Rapid Depressurization & Emergency Descent? What to expect…


“Ladies and Gentlemen, please direct your attention to our flight attendants (or our video screens) as they demonstrate some important safety features …”

And at this point way too many people tune out and miss the most important five minutes of their flights. These are the five minutes of preparation that just might save their lives. These are the five minutes that they might suddenly be wishing they could have back — in the “unlikely event” of an accident or incident.

This week the big news and terribly sad news, is about the Southwest B737, that  experienced a massive engine failure followed by a rupture in the aircraft’s pressurized hull. This in turn, led to a rapid depressurization and emergency descent.  Sadly, one passenger died and several were injured.  This is the kind of event that is specifically covered in every pre-flight safety briefing on every airline flight in the world* but which the majority of passengers ignore. From video taken in the cabin of Southwest flight 1380, it becomes apparent that a lot of passengers obviously did not pay attention to their briefing.

Luckily for them, their captain was able to follow through with the correct and desired response to any serious pressurization problem. She immediately descended the aircraft to a lower altitude where there was enough oxygen to prevent people from losing consciousness. Airline pilots all over the world practice this maneuver over and over again because it is critical to the safety of everyone on board. It is called a Rapid Depressurization and Emergency Descent Drill. Here are some things you might like to know about this procedure before your next flight:

1. The Rapid Depressurization. There are a few reasons that your captain might decide he or she needs to get your aircraft down to a lower altitude ASAP. Evidence of a fire on board the aircraft might be one. Serious electrical problems might be another. But the one we practice most often is the emergency descent following a massive loss of cabin pressure. Pilots practice this one frequently because of the complicating factor that if they (and you!) don’t quickly (and correctly) don your oxygen masks, you will lose consciousness within just a few seconds. This might cause you merely a headache if the loc (loss of consciousness) time is short, or brain damage if for some reason it goes on for too long. And, of course, if your pilot loses consciousness, it’s going to get a whole lot worse for everyone. (Example – this 1999 Learjet accident where everyone on board perished from a subtle loss of cabin pressure.)

Southwest 1380s loss of cabin pressure was anything but subtle, and captain Tammie Jo Shults was apparently able to immediately descend. But had the flight been overhead an area of severe thunderstorms, or high mountains, there could have been a delay before the cabin oxygen levels could be restored to desirable levels. So the first rule is ‘get your oxygen mask on, and get it on correctly — over your mouth and nose.’ Your first clue as a passenger will be when the masks throughout the entire cabin suddenly deploy, probably accompanied by an emergency announcement telling you to put them on.

(note: there are times when severe turbulence or even a hard landing (cough cough), has been know to trigger some of the masks to deploy. Hint – if you’re on the runway when this happens, there is no cabin pressurization issue going on but maybe only a pilot embarrassment issue regarding a “firm” landing.

*The oxygen mask demonstration is only required for flights which will be conducted at higher altitudes where it might become an issue. So, don’t be perturbed if it is omitted from your briefing for that 10 minute inter-airport shuttle that only climbs to 5,000 feet.

To be continued… (next, what might a “Rapid Depressurization” feel like?)

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