View Full Version : Max difference between the 2 primary altimeters?

17th Mar 2005, 15:51
Hi all,

Just wondering if anyone can confirm what the max error is allowed in an altimeter before it would be regarded as unserviceable?

I think I saw somewhere that it is 60ft. Had a brief look through JAR OPS 1 but can't seem to find any particular figure.

Thanks in advance.

17th Mar 2005, 16:03
75 ft. on the ground

17th Mar 2005, 16:17
Doesn't it depend on the actual alt and speed? I say this as I had one recently that was something like 120ft which according to the vol 3 ops manual was acceptable for normal operations, and it did vary with mach speed and alt, the error was reported at fl340 and .85m. Of course it was different if operated under RNP 5 navigation rules.

Charles Darwin
17th Mar 2005, 17:42
RVSM requires that at sea level there is a MAX 25 feet between capt and 1st officers altimeters. MAX 75 feet difference between capt or f/o altimeters and airfield elevation, at all elevations.
At 5.000 feet field elevation there is a MAX 35 feet diff, and if the field is 10.000, there is a MAX 40 feet difference.
Inflight the max difference between capt and f/o is 200 feet.

From Boeing B-757 Ops Manual, limitations chapter.

17th Mar 2005, 18:00
There is a difference between altimeter limitations for RVSM operations and serviceability.

For serviceability, the numbers should be available in the limitations section of your flight manual, as this is aircraft specific.

Exceeding the limits for RVSM operations does not necesarrily mean that your altimeter is unserviceable.

Flight Detent
18th Mar 2005, 03:24
Hi all,
For the B737NG, the limits are:

Grnd: Capt to FO/50 feet - field elev at or below 5,000 feet

Capt to FO/60 feet - field elev 5,001 to 10,000 feet

Either one to field elevation - max 75 feet (all elevations)

Flight: M.78 at or above FL350 - elec to elec max is 100 feet.

From the Boeing production flight test procedures.

Cheers, FD

18th Mar 2005, 10:52
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 ftš

PANS-OPS Vol 1Pt VI, Ch2para

22nd Mar 2005, 12:12
Thanks to everyone for their input, appreciate it.

All the best,

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