Pirate radio stations are causing increasing problems to aircraft flying over the capital, regulators have said.
Ofcom said there were 70 such cases in 2006
Air traffic controllers say the illegal radio broadcasts often block out vital communications with pilots.
Paul Mercer of Ofcom said in 2006 there were 70 reports of interference from pirate stations to "safety of life" services such as air traffic control.
Pirate DJs want to see evidence and are convinced it is another excuse to take their stations off air.
Former Boeing 747 pilot Eric Moody believes pirate radio DJs are underestimating the risk they pose.
"When you're in cloud for the majority of your approach, and you don't see an aeroplane and you're at minute intervals coming into Heathrow... if you miss an instruction and you go flying off on a track you shouldn't be on, it's very, very dangerous."
Mr Mercer said: "Predominantly the complaints of interference were received from the fire brigade in London and of course air traffic control services, so it's not a victimless crime."
DJ "Funky Flirt" told BBC London: "If it is as bad as they say it is, they would be getting in touch with the stations... God forbid anything happens, I just don't know how they can say this without proving it."