A suspected arsonist managed to light multiple fires that set off smoke alarms onboard an Etihad Airways flight from Australia to the United Arab Emirates, including some after the plane was diverted and passengers were searched in Indonesia, witnesses said.
Emirati authorities have detained 12 passengers as part of an investigation into the fires, though no formal arrests have been made, according to the Middle Eastern carrier.
"A comprehensive investigation into the incidents onboard ... is still under way," it said in an emailed statement. "The aircraft was searched and released shortly after arrival at Abu Dhabi when it was confirmed it was safe to do so."
Passengers who were on the Boeing 777-300ER jetliner told the Associated Press that it appeared that someone on the flight set as many as five separate fires in different toilets over the course of the journey from Melbourne to the Emirati capital Abu Dhabi the previous day.
They described smelling smoke a couple of hours into the flight but thinking at first that it was the in-flight meals being heated up or someone smoking illicitly in the lavatory.
Sarah Jeffery, a 37-year-old midwife from England, was sleeping in the back of the plane when an alarm startled her awake.
"Everything was dark and then the cabin crew all came running," she said. "As they opened the toilet door, I saw flames coming out of the bin in the toilet. But they quickly extinguished it. They were very good," she said.
Etihad said 254 passengers and crew were onboard when smoke was detected in two toilets, prompting the initial diversion to Indonesia.
Once on the ground, the plane, passengers and carry-on luggage were searched, and passenger movement was restricted on the captain's orders, according to the carrier.
"The fact that they let everyone board again, that was scary," she said.
Ms Jeffery was also troubled by the decision to have all the passengers re-board the plane to continue its journey, saying "we were all put at risk by being put back on that flight". She said there did not appear to be any police around and no one was questioned specifically about the fires.
"Obviously we were quite aware at the time that there hadn't been any suspects identified at that point. Whoever had lit the fires was back on the plane with the rest of us with obviously the potential for it to continue," Ms Jeffery said.
Gatot Priambodo, the air traffic control co-ordinator at Jakarta's Sukarno-Hatta International Airport, said Australian controllers requested the diversion after smoke alarms went off but that Indonesian authorities did not launch an investigation because the pilot had said prior to landing that there was "no need for assistance on arrival".
Ground crew said burned tissue paper in the toilets appeared to be the source of the smoke, he said.
The flight then departed again to its scheduled destination of Abu Dhabi. Two hours before arrival, another smoke alarm sounded.
The crew dealt with the smoke and the captain directed crew members to be stationed at each of the toilets to secure them for the rest of the flight, according to the airline.
"You're like: 'you've got to be kidding me!'" Ms Martens said. She described the smoke from the last fire, which happened as the plane flew over the Indian Ocean, as some of the thickest.
"I freaked out when I looked at the map and we were in the middle of nowhere. ... That's when we realised this could actually end badly. It's not a joke anymore," she said.
Ms Jeffery said one of the crew members told her that the fires appeared to have been deliberately set in lavatory drawers where sanitary and sick bags were kept, with the arsonist lighting wax-coated bags because they burned longer.
Local authorities interviewed passengers and crew upon arrival, and the events on the flight are under investigation, the airline said.
No injuries were reported and no arrests have yet been made, the carrier confirmed. Officials at the Abu Dhabi police department, which is handling the investigation, could not be reached for comment.
Etihad is the UAE's national carrier and is based in Abu Dhabi. It and Gulf competitors Emirates and Qatar Airways have been rapidly expanding their operations in recent years, turning their desert bases into major transcontinental transit hubs.
Etihad has 10 of the wide-body, twin-engine 777-300ER in its relatively young fleet, according to its website.
Australia is an increasingly important market for Etihad. The government-backed carrier flies to Brisbane, Melbourne and Sydney, and in 2012 began buying a minority stake in Virgin Australia.