The Boeing Corporation remains tight-lipped over whether Indonesian budget carrier Lion Air informed the company of the flight control problem experienced by a brand new Boeing 737 MAX 8 jetliner in the days before it crashed late last month into the Java Sea, killing all 189 people aboard.
A company spokesperson referred Asia Times to a pro forma statement which said Boeing was “taking every measure to fully understand all aspects of this incident, working closely with the investigating team and all regulatory authorities involved.”
Other key questions are what Lion Air’s maintenance staff did in responding to the problem and why Boeing took a week before it issued an urgent warning to all operators of 737 Max 8 and 9 aircraft of a potential malfunction of the Angle-of-Attack (AOA) sensor that could send the plane into a nosedive.
With Indonesia leading the crash investigation, Boeing is bound by International Civil Aviation Organization (ICAO) rules and possible legal constraints about what it can say about the crash. Indonesia’s first preliminary report is due to be issued at the end of November. A full report can take years.
Lion Air Flight JT610, in service since last August, went down barely 13 minutes after taking off from Jakarta’s Sukarno-Hatta international airport on October 29 on a scheduled hour-long flight to Pangkal Pinang on Sumatra’s tin-mining island of Bangka, southwest of Singapore.
The Federal Aviation Administration (FAA), America’s civil aviation regulator, and Boeing have said they are evaluating the need for software or other design changes to the new-generation aircraft, as well as a different approach to operating procedures and training.
The FAA previously issued an emergency airworthiness directive ordering airlines to follow Boeing’s new instructions if they encountered a problem that “could cause flight crew to have difficulty controlling the airplane, leading to excessive nose-down attitude, significant altitude loss and possible impact with terrain.”
In the United States, two pilots’ unions and the Allied Pilots Association (APA) questioned why the jet’s manual failed to explain the potential risks associated with a safety feature which is meant to provide extra protection against air crew losing control.
“It’s pretty asinine for them to put a system on an airplane and not tell the pilots who are operating the airplane, especially when it deals with flight controls,” APA chairman Captain Mike Michaelis told the Wall Street Journal in a quote repeated on the association’s website.
The unions represent pilots on Southwest Airlines and American Airlines, which together have orders for a total of 342 of the 737 MAX; the plane entered service in May last year, just three months before Lion Air took delivery of its first single-aisle MAX 8.
The pilots of the ill-fated Lion Air jet were fighting a losing battle within three minutes of lifting off the runway, struggling to get beyond 5,000 feet at a time when they should have reached 10,000 feet. Even when they radioed to turn back, they were apparently too preoccupied to declare an emergency.
The erratic flight path of the doomed plane had been replicated the day before on a flight from Bali to Jakarta with terrified passengers reporting dramatic variations in altitude and speed soon after take-off, including a 200-meter plunge in 27 seconds.
More troubling is that it wasn’t the first time. In a startling revelation, Indonesia’s National Transport Committee chairman Soerjanto Tjahjono said there had been airspeed indicator malfunctions on the jetliner’s two previous flights as well, raising questions over why the plane was not pulled from service.
The replacement of the AOA sensor after the Bali flight appears to have made little difference, which means investigators will also have to look carefully at the actions of the pilots when the plane was flying in daylight and in clear skies, conditions which should have ruled out disorientation.
Searchers scouring the muddy seabed have yet to find the cockpit voice recorder that would provide answers to what an aircrew with a combined 11,000 hours of flying experience were struggling to deal with as the plane spiraled out of control.
Indonesian aviation sources understand that while the previous three consecutive incidents were reported in the aircraft performance log, Lion Air did not inform Boeing of a possible systematic issue because it affected only one aircraft, apparently flown by different crews.
Aviation experts believe the problem with the AOA, which measures the angle at which the oncoming flow of wind hits the wings and can warn of a possible stall, appears to have been complicated by the malfunctioning airspeed indicator.
The 737 MAX is designed to go into an automatic dive if a stall is detected, the normal tactic to recover and maintain flight. As it was, the black box data recorder recovered from the seabed indicates the Lion Air plane hit the water at high speed, with both engines running.
More than 240 Boeing MAX jets are now in service with 39 airlines and air lease companies across the world. As of September 30, Boeing says it has 4,783 firm orders from 98 different customers, 26 of those in Asia and 14 of them in China.
The Lion Group, which also includes full-service Batik Air, Malaysia’s Malindo Air and turbo-prop operator Wings Air, has 272 aircraft in its fleet, making it the largest airline in the Asia-Pacific region outside of China.
It has already taken delivery of 13 MAX 8s out of a total order of 200 aircraft.