Before last month’s crash of a flight that began in Ethiopia, Boeing Co. said in a legal document that large, upgraded 737s “cannot be used at what are referred to as ‘high/hot’ airports."
At an elevation of 7,657 feet -- or more than a mile high -- Addis Ababa’s Bole International Airport falls into that category. High elevations require longer runways and faster speeds for takeoff. The Ethiopian airport’s altitude hasn’t been cited as a factor in the downing of Flight 302 and likely didn’t cause the crash. But it could have exacerbated the situation because an airplane’s performance degrades at higher altitudes, said a 737 pilot who flies into high-elevation airports such as Denver and agreed to speak on background since he’s not authorized to talk with the media.
Data released last week from the Ethiopian Airlines flight indicated the pilots didn’t cut the 737 Max 8 airplane’s speed after takeoff when they should have. The preliminary report on the disaster said the plane’s anti-stall system pushed the nose of the plane down less than two minutes into the flight because of a malfunctioning sensor. The pilots struggled to control the plane as it hurtled toward the ground at 575 miles per hour.
“The faster the airplane is going, the more force of air there is on its wings and control surfaces which requires more force on the pilots’ part to pull the control” column, said Robert Mark, a commercial pilot and senior editor with Flying Magazine.
Boeing cited the performance of the 737 Max 8 in a case brought before the US International Trade Commission in 2017. Boeing charged that unfair competition from Bombardier -- which beat out Boeing for a large order from Delta Air Lines -- threatened its 737-700 and Max 7, the smallest of its upgraded single-aisle jets. By pointing out the limitations of the Max 8, the planemaker sought to preserve market share for the 700 and Max 7.
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