ATC warning about height on approach
Joined: Jan 2008
Posts: 17,701
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From: Reading, UK
I think you need to check your definition of QNE.
"Mode C and Mode S transponders always send the altitude that would be indicated if 1013.2 hPa were set on the subscale which, at touchdown, will be QNE."
Joined: Jan 2008
Posts: 17,701
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From: Reading, UK
QNE is QNE, whether it's at touchdown or any other phase of flight.
"During conditions of exceptionally low atmospheric pressure it is not possible to set QFE or QNH on some aircraft altimeters. In these circumstances an aerodrome or runway QNE can be requested. The QNE is the reading in feet on an altimeter with the sub-scale set to 1013.2 hPa when the aircraft is at aerodrome or touchdown elevation."
Thread Starter
Joined: Jun 2009
Posts: 1,344
Likes: 80
From: Bedford, UK
So to summarise for the less gifted eg me.....is an accurate readout of height agl available to ATC at the big boy airports?
Last edited by Mr Optimistic; 30th August 2013 at 12:25.
Joined: Feb 2007
Posts: 482
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From: Luton
At Luton it is, as long as you entered the QNH into the ATM properly!
Did wonder once why the inbound was below the level of the airfield at 2 miles. The pressure was high and the QNH had dropped out and de-faulted to 1013.
Did wonder once why the inbound was below the level of the airfield at 2 miles. The pressure was high and the QNH had dropped out and de-faulted to 1013.
Joined: Jan 2008
Posts: 17,701
Likes: 2,046
From: Reading, UK
At Luton it is, as long as you entered the QNH into the ATM properly!
Might well be the same at some airports, but the last time I visited Luton I could have sworn it was on top of a hill.
Joined: Jan 2008
Posts: 17,701
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From: Reading, UK
Any chance of an intelligent response?
That's in answer to your original question, by the way:
is an accurate readout of height agl available to ATC at the big boy airports?
To explain, ATC see height above sea level, not height above ground level. But then any self-respecting airfield controller is going to know the height AMSL of their airfield and the surrounding area, so as LB says, it's easy enough to do the calculation if necessary.
Thread Starter
Joined: Jun 2009
Posts: 1,344
Likes: 80
From: Bedford, UK
I joined this forum because of the acars messages from af447. I have no affinity with commercial aviation. I found other things of interest. You have convinced me I have out stayed my welcome. Your strength is irrelevant. I wont be back on this forum.
