10 seconds of jet terror injures 32 passengers injures 32

A MAN ended up embedded in the ceiling of an aircraft as hundreds of passengers, including the Prime Minister's daughter, endured a terrifying bout of turbulence near Singapore.

Kathryn Blair, 11, returning from a holiday, was among 235 passengers on a British Airways Boeing 747 flying from Australia to Heathrow. Fifty minutes before touchdown in Singapore it hit "clear-air turbulence" - leading to 10 seconds in which the plane fell 300ft from its cruising altitude of 37,000ft, throwing passengers and crew from their seats. A man broke his wrist and a woman broke a rib. Thirty other people were injured.

Kathryn Blair was not reported to be hurt. The flight was delayed while people were treated. It arrived safely in London yesterday.

"There were a lot of people flying around the cabin," said Barry White, from Brisbane, saved by his seatbelt. "Someone went through the panel of the ceiling. All I could see were a pair of legs hanging out." Marlene and Tony Newton, from Tiverton, Devon, returning from a holiday with their two children, said they were just about to have dinner when the plane fell. Mrs Newton said: "We had just experienced a touch of turbulence, then the aircraft just dropped. A steward who was pushing his trolley slammed into the overhead lockers; food and drink flew everywhere. People were hurled out of their seats. It was just terrifying. Even the crew looked terrified."

Clear-air turbulence, which cannot be detected by radar, results from changes in wind speed and direction of as much as 100mph. As the aircraft falls, objects are left behind, so they appear to shoot up. Though the plane is safe, the main risk to passengers and crew is of slamming into overhead lockers, and from flying objects.

The causes of clear-air turbulence are unknown, though distant thunderstorms or the passage of planes on the same route may contribute.

Between 1981 and 1996 there were 252 incidents serious enough to report, though most are barely noticed by passengers. A BA spokesman said yesterday: "The pilots would have had no warning."

In most cases of clear-air turbulence the pilot usually retains control. But in 1966 a BOAC Boeing 707 crashed with the loss of all 124 people when, in a freak accident, it was trapped in the lee of Mount Fuji. In 1997 a woman died of head injuries and 110 people, including nine crew, were injured when a United Airlines Boeing 747 fell 1,000ft from its cruising altitude of 33,000ft between Tokyo and Honolulu.

r Scientists are closer to eradicating jet lag by finding a mechanism that sets the body's biological clock. Jet lag occurs when the body clock is upset by crossing time zones. Researchers hope the discovery may lead to a way of resetting the internal clocks of airline passengers.

A team from Erasmus University in the Netherlands and Tohoku University in Japan say two body proteins, Cry-1 and Cry-2, appear to be affected by the length of day and night. Examination of human and mouse DNA found both proteins contained genes similar to those in plants known to help control opening and closing of leaves in a 24-hour cycle. Research results in the journal Nature showed that when mice lacked Cry-1 their body clocks ran an hour faster.

With Cry-2 missing, the body clock ran an hour slower. When mice lacking both proteins were exposed to total darkness for 24 hours a day, their clocks failed, showing no cycle of rest and activity displayed by normal mice.

Drugs designed to affect or interfere with the function of the proteins may eventually help to overcome jet lag.