Pressure Setting Question

[rustle]

Blackbushe, in common with Farnborough, will give you the London QNH - which is not necessarily the same as 11mb higher than Blackbushe QFE...

Under the TMA you see

[rupetime]

If your radio has failed how did you know the QNH at the arrival airfield ?

rt

[Geardownandlocked]

just make a drawing, and things will be clearer. I draw all the time. I can do an ILS approach and draw a castle at the same time...

[Monocock]

"High to low, down you go"......

I wonder if that's something that Mrs Monocok should be learning too.

[bluskis]

Ruptime

Its on the metar that you got before takeoff. That will be pretty close.

[High Wing Drifter]

Blackbushe, in common with Farnborough, will give you the London QNH - which is not necessarily the same as 11mb higher than Blackbushe QFE...

But the is the QNH, don't explain non why my alty shows me 60' underground on the QFE tho

Not just on one aircraft either, but several.

[FormationFlyer]

12mb Pressure drop - who counted that?!??

1020 - 998 = 22mb....not just a nasty storm - a *really* nasty one...i think in pilot terms it comes under the 'lively' and 'interesting' categories.....i.e. Shouldnt be flying to start with - how silly can you be?!

If your altimeter reads correctly on QNH and then -60 on QFE - even though there is the correct difference between QNH & QFE then you should check your altimeter operation... +50/-75 is typical accpeted tolerences - so you are still inside - however - check the altimeter by winding it through 300' if the difference isnt precisely 10mb it probably needs recalibrating...

[FlyingForFun]

It's quite common for an altimeter to read less than zero on the ground with QFE set. QFE is the pressure at the highest point on the airfield's manoevering area. So unles you happen to be parked on the highest point, you will read less than zero.

Even so, 13mb difference between QFE and QNH, for an elevation of 327', sounds like a lot to me. 27ft/mb is, I think, the generally accepted approximation close to sea level, 13mb difference would suggest that they are using 26ft/mb. It is true that the TMA QNH may be higher than the local QNH, so that might be the reason. Why not pop into the control tower the next time you're there, and ask them? Then you can post the answer here, too!

FFF
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