Drone Impact Ruled Out as Cause of Incident With Damaged Jetliner

A Grupo Aeromexico SAB airliner said to have been hit by a drone last December was actually damaged when a poorly done repair on the plane caused its nose to collapse and crack as it prepared to land.

An examination of the Boeing Co. 737-800’s crimped nose cone by the company’s forensic experts ruled out a collision with a drone or any other object, including birds, according to a report it submitted to the National Transportation Safety Board earlier this month. The document was reviewed by Bloomberg News.

Local media reports said the jetliner hit a drone as it neared Tijuana, Mexico, for a landing on Dec. 12. The plane’s nose cone, also known as a radome, was shown in photos with its front-left side caved in and cracked in multiple places.

The initial story created a stir because it would have been the first time a small consumer drone was implicated in a collision with a large jet. Within days, London’s Gatwick Airport was forced to shut for parts of three days after a drone was sighted flying near its runways. Similar, shorter-lived disruptions occurred at London Heathrow and Newark, New Jersey’s Liberty International in the weeks afterward.

The NTSB initially became involved in the Tijuana probe because aircraft landing there fly through U.S. airspace, said William English, who is leading its investigation.

Later, when it became clear there most likely wasn’t a collision, the safety board continued to work in support of the Mexican investigation, English said.

The dome covering the nose of the Aeromexico 737, which is made of relatively thin plastics, had been repaired improperly in 2017, according to a May 15 letter to the NTSB from Boeing.

The repair “likely” caused it to weaken over time and led it to collapse as air pressure changed during descent, according to the company. The indentation in the nosecone showed no evidence of an impact with a drone.

English and others from NTSB oversaw Boeing’s review.

The company also swabbed the area so that it could be tested for bird remains. An examination of the swab showed no indication of bird feathers or DNA, according to a Feb. 28 letter from the Smithsonian Institution’s Feather Identification Lab.

Mexico’s Communications and Transportation Ministry, in charge of the Directorate General of Civil Aeronautics that leads the investigation into the incident, didn’t respond to requests for comment.

While the NTSB and aviation accident investigators in Canada and Israel have each documented instances of small drones colliding with aircraft — none of which have resulted in injuries — many reports of impacts or near-collisions have proven false or difficult to confirm.

Most of the reports to NTSB of possible drone collisions with other aircraft have proven unsubstantiated, English said. The agency has verified two collisions: a U.S. Army helicopter hit a small commercial drone in September 2017 near New York and a small drone grazed a hot-air balloon in Idaho last August.

The world’s largest civilian drone maker, China-based SZ DJI Technology Co. Ltd., released a report earlier this month saying there is a “glut of inaccurate information” surrounding reports of incidents allegedly involving unpiloted aircraft.