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markharju

Altitude Dispute With Pilot

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On the climb to altitude the (new to skydiving) pilot driving our 182 insisted that we were at 1500m (~4921ft) by pointing at the alti on his console and that I should get out for my hop & pop, but a quick look at everyone else's altimeters showed that we were at less than 762m (~2500ft). It took some convincing to get him to go to 1500m (~4922ft) AGL and he eventually settled on ~1219m (~4000ft) AGL. Maybe the pilot's altimeter was set to MSL (DZ elevation is 1223ft / 372m)? This was new to me despite nearly 25 years of jumping. Posting in the interest of safety and learning whether anyone else has experienced this kind of altitude dispute with a pilot. Thanks!

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Sounds something like that, having the alti on standard above-sea-level figures.

(Another possibility for having the issue in general, although not in your particular case, is zeroing the alti wrong, missing that it is set at -1000 feet instead of 0 feet. That's for altis in feet where one full revolution of the big hand = 1000 feet.)

Since it is vital for pilots to report to air traffic control the proper way, above MSL, I've seen jump planes with a skydiving alti stuck to the instrument panel so that can be zeroed on the ground and the pilot doesn't have to do the mental math all the time either for ATC or skydivers.

I had the same problem once when dropping static line students years ago. I couldn't convince the pilot he was wrong, so I just asked him for an extra thousand feet of altitude for these particular students. Which he gave me, no problem, putting us slightly above our desired altitude instead of at an altitude below what's allowed...

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(edited)
1 hour ago, markharju said:

On the climb to altitude the (new to skydiving) pilot driving our 182 insisted that we were at 1500m (~4921ft) by pointing at the alti on his console and that I should get out for my hop & pop, but a quick look at everyone else's altimeters showed that we were at less than 762m (~2500ft). It took some convincing to get him to go to 1500m (~4922ft) AGL and he eventually settled on ~1219m (~4000ft) AGL. Maybe the pilot's altimeter was set to MSL (DZ elevation is 1223ft / 372m)? This was new to me despite nearly 25 years of jumping. Posting in the interest of safety and learning whether anyone else has experienced this kind of altitude dispute with a pilot. Thanks!

In aviation every aircraft altimeter is set to measure MSL altitude. It's pretty clear that your new pilot missed the part of the training where he should have learned that his job is to take skydivers to their assigned altitude above ground level. Mostly they do the math to figure out what that is in MSL altitude.

Edited by gowlerk

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6 hours ago, markharju said:

On the climb to altitude the (new to skydiving) pilot driving our 182 insisted that we were at 1500m (~4921ft) by pointing at the alti on his console and that I should get out for my hop & pop, but a quick look at everyone else's altimeters showed that we were at less than 762m (~2500ft). It took some convincing to get him to go to 1500m (~4922ft) AGL and he eventually settled on ~1219m (~4000ft) AGL. Maybe the pilot's altimeter was set to MSL (DZ elevation is 1223ft / 372m)? This was new to me despite nearly 25 years of jumping.

Aircraft in the US set their altimeters to MSL not AGL.  (That's why barometric pressure readings are important, so everyone flying in airspace together can agree on what MSL altitude is.)

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On 7/22/2020 at 6:54 PM, billvon said:

Aircraft in the US set their altimeters to MSL not AGL.  (That's why barometric pressure readings are important, so everyone flying in airspace together can agree on what MSL altitude is.)

Because this took place at a DZ in Germany, I think it's safe to assume that a default MSL setting is present there as well (probably an ICAO standard or something - I dunno, I don't drive 'em, I just jump out of 'em).

What I don't get is why the barometric offset was not put in the alti beforehand to get AGL (isn't the pilot supposed to adjust the barometric setting on the alti to get a zero AGL reference for local conditions, or is that optional? This is VFR below 14k after all; or is the pilot expected to take the local elevation into account when looking at the alti? That seems a confusing way to do things) -  anyway, thanks for the responses.

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4 hours ago, markharju said:

What I don't get is why the barometric offset was not put in the alti beforehand to get AGL (isn't the pilot supposed to adjust the barometric setting on the alti to get a zero AGL reference for local conditions, or is that optional? This is VFR below 14k after all; or is the pilot expected to take the local elevation into account when looking at the alti?

If the pilot has only one altimeter, he can set it to MSL and do the mental calculation to get AGL for skydivers, or he can set it to AGL and do the mental calculation to talk to ATC or other airplanes.  ATC and collision avoidance are generally more urgent and the consequences of miscalculation more immediate, so setting to MSL is more common.

What I don't get is why anyone is arguing with the pilot at all.  If you need more altitude, just decline to jump and ask for a higher pass.  

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(edited)
On 7/22/2020 at 6:35 AM, markharju said:

On the climb to altitude the (new to skydiving) pilot driving our 182 insisted that we were at 1500m (~4921ft) by pointing at the alti on his console and that I should get out for my hop & pop, but a quick look at everyone else's altimeters showed that we were at less than 762m (~2500ft). It took some convincing to get him to go to 1500m (~4922ft) AGL and he eventually settled on ~1219m (~4000ft) AGL. Maybe the pilot's altimeter was set to MSL (DZ elevation is 1223ft / 372m)? This was new to me despite nearly 25 years of jumping. Posting in the interest of safety and learning whether anyone else has experienced this kind of altitude dispute with a pilot. Thanks!

I think your dispute is with the DZO. You might kindly ask if they would be so good as to actually train the pilots in the future. You might point out, as reasonably as possible, that knowing how high above the ground ones jumpers are while in flight is a very important part of jump piloting.

Edited by JoeWeber
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On 7/24/2020 at 3:23 PM, mark said:

If the pilot has only one altimeter, he can set it to MSL and do the mental calculation to get AGL for skydivers, or he can set it to AGL and do the mental calculation to talk to ATC or other airplanes.  ATC and collision avoidance are generally more urgent and the consequences of miscalculation more immediate, so setting to MSL is more common.

What I don't get is why anyone is arguing with the pilot at all.  If you need more altitude, just decline to jump and ask for a higher pass.  

The airfield in question (Bitburg) is not exactly remote. Spangdahlem AB is pretty close (~9km apart) and houses fast-movers so I'm sure there is positive ATC in the area. Thanks to all for comments.

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(edited)
On 7/24/2020 at 9:23 AM, mark said:

If the pilot has only one altimeter, he can set it to MSL and do the mental calculation to get AGL for skydivers, or he can set it to AGL and do the mental calculation to talk to ATC or other airplanes.  ATC and collision avoidance are generally more urgent and the consequences of miscalculation more immediate, so setting to MSL is more common.

What I don't get is why anyone is arguing with the pilot at all.  If you need more altitude, just decline to jump and ask for a higher pass.  

(understanding that the OP was not in the USA, just for sake of discussion)
IIRC - In the US - 91.121 Altimeter settings.
(a) Each person operating an aircraft shall maintain the cruising altitude or flight level of that aircraft, as the case may be, by reference to an altimeter that is set, when operating—
(1) Below 18,000 feet MSL, to—
(i) The current reported altimeter setting of a station along the route and within 100 nautical miles of the aircraft

 It is waverable for airshows and low-level aerobatics where you can set it to AGL.

But you also need the pilot to understand that jumpers (except those planning a water landing) don't care flip about the sea level... we do care very much about the ground under us, and how far that is...

JW

 

Edited by fcajump

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