xkcd #3124: Grounded

I was on a flight to Richmond, VA, many years ago. Delayed delayed, mechanical something. We finally board and depart, and right in the middle of the climb after takeoff, the plane turns real hard and heads back to the airport. People were kind of freaked out, they weren't telling us anything.

Back in the airport, we learn that there was some issue with the cabin pressure. They thought they had fixed it, they hadn't. Eventually, they decided, "Fuck it, we're going to fly across the country in this 737 at 7000 feet." Maybe a third of the passengers got back on the plane, I was one. It was cold as fuck.

I think it was a co-worker who told me about flying once from one of the main NYC airports down to Raleigh or Charlotte and they’d been delayed, delayed, delayed by weather. Finally the pilots decided to Leroy Jenkins it and do the entire flight under 10k feet and using the weather radar to maneuver around storms that were dotting the east coast that day. I’m sure it was more formal than I’m remembering but he said it was by far the most unusual commercial flight he’d ever taken. This was within the last 15 years or so, well past when that was common.
why was it cold, because they couldn't maintain an internal cabin atmosphere, including temperature?
Also, I had to look it up, but just wanted to confirm 7000 feet is much lower than typical 737 cruising altitude, which is usually 30,000 - 40,000 feet.
7000 feet is still pretty high and around where oxygen saturation decreases - could you tell any effect? I just assume they were able to still oxygenate the cabin even if they couldn't go as high 🤷‍♀️
- why was it cold, because they couldn’t maintain an internal cabin atmosphere, including temperature?
  No pilot or Jet mechanic but afaik the pressurisation is happening with bleed air from the turbines that is then cooled down to comfortable levels. So there is no "heater" for the cabin so to speak as for a warmer cabin you just cool down the bleed air less. As such without pressurisation there is also no cabin heat.
- 7000 ft is relatively common for small planes like cessnas, they don't even keep pressurized cabins, but It's fine if you stay low. So there's nothing wrong with that altitude, but it's awfully low for a jet. The jet will be flying at low fuel efficiency the whole way and it certainly won't have much wiggle room if something really goes wrong. (You can lose 7000 ft of altitude very quickly)
- No oxygen problems that I recall. I don’t think there’s a hypoxia risk until 10K feet? Cold I’m sure because it was like flying with a window open. The heaters for the cabin air probably couldn’t keep up.
- Anecdotally, the highest altitude I've ever been at hiking was around 11,000ft, and the group I was hiking with started feeling it a little bit around 9000-10,000 ft.
  It wasn't dramatic, where we really noticed it was after we'd made camp, we had a little downtime and there was a bit of an open area, so we started throwing around a Frisbee, and running around chasing the Frisbee we could feel we were getting winded a bit quicker than we usually would.
  Age, fitness, genetics, etc. will of course factor into that, but I suspect that most reasonably healthy people sitting in an airplane probably wouldn't feel much at 7000ft. Maybe they would if they were jogging up and down the aisle of the plane, but even then it probably wouldn't be anything too obvious, and if they didn't know anything about altitude sickness they'd probably chalk it up to being tired from the mental stress of air travel- getting to the airport, making the connection, security, lost baggage, etc.
- ~~actually, cabins are typically pressurized to around 10,000 ft, not sea level, iirc. so this was actually a higher pressure than is typically experienced in a pressurized cabin.~~
  I'm wrong
  I got mixed up. the limit for unpressurized cabins is 10,000 ft, so if you're flying a small plane without supplemental oxygen you can't go higher than that
- just assume they were able to still oxygenate the cabin even if they couldn't go as high
  Aircraft are typically pressurized to the equivalent of about 5000-7000 feet altitude.
  They do not oxygenate the cabin. The oxygen supplies on board are usually in the form of chemical generators, sometimes known as "oxygen candles", and can only provide about 15 minutes supply. That should be plenty of time to descend below 10,000 feet, where everyone can come off oxygen. They don't "burn" those chemical generators except in actual emergencies.
  Pilots and crew have a sufficient supply of bottled oxygen. Pilots and crew are required to go on oxygen if they spend more than 30 minutes above 12,500 feet cabin pressure, or any time over 14,000 feet. Passengers are required to be on supplemental oxygen above 15,000 feet cabin pressure.
  Above 35,000 feet flight altitude, at least one pilot must either be on oxygen, or have a mask that can be donned in less than 5 seconds.
- I frequently fly at 10 to 12 thousand feet msl and have no issues. Supplemental O2 is only required from 12500 to 14000 for durations longer than 30 minutes. It is required above 14k for the crew according to the regs. At 15k, everyone on board needs oxygen or a pressurized cabin.
Did you get a window seat?
Call me an over paranoid wuss, there is no way in hell my ass would be back on that plane
- Silver lining of depression is taking risks and having mildly entertaining stories after.
"How many of y'all haveheard of the Dambusters?"

Yeah, I will need an explanation on this.

Do they plan to taxi all the way to the destination? (Are those bridges clearance charts about height clearances for trucks on the kinds of bridge that passes over a road?)

That's how I understand it. Return to bus.
- They might be referencing this American Airlines “flight” that is actually a bus.
  https://www.nerdwallet.com/article/travel/american-airlines-bus-service-landline-guide
11-foot-8! 11-foot-8!
plane arrives at its gate without the top two feet of its tail fin
- Can opener bridge ~~strikes~~ is struck again!
Yeah, drive the plane on the ground since the storm makes it hard to fly!
You know, those jet engines are LOUD. Sure, they can technically move the plane on regular roads too, but the noise is just astounding.
In a big airport you might not have noticed, because you were either in the terminal or inside a plane when that happened. However, if you’ve visited a smaller airport, you may have stood just outside the fence when someone reved up their jet engines. Imagine that, but even louder, and moving on normal roads. Should be fun for everyone.
- Sure, they can technically move the plane on regular roads too
  Well, not really. Or technically, they can if they move fast enough. If they stop, wherever they are will stop being a road quickly.
  And there's that entire problem of making room for the wings. It's one of the largest problems when designing airports.
- If it were the sound of the Concorde, may she RIP, I think it’s a loud I could tolerate. Sonic booms from like a city block away would relax my nerves.
- Imagine that, but even louder, and moving on normal roads. Should be fun for everyone.
  Of course it'll be fun for me. Im in the airplane, getting to my destination on time.
Yes and yes.
I got thrown for a loop by the word bridge too. It having multiple meanings made me wonder if there's a bridge in flying parlance that meant something else. Clearance is also very unspecific.
I think they plan to ignore ATC, turn up their engines and fly away

I once took an in-country flight in Germany and we taxied so long that I was looking for highway exit signs because we were clearly driving instead of flying.

I read "bridge clearance" as clearance from the ATC to detatch from the bridge and was so confused lol

Sometimes it do be like that

I see Randall has been listening to Cabin Pressure.

Haha, this is just about the Charlotte airport...

About to go through there tomorrow. Is it as bad as I've heard? Only flown twice before (to Mexico and back from Tennessee), went through Knoxville and Atlanta on the way in, then Detroit and Knoxville on the way back.

There really is an xkcd for everything.

They joke, but.... https://www.aa.com/i18n/travel-info/experience/landline.jsp

A bus that boards at a gate and drives to another airport and drops off at a gate..

There was a video of someone deliberately taking these lines and included someone a bit shocked that the 'flight' they booked was just a bus...

i believe this is fairly normal within the same airport for larger ones, the ticket says "gate 15B" but that's out in the middle of the fucking asphalt so to get there you actually go to gate 15A and get on a bus that takes you to the actual gate.