from Hacker News

United flight descends 28,000 feet in 8 minutes for ‘pressurization issue’

by mjirv on 9/15/23, 3:11 PM with 23 comments

  • by dgrin91 on 9/15/23, 3:24 PM

    Those numbers look scary at first sight, by that doesn't seem like a particularly fast rate of decline I think? IANAP, but a normal fight gets to a cruising altitude of ~35k feet in ~ 10 minutes from ground level I think? So this was not some meteoric plummet.

    That being said, obviously there was some serious safety issue, so kudos to the pilot for quickly and safely securing the aircraft

  • by kayodelycaon on 9/15/23, 3:29 PM

    This is a pretty non-event. There are a number of system failures that can cause loss of pressurization.

    I've listened to a lot of ATC recordings and there are many engine fires, bird strikes, and general malfunctions that never get reported on.

    Here's a video of two pilots demonstrating an emergency descent in a simulator: https://www.youtube.com/watch?v=yHawjB2PzK0

  • by crazycanuck on 9/15/23, 3:51 PM

    I was a passenger on AC549 several years ago when this happened. In our case, the oxygen masks were deployed because the cabin had actually lost pressure. From the standpoint of mechanical safety, I have no doubt that these planes are built to safely withstand these rates of descent, and likely a multiple of them. Having said that, I can also say that when the plane began its (sudden and unannounced, understandably) descent, you could feel your guts up in your throat much like when the roller coaster drops over the top of the first hill. From there on down it was calmer, but nonetheless harrowing. It's hard to describe how exactly, but it sure felt like we were coming down in a hell of a hurry.

    Only once we had levelled off were the flight crew able to inform us what had happened. Those intervening 6 or 8 minutes, however, were decidedly Type 3 fun.

    https://globalnews.ca/news/2487158/breaking-vancouver-bound-...

  • by fotta on 9/15/23, 3:30 PM

  • by the_sleaze9 on 9/15/23, 3:48 PM

    I believe something similar to this happened to me on a ~20 minute puddle jumper flight. Late at night, nothing unusual then out of nowhere we descend to what felt like just above the tree-line, as in low enough to make out the edges of license plates on cars below, even in the glow of the street lights. Very distressing, especially because the pilots didn't mention anything over the intercom before during or after. We stayed that low long enough for me to quickly call my close family members.

    There wasn't any feeling of falling at all. Also absent of any feeling of revitalization after a near-death experience, if that is in fact what is was or could have been.

    Then back up just under the cloud layer, landed fine and then that was that.

  • by c7b on 9/15/23, 10:25 PM

    Title: United flight descends 28,000 feet...

    General question: why is it that for such events, it is usually the airline name, or sometimes the flight number, that is mentioned first, and not the plane model? That would seem more relevant to me (not least considering Boeing's safety history).

  • by mannewalis on 9/15/23, 3:47 PM

    My calculations put that at a glide slope of around 3.6 degrees down.