling MCAS for 5 seconds) and then it activating again. > Yes. MAX 8 has two AOA sensors. But I think the MCAS system only gets its input from one! (And it switches each flight.) If true, that's just appallingly bad.
  - outworlder 8y ago
    > No, not quite. By itself MCAS will only trim once, I believe. Under normal operation, that seems to be the case. But note that we are operating with the assumption that the AoA sensor is faulty. So it may still think the plane is in a bad attitude. > But I think the MCAS system only gets its input from one! (And it switches each flight.) If true, that's just appallingly bad. As far as public information goes, that's correct.
  - linuxftw 8y ago
    > No, not quite. By itself MCAS will only trim once, I believe. Unfortunately, we don't know this is actually true. Certainly, it's what Boeing wants us to believe, that their software is perfect in this regard. Might be completely broken. Where's the independent verification. And, allegedly, it's only supposed to trim just a little bit at each increment. If you look at the accounts, there are roller coaster-like drops. Seems to me it started nosing down really hard.
sandworm101 8y ago
>>> Pilots need to understand and know how to work with and around these systems There is a problem with the "working around" some systems. While there are definitely some situations where a pilot should bypass something, one must also look at the situations where that would be a mistake. Some systems cannot be bypassed because the chance of a pilot bypassing them in error is far greater than he or she actually needing to. For instance, asymmetric flaps. One can contrive a situation where the ability to alter flap setting asymmetrically might save an otherwise doomed aircraft (multiple control surface failures) but the risk of misusing that ability far outweighs the benefit. This anti-stall system may well have crashed these aircraft, but are there any situations where is saved an aircraft? Perhaps someone calculated that the risk of allowing pilots to bypass it outweighed the risk of it malfunctioning. Perhaps that judgement call was incorrect in this case, but I wouldn't say that pilots should always be in a position to bypass every system.
cjbprime 8y ago
> Most aircraft have 2-3 redundant systems for almost every control and feature. The 737 MAX only uses one AoA vane when deciding whether to lower the nose, so this just isn't true in the situation we're talking about.
tmd83 8y ago
At least before Lion crash it sounded like the lack of documentation or training at least wasn't exactly a mistake but a purely business decision to make it appear like the regular 737.

jahewson 8y ago

How hard is it to flip through a binder while fighting against the trim system by putting significant force onto the stick and overriding the trim system every 10 seconds? Seems excessively challenging.

capnrefsmmat 8y ago
This is why there are two pilots, and techniques like Crew Resource Management dictate that one pilot be solely responsible for flying the plane while the other pilot attempts to resolve the problem. There were a number of incidents in the 1970s where pilots got so distracted solving a problem that they let the plane crash (by running out of fuel, or by gradually descending into the ground, or several other things), so training tries to explicitly account for this problem by ensuring the pilots are very clear about who is responsible for flying and who is solving the problem, and that they clearly communicate the steps they are taking to each other.
- kayfox 8y ago
  Two examples of crashes due to the lack of CRM: https://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401 https://en.wikipedia.org/wiki/Eastern_Air_Lines_Flight_401 https://en.wikipedia.org/wiki/United_Airlines_Flight_173 https://en.wikipedia.org/wiki/United_Airlines_Flight_173 One example of CRM success: https://en.wikipedia.org/wiki/United_Airlines_Flight_232 https://en.wikipedia.org/wiki/United_Airlines_Flight_232
ralph84 8y ago
The pilot flying (PF) controls the aircraft while the pilot monitoring (PM) calls out the checklist items. It's very manageable with an experienced crew. But apparently the first officer in the Ethiopian crash only had 200 hours of experience, so it will be interesting to see if his inexperience was a contributing factor.
- dragontamer 8y ago
  But the captain had 8000 hours of experience. But I agree, maybe the less-experienced pilot was a contributing factor. The black box recording should provide insight if there were any cockpit squabbles...

burlesona 8y ago

Money quote is as the end, from a Max pilot: “Tecce did not fault the FAA for taking a wait-and-see approach. “A lot of people throwing a lot of rocks at the FAA. Since 2010 we’ve had one aviation fatality” in the United States. “Our safety record is astonishing,” he said. “I don’t think there’s anything wrong with the airplane. If you talk to the pilots who fly them, they’ll tell you it’s not the airplane so much as whether or not the manual properly describes what’s going on.”” Seems more and more consensus is forming around this idea, that the MCAS system generally did what it was supposed to do, _and_ has an appropriate safety cutoff for the pilot if needed, but that Boeing did not focus a lot of attention on this new system in their training/documentation when in fact they needed to.

