I recently installed a new Garmin G5 purchased at Oshkosh. Install was easy and the unit powers up as advertised. Only problem is that when I set the current barometer setting while on the ground at my home airport, the altimeter reads 30 feet higher than the field elevation published for my home airport. How do I correct the G5 so it reads an accurate altitude when the current barometer is known.
Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
Garmin G5 Altimeter Setting Problem
- Thread starter Chet66
- Start date
SmilingJack
Well Known Member
Sorry....have to ask....did you install pilot/static lines to this? It just souds like you are reading GPS altitude.
Not having a G5 ...maybe there is a setting GPS alt or Pressure Alt if you installed pilot/static lines.
Just a guess from the peanut gallery
Not having a G5 ...maybe there is a setting GPS alt or Pressure Alt if you installed pilot/static lines.
Just a guess from the peanut gallery
Last edited:
az_gila
Well Known Member
By any chance is the altitude correct if you set the baro to 29.92?
Don't know what kind of altitude reading il get if I set to 29.92. Ill check that next time I'm at the airport
The G5 has a calibration screen but it states the pitot and static must be connected together in order to avoid damage to the air sensors. I think I need to hook it up to an air data test set and then do the internal calibration. I don't think I should have to spend the $ for this as the unit is new
The G5 has a calibration screen but it states the pitot and static must be connected together in order to avoid damage to the air sensors. I think I need to hook it up to an air data test set and then do the internal calibration. I don't think I should have to spend the $ for this as the unit is new
RTFM
Just a wild guess here, but with a Dynon D10A or D6 there is a page that lets you adjust the altitude up or down to match the field altimeter setting. For 30 feet, your local airfields equip could be in error and the G5 correct. Check carefully at a couple of airfields before you do anything. If it was hand held inside your car with the windows down and no fans running, it would be an easy check with the P/S ports open. I do not know the G5 manual but I would assume a high probability of there being a user adjustable offset, similar to other EFIS brands.
Just a wild guess here, but with a Dynon D10A or D6 there is a page that lets you adjust the altitude up or down to match the field altimeter setting. For 30 feet, your local airfields equip could be in error and the G5 correct. Check carefully at a couple of airfields before you do anything. If it was hand held inside your car with the windows down and no fans running, it would be an easy check with the P/S ports open. I do not know the G5 manual but I would assume a high probability of there being a user adjustable offset, similar to other EFIS brands.
There are two versions of the Garmin G5 Attitude Indicator unit. One for Certified Aircraft and the other for Experimental.
For the certified units, the G5 is connected into the aircrafts pitot and static plumbing. The calibration procedure is to attach the static system tester to the static port and also to the pitot tube. The tester provides separate connections for static and pitot, and can dial in separate airspeed and altitude values. This is how the altitude / barometer settings are calibrated for the G5 unit.
I have not read the install instructions for the Experimental version of the G5 unit, but I'll bet they are similar.
For the certified units, the G5 is connected into the aircrafts pitot and static plumbing. The calibration procedure is to attach the static system tester to the static port and also to the pitot tube. The tester provides separate connections for static and pitot, and can dial in separate airspeed and altitude values. This is how the altitude / barometer settings are calibrated for the G5 unit.
I have not read the install instructions for the Experimental version of the G5 unit, but I'll bet they are similar.
As near as I can tell, the Experimental and Certificated G5 are the same. I purchased two EXPERIMENTAL G5 units and both have FAA / PMA stickers on them.
Having read the Certificated manual and the Experimental manual, the Certificated unit comes with the battery and the Experimental unit does not. Could not find anything different between the two in the paper work other than the STC.
Hello,
Every G5 spends over 40 hrs in an automated facility that calibrates and tests each unit over a temperature range from -20C to +60C. Much of that time is spent hot/cold soaking to reach thermal equilibrium at each temperature test/calibration point.
No G5 or GSU 25 ADAHRS is shipped unless the altimeter function meets or exceeds the accuracy requirements of TSO-C10b over this temperature range and the altitude range from -1,000 ft to 30,000 ft.
