Boeing’s MCAS (the Maneuvering Characteristics Augmentation System) was an honest mistake, but the secrecy shrouding the program’s very existence told you it wasn’t a 100 percent honest honest mistake:
According to Rick Ludtke, a former Boeing employee, Boeing agreed to rebate Southwest $1 million for every MAX it bought, if the FAA required level-D simulator training for the carrier’s pilots.
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Simulator training for Southwest’s 9,000 pilots would have been a pain, but hardly ruinous; aviation industry analyst Kit Darby said it would cost about $2,000 a head. It was also unlikely: The FAA had three levels of “differences” training that wouldn’t have necessarily required simulators. But the No Sim Edict would haunt the program; it basically required any change significant enough for designers to worry about to be concealed, suppressed, or relegated to a footnote that would then be redacted from the final version of the MAX. And that was a predicament, because for every other airline buying the MAX, the selling point was a major difference from the last generation of 737: unprecedented fuel efficiency in line with the new Airbus A320neo.
The MAX and the Neo derived their fuel efficiency from the same source: massive “LEAP” engines manufactured by CFM, a 50-50 joint venture of GE and the French conglomerate Safran. The engines’ fans were 20 inches — or just over 40 percent larger in diameter than the original 737 Pratt & Whitneys, and the engines themselves weighed in at approximately 6,120 pounds, about twice the weight of the original engines. The planes were also considerably longer, heavier, and wider of wingspan. What they couldn’t be, without redesigning the landing gear and really jeopardizing the grandfathered FAA certification, was taller, and that was a problem. The engines were too big to tuck into their original spot underneath the wings, so engineers mounted them slightly forward, just in front of the wings.
This alteration created a shift in the plane’s center of gravity pronounced enough that it raised a red flag when the MAX was still just a model plane about the size of an eagle, running tests in a wind tunnel. The model kept botching certain extreme maneuvers, because the plane’s new aerodynamic profile was dragging its tail down and causing its nose to pitch up. So the engineers devised a software fix called MCAS, which pushed the nose down in response to an obscure set of circumstances in conjunction with the “speed trim system,” which Boeing had devised in the 1980s to smooth takeoffs. Once the 737 MAX materialized as a real-life plane about four years later, however, test pilots discovered new realms in which the plane was more stall-prone than its predecessors. So Boeing modified MCAS to turn down the nose of the plane whenever an angle-of-attack (AOA) sensor detected a stall, regardless of the speed. That involved giving the system more power and removing a safeguard, but not, in any formal or genuine way, running its modifications by the FAA, which might have had reservations with two critical traits of the revamped system: Firstly, that there are two AOA sensors on a 737, but only one, fatefully, was programmed to trigger MCAS. The former Boeing engineer Ludtke and an anonymous whistle-blower interviewed by 60 Minutes Australia both have a simple explanation for this: Any program coded to take data from both sensors would have had to account for the possibility the sensors might disagree with each other and devise a contingency for reconciling the mixed signals. Whatever that contingency, it would have involved some kind of cockpit alert, which would in turn have required additional training — probably not level-D training, but no one wanted to risk that. So the system was programmed to turn the nose down at the feedback of a single (and somewhat flimsy) sensor. And, for still unknown and truly mysterious reasons, it was programmed to nosedive again five seconds later, and again five seconds after that, over and over ad literal nauseam.
