FAA officials explained how in the forthcoming, revised MCAS, the software would rely on two AoA sensors instead of one. In any cases of disagreement, it would shut down. De Luis listened in disbelief. Even the space shuttle, developed in the 1970s, had five redundant computers. Airbus planes typically used three sensors. The solution also seemed shockingly clunky: If the software was necessary to keep the plane’s nose from pitching up in certain situations, what would happen in a flight that encountered one of those rare situations and didn’t have MCAS available?
