WASHINGTON (NYTIMES) - On the list of possible mid-air emergencies, airline passengers are instructed on every flight what to do if the cabin pressure suddenly drops.
"If the airplane loses pressure, oxygen masks will drop automatically," the safety video on American Airlines flights says. "The yellow cup goes around your mouth and nose."
But selfies and videos snapped on Tuesday by passengers on Southwest Airlines Flight 1380, which suffered an engine explosion and depressurisation that caused the masks to fall, are proof that the safety warnings before takeoff are not always heeded.
The photos show panicked passengers with the yellow oxygen masks around their mouths, but not their noses.
Immediately after the engine exploded, throwing fragments into the side of the plane and fatally wounding one passenger, many of the passengers believed the airplane was going to crash.
Their minds raced to how they could say goodbye to loved ones. Whether their masks were on properly was not a priority, some said later.
Mr Timothy Bourman, 36, a pastor from Woodside, New York, whose wife, Amanda, was scrambling to get a message to their three daughters, said he could not figure out how to use his mask and quickly gave up trying.
"I wasn't having trouble breathing," he said on Thursday (April 19).
He also felt that fiddling with the mask was pointless. "I was thinking, 'This plane is going into the ground.'"
When the engine exploded just after 11am, about 20 minutes into the four-hour flight to Dallas from New York, the plane had reached an altitude of about 9,906 metres, short of its planned 11,582 metres, according to the flight data website FlightAware.
At that altitude, supplemental oxygen is definitely necessary for survival, but the plane then descended so rapidly that it soon reached an altitude humans could tolerate for short periods.
Federal aviation regulations require supplemental oxygen for those flying at 3,810m or higher for 30 minutes or longer in a non-pressurised aircraft. At altitudes above 4,267m, pilots must use oxygen at all times. Above 4,572m, all occupants must be provided oxygen.
Without supplemental oxygen, the human body begins to decline quickly above 7,924m.
In the two minutes after the explosion, Southwest 1380 plunged about 2,438m, to about 7,498m.
Within the next five minutes, the aircraft descended to about 3,352m. It was on the ground about 10 minutes later.
Former flight attendants said that Flight 1380 underscored the importance of the safety instructions delivered to passengers as the planes taxi to the runway. But it also revealed what many flight attendants already know: Passengers tune them out.
"They probably didn't pay attention to the emergency instructions," Ms Marguerite Bartlett, an American Airlines flight attendant in the 1960s, said in an interview. "I have been on many, many flights as a passenger, and an awful lot of do not pay attention."
Mr Bourman, who flies three or four times a year, acknowledged that over time, he began tuning out the safety instructions, but that would not be the case going forward.
"Next time I'm on a plane - it's not going to be for a while, when I get the guts to get back on - I will listen," he said.
"The only way you're going to get people to do it is to scare the crap out of them," he added.
During her five years as a flight attendant, Ms Bartlett said, the oxygen masks never dropped during an emergency. But one flight that landed in Cincinnati skidded off the runway during a snowstorm.
In that moment, she said, it was clear the passengers had not remembered what to do.
"Everybody got out safely, but they really didn't know the instructions," she said, adding that she had to remind each passenger what to do in an emergency.
For years, a flight attendant recited safety instructions over a loudspeaker, while another walked the aisle and demonstrated how to fasten a seat belt or inflate a life vest. In recent years, the in-person instructions have been replaced with splashy, choreographed videos.
When Ms Grayce Schor started as a flight attendant in the 1970s for American Airlines, she would demonstrate for passengers how to tighten an oxygen mask if there was an emergency. But not once in her 35 years as a flight attendant were the oxygen masks needed in flight, she said.
"It's not a big mask," Ms Schor, who retired from American Airlines in 2006, said in an interview, but "it is supposed to be around your nose and mouth".
When Ms Schor saw a photo from the Southwest Airlines flight on Tuesday, however, she shrugged off the passengers' mistakes.
"I wouldn't make a big deal," she said. "They are still going to get the oxygen through (their) mouth."