The Alaska Airlines flight was scheduled for a security checkpoint on the day the panel blew off
A day before the doorplug blew off an Alaska Airlines flight on January 5, airline engineers and technicians were so concerned about mounting evidence of a problem that they wanted the plane to be taken out of service and undergo maintenance the following evening . , according to interviews and documents.
But the airline opted to keep the plane, a Boeing 737 Max 9, in service with some restrictions on January 5, carrying passengers until it completed three flights that would end that night in Portland, Oregon, the site of one of the airline’s maintenance facilities.
Before the aircraft could complete the scheduled series of flights and enter for the maintenance check, the door plug blew out at 16,000 feet, minutes after boarding the second flight. flight of the day, from Portland to Ontario International Airport in California.
The plane landed safely and no one was seriously injured, but the incident drew new attention to Boeing’s manufacturing processes and the safety procedures followed by airlines.
The schedule for the aircraft’s maintenance check has not previously been reported. This shows that the airline chose to keep the plane in service while it was en route to the maintenance facility, rather than fly it to Portland without passengers.
Alaska Airlines confirmed the sequence of events. But the airline said the warnings on the plane did not meet standards for its immediate removal from service.
Donald Wright, Alaska Airlines’ vice president of maintenance and engineering, said the warning lights – a light that indicates problems with the plane’s pressurization system – had come on twice in the past 10 days instead of the three times the airline the trigger eight to take. more aggressive action.
Alaska Airlines has repeatedly said there is no evidence the warning lights, which could also be caused by electronic or other problems, were related to the impending plug failure.
“From my perspective as a safety guy, looking at all the data and all the leading indicators, there was nothing that would cause me to make a different decision,” Max Tidwell, Alaska Airlines’ vice president of safety and security, said in an interview .
The airline’s engineers had called for the plane to undergo a rigorous maintenance check on January 5 to determine why the warning lights were activated based on their use of “a predictive tool” rather than the number of times the warning lights had gone out. the airline said.
Although the airline kept the aircraft in service, the airline placed restrictions on it at the recommendation of the engineers. It limited the aircraft to flying long-distance routes over water, such as to Hawaii, or remote continental areas in case of an emergency landing.
Extensive evidence of a possible problem with the plane had been accumulating for days and possibly weeks, according to interviews with the airline and data from the investigation into the explosion. In addition to the flashing lights, investigators say the door plug gradually slid upwards, a potentially crucial link in the accumulating chain of evidence. The airline said visual inspection in the days leading up to the blowout did not reveal any movement of the door plug.
A door plug is a panel that is placed where an emergency exit would be in an aircraft with the option to expand the number of passenger seats.
A preliminary report released last month by the National Transportation Safety Board said four bolts intended to secure the door plug in place were missing before the panel emerged from the plane. It outlined a series of events that took place at Boeing’s plant in Renton, Washington, that may have led to the plane being delivered without the bolts in place.
Mark Lindquist, an attorney representing passengers on the Jan. 5 flight, said the string of accidents involving the Alaska Airlines plane was alarming, adding that both the airline and Boeing, the manufacturer of the 737 Max 9, would struggle have to explain the events in court.
“If jurors find out that they have been warned by engineers to ground the plane and instead put it on commercial rotation, the jurors will be more than stunned – they will be angry,” Mr. Lindquist said.
In his lawsuit, Mr. Lindquist said passengers on an earlier flight heard a “whistling sound” coming from the area of the door plug. According to the documents, passengers brought the noise to the attention of the flight attendant, who then reported it to the pilots. When asked about the report, Alaska Airlines said it could find no record of a whistle coming from the plane.
Nearly a week before the blowout, the 737 was taken out of service on December 31 due to a problem with the front passenger entry and exit door. Records show the aircraft resumed service on January 2. However, on January 3, a pressurization warning light activated during at least one of the aircraft’s flights. Alaska Airlines officials said the plane was inspected by engineers and the airline determined it was safe enough to keep the plane flying.
The next day the same light was activated again.
An Alaska Airlines spokeswoman said at that time engineers and technicians had scheduled a more in-depth inspection of the plane for the night of Jan. 5 in Portland. But the airline opted to fly the plane with passengers as it flew across the country that day.
The revelations about the warning signs of a potential problem have raised questions about whether routine inspections should have been able to weave together different indications of a problem and prevent the incident.
Jennifer Homendy, the chairman of the National Transportation Safety Board, told reporters last week that during the 154 flights the plane had flown since it entered service in the fall, small upward movements of the door plug had left visible marks and possibly created a gap between the panel and the hull.
Alaska Airlines officials said they noticed no unusual gaps between the door plug and the plane’s fuselage during inspections in the days leading up to the door plug’s release.
Additional evidence includes pressurization lights on previous flights and unconfirmed reports of a whistling sound.