Auto Descend

Jaybird180

Jaybird180

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Jaybird180
I'm sure there are aircraft with such systems that when pilot incapacitation is detected at high altitude, the aircraft descends, right?

What's the quickest way to descend? Can it be calculated? What would this value be called, Yv, the reverse of Vy? Is it more efficient to pitch over and firewall the throttle, and throttle back as approaching Vne to get from say FL330 > 10k MSL or to chop the throttle and nose over, reducing the pitch as approaching Vne?

You mathematicians please speak up.
 
The quickest way to descend?

That's a private pilot check ride item. Emergency descent.

One way is to idle the engine, push the prop to fine, point the nose down to Vno, and pull into a steep turn. Another is to descend in slow flight with the flaps and gear hanging out.

There is no "fastest descent" speed. Drag goes up without bound as you get faster.
 
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Jaybird180 said:
I'm sure there are aircraft with such systems that when pilot incapacitation is detected at high altitude, the aircraft descends, right?

What's the quickest way to descend? Can it be calculated? What would this value be called, Yv, the reverse of Vy? Is it more efficient to pitch over and firewall the throttle, and throttle back as approaching Vne to get from say FL330 > 10k MSL or to chop the throttle and nose over, reducing the pitch as approaching Vne?

You mathematicians please speak up.
Click to expand...

My guess would be a max speed slip, no throttle. Wouldn't that get you max descent angle up to the max speed limit of the airplane. Thats not math, and i'm just a student pilot so I'm probably way off. I wouldn't think they would automate that to an extreme/max descent.
 
MAKG1 said:
That's a private pilot check ride item. Emergency descent.
Click to expand...

It is now, but wasn't until a few years back. Most of us did not have to do it on the ride, and I'm sure I wasn't the only one who was never taught such a maneuver before getting the certificate.

I've seen it covered since, of course.
 
MAKG1 said:
The quickest way to descend?

That's a private pilot check ride item. Emergency descent.

One way is to idle the engine, push the prop to fine, point the nose down to Vno, and pull into a steep turn. Another is to descend in slow flight with the flaps and gear hanging out.

There is no "fastest descent" speed. Drag goes up without bound as you get faster.
Click to expand...

Okay, I guess I asked for that one.:mad2:
Just play along nicely.
 
I don't know if there is such a system. I know in my airline training I was told by one instructor to immediately set 10,000' and select a vertical mode. This way in case you do become incapacitated you have some chance of being alive at the end.
 
At 33 k pull back throttle ,drop nose ,be on o2. Enjoy the rapid decent.
 
I dunno, find me an airplane that won't auto descend eventually.
 
frfly172 said:
At 33 k pull back throttle ,drop nose ,be on o2. Enjoy the rapid decent.
Click to expand...

Be on o2, throttle back, nose down (w or w/o gear down).

Auto descend, yeah forget that, system screws up and I'm eating a mountain.
 
ARFlyer said:
I don't know if there is such a system. I know in my airline training I was told by one instructor to immediately set 10,000' and select a vertical mode. This way in case you do become incapacitated you have some chance of being alive at the end.
Click to expand...
It's funny that I was going to say, wait until Cirrus designs one.

JasonM said:
Cirrus will auto descend if you have the newer models.
Click to expand...

Thanks for posting that. I wonder what the max descent rate is and if the system uses GPWS and/or ADS-B traffic to make other autopilot based decisions to NOT HIT SOMETHING on the way down. It's cool that they thought of that. Could have possibly saved the Pilatus pilot and wife a couple years ago.
 
James331 said:
Be on o2, throttle back, nose down (w or w/o gear down).

Auto descend, yeah forget that, system screws up and I'm eating a mountain.
Click to expand...

Remember, the premise here is that you're already out of the l00p (flying single pilot) and you NEED the automation to save you. Would you disable such a system if it was included with the avionics systems???? Seems kinda silly to me.
 
Hello

This is from our Gulfstream 550 checklist

We also have EDM. Emergency Descent Mode (EDM) 2'nd check list down.

The first one is for you did not pass out and the 2'nd is for you did. Lol.

It turns 90 left on EDM to avoid descending through the tracks going across the ocean.


Loss of Pressurization
If cabin pressurization is lost, proceed as follows:
1. Crew Oxygen Masks ................................................................ DON
2. Emergency Descent Procedure / Checklist ............ COMMENCE
NOTE:
3. Passenger Oxygen Masks ............................ MANUALLY DEPLOY
4. Passenger Oxygen Masks ........................ VERIFY DEPLOYMENT
5. Pressurization ................................................................ RESTORE
NOTE:
Emergency Descent Procedure
NOTE:
airplane structural integrity is in doubt, limit speed as much as possible and
avoid high maneuvering loads.
1. Power Levers ........................................................................... IDLE
2. Airspeed .................................................... ESTABLISH M / V
NOTE:
commence descent. As speed approaches M / V, extend the speed
brakes to maximize the rate of descent. Adjust pitch attitude as necessary
to avoid an overspeed condition.
3. Airspeed ....................................................... MAINTAIN M / V
NOTE:
in order to achieve the maximum descent rate.
4. SEAT BELT / NO SMOKE ......................................................... ON
5. Transponder Code ........................................................... SET 7700
6. Air Traffic Control (ATC) ..................................................... NOTIFY
7. Level Off ...........................................................................................
....... 15,000 FT OR MINIMUM ENROUTE ALTITUDE, IF HIGHER
REVISION 33 (RE-ISSUE) ABNORMAL / EMERGENCY PROCEDURES

