An American Airlines mechanic upset over stalled union contract negotiations was arrested Thursday, charged with doing the unthinkable — sabotaging an aircraft that was set to carry 150 passengers.

This coming after the union president promised “the bloodiest, ugliest battle” ever seen in the U.S. labor movement.

Abdul-Majeed Marouf Ahmed Alani, a veteran AA employee, allegedly disabled a navigation system on a flight scheduled to take off from Miami International Airport earlier this summer, the Miami Herald reported.

The July 17 flight was heading to Nassau, Bahamas, and was aborted when an error alert activated as the pilots powered up the plane’s engines on the runway.

The aircraft was taken out of service for maintenance at America Airlines’ hangar at Miami International Airport and tampering with the air data module was discovered during an inspection, the newspaper reported.

The inspection revealed a loosely connected tube in front of the nose gear under the cockpit had been deliberately obstructed with hard foam material.

If the tampering had not been discovered, the pilots reportedly would have had to fly the aircraft manually because the ADM system would not have received any computer data.

Alani told federal air marshals “his intention was not to cause harm to the aircraft or its passengers,” according to his arrest affidavit.

The mechanic said his motivation was “to cause a delay or have the flight canceled in anticipation of obtaining overtime work” because stalled contract negotiations with American Airlines “had affected him financially.”

Surveillance video captured Alani, who walks with a limp, approaching the plane on the tarmac and accessing the compartment where the navigational system was. He allegedly spent about seven minutes sabotaging the aircraft.