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Software engineers are not aerospace engineers. I doubt the software people would have understood the aerodynamic effects of the MCAS system by looking at the r

Software engineers are not aerospace engineers. I doubt the software people would have understood the aerodynamic effects of the MCAS system by looking at the requirements.

bdavis__ 7y ago
some would, some would not. those that have been doing aircraft software for 20 years probably have a fair knowledge of airplanes, aerodynamics, and flight controls. your comment expresses my feelings exactly on 'was this a software failure?'. No. But software was involved.
_ph_ 7y ago
That is the problem with having pure software engineers implementing such a software. They need to have some aerospace engineering knowledge too. Or at least work directly in one team with aerospace engineers. I am working as a "software engineer" in the semiconductor industry. By education, I am a physicist. I am in my job for more than 10 years now, and beyond my university education, I have quite a grasp of electrical engineering. Furthermore, most of my colleagues are eletrical engineers. So in doubt, I can just walk over to their desk and discuss any question beyond pure software development issues. And some of the software developers here are just electrical engineers, which expanded their skill profile into software territory. Doing business this way is quite more expensive than having software developed by a contractor, but it creates safeguards.
- sn41 7y ago
  That is true. But please keep in mind that the whole MCAS fiasco was precipitated by a dubious cost-cutting initiative related to an engine placed more in front than would be aerodynamically stable. The game was lost in the first quarter. The whole point is that civilian aircraft, unlike fighter jets, have to be aerodynamically stable without the need for such software, whether developed by holistic engineers, or compartmentalised subcontractors.
  - _ph_ 7y ago
    The 737 MAX is aerodynamically stable. MCAS isn't even active while any flap is extended. MCAS should be active only at angle of attacks, which wouldn't be reached at extreme angle of attacks. The sole purpose of MCAS is to emulate the exact reactions of the older 737 machines in this domain, as this was required for maintaining the same type rating. That is also the reason, the pilots are supposed to deactivate MCAS via the runaway stabilizer checklist. This software isn't required for stable operations of the airplane - Lion air had a MCAS malfunction the day before the crash, but disengaging the electric stabilizers solved the problem and they were able to finish their flight without incidents.
    - salawat 7y ago
      Incorrect. The aircraft is not aerodynamically stable in pitch unaided by software, thereby failing the demonstration of positive pitch stability as written in FAR 25.173. The non-compliance is of the form of a slackening of control stick response force at high AoA due to extra lift generation ahead of the center of gravity caused by the forward mounted engine nacelles. In regulatory parlance, this specifically means the airframe (the specific physical assembly of parts that collectively determine the flight characteristics of the object in question) possesses an "instability" that disqualifies it from being certified airworthy as a Civil Transport Aircraft unless the FAA amends or reinterprets the requirement. The penultimate Lion Air flight only recovered thanks to The intervention of a third pilot; a luxury not universal to every cockpit. >MCAS should be active only at angle of attacks, which wouldn't be reached at extreme angle of attacks. The potential for MCAS subroutine activation is active during all phases of manually controlled (Autopilot off), flaps up flight,and is gated only by readings from an AoA sensor; which can fail in flight to catastrophic effect. >The sole purpose of MCAS is to emulate the exact reactions of the older 737 machines in this domain, as this was required for maintaining the same type rating. Incorrect. The sole purpose of MCAS is to induce an intentional "mistrim" during certain points of the flight envelope to counter the extra lift generated by the repositioned engines, with the end goal of smoothing out the non-compliant stick force response curve. Note, jury is still out whether this should even be allowed. I've gotten wildly different responses based on who I've talked to. Pilots seem to express horror or extreme discomfort. Aerodynamicsts are disconcertingly quiet, but tend toward hard reconfiguration to obviate the need for a software based solution. Also, MCAS specifically deviates from oldaircraft behavior in that it removes an override of auto-trim commands activated by heavy back pressure on the yoke. There were also specific reconfiguration of the stabilizer trim cutout switches that removed any capability of locking out the MCAS system's ability to actuate the trim motor, while leaving pilot's thrim switches active. https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards/ https://www.seattletimes.com/seattle-news/times-watchdog/the... https://www.seattletimes.com/business/boeing-aerospace/boeing-altered-key-switches-in-737-max-cockpit-limiting-ability-to-shut-off-mcas/?amp=1 https://www.seattletimes.com/business/boeing-aerospace/boein... Make no mistake: Boeing screwed the pooch. Big Time.
SteveGerencser 7y ago
This is the larger problem. There are plenty of aero engineers that are brilliant programmers yet the reverse is a much smaller number. Add to that, aeros that can code are far more expensive than software engineers, it becomes easy to see why they outsource to software people.

