Lufthansa CityLine Regional plane
Credit: Mateusz Wlodarczyk/NurPhoto via Getty Images

Pilots of a Lufthansa flight accidentally triggered a hijack alert as their plane was landing at Frankfurt Airport this week.

There had been a technical problem in the cockpit, a spokesperson for the airline said, and the pilots could send out messages to air traffic control but could not receive. When they tried to report the problem, they instead accidentally entered a code that signaled the plane was being hijacked.

About 15 minutes later, the pilots realized their mistake but by that time, action had already been taken on the ground. Security was on high alert; the German army and local and federal police were at the ready; the German air force was preparing fighter jets to intercept the plane if necessary.

The pilots reported their mistake to air traffic control who alerted those who had been mobilized.

The aircraft, an Embraer ERJ-190, was carrying 43 passengers from Aberdeen, Scotland, to Frankfurt. It landed safely, with a slight 15-minute delay.

Once on the ground, mechanics repaired the aircraft’s communication system. It flew again, without problems, a few hours later.

A Lufthansa spokesperson said that the incident was “very unusual.”

Not only is there a code to signal hijackings to air traffic, pilots have a secret code to alert cabin crew. By dinging the seatbelt sign several times, pilots can signal an emergency situation to cabin crew without alarming passengers.