Possible altimeter problem

murphey

murphey

Touchdown! Greaser!
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murphey
Here we go....this might be a PPL question but I'm thinking it's really a maintenance issue.
I'm at home field, altitude 5510. I set the altimeter to that altitude. Yesterday when I got the ATIS, the difference on the Kollman was 0.50 so when I set to the ATIS, the altimeter read substantially lower (like 400 ft!) than field.
Another data point - temps were in the 80s, so DA was much higher than field.
Question - do I need to send the altimeter to the shop?
 
How old was the ATIS, any weather?

If you have a iPhone 6 or above you can download the barometer app and check that against your altimeter.

In my experience analog altimeters are fairly maintance free.
 
ATIS was 5 min old, clear, no wind weather. No, I don't have an iPhone. Or an Android phone. I have a plain, stupid, boring cell phone.
 
Age of ATIS, your position on airport versus where field elevation was measured at, rapidly changing barometric pressure, altimeter error and more could all affect this. How long since your static system was checked?
 
SkyDog58 said:
Age of ATIS, your position on airport versus where field elevation was measured at, rapidly changing barometric pressure, altimeter error and more could all affect this. How long since your static system was checked?
Click to expand...
Last year for the IFR cert. As for position on the airport - not a 400' difference! Maybe 75 ft at most. I've seen a 50-100 ft diff for the past couple years, but not this much!
 
Oh I agree that 400' difference on field would be extreme but it was listed due to it being one of the possible errors that could be added up to 400'.
 
If I saw that difference I would restrict myself to day vfr uncontrolled airspace and get the airplane (not just the altimeter) to my avionics guy.
 
Something we may forget to do here is make sure the system is dry. Check the drains if you haven't done so.
 
They can get out of calibration, and you would probably notice that post flight. Sometimes they can be adjusted "on wing" (in the aircraft). Had there not been a problem noticed post flight, then, I'd suspect a possible static line blockage.
 
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i would check it at another airport first thing, maybe it was their equipment?

bob
 
Clark1961 said:
Something we may forget to do here is make sure the system is dry. Check the drains if you haven't done so.
Click to expand...

OP, what's the type aircraft? Cherokee models usually need the button pushed to drain. Cessna, if there's a moisture issue, it's MX time.
 
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