Pirate broadcasters have been risking lives by posing as air crew and sending bogus messages to air traffic controllers at Leeds-Bradford Airport.

A police investigation has begun to catch the illegal broadcasters who have been using specialist equipment – and specific airline ‘call signs’ – to disrupt planes landing or taking off from the Yeadon airport.

There have been two incidents reported to police by airport staff since Christmas, sparking safety concerns.

Mark Winterbourne, chairman of Project Griffin, the airport’s anti-terrorism operation, said: “These people just think they are having a laugh but it is a very juvenile and immature act where the consequences could be so dire, you cannot imagine.”

He said that, although air traffic controllers were aware of all of the planes’ flight paths, the illegal broadcasts could cause danger by increasing the possibility of aircraft colliding.

They have sent calls on the correct radio frequency – one of thousands available – used by the airport, said Mr Winterbourne.

They are understood to have been near the airport when the broadcasts were made.

Mr Winterbourne said: “The calls were pretending to be for air traffic controllers and anybody broadcasting on that frequency is creating not only a danger to the air traffic control but also a danger to the pilot and the public, passengers and people on the ground.”

Andy Leat, a constable with the Leeds-Bradford Airport police, who is based in Otley, said West Yorkshire Police had stepped up patrols around the airport in a bid to catch the airwave pirates.

They are believed to be in their late teens or early 20s and have “specialist knowledge” of aircraft and airports.

PC Leat said: “To be able to broadcast on an airport frequency, you need specialist equipment.

“Each airline has a call sign and they were using the correct call sign for an airline which uses Leeds-Bradford Airport.

“It generated into general chat but they initially called up as an airline.”

A spokesman for Leeds-Bradford Airport said it did not want to comment as the incidents were being investigated jointly by the police and Project Griffin staff.

Anyone with information should contact the Leeds-Bradford Airport Neighbourhood Policing Team on (01274) 471474.