Quick Reference Handbook
Emergency Descent Procedure, FWG… AFM 04-21-40
Approach and landing:
8. Normal Approach ........................................................... PERFORM
9. Gear .................................................................. DOWN / 3 GREEN
If unable to extend landing gear and a gear-up landing is planned:
10. Pressurization ................................................................... MANUAL
11. Outflow Valve ......................................................................... OPEN
12. Landing .......................................... PERFORM UNPRESSURIZED
END

2)
Automatic Emergency Descent Mode (EDM) AFM 04-21-90
The autopilot has an automatic EDM mode that is armed any time
airplane altitude is greater than 40,000 feet with the autopilot selected
ON. When the Cabin Pressure Low warning message illuminates on
the CAS with the airplane above 40,000 feet and the autopilot ON, the
following occurs:
1. Speed target on guidance panel changes to 340 KCAS in the
manual mode.
2. The altitude preselect is set to 15,000 feet.
3. The autopilot commands a left turn with a 90° heading change in
the heading hold mode.
4. The autothrottle (if engaged) retards power levers to idle. If the
autothrottle is not engaged, it automatically engages and retards the
power levers to idle.
5. The airplane descends at / to 15,000 feet. MV MO MO
6. At 15,000 feet, the speed target changes to 250 KCAS.
7. The autothrottle sets power to maintain 250 KCAS.
8. The pilot may override this mode by disconnecting the autopilot.
END
 
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Pghsteel said:
Hello

This is from our Gulfstream 550 checklist

We also have EDM. Emergency Descent Mode (EDM) 2'nd check list down.

The first one is for you did not pass out and the 2'nd is for you did. Lol.

It turns 90 left on EDM to avoid descending through the tracks going across the ocean.


Loss of Pressurization
If cabin pressurization is lost, proceed as follows:
1. Crew Oxygen Masks ................................................................ DON
2. Emergency Descent Procedure / Checklist ............ COMMENCE
NOTE:
3. Passenger Oxygen Masks ............................ MANUALLY DEPLOY
4. Passenger Oxygen Masks ........................ VERIFY DEPLOYMENT
5. Pressurization ................................................................ RESTORE
NOTE:
Emergency Descent Procedure
NOTE:
airplane structural integrity is in doubt, limit speed as much as possible and
avoid high maneuvering loads.
1. Power Levers ........................................................................... IDLE
2. Airspeed .................................................... ESTABLISH M / V
NOTE:
commence descent. As speed approaches M / V, extend the speed
brakes to maximize the rate of descent. Adjust pitch attitude as necessary
to avoid an overspeed condition.
3. Airspeed ....................................................... MAINTAIN M / V
NOTE:
in order to achieve the maximum descent rate.
4. SEAT BELT / NO SMOKE ......................................................... ON
5. Transponder Code ........................................................... SET 7700
6. Air Traffic Control (ATC) ..................................................... NOTIFY
7. Level Off ...........................................................................................
....... 15,000 FT OR MINIMUM ENROUTE ALTITUDE, IF HIGHER
REVISION 33 (RE-ISSUE) ABNORMAL / EMERGENCY PROCEDURES

2)

Quick Reference Handbook
Emergency Descent Procedure, FWG… AFM 04-21-40
Approach and landing:
8. Normal Approach ........................................................... PERFORM
9. Gear .................................................................. DOWN / 3 GREEN
If unable to extend landing gear and a gear-up landing is planned:
10. Pressurization ................................................................... MANUAL
11. Outflow Valve ......................................................................... OPEN
12. Landing .......................................... PERFORM UNPRESSURIZED
END
Automatic Emergency Descent Mode (EDM) AFM 04-21-90
The autopilot has an automatic EDM mode that is armed any time
airplane altitude is greater than 40,000 feet with the autopilot selected
ON. When the Cabin Pressure Low warning message illuminates on
the CAS with the airplane above 40,000 feet and the autopilot ON, the
following occurs:
1. Speed target on guidance panel changes to 340 KCAS in the
manual mode.
2. The altitude preselect is set to 15,000 feet.
3. The autopilot commands a left turn with a 90° heading change in
the heading hold mode.
4. The autothrottle (if engaged) retards power levers to idle. If the
autothrottle is not engaged, it automatically engages and retards the
power levers to idle.
5. The airplane descends at / to 15,000 feet. MV MO MO
6. At 15,000 feet, the speed target changes to 250 KCAS.
7. The autothrottle sets power to maintain 250 KCAS.
8. The pilot may override this mode by disconnecting the autopilot.
END
REVISION 33 (RE-ISSUE) ABNORMAL / EMERGENCY PROCEDURES
Nov 24/10 Page EH - 4
Click to expand...

