Rebelyell

My wife was on Comair flight 5535 yesterday (LGA-CVG), a 70-seat CRJ, and was being served her drink by the flight attendents. Suddenly one of them said, "Decompression," slammed several drinks on her tray table and both of them ran back to the galley with the drink cart and strapped themselves into their seats.

She was reading a book and doesn't know if they "felt" something or if there was a signal from the cockpit. There was time enough for the captain to announce that there was a problem maintaining cabin pressure and that the plane would descend to 10,000 feet so they could try to "even things out." She said the plane then went into the steepest dive she could imagine, and all she saw was land coming at her at her. Surprisingly, everone aboard remained calm.

I asked her if it was cold on board, but she said just the opposite, that all the cold air escaped from the plane and that it was incredibly hot. After a few minutes the captain announced that they would be diverting to Philidelphia and started doing some S-turns. When they arrived in PHL they were "contained" on the plane for 30 minutes, which she found an odd choice of words.

The plane was apparently repaired in PHL and resumed its journey to CVG after about four hours, although I certainly wouldn't have reboarded until it had been "tested" out a couple of times. But she made it home safely and reasonably calm, thanks to a couple of Ativans.

A few questions for the more knowledgable:

1. Isn't this incredibly rare (and dangerous)?
2. Is there a danger of a plane picking up too much speed on a 30,000-foot dive?
3. Anyone know a reason for all the S-turns?

dll

Decompressions are not all THAT rare but they can be very painful for those involved - I experienced one after takeoff a couple years ago on an A320 in Europe and while we weren't even close to cruise yet, it was painful for the ears. They're not particularly dangerous, unless the reason FOR the decompression is something other than a seal or mechanical problem - for instance, if part of the airplane's skin is separated (as happened to Aloha one fateful day, stress and corrosion fatigue).

There is a danger of a plane picking up too much speed, yes; they probably did a dive down to approx. 9000 feet. Doubt they were in any real danger; sometimes you feel things more in a CRJ as it's narrower and shorter than a comparable 737 or Airbus, as you would in a small car vs. a van or bus.

Lastly, doesn't look like the flight did any real S-turns:
http://flightaware.com/live/flight/COM535

Just trying to get into the arrivals path for PHL, which itself might require an act of God at times

jmw1515

That sounds really scary! I'm glad she was ok...I have been on that flight twice in the last 4 months!

jwillett13

Decompression are not common at all and in my book rare. I have been professional flying turbine powered aircraft for the past 11+ yrs and logged over 8000 hrs. I have never (fingers crossed) had a rapid decompression. With that being said I have temp lost control of the pressurization controller but was able to manage cabin altitude with the back-up or emergency pressurization controller. I have never had a cabin altitude exceed 12,000' yet. They aren't really dangerous if the crew knows what is happening (think Payne Stewart) we have alarms that will let us know if the cabin exceeds 10,000'

As far as the aircraft picking up speed goes. There is a maximum speed the aircraft can accelerate safely to and normal that will be the airspeed that will be use in a emergency descent.

S-turns were probably used to allow the crew to loose altitude without getting closer to the airport. Think of them as delaying turns.

Rebelyell

She's ok. She's spent the day laying about resting from a rather trying trip.

Her company just started sending her to New York. On her first trip an 80-year-old woman was shot dead just for fun (or else a stray bullet) in front of the school where she was working, and it flooded like mad. And it flooded again this trip and the city had its first-ever tornado. And now this. Hmmmmm... Maybe she's bringing the city bad luck. Or the city is bringing her bad luck.

SCruzFlyer

About 15 years ago I was on the "Shuttle by United" (that in istelf was a nightmare, pre-TED) betweeen SFO and LAX. Over Monterey Bay there was a loud POP and the same deep descent you describe.

The masks came down but evereyone just kinda stared at them until the FAs came through the cabin and instructed us to put them on.

We returned to SFO and when we pulled up to gate 74 (I think) no one from UA even knew that we had come back. The GA who was a friend was still at his position and when I showed up to be re-ticketed looked at me and said, "What the hell are you doing here?"

Another "adventure in travel" I guess.

indufan

Didn't the oxygen masks fall? I have been on over 1,000 Delta flights and I have never been decompressed.

MikeMpls

Sounds like a quick reaction from the crew ^ to a developing situation, and maybe the pressure never dropped low enough for the masks to appear.

I'd bet there was some non-verbal indicator meaning "strap everyone in, we're diving".

Every plane decompresses at least once per flight -- if it didn't, the doors wouldn't open.

clarence5ybr

I thought they only pressurized cabins to an altitude equivalent of 8,000 feet ASL, which means you'd be able to open the aircraft door at most US airports (and most int'l airports as well) even with 'full' cabin pressurization active. One of the 787's good features is supposed to be a 6,000-ft-ASL pressurization, which is better than other aircraft, but still a lower air pressure than the ambient pressure at most airports. Assuming my info on pressurization altitude equivalent is correct, opening the door at cruising altitude would, indeed, require a depressurization, but opening the door on the ground would seem to be a different matter.

jimrpa

Most American airports are at significantly lower altitudes than 8,000 feet. Think about it for a second - the air pressure outside the aircraft (at an airport below 8,000 feet) is HIGHER than the air pressure inside the aircraft AND the aircraft doors open OUTWARD. It's probably pretty tough to open the aircraft door while the cabin is pressurized for the same reason it's tough (almost impossible) to open a car door when the car is submerged in water.

jzumrick

The greatest danger in decompression is for a gradual increase in altitude without a proper warning. This will cause the pilot along with all others aboard to pass out if they do not get on oxygen fast enough. Military pilots must undergo a altitude test where they remove their oxygen masks at high altitude. Most become giddy and don't recognize that they are unable to function - much like having to totally drunk pilot just prior to passing out. So if the masks fall get on oxygen first yourself than help others less you pass out trying to help them.

Decompression sickness as also a possibility for atltitudes above about 19,000 feet. But it will usually be mild and is treated by descending and usually resolves guickly after that. In a few extreme cases hyperbaric treatment may be needed.

These incidents are resolved long before high altitude pulmonary or cerebral edema can become an issue. The resolution is called a crash or unscheduled landing similar to a water landing.

blagger

AFAIK, all doors on pressurised aircraft open inwards slightly and then swing outward (or slide upward). If the door could just open outward that would present a significant safety issue at altitude!

bankops

Actually, most transport class aircraft doors open IN, then OUT (see the AA Miami accident report where the FA fell out of an Airbus by opening the door while still under pressure). But the smaller ones, like the CRJ of the OP do open OUT. Of course only after the locking mechanism is disengaged, thus removing the pins that keep the door from opening out. Opening and locking mechanisms are completely seperate. Kinda like having a deadbolt on the outside of the door.

Rebelyell

The oxygen masks didn't fall. Apparently the plane got down quickly enough that they didn't need to.

mikey1003

In over 5MM I have never (fingers crossed) experienced decompression. The only time I ever saw the masks come down was when a DL pilot landed so hard--actually banged into runway with wheels---that a few masks came loose. People were grabbing them. I was laughing saying, hey we on the ground you dont need them.

I was on one flight out of New Orleans where the entire wing flap tore loose on take off. I have been on several aborted landings (one where wheels actually touched down). I have seen strange people on planes.

But never decompression .. Note to self say a prayer that you dont bring this on yourself in the future.