By Alan Levin / Bloomberg
Pilots on a Republic Airways Services Inc. flight leaving Atlanta in November lost the ability to raise and lower their Embraer EMB-175’s nose, investigators said on Wednesday, a failure reminiscent of what helped lead to the two deadly 737 Max crashes.
The National Transportation Safety Board issued 10 recommendations to Brazil, where the jet was made, and U.S. aviation regulators.
One of the issues was that the emergency procedures followed by the pilots, who were operating the flight for American Airlines Group Inc., didn’t seem to immediately stop the problem, the NTSB said. The failure was also difficult for pilots to detect, a situation which occurred in the 737 Max crashes that killed 346 people.
The regional jet carrying six passengers and four crew members had just lifted off when the captain noticed the plane was trying to aggressively pull the nose up into a climb.
The captain and copilot followed an emergency procedure they’d memorized for the problem, but it didn’t correct the problem, the NTSB said. The pilots reported that they both needed to push the control column with two hands to maintain control of the plane, preventing them from reaching for their emergency checklists.
Eventually, the copilot was able to use a thumb switch to help keep the jet’s nose level, and they returned for a safe landing, NTSB said.
While the Boeing 737 Max crashes involved a separate failure involving software, it also caused what’s known as the pitch trim system on the plane to malfunction. In those cases, it was driving the nose down and pilots weren’t able to diagnose the issue and disconnect the motor that was causing it.
Investigations into those crashes also raised concerns about emergency procedures.
In the Atlanta incident, NTSB investigators found the captain’s thumb switch that adjusts the trim — which would raise and lower the nose — had been installed upside down. That could cause a situation in which attempts to lower the nose would actually cause it to go up instead.
The NTSB said it also found evidence of chafed wires in the system controlling the trim on the plane. Such chafing could trigger a short circuit, leading to a trim failure.
The NTSB didn’t say whether either of these issues caused the problems the pilots encountered.
Embraer said in a statement that since 2015 it has told operators of the plane to modify the switch so that it couldn’t be installed improperly. It has also advised airlines to inspect for damaged wiring, the company said. Representatives of Republic didn’t immediately respond to a request for comment.
The safety board called on Brazil’s National Civil Aviation Agency and the Federal Aviation Administration to mandate inspections for similar wiring problems, require Embraer’s switch repair, and to examine whether the plane’s emergency checklist needs to be revised.
It applies to several similar models, the EMB-170, EMB-175, EMB-190 and EMB-195.