cardiomd

Hi all - I am a long time lurker on the forum, and grew up loving to fly planes, from R/C planes as a kid to private flying as a teen and young adult. I ended up becoming a doctor, and now fly extremely frequently as a passenger.

On a recent flight on US Airways from SFO to PIT, I experienced an "incident." Here is a description I emailed to some of my colleagues:

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Flight very smooth out of SFO, slept right after takeoff, full flight. About 1 hour prior to landing, cabin lights suddenly come on, seat belt sign beeps, and plane starts diving -- not so fast that anybody was screaming, but definitely faster than anything I had ever experienced before, probably 30 degrees nose down or so, and people were anxiously looking at each other, heard a few people mutter "diveboming?". I thought the pilots had suddenly gotten landing clearance or waited too long to begin the descent, but it was still early (1 hr ahead of schedule)

Plane gets down pretty close to the ground, then pilot comes on with a hissing sound and muffled voice (I think he was wearing his oxygen mask)

"As you have all noticed, we had to rapidly descend, as we lost compression at 37,000 feet, we will continue at 10,000 for twenty-five minutes into Pittsburgh, then land. Air traffic is aware of us, and there is nothing else wrong with the plane."

It seemed like it was a bit harder to breathe than normal, but I was at first thinking it was just due to my anxiety after he made this announcement, but as time went on it was really, really noticeable -- very thin air. The lady next to me started crying but everybody else was pretty calm and relatively unconcerned.

We dropped to 8k (pilot made announcement), flying low in choppy weather clouds for half an hour then landed smoothly in Pittsburgh. A few people (including me) did applause after the landing. Pilot came on after landing thanking everybody for cooperation (heh, what did we do besides not scream) and noting that it was a slow decompression and with our rapid descent the automatic masks did not meet criteria to deploy.

I just read on the way home, it appears this is really common, happens well over 50 times per year (per wikipedia refs)... Apparently the masks will only deploy if cabin pressure is pretty low, not sure exactly but think 15k feet? I'll see if it makes the news but probably is way too common an occurrence (Flight 1485 SFO-PIT 6/14/09).

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You can also see the flight path of it here:

FlightAware > Live Flight Tracker > Track Log > AWE1485 > 13-Jun-2009 > KSFO-KPIT


At 5:03 AM we were at 38,900 feet
at 5:09 AM we were at 11,700 feet

(That spurious value of 10,000 feet at 5:05 is most likely erroneous, as the plane did not go down then up, just dove relatively sharply.)

We went the rest of the time cleared to maintain at 10,000 feet before starting a shallow approach to PIT as you can see from the logs.

I felt kind of "tingly" all over for a bit this morning, but it is hard to say if that was just anxiety from the scary event versus any effects from alkalemia from rapid breathing at high altitude. I'm completely back to normal though now.

<continued>

cardiomd

After I got back, surprisingly a few people didn't believe me until I found the flightaware tracking log when searching on the internet, which exactly corroborated what happened.

I searched the news a few times, but as expected nothing made any waves. I searched the NTSB database, but after a couple weeks there was no incident report. Out of curiousity, I sent an email to US Airways essentially recounting above, and asking for any information which would be appreciated. I received the following response:

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Dear Dr. <CARDIOMD>:

Thank you for contacting Customer Relations at US Airways.

Regarding flight 1485 on June 13 from San Francisco to Pittsburgh, our
records only show that the flight left 10 minutes early and arrived 24
minutes early. Our pilot did not report any issue with this flight. If
there were a loss of pressure, the oxygen masks would have dropped.

We appreciate the opportunity to address your concerns. We look forward
to serving you on a future US Airways flight.

Sincerely,

Colleen Brosnan
Customer Relations
US Airways Corporate Office

cpb


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I wrote back providing the flightaware link as proof of the descent, and asking for any information, and certainly a followup to ensure that they are tracking these things. A few more weeks passed, so I sent a followup, and received today a call from customer service, saying:


"Dear Doctor <cardiomd>, just responding to your email you sent back to us and your concerns regarding what you said was what you said was a depression of the cabin and rapid descent from the pilots. We have not discovered any information regarding this incident, but would certainly if you feel you would like to discuss any further issues call (866) 523-5333."


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I called the number, but it is just the general access number for US Airways.

To be honest, now I am kind of irritated at the tone of customer service, clearly not believing me? or completely ambivalent to the issue? I understand that they have to deal with a lot of screaming passengers and have a high threshold of indifference, but this refusal to take things seriously is concerning.

So, to the pilots on this forum (or the pilots of my flight if they are reading

How common is slow cabin pressurization loss?

My main issue for following up is how it happened -- will this happen again if it is not reported? I was simply curious before, but now I am concerned.

Thanks for reading. -cardiomd

Sink r8

Hi CardioMD,

Most of us that would respond have never experienced it. 50/year sounds reasonable. It also sounds insignificant, statistically speaking. Find out how many flights occur per year for the region in question (the one with fifty incidents), and you'll figure out it's a very, very small % of all flights.

