January 7, 2014 - Air traffic controllers ordered the “lockdown” after their scanners picked up the bizarre object in the sky.
Staff were so bemused by the lights and shape of the UFO that they immediately put an emergency plan into action.
They cancelled and diverted all flights that were due to use the same area.
Officials said the mystery craft dominated radars at Bremen airport in Germany for three hours on Monday.
A police spokesman said: “We still don’t know what it was… but it was there.”
“It moved and was lit up. Because the officials could not assign it, and it had no business being there, my colleagues informed the police”
Officers scrambled helicopters and scoured the airspace. But although controllers kept track of the craft with binoculars, no-one could get near it.
One passenger jet from Paris was forced to remain airborne because of the alert before being cleared to land.
German Air Traffic control spokesman Axel Raab said: “My colleagues discovered the unknown object.
“It moved and was lit up. Because the officials could not assign it, and it had no business being there, my colleagues informed the police.
“The object was monitored for three hours... and then it was gone.
“UFO means unidentified flying object, so while we do not believe in aliens, yes, it is an unidentified flying object.”