How long to get down question

An OT query for folks here. While discussing things that can happen
between the jetways, I posited that it's a really bad to be aloft
in Big Iron in a medical emergency, etc. -- based on how long it
takes to get on the ground.



That brings up the question of how long that time really is....

So:
If you are at cruise in Boeing's finest at FL430 & declare an
emergency; how fast CAN you be down and stopped? (Or Airbus, for
that matter....)

Assuming ATC can clear a lane, I assume it's a function of how
steep a decent you can use without exceeding the max IAS. What are
the limits on speed brakes, dropping gear, etc. to dirty things ups?

Do you slow to gear-down speed, drop them, then nose over? Or is
the higher speed possible w/ gearup better?

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

If you are directly over the airport you can land at, then follow the
emergency decent procedures for that plane (and they differ from plane
to plane) and come down about 2000 fpm (I really don't know, and it
would depend on the plane), but lets use that figure. Then it would
take 21 1/2 minutes to get down and maybe 1 1/2 minutes in the pattern
and 1 minute of taxi, so that is 23 minutes, assuming the airport is at
sealevel. That would be fast.

Hmm, make that 24 minutes.

Most jets can descend over 10,000fpm. Getting down is not a problem.

Mike
MU-2

"David Lesher" wrote in message
...



An OT query for folks here. While discussing things that can happen
between the jetways, I posited that it's a really bad to be aloft
in Big Iron in a medical emergency, etc. -- based on how long it
takes to get on the ground.



That brings up the question of how long that time really is....

So:
If you are at cruise in Boeing's finest at FL430 & declare an
emergency; how fast CAN you be down and stopped? (Or Airbus, for
that matter....)

Assuming ATC can clear a lane, I assume it's a function of how
steep a decent you can use without exceeding the max IAS. What are
the limits on speed brakes, dropping gear, etc. to dirty things ups?

Do you slow to gear-down speed, drop them, then nose over? Or is
the higher speed possible w/ gearup better?

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

2000fpm is not even a "normal" rate of descent in a jet. At 450kts, 2000fpm
is less than a 3% gradient!

Mike
MU-2


"Doug" wrote in message
ups.com...
If you are directly over the airport you can land at, then follow the
emergency decent procedures for that plane (and they differ from plane
to plane) and come down about 2000 fpm (I really don't know, and it
would depend on the plane), but lets use that figure. Then it would
take 21 1/2 minutes to get down and maybe 1 1/2 minutes in the pattern
and 1 minute of taxi, so that is 23 minutes, assuming the airport is at
sealevel. That would be fast.

Ah, ok. well at 10,000 fpm, wow can that really be? It would be 4 1/2
minutes (rounding a bit), still about 1 1/2 minutes "in the pattern"
(you need some time to level out, slow down and line up) and 1 minute
to taxi, giving 6 minutes. That would be REALLY fast!

I did the scenario in a Falcon 50EX simulator at Flight Safety. From on fire
at FL410 to a emergency evacuation on the ground in 4 minutes 23 seconds.
Lots of fun in the sim!

Karl
"Curator N185KG"


"David Lesher" wrote in message
...



An OT query for folks here. While discussing things that can happen
between the jetways, I posited that it's a really bad to be aloft
in Big Iron in a medical emergency, etc. -- based on how long it
takes to get on the ground.



That brings up the question of how long that time really is....

So:
If you are at cruise in Boeing's finest at FL430 & declare an
emergency; how fast CAN you be down and stopped? (Or Airbus, for
that matter....)

Assuming ATC can clear a lane, I assume it's a function of how
steep a decent you can use without exceeding the max IAS. What are
the limits on speed brakes, dropping gear, etc. to dirty things ups?

Do you slow to gear-down speed, drop them, then nose over? Or is
the higher speed possible w/ gearup better?

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

kgruber wrote:
I did the scenario in a Falcon 50EX simulator at Flight Safety. From on fire
at FL410 to a emergency evacuation on the ground in 4 minutes 23 seconds.
Lots of fun in the sim!

So you were probably dead for only 1 minute 15 seconds when you landed.
;-)

A friend left me a message while in 777 school with a major that he
had an interesting day, "We had a fire in the luggage hold, one engine
dead, IMC for a CAT I approach on a very short runway." Sounds like
an average day in school. I think he also said something about the
food being lousy.


gerald

"Doug" wrote in message
oups.com...
Ah, ok. well at 10,000 fpm, wow can that really be? It would be 4 1/2
minutes (rounding a bit), still about 1 1/2 minutes "in the pattern"
(you need some time to level out, slow down and line up) and 1 minute
to taxi, giving 6 minutes. That would be REALLY fast!


Yup, 10,000fpm is 100kts *down*. I think a lot of jets will do *well* over
10,000fpm. My MU-2 will do almost 6,000fpm in a straight, clean, power off
descent (no bank) and 10,000fpm in a slip. Keep in mind that many jets can
*climb* 5,000fpm when lightly loaded.

Mike
MU-2

Approaching the runway from this altitude, the Space Shuttle has a 22º
glide slope and a rate of descent approaching 22,000 feet per minute.
Shuttle Training Aircraft (STA) are Gulfstream II business jets
modified to simulate the landing characteristics of the Space Shuttle
and used to train astronauts. In order to approximate the high descent
rate of the Shuttle, the Gulfstreams pitch nose down into a 20°
glideslope with the main landing gear down and thrust reversers
deployed. This configuration creates very high drag and gives the STA a
rate of descent around 14,000 feet per minute (4,265 m/min) while
maintaining a 300 knot dive. Now that's getting down fast!
--
Gene Seibel
Gene & Sue's Aeroplanes - http://pad39a.com/gene/planes.html
Because we fly, we envy no one.