5 ms·

> MCAS is quite safe A few hundred people who died as a result of MCAS would disagree. MCAS is not safe as currently implemented, or the 737 Max would still be

> MCAS is quite safe A few hundred people who died as a result of MCAS would disagree. MCAS is not safe as currently implemented, or the 737 Max would still be flying.

admax88q 8y ago
MACS is safe but its not zero delta training as Boeing advertised. Pilots who were trained on it properly are able to recognize the problem and fix it when it occurs.
- jfk13 8y ago
  A problem of such potential severity should not be happening with anywhere remotely like the frequency we've seen.
  - admax88q 8y ago
    I think you'd be surprised how often small problems can occur on planes. They all have _potentially_ huge severity, but none of them have huge consequences because they are expected problems that pilots are trained to respond to.
- bekman 8y ago
  If it’s needed to be fixed then it’s not safe.
- drcross 8y ago
  MCAS is safe in its current implementation like nuclear power is safe- it works well when you know exactly what you're doing at all times.
  - CydeWeys 8y ago
    I disagree; modern nuclear power is way safer, and is a result of decades of continuous improvement. MCAS on the other hand is basically a bad hack that was necessary for business reasons. It's a serious step backwards in safety from previous iterations, which has not happened with modern nukes.
    - theluketaylor 8y ago
      I'd say MCAS is a predictable business hack that resulted from terrible regulatory pressure. Airplane certification is expensive for both manufacturer and airlines that might want to fly it. So there is a quicker process if you just make minor revisions, a reasonable compromise on the surface. Certification is so expensive and not having to retrain pilots is such a huge selling feature it creates a pressure to make planes that meet the same type requirements rather than design new airframes. Boeing is all set to design a new airframe to replace the 737 that will be more fuel efficient and be built for today's point to point flights. Along comes airbus with the a320neo (new engine option) that kills the 737-800 on fuel efficiency and Boeing panics. They scrap 2020 plans for a 737 replacement and design the MAX. Now the problems mount. Fuel efficiency needs turbines that spin slower but have more surface area and are therefore larger. 737 is a low slung plane, dating back to hub and spoke flight concepts where the 737 might land places that don't have jetways. Since the plane is so close to the ground, Boeing has to move the engines forward so they can raise them. This generates more lift than previous 737s, but to meet same type requirements the plan has to be the same. Not meeting same type means they can't sell to airlines like southwest who only fly a single type and any airlines who do commit will have to spend training dollars, raising the total cost of operation without adding anything to the bill of materials. Enter MCAS, a system designed to meet the same type regulation with disastrous unintended side effects. Side effects made much worse by the fact pilots don't know the system even exists since this plane is the same as every other 737 as far as they know. I don't think the same type regulation should be scrapped since it would stop things like fuel efficiency gains during an airframe's lifespan, but there needs to be a same type minimum training and documentation that has to be done even if the only thing you change is thickness of the paint. If anything the definition of what meets same type should be slightly expanded allowing more flexibility in what can be changed. Combined with mandatory training for all subtypes (but still much shorter than different type training) the perverse incentive to make the plane behave exactly the same is removed. That leaves room for the better technical fix to win the day rather than the one that will meet the regulation. Training costs will go up some, but less than full different type certification.
      - inferiorhuman 8y ago
cal5k 8y ago
Saying that something requires training to be operated safely does not mean that it is unsafe. It means that it's a complex system that requires training to operate. Place a random passenger into the cockpit of a modern commercial airliner without training and ask them to fly the thing safely and you'd probably have a 100% loss rate.
- GiorgioG 8y ago
  > Saying that something requires training to be operated safely does not mean that it is unsafe. This ultimately is not a training issue. Why was a system that can potentially plow the aircraft's nose into the ground utilizing only a single sensor without any redundancy in place? Boeing screwed up. Now both sensors will be used. Great, but sometimes 2 sensors fail. If pilots that operate these aircrafts are trusted with the lives of 150+ passengers, they should have an "easy button" to take complete manual control of the aircraft. My human sensors should trump any mechanical sensor(s) when my life is on the line.
  - cal5k 8y ago
    They do have an "easy button": two highly visible switches right underneath the throttle. Bottom right here where it says "stab trim": http://www.sjap.nl/wp-content/uploads/IMG_0825-e1464602357745.jpg http://www.sjap.nl/wp-content/uploads/IMG_0825-e146460235774... Activating those switches cuts off electric trim and would completely deactivate MCAS. It can be done in seconds.
    - omegaworks 8y ago
      But can the determination to perform the stab trim cut-off be done in seconds? Are there other feedback mechanisms present that can interrupt that determination? That appears to be the case in these scenarios. The MCAS doesn't perform the incorrect action continuously, it looks like initial corrective measures fix the problem until they suddenly don't.
    - GiorgioG 8y ago
      > Activating those switches cuts off electric trim and would completely deactivate MCAS. It can be done in seconds. That's great...if they'd understood that the system was malfunctioning...but they had no such indication because their airline didn't pay for the optional "feature."

