A fleet of passenger aircraft is stabled at Las Vegas McCarran International Airport that it's impossible to buy tickets for.

They don't carry any company logos – they're plain white with a red band down the side - and anyone who boards one is sworn to secrecy about where they're going and what they do for a living.

The reason that the aircraft, mostly Boeing 737s, are so shadowy in nature, is because they serve America's most secret military base, Area 51 in Nevada, which conspiracy theorists claim houses UFO technology.

Scroll down for video

At Las Vegas McCarran International Airport is a fleet of passenger aircraft (pictured) it's impossible to buy tickets for - because they fly to the US's secret Area 51 military base

They are run by the United States Air Force and operate from a private terminal at McCarran nicknamed Gold Coast, according to Flight Club.

The fleet does have a name of sorts – Janet Airlines, because that's the call sign the planes in it use while in civilian airspace.

From Las Vegas they fly north-west to a place that has what's widely regarded as the most restricted airspace in the world, the Area 51 base in the Nevada Test and Training Range.

In fact, Flight Club calls it 'restricted airspace inside restricted airspace'.

It claims that once the Janet aircraft approach this secretive area their call signs change from the likes of 'Janet 210' to 'bones 58'.

Once they touch down, the passengers disembark into a facility that's inspired countless books, TV shows and movies, but about which very little is known.

The Area 51-bound planes are run by the United States Air Force and operate from a private terminal at McCarran nicknamed Gold Coast (pictured)

UFO expert Nick Pope said: 'Area 51 [pictured] exists - it's part of a military testing range in Nevada - and because of the remote and sparsely-populated location, it's where various secret prototype aircraft and drones are developed and test flown'

Nick Pope, author of Encounter in Rendlesham Forest and the man who used to investigate UFOs for the British Ministry of Defence, explained to MailOnline Travel that Area 51 is the place where some of America's most hi-tech military hardware is built and tested – but he doubts any of it is extra-terrestrial in origin.

He said: 'Area 51 exists - it's part of a military testing range in Nevada - and because of the remote and sparsely-populated location, it's where various secret prototype aircraft and drones are developed and test flown.

'The UFO and conspiracy theory community think it's the place where crashed UFOs are kept and where the US military are trying to back-engineer this alien technology, and even Hillary Clinton has said that if she's elected President she'll look into the claims.

'Sadly, despite the rumours, I've seen no evidence that we've recovered any extraterrestrial technology.