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How long to get down question



 
 
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  #1  
Old November 22nd 05, 04:30 AM posted to rec.aviation.owning
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Default 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
  #2  
Old November 22nd 05, 04:57 AM posted to rec.aviation.owning
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Default How long to get down question

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.

  #3  
Old November 22nd 05, 06:02 AM posted to rec.aviation.owning
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Default How long to get down question

Hmm, make that 24 minutes.

  #4  
Old November 22nd 05, 06:11 AM posted to rec.aviation.owning
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Default How long to get down question

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.



  #5  
Old November 22nd 05, 06:55 AM posted to rec.aviation.owning
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Default How long to get down question

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.

  #6  
Old November 23rd 05, 04:13 AM posted to rec.aviation.owning
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Default How long to get down question

If I need to get on the ground that fast.. screw the "pattern" and taxi
time.. The descent will be planned to have me on final and "configured" for
landing.. I'll stop on the runway or turn off and shut down.. the trucks can
meet me there... screw "taxi"...
BTDT

BT

"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.



  #7  
Old November 22nd 05, 06:06 AM posted to rec.aviation.owning
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Default How long to get down question

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



  #8  
Old November 22nd 05, 06:19 AM posted to rec.aviation.owning
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Default How long to get down question

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!

  #9  
Old November 22nd 05, 06:32 AM posted to rec.aviation.owning
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Default How long to get down question


"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


  #10  
Old November 22nd 05, 03:14 PM posted to rec.aviation.owning
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Posts: n/a
Default How long to get down question


"Mike Rapoport" wrote in message
k.net...
Getting down is not a problem.

Mike
MU-2



You're right, hence aviation's perfect record of never leaving one up there.


 




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