Rest assured we either a) have an out where we can descend promptly to 10,000ft, or b) have supplemental oxygen so that we can reach 10,000 before you run out of oxygen.

Unfortunately, I can't tell you how much more common slow depressurizations are than the rapid kind, but I would guess it's ten times more common. The latter seems to make its' way on CNN, while the former doesn't.

With that being said, I'm sorry you're getting poor answers when trying to confirm something you know is ture. I assume it's deflection from layers of lawyers, surrounded by layers of incompetent fools, protected by layers of ignorant CSA's. The whole thing is run by greedy, incompetent, ignorant executives in the background.

xkuzme1

I assure you that this is not as common as it sounds. Even at 50 a year that is not even a drop in the bucket compared to the 10,200,000 flights a year operated within the USA.

Now about your situation. A rapid decent is not a normal part of an airline pilots life but, that does not mean that a rapid decent is reaching the limits of a catastrophic death either. In all actuality you were in very little danger. If the mask on the airplane had dropped, then that means you would have mostly likely been at a cabin altitude that could have started to produce dangerous symptoms to some passengers. Because the mask did not drop you were never at an altitude that the FAA deems dangerous to passengers.

Did the pilots declare an emergency? Probably yes, but mostly because they would be bound to by FAA laws. Now from a companies stand point yes an out of the ordinary circumstance existed, but with aviation what exactlly is ordinary? Was anyone hurt? Was anyone inconvenienced by a disruption of service? According to the FAA, you could have done the whole flight legally at 10,000 feet. So was safety ever compromised? NOPE. So if the company is telling you that they have no record of an emergency, the HR people that you are talking too are most likely telling you the truth according to the FAA rules and regulation regarding passenger safety.

There are so many FAA rules and regulations that no pilot could ever be in complete compliance with all of them at the same time. That means there are a lot of loopholes. Some are exploited by the company, and some are rigorously adhered to. That is also how the FAA and the NTSB is almost always able to turn any accident into a case of pilot error.

Clear as mud?

Carl Spackler

First of all, nice job of documenting the incident with the internet links etc.

Your experience is EXTREMELY uncommon. I've been flying large jets for 31 years, and I've had far more than my share of inflight problems. Engine failures, electrical fires, etc. In those 31 years, I have never had a pressurization leak - a fast one or a slow one. They are EXTREMELY rare.

Your Captain was correct in telling you that the masks won't drop automatically unless a certain cabin altitude threshold is met (Above ~12,000 feet for most large jets). The flight crew can always manually drop the masks anytime if they feel the situation warrants.

Your labored breathing had little to do with your stress. Cabin altitudes around 10,000 feet will affect everyone this way. Your crew may have wanted to stay at 10,000 feet for a smoother ride, but was then forced down to a lower altitude for easier breathing of the passengers. I'm sure they felt they would sacrifice the smoother ride for better breathing.

Sounds like they did everything right. Even IF the cabin leak was slow, they couldn't take the chance that it could turn into a rapid leak. The decision to initiate an emergency descent is exactly what I would have done.

The airline's PR department pretending that nothing happened is also no surprise.

Hope this was helpful.

Carl

wonkable

I've had a rapid cabin depressurization. The system failed completely and the cabin rate was in excess of 5000 fpm climbing. And yet from a drop from the high 20,000s, the masks did not automatically drop. The highest cabin we got was about 13,000 before we were below that altitude. If we hadn't dropped the masks manually they would not have deployed.

As for the labored breathing, I noticed it immediately when the system failed, even though the cabin was about 4000 ft to begin. If fact, I could not breath in, just out. So it is possible that the labored breathing was in air being sucked out of the cabin, or the cabin being higher than normal.

Sink r8

What aircraft type? Airline?

III Corps

While it may have seemed like 30deg, I have never had an airliner much of 10-15 deg nose low. They do come down rapidly with that pitch. It is not uncommon to see rates of descent in excess of 4000fpm and the flight track shows an overall rate of about 4000frpm

At 39,000ft, the cabin altitude would have been around 7800ft so the leak must have been a slow one. Masks usually deploy at a cabin altitude of around 14,000ft. No masks. No cabin altitude near 14,000ft. The standard drill is to descend to 10,000ft. and not only to level off but to decrease the onset of pressure in the ears, most crews will begin to shallow the descent nearing 10,000ft.

But above 10,000ft, you will begin to feel the effects of hypoxia, lack of oxygen and the ride to KPIT for the last :30 may have been sufficient to induce some symptoms. Remember that being dehydrated, having alcohol and other factors increase the onset of hypoxia.

That the company would say nothing happened is most odd. The crew would have had to advise ATC of the problem and while they may not have declared an emergency, it certainly fits the criteria for an incident.

Ms. Brosnan may be correct in that the crew may not have reported it. Some crews don't (??). But the FAA will probably have some record of the event and if not, your inquiry will gain their attention. You can google and find the FAA office in Pittsburgh and talk to them about your concerns.

wonkable

Embraer 145 other than that I am trying to stay anonomous. This a new account name for me.

Sink r8

Thanks. I was curious to know if we were talking scheduled airline, or something else.