cjbprime 8y ago
The entire world focused attention on the new system after the Lion Air crash, and it was not enough to stop the Ethiopian Airlines crash from happening. The FAA thinks it's likely that the crashes are related.
- linuxftw 8y ago
  I don't think they had the altitude to recover, if it was even a recoverable MCAS issue to begin with.
  - cjbprime 8y ago
    I think they did -- it looks like it took six minutes from the first distress call claiming a control issue (at 7000ft) to impact, and they stayed at around 7000ft for much of those six minutes.
    - linuxftw 8y ago
      You're confused as the information is not widely available. That's 7k ft about sea level. From [1]: > The aircraft climbed very slowly and only to about 1,000ft above ground before crashing. https://leehamnews.com/2019/03/15/bjorns-corner-the-ethiopian-airlines-flight-302-crash/ https://leehamnews.com/2019/03/15/bjorns-corner-the-ethiopia...

antirez 8y ago

It almost looks like if it was an error to call this plane 737 MAX instead of, let's say, 738, to communicate that it's quite a different plane because of aerodynamic differences and electronic systems to require a training for the pilots. Aircraft semaver.

cjbprime 8y ago
Boeing fought extremely hard to avoid doing this because it would introduce new costs in certification and new requirements for pilot training. It wasn't accidental.
- antirez 8y ago
  Oh interesting, thanks for the background info.
- SketchySeaBeast 8y ago
  I blows my mind that a naming convention can be used to determine the similarities between vehicles. "I don't need a licence as this isn't a bus, it's clearly a tricycle, look on the side."
  - cjbprime 8y ago
    I think it does actually reuse the >50 year-old 737 airframe design, as a condition of continuing the same type rating. Just.. not much else.
    - ams6110 8y ago
      Yes it's the same basic design, but you might be hard pressed to believe it. Notice especially the engines. Original 737: https://en.wikipedia.org/wiki/Boeing_737#/media/File:D-ABEA_B737-130_Lufthansa_MAN_31JUL72_(6141699137).jpg https://en.wikipedia.org/wiki/Boeing_737#/media/File:D-ABEA_... Max: https://en.wikipedia.org/wiki/Boeing_737_MAX#/media/File:HS-LSI_(44161228802).jpg https://en.wikipedia.org/wiki/Boeing_737_MAX#/media/File:HS-... The fuselage, tail, wings and control systems are close enough to the original type to stay certified.

United857 8y ago

Refreshingly good analysis of the 737MAX from the pilot's perspective. Most are focusing on the flaws of the plane (which I'm not discounting) but pilot training is also a big part in recovering from unexpected situations, overriding MCAS or automation in general when things go south, and hand-flying the airplane. The two crashes happened in developing countries, Indonesia and Ethiopia, with local crew. While I don't know the specifics here, often times local airline pilots in developing countries (i.e. no pool of experienced general aviation or military pilots to recruit from) are trained ab initio to have a high reliance on automation, not so much hand-flying the jet. That's how you get, e.g. a first officer with 200 hours. I do believe that the US civil and military pilot training pipelines, flawed as they are, teach hand-flying and build up experience, and these crashes would be very unlikely to happen with a US carrier and crew.

vkou 8y ago
The Lion Air pilot had 6,000 hours of flight experience, and the co-pilot had 5,000 hours of flight experience. Also, these same airline pilots in developing countries have managed to fly the older 737 models just fine, for decades...
- kayfox 8y ago
  Did Ethiopian manage to fly 737s just fine? https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_409 https://en.wikipedia.org/wiki/Ethiopian_Airlines_Flight_409
  - mimixco 8y ago
    Another sad example. All lives lost on that 737, too.
- ralph84 8y ago
  To say Lion Air in particular has been flying 737s just fine simply doesn't agree with the facts. https://en.wikipedia.org/wiki/Lion_Air#Incidents_and_accidents https://en.wikipedia.org/wiki/Lion_Air#Incidents_and_acciden...

