A young Romanian risked death stowing away in the undercarriage of a jumbo jet to Britain despite being entitled to come into the country legally.
The 20-year-old was discovered by security staff at Heathrow after falling out of the rear wheel compartment.
Last night an official at the Civil Aviation Authority said he was lucky to be alive with planes usually flying at around 35,000 feet in freezing temperatures.
"A lot of times stowaways die from hypothermia and lack of oxygen. Those travelling long distance who do survive are often unconscious for a large portion of the flight, and that is the only reason they survive because their body slows down.
"Furthermore if you are not in the right bit of the wheel well you can be crushed when the undercarriage comes up, which quite often happens," he explained.
Since joining the EU in 1997, Romanian citizens, in the words of the UK Border Agency, "have every right" to come to the UK. The only stipulation is that they must have Accession Worker Cards before taking on employment.
The man, Austrian police said, had been hoping to find work in Britain, so he crawled under the wire of the fence surrounding Vienna Airport and climbed into the landing gear of a private jet belonging to a sheikh from the United Arab Emirates.
The plane made its hour and a half journey from the Austrian capital and arrived at Heathrow on Sunday night. Upon landing at Heathrow he fell out of the gear's cavity and was caught by security.
The jet would normally have been travelling at 37,000ft in temperatures of around minus 50C to maximise fuel efficiency, but the pilot had chosen to fly at 25,000ft due to bad weather.
Last night a Metropolitan Police spokesman said that the man was arrested for stowing away in an aircraft contrary to the Air Navigation Order 2009 and taken into custody at Heathrow police station where he was cautioned for the offence of being a stowaway and entering Britain without a passport.
"Police were alerted at 7.37pm on Sunday, 6 June regarding a suspected stowaway on a private aeroplane that had landed at Heathrow. A 20-year-old Romanian national was arrested for stowing away on an aircraft," said a spokesman, adding that he had since been released.
The young man was said to be "in incredibly good shape" despite his ordeal. The police spokesman added: "We called London Ambulance Service and they checked him over but there were no obvious signs of medical impairment."
Vienna airport's police chief, Leo Lauber, told the Evening Standard: "He aimed for any jet, it would seem, not one in particular. After wriggling under the fence he headed for the aircraft nearest to the fence. He had no idea where it was going to. Initial inquiries here seem to indicate he wanted to go abroad to find work."
Many desperate stowaways have lost their lives in recent years.
In October 1996, Vijay Saini, 19, fell 2,000ft from a jet as it was approaching Heathrow. A post-mortem examination found that he was already dead when he tumbled from the plane. His brother Pardeep, 22, survived the 10-hour journey from Delhi.
In January 2007, a pilot making a routine inspection shortly before a British Airways flight was due to return to London from Los Angeles discovered the body of young man in the front wheel well of the 747-400. The airline said he had probably stowed away in some other country on the plane's route.