> MCAS is quite safe A few hundred people who died as a result of MCAS would disagree. MCAS is not safe as currently implemented, or the 737 Max would still be flying.

admax88q 8y ago

MACS is safe but its not zero delta training as Boeing advertised. Pilots who were trained on it properly are able to recognize the problem and fix it when it occurs.

jfk13 8y ago
A problem of such potential severity should not be happening with anywhere remotely like the frequency we've seen.
- admax88q 8y ago
  I think you'd be surprised how often small problems can occur on planes. They all have _potentially_ huge severity, but none of them have huge consequences because they are expected problems that pilots are trained to respond to.
bekman 8y ago
If it’s needed to be fixed then it’s not safe.
drcross 8y ago
MCAS is safe in its current implementation like nuclear power is safe- it works well when you know exactly what you're doing at all times.
- CydeWeys 8y ago
  I disagree; modern nuclear power is way safer, and is a result of decades of continuous improvement. MCAS on the other hand is basically a bad hack that was necessary for business reasons. It's a serious step backwards in safety from previous iterations, which has not happened with modern nukes.
  - theluketaylor 8y ago
    I'd say MCAS is a predictable business hack that resulted from terrible regulatory pressure. Airplane certification is expensive for both manufacturer and airlines that might want to fly it. So there is a quicker process if you just make minor revisions, a reasonable compromise on the surface. Certification is so expensive and not having to retrain pilots is such a huge selling feature it creates a pressure to make planes that meet the same type requirements rather than design new airframes. Boeing is all set to design a new airframe to replace the 737 that will be more fuel efficient and be built for today's point to point flights. Along comes airbus with the a320neo (new engine option) that kills the 737-800 on fuel efficiency and Boeing panics. They scrap 2020 plans for a 737 replacement and design the MAX. Now the problems mount. Fuel efficiency needs turbines that spin slower but have more surface area and are therefore larger. 737 is a low slung plane, dating back to hub and spoke flight concepts where the 737 might land places that don't have jetways. Since the plane is so close to the ground, Boeing has to move the engines forward so they can raise them. This generates more lift than previous 737s, but to meet same type requirements the plan has to be the same. Not meeting same type means they can't sell to airlines like southwest who only fly a single type and any airlines who do commit will have to spend training dollars, raising the total cost of operation without adding anything to the bill of materials. Enter MCAS, a system designed to meet the same type regulation with disastrous unintended side effects. Side effects made much worse by the fact pilots don't know the system even exists since this plane is the same as every other 737 as far as they know. I don't think the same type regulation should be scrapped since it would stop things like fuel efficiency gains during an airframe's lifespan, but there needs to be a same type minimum training and documentation that has to be done even if the only thing you change is thickness of the paint. If anything the definition of what meets same type should be slightly expanded allowing more flexibility in what can be changed. Combined with mandatory training for all subtypes (but still much shorter than different type training) the perverse incentive to make the plane behave exactly the same is removed. That leaves room for the better technical fix to win the day rather than the one that will meet the regulation. Training costs will go up some, but less than full different type certification.
    - inferiorhuman 8y ago

cal5k 8y ago

Saying that something requires training to be operated safely does not mean that it is unsafe. It means that it's a complex system that requires training to operate. Place a random passenger into the cockpit of a modern commercial airliner without training and ask them to fly the thing safely and you'd probably have a 100% loss rate.

GiorgioG 8y ago
> Saying that something requires training to be operated safely does not mean that it is unsafe. This ultimately is not a training issue. Why was a system that can potentially plow the aircraft's nose into the ground utilizing only a single sensor without any redundancy in place? Boeing screwed up. Now both sensors will be used. Great, but sometimes 2 sensors fail. If pilots that operate these aircrafts are trusted with the lives of 150+ passengers, they should have an "easy button" to take complete manual control of the aircraft. My human sensors should trump any mechanical sensor(s) when my life is on the line.
- cal5k 8y ago
  They do have an "easy button": two highly visible switches right underneath the throttle. Bottom right here where it says "stab trim": http://www.sjap.nl/wp-content/uploads/IMG_0825-e1464602357745.jpg http://www.sjap.nl/wp-content/uploads/IMG_0825-e146460235774... Activating those switches cuts off electric trim and would completely deactivate MCAS. It can be done in seconds.
  - omegaworks 8y ago
    But can the determination to perform the stab trim cut-off be done in seconds? Are there other feedback mechanisms present that can interrupt that determination? That appears to be the case in these scenarios. The MCAS doesn't perform the incorrect action continuously, it looks like initial corrective measures fix the problem until they suddenly don't.
  - GiorgioG 8y ago
    > Activating those switches cuts off electric trim and would completely deactivate MCAS. It can be done in seconds. That's great...if they'd understood that the system was malfunctioning...but they had no such indication because their airline didn't pay for the optional "feature."