4 ms·

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 alt

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

MerelyMortal 3y ago
Correct, the headline equates to 3,500ft/min. It's about double of the usual rate of decent, but still common enough that regular passenger carriers will sometimes decend at that rate.
- HPsquared 3y ago
  Rule of thumb is that 1 kn ≈ 100 ft/min. So 3500ft/min is about 35 knots vertical speed. Not much compared to the horizontal speed, which is closer to 500 kn.
  - cameldrv 3y ago
    40mph straight down is a pretty fast rate of descent. That said there’s nothing inherently unsafe about it. If you’re losing cabin pressure, you really want to be at a breathable altitude ASAP.
    - HPsquared 3y ago
      Yeah it's definitely steep, but just to put it in perspective it's something like a 7% gradient
- buildsjets 3y ago
  I have been in several models of commercial aircraft during certification testing where we had to perform a max effort emergency descent as a part of the flight test profile. We routinely would hit rates of descent in the of 9,000-10,000 FPM range. I normally experienced this while strapped into a flight test workstation in the back of the plane, but once or twice had the opportunity to sit in the flight deck jumpseat. Once the aircraft is established in the descent, there is a bit of additional buffeting (light turbulence) and wind noise, but there is no highly unusual attitude involved. Initially, depending on how aggressively the pilot transitions from level flight to the descent, there can be a brief second of reduced or even zero G, but a smooth transition does not increase the total descent time by too much. I have a colleague who was involved with the flight testing of the C-17 military cargo plane. That aircraft can safely deploy all four thrust reversers while in-flight to make a high angle tactical descent - it can hit in excess of 25,000 FPM. Supposedly everyone on the test flight was supposed to have been medically cleared for this flight, but one crew member had a lingering ear infection, and blew out both eardrums during the test.
  - CobaltFire 3y ago
    I did a Space-A flight with my family on a C-17. They didn't do the full thing, but they absolutely pushed that bird up and down hard, with some banking, on takeoff and landing. They warned us, and a good time was had by all. Worst landing I ever had was a dirt field in a fully PAX loaded C-130. It wasn't the descent rate, it was just the landing. No thanks.
kortilla 3y ago
Track log on flight aware shows max decent rate around 6,000 ft/min. Ascent to cruise was around 1,000-2,000 ft/min.
- ta1243 3y ago
  That's about 70mph vertically downwards.
  - kayodelycaon 3y ago
    According to https://aviation.stackexchange.com/questions/32111/what-is-the-descent-rate-in-emergency-situations https://aviation.stackexchange.com/questions/32111/what-is-t... it's a relatively safe speed in an emergency. Note, speed brakes are deployed to increase drag, which helps increase vertical descent without overspeeding the wings. The plane doesn't need to be pitched down all that steeply to drop quickly and if you're falling at a steady rate, everything will be at 1G.
    - ta1243 3y ago
      When you stand next to a fast road and a car goes past at 70mph it feels really fast. I guess that I never really "get" just how high planes are at cruising altitude I guess it's only 3.5 miles or 20,000 feet in 7 minutes, and planes are a long way up.
blktiger 3y ago
It's pretty fast, but pretty well required because once you lose pressurization you want to get down to a normal pressure level quickly as staying at a high altitude is not particularly comfortable and everyone in the aircraft needs to have supplemental oxygen until you get under 10,000 feet. If anyone doesn't get a mask on they could be in trouble due to lack of oxygen.

MerelyMortal 3y ago

Correct, the headline equates to 3,500ft/min. It's about double of the usual rate of decent, but still common enough that regular passenger carriers will sometimes decend at that rate.

HPsquared 3y ago
Rule of thumb is that 1 kn ≈ 100 ft/min. So 3500ft/min is about 35 knots vertical speed. Not much compared to the horizontal speed, which is closer to 500 kn.
- cameldrv 3y ago
  40mph straight down is a pretty fast rate of descent. That said there’s nothing inherently unsafe about it. If you’re losing cabin pressure, you really want to be at a breathable altitude ASAP.
  - HPsquared 3y ago
    Yeah it's definitely steep, but just to put it in perspective it's something like a 7% gradient
buildsjets 3y ago
I have been in several models of commercial aircraft during certification testing where we had to perform a max effort emergency descent as a part of the flight test profile. We routinely would hit rates of descent in the of 9,000-10,000 FPM range. I normally experienced this while strapped into a flight test workstation in the back of the plane, but once or twice had the opportunity to sit in the flight deck jumpseat. Once the aircraft is established in the descent, there is a bit of additional buffeting (light turbulence) and wind noise, but there is no highly unusual attitude involved. Initially, depending on how aggressively the pilot transitions from level flight to the descent, there can be a brief second of reduced or even zero G, but a smooth transition does not increase the total descent time by too much. I have a colleague who was involved with the flight testing of the C-17 military cargo plane. That aircraft can safely deploy all four thrust reversers while in-flight to make a high angle tactical descent - it can hit in excess of 25,000 FPM. Supposedly everyone on the test flight was supposed to have been medically cleared for this flight, but one crew member had a lingering ear infection, and blew out both eardrums during the test.
- CobaltFire 3y ago
  I did a Space-A flight with my family on a C-17. They didn't do the full thing, but they absolutely pushed that bird up and down hard, with some banking, on takeoff and landing. They warned us, and a good time was had by all. Worst landing I ever had was a dirt field in a fully PAX loaded C-130. It wasn't the descent rate, it was just the landing. No thanks.

kortilla 3y ago

Track log on flight aware shows max decent rate around 6,000 ft/min. Ascent to cruise was around 1,000-2,000 ft/min.

ta1243 3y ago
That's about 70mph vertically downwards.
- kayodelycaon 3y ago
  According to https://aviation.stackexchange.com/questions/32111/what-is-the-descent-rate-in-emergency-situations https://aviation.stackexchange.com/questions/32111/what-is-t... it's a relatively safe speed in an emergency. Note, speed brakes are deployed to increase drag, which helps increase vertical descent without overspeeding the wings. The plane doesn't need to be pitched down all that steeply to drop quickly and if you're falling at a steady rate, everything will be at 1G.
  - ta1243 3y ago
    When you stand next to a fast road and a car goes past at 70mph it feels really fast. I guess that I never really "get" just how high planes are at cruising altitude I guess it's only 3.5 miles or 20,000 feet in 7 minutes, and planes are a long way up.

blktiger 3y ago

It's pretty fast, but pretty well required because once you lose pressurization you want to get down to a normal pressure level quickly as staying at a high altitude is not particularly comfortable and everyone in the aircraft needs to have supplemental oxygen until you get under 10,000 feet. If anyone doesn't get a mask on they could be in trouble due to lack of oxygen.