Gatwick Airbus A330 alert caused by faulty smoke alarm
A plane made an emergency landing at Gatwick, seriously injuring two people, because of "spurious" smoke warnings from the cargo hold, a report has said.
The Virgin Atlantic Airbus A330 left Gatwick bound for the US on 16 April 2012 but returned 29 minutes later.
It landed safely and more than 300 people exited using emergency chutes.
The Air Accidents Investigation Branch (AAIB) said a hidden "fault" in a smoke detector, combined with possible high levels of humidity, was to blame.
The aircraft was carrying a cargo largely comprised of perishable goods, which the AAIB said could have caused the humidity, leading to circumstances "sufficient to generate multiple spurious aft cargo compartment smoke warnings".
'Scenes of panic'
Fifteen smoke warnings were generated during the flight but there was no evidence of fire, smoke or heat damage, the report found.
Three flight crew, 10 cabin crew and 304 passengers, including three infants, were on board the 11:48 BST flight to Orlando, Florida.
Early in the flight, the crew received a series of smoke warnings from the aft cargo hold and the commander decided to return to Gatwick, the AAIB said.
"The crew carried out the appropriate emergency drills, including the discharge of the fire extinguishers in the aft cargo hold, but the smoke warnings continued," it explained.
The AAIB said the message that there was smoke in the cargo hold was misunderstood by air traffic controllers at Brest in France, and the message was "corrupted during onward transmission", leading to Gatwick's rescue and firefighting service positioning vehicles at the wrong end of the aircraft.
Once the aircraft had landed on the runway, the crew tried to establish the extent of any fire, but "this produced conflicting evidence and, with smoke warnings continuing, the commander ordered an emergency evacuation".
All the passengers left the aircraft within 90 seconds, but two were seriously injured, the AAIB said.
However, one of the escape slides did not inflate properly, which meant that exit was unusable.
The report also said there was confusion between the incident commander on the ground and the air traffic control watch manager over the correct status of the incident.
At the time, passengers described "scenes of panic", with people landing on top of each other at the bottom of the chute as the plane was cleared on the runway.
The report said at one point, at the bottom of one slide, a fireman tried to protect those already lying on the floor from those coming down by lying across the bottom of it.
Fifteen people needed hospital treatment for suspected fractures.
'Safety top priority'
The AAIB made a number of safety recommendations including calling for visual aids to show passengers, including those with young children, how to use escape devices.
All flights at Gatwick were suspended for about an hour and 40 minutes during the alert.
In a statement, Virgin Atlantic said: "The safety of our passengers and crew is Virgin Atlantic's top priority.
"We co-operated fully with the AAIB throughout the investigation and whilst the report makes no formal recommendations to the airline, we took many actions immediately after the event in order to identify any areas where we could enhance our procedures.
"Virgin Atlantic carries out all training to strict guidelines set by our regulators and we are very proud of the actions our crew took on the day."