But can you activate that mode manually without the cabin pressure being low? I think what the OP is asking would encompass other situations besides loss of pressurization.

We did the auto emergency descent in the sim today (not a Gulfstream). Our airplane does not have autothrottles or autospoilers so you need to be awake enough to do that part yourself.
 
I can't think of any way for the plane to detect pilot incapacitation unless you're wearing some kind of bio-sensors.

Since you're asking about an emergency descent from FL330 then you're talking about predominately jets and not piston powered planes.

First and foremost, get the mask on.
In jets you don't just pitch over, they don't like negative G's, think fuel system, and you don't want to put your pax on the ceiling. You roll into a bank and use some rudder to slide the nose below the horizon depending on the plane maybe -20 degrees pitch at first. That way you never pull negative G and it puts you off the airway, a holdover from pre-GPS days.

Power all the way back or you'll exceed Vmo/Mmo real quick and deploy the speed brakes/spoilers whatever the manufacture may call them. All of this is done in a very quick succession. There's probably a pitch adjustment back to maybe -15 -10 degrees and maintain speed to just under Vmo/Mmo.

I believe the certification rules require an 8,000' cabin all the way up to the planes certificated ceiling. I also believe there is a maximum time limit to descend from the max ceiling to a set altitude in so many minutes, but I don't remember what it is.
 
Nope. Its automatic or nothing Above FL400 You can not choose to do it at anytime.

I'm surprised you are doing Automatic Emergency Descents with out auto throttles

What type of airplane ya flying?
 
Pghsteel said:
Nope. It automatic or nothing Above FL400 You can not choose to do it at anytime.

I'm surprised you are doing Automatic Emergency Descents with out auto throttles

What type of airplane ya flying?
Click to expand...
Cessna 680 (Sovereign).
 
I hear G-V, G-550, and G-650 all have auto emergency descent but it's based on rapid decompression and not pilot status / consciousness.
 
Nice!!! Flew the Citation X for 6 years before the G-550. Loved that thing.

Have fun in school. Don't drink to much. Lol.
 
Pghsteel said:
Nice!!! Flew the Citation X for 6 years before the G-550. Loved that thing.

Have fun in school. Don't drink to much. Lol.
Click to expand...
Haha. Checkride tomorrow but it's just a 135 PIC recurrent.
 
Jaybird180 said:
What's the quickest way to descend? Can it be calculated? What would this value be called...You mathematicians please speak up.
Click to expand...
L/Dmin(unaccelerated) (or D/Lmax) to determine the descent angle, Rate of descent will be Vtrue*-Dmax/Weight in stabilized wings-level descent. Recommend looking at Vle, Vfe and Vne and the drag in the corresponding configurations to see which is higher.

Nauga,
and his dirty dive for the deck
 
nauga said:
L/Dmin(unaccelerated) (or D/Lmax) to determine the descent angle, Rate of descent will be Vtrue*-Dmax/Weight in stabilized wings-level descent. Recommend looking at Vle, Vfe and Vne and the drag in the corresponding configurations to see which is higher.

Nauga,
and his dirty dive for the deck
Click to expand...

Clear as Mud.
 
James331 said:
Be on o2, throttle back, nose down (w or w/o gear down).

Auto descend, yeah forget that, system screws up and I'm eating a mountain.
Click to expand...

Yup, G1000s even have auto-nondescend. That is, they ignore your descent profile (or the ILS GS) and just keep on truckin' level even when you don't want them to.
 
Jaybird180 said:
I'm sure there are aircraft with such systems that when pilot incapacitation is detected at high altitude, the aircraft descends, right?

What's the quickest way to descend? Can it be calculated? What would this value be called, Yv, the reverse of Vy? Is it more efficient to pitch over and firewall the throttle, and throttle back as approaching Vne to get from say FL330 > 10k MSL or to chop the throttle and nose over, reducing the pitch as approaching Vne?

You mathematicians please speak up.
Click to expand...

My airplane does not have a feature like that and I have honestly never heard of one on any airplane. An incapacitated pilot and the aircraft automatically gets closer to the ground, kinda scary.

For my plane idle thrust gives me a 300 ft/NM descent and the slats, landing gear, and speed brakes are listed as "drag devices" each giving me an additional 150 ft/NM. So yes it can be calculated.

Total altitude to lose or gain divided by the distance will give you the gradient in ft/nm. Multiply that by your TAS in minutes and you get the required vertical speed.
 
Gucci Pilot said:
My airplane does not have a feature like that and I have honestly never heard of one on any airplane. An incapacitated pilot and the aircraft automatically gets closer to the ground, kinda scary.
Click to expand...
Ours posts 15,000' on the altitude select when it does the emergency descent so it levels off there. You need to wake up eventually to advance the throttles and retract the spoilers.
 
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