Altitude Changes

[john_richard]

I set the barometer to the airport elevation. Afterward the altitude continually creeps, usually downward as best I can remember. Also, the EFIS indication and the GPS altitude readings don't agree on the ground or in the air. Please help with troubleshooting and whether to send the unit in.

 

[john_richard]

I forgot to include in my post that the unit is a D180 in an RV-12 built to Van's specs.

 

[dynonsupport]

GPS altitude and barometric altitude aren't expected to exactly match. GPS is measuring geometric height above Mean Sea Level, and at times it can be very different from the altitude displayed by regular altimeter.

As for the creeping - a small amount of that is expected as the unit warms up. How much change do you see though?

 

[john_richard]

The airport elev. is 75' and we have seen the unit creep to at least 50'. We don't know how far it would actually continue to change on the ground because we're taking off before any more creep. We will get more data and report later on.

I don't know if we read this or were told that the GPS feeds a correction to the EFIS. I this incorrect?

 

[dynonsupport]

GPS doesn't calibrate pressure altitude in any way. When you've collected more data, get in touch with our support staff directly at support at dynonavionics dot com, and they can help determine whether there's a fundamental issue that needs to be addressed.

 

[light01]

Hi!
How is it going with this problem, Any solution?
I do have the same problem.
When I'm set barometer the altitude is going down about 50' after some minutes. I can't say if it's going down more after that in flight.
Outside temp and inside the cockpit at startup was about 0*C but it will rise at enginestart. I don't know if it have something to do with that.

 

[DBRV10]

Folks, the dynon altitude will stabilise over a period of 5 minutes. If you saw what an altitude encoder does when you turn on an old style transponder and encoder you would see the same thing.

I have several thousand hours of Dynon operations and the altitude function is always 100% spot on. This drift you get of about 20-40 feet at start up of the panel is normal.

The other thing that affects it is when you start the plane up the pressure changes all around the fuselage and that then changes the static port pressure until you get off the ground.

Start your panel up, do all your pre flight checks, jump in, set QNH and then start your engine. You will see the static change after engine start, but you will know you are set right.

If at an airport with an ATIS/AWIS use the QNH from there.

GPS altitude can be accurate and it can be off by 60-100 feet, and as you climb it is often 300-400 feet different to the PA which is why we all use PA in flight and 1013/29.92 above transition.

 

[jakej]

Several thousand hours ? Really ?

Jake J

 

[SEQFTA]

Hi There

Could you advise me please.
I have a Dynon D10 in a Jabiru.
My airport alevation is 1070ft.
Up until 2 weeks ago I could set elev" without problem
BARO> + - to 1070ft , no problem.
Now though : BARO + , and it wil only go up to 930ft ?????
I can't get it to go up to the aerodrome elevation of 1070ft
any more .
Could you advise kindly ?
Thanks
Wayne

 

[DBRV10]

Several thousand hours ? Really ?

Jake J

Yes, if you look at the "up time" of the Dynon products I have owned, collectively this is true. Several units times the hours on the aircraft, roughly 3200+ hrs

 

[Dynon]

What's the numerical BARO setting that you're actually using? Does it match what is being reported locally? What is SETUP>ALTADJ set to?

 

[mmarien]

Yes, if you look at the "up time" of the Dynon products I have owned, collectively this is true. Several units times the hours on the aircraft, roughly 3200+ hrs

So if I can pack 10 units in my panel, I can get ten times the experience? Bonus eh!