Last week the pilots on a Lufthansa flight made a big mistake.

While the plane was landing at the airport at in Frankfurt, Germany, they “accidentally triggered a hijack alert“, according to Travel + Leisure.

A spokesperson for Lufthansa said that there was a problem in the cockpit. Messages could be sent to air traffic control but they couldn’t be received. While trying to report this issue, they entered the code for a hijacking by accident.

The pilots realized the mistake they made around 15 minutes after sending the hijacking alert. However, by this time, “action had already been taken on the ground“.

Once the pilots reported their mistake, the agencies who had already responded were notified of the error.

When the plane landed, the communication system was fixed. The plane flew again a few hours later without issue.

Find out more from Travel + Leisure here.