A Southwest Airlines airplane suffered a major engine failure during a flight on Tuesday.
Engine shrapnel pierced the airplane's fuselage, blew out a window, and caused the cabin to depressurize. One passenger died.
Some passengers wore their oxygen masks incorrectly during the emergency landing, according to a former flight attendant.
Not breathing enough oxygen at high altitudes can lead to loss of consciousness and hinder evacuation procedures.
Southwest Airlines Flight 1380 suffered a major engine failure on Tuesday, forcing its pilot to make an emergency landing.
The pilot, Tammie Jo Shults, who used to fly US Navy fighter jets, guided the airplane, which took off from New York and was bound for Dallas, to a landing in Philadelphia.
Oxygen masks dropped from the cabin ceiling during the incident, according to a public Facebook post by Marty Martinez, a passenger on the flight.
Bobby Laurie, a former flight attendant who now hosts a TV show, shared one of Martinez's photos on Twitter along with a reminder that people should cover their nose and mouth with an oxygen mask in an emergency.
"PEOPLE: Listen to your flight attendants!" Laurie said. "ALMOST EVERYONE in this photo from @SouthwestAir #SWA1380 today is wearing their mask WRONG."
Why you need oxygen if an aircraft cabin loses pressure
Flying at high altitudes with a hole in an airplane is, to put it lightly, dangerous.
At altitudes above 15,000 feet, people struggle to breathe and keep enough oxygen in their blood. They can lose consciousness within minutes — a condition called hypoxia.
Symptoms of hypoxia include "nausea, apprehension, tunnel vision, headaches, fatigue, dizziness, blurred vision, tingling sensations, numbness, and mental confusion," according to the Aircraft Owners and Pilots Association.
The problem isn't the percentage of oxygen in the air, which stays relatively constant at about 21% until about 70,000 feet — it's the lack of air pressure.
High pressure makes air dense, which helps force oxygen through lung tissue and into the bloodstream. Insufficient pressure lowers air density, thereby decreasing the amount of available oxygen.
Adding a flow of 100% oxygen helps counter this physiological problem. But you have to wear and use the mask correctly.
If you don't cover both your nose and your mouth with the mask, you may not get enough oxygen into your bloodstream, putting you at risk of losing consciousness.
How correctly wearing an oxygen mask could save your life — and those around you
The Southwest flight's engine failure happened when the plane was about 31,000 feet in the air, based on passenger reports.