altitude setting

[BrendAn]

when we are doing preflight checks we always switch to atis and put in the latest qnh .

if you are flying out of the same place all the time why not just turn the altimeter to the known height, like outside our hangar it is 130 ft asl.

wouldn't that be the same result as the atis advice or am i thinking this wrong.

[Red]

If your altimeter is calibrated and correct and you are parked at a spot that has the same elevation as at the centre of the longest runway (or you know for sure elevation at your position) then yes it should match.

I fly mostly in and out of farm strips with of course no ATIS so the procedure I adopt is as you mention dial in known elevation before taxiing then check when Im in vicinity of a airport with ATIS that it matches

Saying all that, anywhere that has an ATIS is likely to require you speak to them before departure and that info will be given anyway

 

(speaking of UK, though should be same..... I must remember to add that disclaimer)

Edited Monday at 11:55 AM by Red

[BrendAn]

7 minutes ago, Red said:

If your altimeter is calibrated and correct and you are parked at a spot that has the same elevation as at the centre of the longest runway (or you know for sure elevation at your position) then yes it should match.

I fly mostly in and out of farm strips with of course no ATIS so the procedure I adopt is as you mention dial in known elevation before taxiing then check when Im in vicinity of a airport with ATIS that it matches

Saying all that, anywhere that has an ATIS is likely to require you speak to them before departure and that info will be given anyway

 

(speaking of UK, though should be same..... I must remember to add that disclaimer)

Thanks red.  Atis is an automatic broadcast that runs 24/7. You just tune in to get wind speed and direction ,temp ,dewpoint and qnh.

[Red]

Yes ATIS - Automatic Terminal Information Service, Generaly found only on large airfields with commercial activity in my country, do smaller aerodromes have it in Aus?

 

[BrendAn]

7 minutes ago, Red said:

Yes ATIS - Automatic Terminal Information Service, Generaly found only on large airfields with commercial activity in my country, do smaller aerodromes have it in Aus?

 

i think its on most of the larger regional airfields.   we only have it because its at the raaf base 10km away.

[RFguy]

Brendan

The answer is .. yeah you can just set it to the known height- that's good enough for circuit work. There may be some difference with the published local QNH, perhaps a hecto either way.

 

Once you get airborne though,  flying hemispherical altitudes (4500,5500,6500,7500 etc)  you are expected to be flying on the area QNH, regardless of what your altimeter /setting was at the aerodrome. 

and ATC separation requires / expects  this. 

 

At Cowra, I just set the altimeter to the airport height 970', and then if going somewhere, once established, I set the altimeter to the area QNH (which I will have got from my weather and NOTAM checks before flight).

or, you can call up Centre on the radio, and request the area QNH.  When in the vicinity of my destination, I'll set the altimeter to the AWIS broadcast QNH, if AVBL.

 

[IBob]

I had a altimeter fail very gradually: the first indication of that was when I set the QNH correctly preflight , it did not show the correct field elevation.

Over a number of days it drifted further and further out.

I would guess that one of the two internal bellows or cells sprung a tiny leak, and on inspection it looked as though one of them had not been put through a final plating process.

[IBob]

Edited 21 hours ago by IBob

[BrendAn]

30 minutes ago, IBob said:

They are amazing instruments when you think how they react to such minute pressure changes.

[facthunter]

IVSI's are better. they have a rattler in them to prevent hysteresis..    Nev

[BrendAn]

15 minutes ago, facthunter said:

IVSI's are better. they have a rattler in them to prevent hysteresis..    Nev

[Bosi72]

On 14/10/2024 at 10:04 PM, BrendAn said:

when we are doing preflight checks we always switch to atis and put in the latest qnh .

if you are flying out of the same place all the time why not just turn the altimeter to the known height, like outside our hangar it is 130 ft asl.

wouldn't that be the same result as the atis advice or am i thinking this wrong.

yes you can set altimeter if you know exact elevation of your hangar, and you should be able to confirm accuracy at the thresholds, reference points. 

Assuming this is in ywsl, I am curious if all elevations are between 62ft and 93ft, are you sure 130ft  is right?

 

The main reason for setting qnh from atis/awis is to have everyone's altimeter on the same pressure (elevation). When flying in the levels above 10000ft, everyone is on 1013.

Edited 5 hours ago by Bosi72