View Full Version : VFR Flight "Difference in altimeters".

24th Mar 2009, 20:13
Ok i know that for a vfr flight you only need 1 altimeter but what i'm asking is " is there an allowed difference between the two altimeters like in Instrument flying where the allowance is 5oft"?

I was cross checking the qnh was set on both altimeters today and i asked this question and my instructor wasn't sure.

Thanks for replies.

26th Mar 2009, 11:28
If an altimeter is more than 50ft out i usually cover it up and make my students use the more accurate one. Not sure what the actual legal requirement is but this ensures that they certainly think about the issue and are more discriminating on its errors.

26th Mar 2009, 14:29
There must not be a difference of more that 60 ft on the same pressure setting. If for example both is set to read zero ft above ground ( QFE ) there must not be a difference of more than 2 mb.

Pugilistic Animus
26th Mar 2009, 16:41
In the US if the difference between between 'QNH' and 'QFE' or set the altimeter and read what the difference is from the actual field elevation [listed in an aeronautical publications and is greater than 75' ---
--- than it is unusable for IFR flight but there is no requirement here for an accurate altimeter---I generally use that figure for VFR flight too

WE don't have a requirement for duall altimeters here

NOTE: don't attempt to 'carry the error through' just use the altimeter normally; if 75' really makes a difference--- then you should not be doing what you're doing:\


26th Mar 2009, 17:30
it depends on the altimeter scale:
60ft for 25000ft altimeter
75ft for 45000ftc