hencq 8y ago

It seems like there's a never ending barrage of 'news' around this. All of this is speculation at this point though. Investigation takes time, which is almost unusual in a time of minute by minute updates on absolutely everything. I would not be surprised if the cause ends up being more complicated than the currently suggested causes. There's definitely a lot to suggest that the cause of the Ethiopian and Lion Air crashes is the same, but the current explanation seems overly simplistic. The failure modes in the leading theory for the Lion Air crash were a broken AOA sensor causing the MCAS to kick in erroneously, combined with the pilots not reacting properly to a runaway trim situation. From what I understand, while MCAS is new, the process for reacting to runaway trim is not new to the 737 Max. This is probably also why the FAA and airlines like Southwest were confident their pilots would handle this situation correctly. For the cause of the Ethiopian crash to be the same, the pilots would also need to be unfamiliar with the runaway trim process. This seems unlikely though after the Lion Air crash since it put so much attention on that scenario. That suggests to me there might at least be other contributing factors to both these crashes. I think we just need to wait and see what the investigations of both these crashes find.

linuxftw 8y ago
> This is probably also why the FAA and airlines like Southwest were confident their pilots would handle this situation correctly. It's interesting to note that American Airlines released a statement that they have not observed any MCAS related malfunctions in any of their fleet data. In particular, there is only one account of (alleged) MCAS malfunction (possibly due to a faulty AoA sensor, which was subsequently replaced... hmmm.... new part still didn't fix it?) where the plane wasn't destroyed. And that account notes several drops in altitude before being able to stabilize. So, you better hope MCAS malfunctions at 8k feet about ground instead of 800.

gscott 8y ago

The important part of the article ---------- “When Boeing built the MAX, in order to increase fuel efficiency, they went with a different engine, explained Fred Tecce, a commercial aviation expert. “Because the 737 sits pretty low on its landing gear, [Boeing] had to move the engines up a little bit and move them forward a little bit” on the MAX versions. “In order to compensate, they extended the nose gear by eight to 12 inches" and repositioned the engines which "affected the airplane’s pitch characteristics and center of gravity.” Tecce concurred that control inputs and the resulting pitch changes were challenges that had to be overcome in the latest version of the world’s best-selling aircraft. “In order to compensate for what the engineers perceived to be an issue with respect to pitch, they added this MCAS system that operates when the autopilot is off and the angle of attack exceeds certain limitations and when the airplane is banked pretty steeply.” He said the technology runs the stabilizer pitch down for several seconds and it “reassesses and will start again until it believes the airplane has reached a safe angle of attack, and it operates without the pilots knowing [about it].” Tecce noted that in the case of the Lion Air Boeing 737 MAX crash, “now the airplane is pitching down and actually moving the control wheel will not stop that system. If the pilot uses the trim system on the yoke, the [MCAS] system will stop" but "if the airplane isn’t in the proper attitude it will reactivate,” Tecce said, further forcing the aircraft downward if pilots fail to recognize the situation and take proper corrective action. A pilot familiar with the system pointed out that recognizing this scenario was crucial to determine if there was a problem that warranted activating the trim cutoff switches. Additionally, if the autopilot is engaged, activating a yoke trim switch disconnects the autopilot and gives full control back to the pilot immediately. Tecce did not fault the FAA for taking a wait-and-see approach. “A lot of people throwing a lot of rocks at the FAA. Since 2010 we’ve had one aviation fatality” in the United States. “Our safety record is astonishing,” he said. “I don’t think there’s anything wrong with the airplane. If you talk to the pilots who fly them, they’ll tell you it’s not the airplane so much as whether or not the manual properly describes what’s going on.”

tim333 8y ago

There is some evidence that doesn't fit with the faulty angle of attack sensor triggering MCAS hypothesis. With the LionAir crash, they thought there was an a problem with the AoA sensor and replaced it but problems continued. On the flight before the fatal one and "Passengers in the cabin reported heavy shaking and a smell of burnt rubber inside the cabin." (wikipedia) " The plane floor is hot. During the flight, it's never been like that" (https://news.detik.com/berita/d-4278530/kesaksian-penumpang-soal-masalah-di-lion-air-denpasar-jakarta https://news.detik.com/berita/d-4278530/kesaksian-penumpang-...) also "erroneous airspeed indications were still present" Then with the Ethiopian flight several witnesses reported smoke and a weird sound from the plane. Also the pilots were aware of the Lionair crash and MCAS issues. I guess they'll figure it eventually.

cmurf 8y ago

Not in any discussion I've read so far: what is the stall behavior of 737NG compared to 737MAX when MCAS is disabled via STAB TRIM set to cutoff? We don't know, but will eventually find out, whether either plane was flying during the final descent to crash. By that I mean, was the wing producing any lift (dive to crash), or was the wing stalled (stall to crash) or some combination of both and in which order? And the stall behavior very well may become highly relevant. It's a whole lot of ifs, a lot of questions, and not many answers.