Software engineers are not aerospace engineers. I doubt the software people would have understood the aerodynamic effects of the MCAS system by looking at the requirements.

bdavis__ 7y ago

some would, some would not. those that have been doing aircraft software for 20 years probably have a fair knowledge of airplanes, aerodynamics, and flight controls. your comment expresses my feelings exactly on 'was this a software failure?'. No. But software was involved.

_ph_ 7y ago

That is the problem with having pure software engineers implementing such a software. They need to have some aerospace engineering knowledge too. Or at least work directly in one team with aerospace engineers. I am working as a "software engineer" in the semiconductor industry. By education, I am a physicist. I am in my job for more than 10 years now, and beyond my university education, I have quite a grasp of electrical engineering. Furthermore, most of my colleagues are eletrical engineers. So in doubt, I can just walk over to their desk and discuss any question beyond pure software development issues. And some of the software developers here are just electrical engineers, which expanded their skill profile into software territory. Doing business this way is quite more expensive than having software developed by a contractor, but it creates safeguards.

sn41 7y ago
That is true. But please keep in mind that the whole MCAS fiasco was precipitated by a dubious cost-cutting initiative related to an engine placed more in front than would be aerodynamically stable. The game was lost in the first quarter. The whole point is that civilian aircraft, unlike fighter jets, have to be aerodynamically stable without the need for such software, whether developed by holistic engineers, or compartmentalised subcontractors.
- _ph_ 7y ago
  The 737 MAX is aerodynamically stable. MCAS isn't even active while any flap is extended. MCAS should be active only at angle of attacks, which wouldn't be reached at extreme angle of attacks. The sole purpose of MCAS is to emulate the exact reactions of the older 737 machines in this domain, as this was required for maintaining the same type rating. That is also the reason, the pilots are supposed to deactivate MCAS via the runaway stabilizer checklist. This software isn't required for stable operations of the airplane - Lion air had a MCAS malfunction the day before the crash, but disengaging the electric stabilizers solved the problem and they were able to finish their flight without incidents.
  - salawat 7y ago
    Incorrect. The aircraft is not aerodynamically stable in pitch unaided by software, thereby failing the demonstration of positive pitch stability as written in FAR 25.173. The non-compliance is of the form of a slackening of control stick response force at high AoA due to extra lift generation ahead of the center of gravity caused by the forward mounted engine nacelles. In regulatory parlance, this specifically means the airframe (the specific physical assembly of parts that collectively determine the flight characteristics of the object in question) possesses an "instability" that disqualifies it from being certified airworthy as a Civil Transport Aircraft unless the FAA amends or reinterprets the requirement. The penultimate Lion Air flight only recovered thanks to The intervention of a third pilot; a luxury not universal to every cockpit. >MCAS should be active only at angle of attacks, which wouldn't be reached at extreme angle of attacks. The potential for MCAS subroutine activation is active during all phases of manually controlled (Autopilot off), flaps up flight,and is gated only by readings from an AoA sensor; which can fail in flight to catastrophic effect. >The sole purpose of MCAS is to emulate the exact reactions of the older 737 machines in this domain, as this was required for maintaining the same type rating. Incorrect. The sole purpose of MCAS is to induce an intentional "mistrim" during certain points of the flight envelope to counter the extra lift generated by the repositioned engines, with the end goal of smoothing out the non-compliant stick force response curve. Note, jury is still out whether this should even be allowed. I've gotten wildly different responses based on who I've talked to. Pilots seem to express horror or extreme discomfort. Aerodynamicsts are disconcertingly quiet, but tend toward hard reconfiguration to obviate the need for a software based solution. Also, MCAS specifically deviates from oldaircraft behavior in that it removes an override of auto-trim commands activated by heavy back pressure on the yoke. There were also specific reconfiguration of the stabilizer trim cutout switches that removed any capability of locking out the MCAS system's ability to actuate the trim motor, while leaving pilot's thrim switches active. https://www.seattletimes.com/seattle-news/times-watchdog/the-inside-story-of-mcas-how-boeings-737-max-system-gained-power-and-lost-safeguards/ https://www.seattletimes.com/seattle-news/times-watchdog/the... https://www.seattletimes.com/business/boeing-aerospace/boeing-altered-key-switches-in-737-max-cockpit-limiting-ability-to-shut-off-mcas/?amp=1 https://www.seattletimes.com/business/boeing-aerospace/boein... Make no mistake: Boeing screwed the pooch. Big Time.

SteveGerencser 7y ago

This is the larger problem. There are plenty of aero engineers that are brilliant programmers yet the reverse is a much smaller number. Add to that, aeros that can code are far more expensive than software engineers, it becomes easy to see why they outsource to software people.