PPRuNe Forums - Altimeter setting

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Altimeter setting

Anyone AT controller:

Descending into Heathrow, passing, let's say, FL080, I am instructed to descend to 4000 feet. Usually, we set the QNH at the present level and start descent. Now, what if I am climbing out of Heathrow and passing 3000 feet, instructed to climb to FL110. Do I set my QNE right at the present altitude or I wait till 6000 (transition alt.) to set it?
I had this issue on a recent departure from that airport.:ugh:

Appreciate any answers

As Heathrow is in the UK, the following from the UK AIP ENR would apply:

Quote:

GENERAL

Vertical positioning of aircraft when at, or below, any Transition Altitude will normally be expressed in terms of Altitude.

Vertical positioning at, or above, any Transition Level will normally be expressed in terms of Flight Level.

When descending through the Transition Layer vertical position will be expressed in terms of Altitude, and when climbing in terms of Flight Level. It should not be assumed that separation exists between the Transition Altitude and the Transition Level.

CLIMB

While flying at, or below, the Transition Altitude vertical position will be expressed in terms of altitude based upon the Aerodrome QNH. When cleared for climb to a Flight Level, vertical position will be expressed in terms of Flight Level, unless intermediate altitude reports have been specifically requested by Air Traffic Control.

DESCENT

When an aircraft is descended from a Flight Level to an Altitude preparatory to commencing approach for landing, ATC will pass the appropriate aerodrome QNH. On vacating the Flight Level, the pilot will change to the aerodrome QNH unless further Flight Level vacating reports have been requested by ATC, in which case, the aerodrome QNH will be set following the final Flight Level vacating report.

Other States may do it differently, so check their AIPs before flight in their airspace.

Aims - to clarify PPR's post, in the UK in both cases set the appropriate setting at the time ie QNH when descending and 1013.2 (29.92) when climbing to a flight level. Do NOT wait until TA. Any required altitude reports on the way up can be given from the standby which can remain on QNH until no longer required.

This system has been standard for a while now and is designed to prevent 'level busts'.

Quote:

Originally Posted by BOAC (Post 2896252)

Aims - to clarify PPR's post, in the UK in both cases set the appropriate setting at the time ie QNH when descending and 1013.2 (29.92) when climbing to a flight level. Do NOT wait until TA. Any required altitude reports on the way up can be given from the standby which can remain on QNH until no longer required.

Quote:

Originally Posted by BOAC (Post 2896252)

This system has been standard for a while now and is designed to prevent 'level busts'.

Thank you very much; this clarifies the whole lot.

Also depends on the operators' SOP's!

aimscabinet.
QNE is not an altimeter pressure setting. The QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 mb when the aircraft is at aerodrome or touchdown elevation. QNE is used during conditions of exceptionally low atmospheric pressure when it is not possible to set QFE or QNH on an altimeter.

Surely you have a 3rd standby altimeter you can use to read off the current Altitude.

'skiesfull' - interested to know if:-

a) you are with a UK airline and
b) if your procedures (for LHR) differ from the UK AIP?

BOAC
(a) no
(b) no- SOPs haven't quite caught up yet! I use the recommended altimeter setting procedures as detailed in Jeppesen - some of my colleagues prefer to change setting at TA/TL.

But if you have been cleared to a flight level you then change to 1013.25. You still have a 3rd altimeter at your disposal.

skiesfull - in which case, stick with your post #6 - that way you are 'protected':)

Quote:

The QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 mb when the aircraft is at aerodrome or touchdown elevation.

Is there an equivalent Q code for other altimeter settings when the knob comes off in your hand...?

Oxford once kindly calculated the circuit altitude and landing altitude for me when that exact thing happened when I tried to set their QNH. I was previously on Cranfield's (not 1013.2) so they had to do a bit of maths...

Tim

Hi,

I agree with PPRune radar. That's correct. If the acft is cleared to descent to altitude and at the moment is at the FL, QNH may be set as given by ATC if the pilot is not requested to report any FL passing. When is acft airborn and climbing to a FL, pilot is expected to change his altimeter settings from QNH to QNE when passing transition altitude. When passing transition altitude, you are sure you are clear of any obstacle around you.

BRGDS

Quote:

Originally Posted by Talkdownman (Post 2897481)

QNE is NOT an altimeter pressure setting. The QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 mb when the aircraft is at aerodrome or touchdown elevation. QNE is used during conditions of exceptionally low atmospheric pressure when it is not possible to set QFE or QNH on an altimeter.

!!!!!!!!!!

BOAC:-
Thanks for the advice, would that everyone always followed SOP's!!
Having reviewed my company's SOP's regarding altimeter settings, I have found that our SOP's follow half the ICAO recommended procedures and in my experience most of my colleagues only follow half of the SOP's! I will not go into any further details, suffice it to say that the correct setting is always set on the subscale but not necessarily at the time preferred in the ICAO recommendations. I will, of course, send a memo to the big cheese but despite marking it "NOT for bin 13" do not anticipate any changes soon!!

Good luck pushing 'it' uphill:)