I wouldn't be too eager to modify that high accuracy factory calibration with something done in the field. It is rare for one of our ADAHRS units, which utilize very low drift sensors, to require this re-calibration even after years of service.
Thanks,
Steve
Every G5 spends over 40 hrs in an automated facility that calibrates and tests each unit over a temperature range from -20C to +60C. Much of that time is spent hot/cold soaking to reach thermal equilibrium at each temperature test/calibration point.
No G5 or GSU 25 ADAHRS is shipped unless the altimeter function meets or exceeds the accuracy requirements of TSO-C10b over this temperature range and the altitude range from -1,000 ft to 30,000 ft.
I wouldn't be too eager to modify that high accuracy factory calibration with something done in the field. It is rare for one of our ADAHRS units, which utilize very low drift sensors, to require this re-calibration even after years of service.
Thanks,
Steve
I would file this under, "Much ado about nothing". First of all, is the airplane sitting on the official airport reference point? Or higher? Don't forget your altimeter is 4 feet higher than the ground. And is the setting off the ATIS, which could be an hour old?
Run an altimeter calibration with a good test set, up to 20,000' or so. If the altimeter always reads high, then try to correct. But if it's 30' high at sea level, but 30' low at 10,000', just leave it alone. That's well within ifr tolerances.
Run an altimeter calibration with a good test set, up to 20,000' or so. If the altimeter always reads high, then try to correct. But if it's 30' high at sea level, but 30' low at 10,000', just leave it alone. That's well within ifr tolerances.
Walt
Well Known Member
Actually IFR limits are 20' up to 1000' and limits increase slowly as you go higher. Ref CFR part 43 appendix E.
For my day job, I fly B777. Our altimeter limits are +/-50 of airfield altitude with QNH set (that's 20' instrument error plus 30' for up to 1mb due to rounding down - as "Control" alludes to). The Captain and FO altimeters have to be within 20' of each other.
This is for a system which has an Air Data Computer to correct for all sorts of errors and is certified for RVSM........
This is for a system which has an Air Data Computer to correct for all sorts of errors and is certified for RVSM........
1flyingyogi
Well Known Member
I have the same issue
My G5 has done the same thing since I installed it almost a year ago. It CONSISTENTLY reads higher than my traditional altimeter (which is accurate). I have gotten in the habit of adjusting my G5 .04" less than whatever I have set on my altimeter (what I hear on ATIS) - and this will get my readings on both instruments to match.
For example, if the ATIS at my field is 29.98 for a particular day, I'll set that and my altimeter will read 100ft (which is my field elevation), but on my G5 29.98 will give a reading of 130ft. So I will need to set my G5 to 29.95 for it to read the correct elevation of 100ft.
It would be nice to have it re-calibrated, but I'm so used to it by now that it doesn't bother me much anymore...
My G5 has done the same thing since I installed it almost a year ago. It CONSISTENTLY reads higher than my traditional altimeter (which is accurate). I have gotten in the habit of adjusting my G5 .04" less than whatever I have set on my altimeter (what I hear on ATIS) - and this will get my readings on both instruments to match.
For example, if the ATIS at my field is 29.98 for a particular day, I'll set that and my altimeter will read 100ft (which is my field elevation), but on my G5 29.98 will give a reading of 130ft. So I will need to set my G5 to 29.95 for it to read the correct elevation of 100ft.
It would be nice to have it re-calibrated, but I'm so used to it by now that it doesn't bother me much anymore...
Mine does this exact same thing. I am waiting to get my transponder "fixed"
by replacing my Navworx so I can take it for the avionics shop for a pitot/static/transponder check and go to the calibration page on the G5 to set it to match my other altimeter and field elevation. My home airport is 766 feet so it won't let me adjust it as-is (it wants it to be closer to sea level). Until then, I will continue to set it 0.04" lower or match the known field elevation.
