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Gaper

Descendent with jumpers

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As long as the plane isn't descending all that fast once it gets below 1500' or so, it doesn't matter.

The individual jumpers are descending very fast in freefall, aren't they?

And if the plane is still coming down that fast when it gets that close to the ground, there are bigger problems to worry about than having the AADs fire.
"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

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wolfriverjoe

As long as the plane isn't descending all that fast once it gets below 1500' or so, it doesn't matter.

The individual jumpers are descending very fast in freefall, aren't they?

And if the plane is still coming down that fast when it gets that close to the ground, there are bigger problems to worry about than having the AADs fire.



Cypres' can be set up to 1750 firing altitude. Should use 1000' above that. Student cypres' fires about 2500'/min. So no greater than say 1500'/min below 3000'. That assumes no great altitude offset.

Ask Airtec, A.A.D. and MARs.
I'm old for my age.
Terry Urban
D-8631
FAA DPRE

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typical dz.com nonsense :S... *claps*

below is a list of some of the most common AADs in use today, all statements without guarantee, see links for user manuals

to avoid accidental firing stay well below those speeds/ go and RTFM yourself :)
ETA: activation altitudes may be permanently altered (see gowlerks answer), set to fire higher by the user, all stated data are referring to default settings

CYPRES AADs

Expert Cypres : ca. 35 m/s at 225m AGL

Tandem Cypres: ca.35 m/s at ca. 580 m AGL

Student Cypres: between 13m/s and 35m/s at 300m AGL, > 35m/s at 225m AGL, if it detects an open and flying canopy between 800m and 300m (>3m/s < 13m/s) it raises activation speed to 20m/s

Speed Cypres: 46m/s at 225m AGL

Wingsuit Cypres: freefall mode 20m/s at 225m AGL/ Canopy mode same as Expert or Speed

VIGIL AADs

for Vigil copied from the manual

3.3.1. “PRO” Mode
The Vigil® Cuatro activates in “PRO” mode when it measures* 1100 ft (335 meters) (average altitude** between 840 ft and 1100 ft,
depending on body position) and below, until 150 ft (46 meters), if the freefall speed is equal or superior to 115 ft/sec. (78 mph or 35 meters/sec).
The Vigil® Cuatro activates in “STUDENT” Mode when it measures* 1300 ft (396 meters) (average altitude** between 1040 ft and 1300 ft,
depending on body position) and below, until 150 ft (46 meters), if the freefall speed is equal or superior to 65 ft/sec. (45 mph or 20 meters/sec).
The Vigil® Cuatro activates in “TANDEM” Mode when it measures* 2300 ft (701 meters) (average altitude** between 2040 ft and 2300 ft,
depending on body position) and below, until 150 ft (46 meters), if the freefall speed is equal or superior to 115 ft/sec. (78 mph or 35 meters/sec).
The Vigil® Cuatro activates in “XTREME” Mode when it measures* 1100 ft (335 meters) (average altitude** between 840 ft and 1100 ft,
depending on body position) and below, until 300 ft (91 meters), if the freefall speed is equal or superior to 141 ft/sec (96 mph or 43 meters/sec).

VIGIL 1

PRO
MODE
The Vigil releases at
840 Ft. (256 meters) and below
if the freefall speed is equal or superior to
35 m/sec. (78 mph)


STUDENT
MODE
The Vigil releases at
1040 Ft. (317 meters) and below
if the freefall speed is equal or superior to
20 m/sec. (45 mph)


TANDEM
MODE
The Vigil releases at
2040 Ft. (622 meters) and below
if the freefall speed is equal or superior to
35 m/sec. (78 mph)

Some variations between the versions 1, 2, 2+ ect, but the activations speeds are more or less the same


MARS M2 AAD

Student Mode: approx. 330m / 1 100ft and fall rate is higher than approx. 13m.s-1 / 29mph.

Intermediate: approx. 330m / 1 100ft and fall rate is higher than approx. 20m.s-1 / 45mph.

Professional: approx. 270m / 885ft and fall rate is higher than approx. 35m.s-1 / 78mph.

Canopy Piloting: approx. 270m / 885ft and fall rate is higher than approx. 45m.s-1 / 101mph

Tandem: approx. 610m / 2 000ft and fall rate is higher than approx. 35m.s-1 / 78mph


http://www.m2aad.com/download-en/user-manuals-m2-multi
https://www.cypres.aero/documents/manuals/
http://www.vigil.aero/manuals
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To absent friends

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I have wondered the same thing - as in the original poster's question. It is obvious that this question does not present itself above the arming altitude of your AAD device 1000 feet....1200 feet uh...1400 feet....what ever the device arms at.

But, his question is still lurking. BELOW the arming altitude how fast must the airplane descend for your AAD to fire?

So, distilling the math (in my head) and seeing that most (OK not all) of the devices are arming at 78 miles per hour descent rate...wow!- the airplane would have to almost be "standing on it's head" to achieve a 78 mph descent rate. At that point, and at that altitude (below 1200 feet for example) the pilot better pull off some miracle to recover from a 78 mph descent rate. A rate I would compare to being in a helluva dive.

Tell me if I'm wrong here, but it is my conclusion that below the 1200 foot or 1000 foot AGL altitude an airplane would be in a "ready to crash" mode to have a 78 mph descent rate.

So, I am not inclined to worry about an AAD fire below 1000 feet; even if the pilot is descending so fast as to float me to the ceiling! At 1000 feet and below, that would (as Wendy more or less said) be an airplane in big trouble.

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Speeds that high (expert setting) so close to the ground would definitely make me question my decision to stay within the AC.
:P
What I was refering to as "DZ.com nonsense" was the unspecific, generic answer to a rather precise question. Especially the different student settings, wingsuitmode or the intermediate of the M2 aren't that hard to reach in a descending plane and should be well known at least by the people jumping them/monitoring them (teachers)
I hope, it didn't come across as an insult.
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To absent friends

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You don't need to get speeds that high. You just need to get cabin air pressure changes that would mimic speeds that high. For example, you could slip an open-door aircraft (like a Caravan), then straighten it out. You might do this if you were making an engine-out approach and needed to scrub off some altitude after arriving high on final.

-Mark

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If I was doing an engine out approach I don't think I would be worried about popping a reserve on final. Nobody would be near the door anyway...

And why would slipping mimic a high rate of decent? If the door is open there might be an increase in drag but a barometric change enough to fire and aad, I doubt it.
Replying to: Re: Stall On Jump Run Emergency Procedure? by billvon

If the plane is unrecoverable then exiting is a very very good idea.

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DBCOOPER

If the door is open there might be an increase in drag but a barometric change enough to fire and aad, I doubt it.



Suddenly the cabin may go from a fairly normal static pressure to having air scooped in by the door being exposed more to the dynamic pressure of the forward speed, when the rudder is kicked and the plane yawed. Sudden pressure increase of course looks like high speed descent, even if this increased rate of change only occurs at the start of the maneuver.

But how much of a factor this is, in different aircraft with different doors and cabin air volumes, that I don't know....

Certainly an AAD like a Vigil can be fired by putting a rig in a plastic bag and squeezing. (A local rigger did that when putting a rig into temporary storage. Oops.)

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pchapman

Suddenly the cabin may go from a fairly normal static pressure to having air scooped in by the door being exposed more to the dynamic pressure of the forward speed, when the rudder is kicked and the plane yawed. Sudden pressure increase of course looks like high speed descent, even if this increased rate of change only occurs at the start of the maneuver.



This is the best explanation for what happened.

-Mark

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