A Virgin Atlantic incident earlier this week, in which 15 passengers had to be treated in hospital after an emergency landing evacuation, was due to "a number of alarms being triggered in-flight", the airline said on Friday.
Virgin said on Friday the crew of the Airbus A330 had taken positive action in line with procedures by returning to Gatwick and evacuating the plane which has now been certified for a return to service.
A Virgin Atlantic spokesman said: "We can confirm that the investigation following Monday's incident on flight VS27 from London Gatwick is now complete.
"A full technical evaluation and systems assessment has been completed in conjunction with the airworthiness authorities and the manufacturer, and the aircraft has been certified for a return to service.
"The investigation identified that a number of alarms were triggered in-flight, in response to which our flight crew took positive action in line with procedures by returning to Gatwick and completing an evacuation of the aircraft."
"We again apologise to all of those passengers that were impacted by this difficult but rare situation."
Passengers spoke of people landing on top of each other after the Florida-bound Virgin plane was evacuated at Gatwick having had to turn back to the West Sussex airport on Monday.
After the evacuation, one passenger, Tom Aldridge, said: "The people panicking as they were jumping off were throwing themselves out of the plane down the chute and there was a big pile of bodies at the bottom where people were just landing on top of each other and there were quite a few injuries."
Fellow passenger Kirsty Bonwick said: "A lot of people were hurt, scraping their arms and legs and elbows and bleeding.
"You think you're going to stop at the end of the chute and then get up, but you go flying off it and you just went across the concrete, which is why everybody cut their arms and legs and were bleeding."
The incident is being looked at by the Air Accidents Investigation Branch, which will publish a report.