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A-3TWENTY
7th Mar 2009, 19:23
As stated at RVSM rules , we are supposed to check altimeters before "entering RVSM airspace".(We most fly in Europe).

I usually do it(for RVSM purposes) on ground and during climb passing about 25000, 26000 FT and then every hour in cruise, but I have lots of co-workers who say this is useless because we already cross checked altimeters on ground and after take off when we set both altimeters to standard.

Despite I am sure about the correct procedure , I`d like to hear the opinion of you all guys and get if possible some documentation about that.

Rainboe
7th Mar 2009, 19:25
You check on the ground anyway. You check in the climb. But I believe you should log the readings and errors on your Plog at least once an hour, prefereaby when you do your fuel check.

bdairbusdriver
7th Mar 2009, 20:22
My company only completes an RVSM check once sitting in the cruise IN RVSM airspace, raised this issue during line training but fell on deaf ears :confused:.
Definitely an advocate of checking altimeters in the climb and every hour there after.

Otto Throttle
7th Mar 2009, 20:45
Altimeters cross-checked on the ground prior to taxying, again when changing baro setting to STD, again on passing FL100, 200, 300 & 400, and a final check in the cruise when in RVSM every hour.

Capt Claret
7th Mar 2009, 21:10
Excerpt from a 717 Ops Manual:

RVSM altimeter comparison need only be completed once at the start of cruise as the altimeter comparator satisfies the RVSM Operational Approval requirement for hourly cross-checks.

airmen
7th Mar 2009, 21:38
RVSM course with CAE, FS and others say check of altimeters before entering RVSM airspace and then once every hour, which make sense for me!
Capt claret- perhaps you do not check your altimeters in cruise because the ops manual say so, then the comp monitor advise you only when the limit is passed, if you check it yourself you might be able to see the trend and react before you have to leave RVSM...

Rainboe
7th Mar 2009, 22:08
Let's not go making work. If you have a good comparator, and the manual says do it at start of cruise, that's just fine! It would be a bit anal to then decide you were going to do it every hour as well, to try and pick up a trend! There are far more important things to do! You havea comparator monitoring it for you.

MarkerInbound
7th Mar 2009, 22:38
I never quite figured the logging of altimeters. Since if they are out of limits you have to write them up, by default if there are no write ups, you're good to go. I'm not going to wait an hour to point it out if, between paper, meal, crossword, or just looking out the window I see a 50 foot split.

Yes, at my last job we recorded all three every hour.

Capt Claret
8th Mar 2009, 00:18
Capt claret- perhaps you do not check your altimeters in cruise because the ops manual say so, then the comp monitor advise you only when the limit is passed, if you check it yourself you might be able to see the trend and react before you have to leave RVSM...

Altimeters are checked on the bay, passing transition and again levelling in the cruise. ALT can be made to display by a 1hPa split between altimeters, though I can't remember what altitude split sets it off.

Slingshot22
8th Mar 2009, 01:11
Both types of response are correct - it depends on the systems installed in the aircraft.

If the aircraft has an EICAS system (in this case an 'altimeter comparator') which announces, visually or aurally (or both), that the two primary altimeters are out of tolerance, then it satisfies the requirement to cross check the altimeters in cruise in RVSM airspace, and there is no need for the pilots to do it every hour.

If the aircraft does not have an 'altimeter comparator' system, then the pilots are required to crosscheck the altimiters in cruise, and this is usually annotated in the Ops manual as 'once every hour...'

JammedStab
16th Mar 2009, 14:08
Hi Rainboe. I am flying a 727 and our "ALT" comparator is for the radio altimeter only. Is it used for pressure altimeters on some other aircraft?

Rainboe
17th Mar 2009, 00:32
Hello there. I don't think pressure altimeters have comparators in EICAS aeroplanes at all. They can differ quite markedly if they vary either side of the correct figure- if you can work out what the correct figure is! There is a lot of error in pressure altimeters judging by the variations you get across the three, so comparators would end up working rather hard!

Procedure is to do an RA check at 2500'RA when they come alive. We do RVSM checks every hour every flight on the PAs. Everywhere seems to have gone RVSM, even Africa (God forbid!)

PantLoad
17th Mar 2009, 03:43
Our SOP requires that we check the altimeters on the ground as part of the instrument check.

Then, we do the check at transition altitude.

Then, we do the check at TOC.

Then, we do the check APPROXIMATELY every hour thereafter.

However, the ONLY check we make that is RECORDED is the TOC check.

Note: if we change altitudes (e.g. step climb at some point in cruise), we do another check that is also recorded.

Again, the cruise altitude INITIALLY is recorded. Other than that, it's just
a check that is verbalized by the pilots.

Also note: the recording at TOC includes the Standby Altimeter reading.

The way I read the regulations (MNPS over the Atlantic, etc.) is that the hourly checks need not necessarily be recorded.....

This is my company's SOP. Other companies may vary.

galaxy flyer
17th Mar 2009, 03:46
Rainboe

don't think pressure altimeters have comparators in EICAS aeroplanes at all.

My bizjet has a comparator that give an amber ALT when the difference exceeds 200 feet. Functionally tested recently in turbulence with altimeters that were close to the edge.

GF

arba
17th Mar 2009, 06:48
my SOP is to check once at PREFLIGHT and once to be recorded at ToC.


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