Altimeter Accuracy
 

For a commercial flight, I understand that the accuracy of the altimeter should be verified during the pre-flight checks on the ground to within +50 and -75 feet.

Where do these figures come from, i.e. is it JAR, CAA, ICAO or what?

A direct reference would be helpful.

Thanks.

Probably JAR-OPS 1

Had a quick look but couldn't find it.#
Try a search on the CAA web site

Thanks for looking, but done that. Spent about 3 hours googling for it too, before trying here...

I'd be interested to know how the figures were calculated also...

It may be to do with RVSM, rvsm

From my recollection the right seat altimeter compared with left seat altimeter shall be within 50' and each shall be within 75' of ground elevation, at PRE-START. For RVSM max diff is 200' in RVSM airspace IE above FL290.

LD Max, I went through the same evolution a few years back. All I found in documentary form was in PANS-OPS, as follows:

“A serviceable altimeter will indicate the height
of the altimeter in relation to the QFE reference point
within a tolerance of +/- 20m or 60 ft for altimeters
with a test range of 0-30K ft”
PANS-OPS Vol 1 Pt VI, Ch2 para 2.2.1.3."

I looked in JARs but discovered that the limits were in JTSOs (Joint Technical Standards Orders), but that JTSOs hadn't actually been written yet! So I felt free to rewrite our SOP according to ICAO.

There are other standards in there for altimeters with a greater range also.

Thanks Guys.

'LD Max' -

for me, it's in the B737NG FCOM, Volume I, under Limitations.

Cheers, FD :E

Ohw nice, so for an A320 or a B747 it is not applicable.:mad:

for altimeters rangeing from 0-30000 it should be 60'. And with a range from 0-50000 it should be 80'.

Martin

It has to do with RVSM,and it's a predeparture check that you have to do.At cruising level the difference must be less than 200'.