If a passenger dies on board a flight, cabin crew members like Jay Robert have to think fast.

“We go from service to lifesaving to mortician, dealing with dead bodies and then doing crowd control,” the 40-year-old says. “We’re having to calculate: ‘Okay, we still need to serve 300 people breakfast or dinner and we have to deal with this’.”

Jay, a cabin manager for a major European airline and a former crew member for Emirates, has more than a decade’s experience working on planes. Like all cabin crew, he has been trained to deal with passenger deaths, but has only experienced one himself.

He says deaths on planes are “very uncommon” and that people are more likely to die on longer flights because of the physical toll of being immobile for a long period. Some flight crew don’t experience an on-board fatality during their entire career, he says.

A study published in the New England Journal of Medicine in 2013 concluded that dying on a flight was “rare”. The study, which looked at emergency calls from five airlines to a medical communications centre between January 2008 and October 2010, found that 0.3% of patients who had an in-flight medical emergency died.

Last month, an Australian couple spoke about their “traumatic” experience of sitting next to a body on a plane from Melbourne to Doha after a woman died during the flight.

Mitchell Ring and Jennifer Colin said cabin crew placed her corpse, covered in blankets, next to Mr Ring for the remaining four hours of the flight without offering to move him. Qatar Airways said it followed appropriate guidelines and apologised for “any inconvenience or distress this incident may have caused”.

BBC News has spoken to cabin crew and other aviation experts about how mid-air deaths are usually handled, what the rules are around storing corpses on planes and what it’s like to work on a flight when someone has died.

Flight crew themselves can’t certify a death – this has to be done by medical personnel. Sometimes, this happens on the plane if there’s someone qualified on board but more often, it is done upon landing. Most airlines follow the International Air Transport Association’s (IATA) guidelines on what to do if a passenger has been presumed dead, though policies vary slightly by airline.

In a medical emergency, cabin crew would administer first aid and seek help from any passengers who were medical professionals, while the captain would use a telecommunications system to get instructions from emergency doctors on the ground, says Marco Chan, a former commercial pilot and a senior lecturer at Buckinghamshire New University. If necessary, the captain would divert the flight as soon as possible.

But it’s not always possible to save a passenger.

If a passenger is presumed dead, the person’s eyes should be closed and they should be placed in a body bag, if available, or otherwise, covered with a blanket up to the neck, according to the IATA guidelines.

Planes have very limited space, and it’s a challenge to find a suitable spot to place the body without disturbing other passengers and compromising the plane’s safety. Per the IATA, the body should be moved to a seat away from other passengers or to another area of the plane, if possible. But if the plane is full, they would usually be returned to their own seat.

In a narrow-body plane – those typically used for short-haul flights across the UK or within Europe – there isn’t enough room on board “to really shield a passenger from what has happened”, says Ivan Stevenson, associate professor in aviation management at Coventry University.

Space on these planes is “very, very confined”, he says. “If someone dies on board an aircraft like that, it’s quite likely they will need to be placed in a seat.”

Prof Stevenson acknowledges it’s “very unfortunate, very unpleasant” but that crew have to put the plane’s safety first.

Crew will “try to give some decency to the dead body” by placing it on an empty aisle and using curtains, blankets and dim lights, Jay says, but they might not have much choice.

The body can’t be placed in the galley in case it blocks an emergency exit. It also can’t be left in the aisles in case there is an emergency evacuation, Jay says, or placed in the crew rest area on a long-haul flight.

It’s also hard to physically manoeuvre a body in such a confined space, Jay says. This is what happened in the Qatar Airways case, when Mr Ring said the deceased passenger couldn’t be carried down the aisle.

A plane would divert to save a passenger’s life in the event of a medical emergency – but it usually wouldn’t if they were already presumed dead, aviation experts and cabin crew say. There’s “no point diverting”, Mr Chan says.

The captain would inform both the airline’s operations centre and air traffic control of the passenger’s death as soon as possible, and the plane would be met by local authorities, Prof Stevenson says. Either local authorities or a representative from the airline would contact the passenger’s family if they were flying alone.

Ally Murphy, who hosts the Red Eye Podcast where she interviews flight attendants, experienced one passenger death during a flight in her 14 years working as cabin crew.

A male passenger who had been travelling alone from Accra, Ghana, to London passed out in his seat. After being alerted by the passenger in the seat next to him, the crew realised he wasn’t breathing normally and didn’t have a pulse.

The crew moved the man to the galley to perform CPR. “You’re kind of trapped in a tin can that’s not designed for roaming around,” Ally recalls. But there was more space than usual in the galley because the carts were out for meal service.

Ally and another crew member performed CPR for 40 minutes without success. The captain then decided to divert the plane to Lyon, France, and though Ally and her colleague knew they should have strapped themselves in for landing, they continued performing CPR the whole time, she says.

“We didn’t want to leave him.”

After landing, paramedics took the passenger away. He was declared dead, having suffered an abdominal aortic aneurysm, Ally recalls.

“I held him in my arms for the final moments of his life,” she says. “He probably would have chosen someone else for that, but he got me.”

After the plane set off again following the diversion, the passengers were “quite quiet and sombre,” she says. But on arrival at their destination airport, one passenger from the flight started shouting at her because he missed his connecting flight.

“That’s the one and only time that I’ve ever told a passenger where to go,” she says.

Witnessing a passenger dying was a traumatic experience for Ally.

“I went home and sat in the bath and I cried. I could taste the man’s breath for about a week afterwards,” she says. “It was a little traumatising for a while. I couldn’t watch anything with CPR for a long time.”

Cabin crew are offered support after a passenger dies, including therapy and the option to have their rosters cleared for a few days so they can process what has happened, Jay says.

Ally and her colleagues had a debrief with her airline after the passenger died where they were given “reassurances that we did everything that we could”. Afterwards, she was able to schedule her shifts with a friend for a month because she felt “a bit shell-shocked”.

Because cabin crew aren’t used to passenger fatalities, it can be an especially harrowing experience when a passenger does die on board, Jay says.

“We are not doctors, we are not nurses,” Jay says. “While we are trained to deal with it, we don’t face it every day, so we’re not really immune to it.”