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National CAA policies around Europe on busting pilots who bust controlled airspace (and danger areas)

More to the point, there is no scenario involving, ahem, flying a plane, which requires you to do such a calculation.

Also it is one thing doing it in an armchair and another doing it when hand flying in turbulence etc.

Aviation is full of pointless crap like this, for sorting real triple-Y-chromosome knuckle-dragging men from sheep and other subclasses that are undeserving of the great privilege

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

In real life a pilot never does these altimetry calculations. You set a QNH for altitude-based airspace (or flight) and you set 1013 for FL-based airspace (or flight).
More to the point, there is no scenario involving, ahem, flying a plane, which requires you to do such a calculation.

How do you calculate takeoff and landing performance without converting airfield altitude to pressure altitude?

ESKC (Uppsala/Sundbro), Sweden

Yes it is the same calculations and both act the same way (no able to takeoff and busting FLs on QNH) but I think the point is that mis-calculating 1000ft of pressure altitude for take-off performance is far less problematic than mis-calculating 100ft when near CAS for infringments but as rule of thumb one should just assume CAS starts 300ft earlier…

Last Edited by Ibra at 15 Jul 18:28
Paris/Essex, France/UK, United Kingdom

How do you calculate takeoff and landing performance without converting airfield altitude to pressure altitude?

Here ya go

And here to land

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

There is an easy test: set 1013 on the altimeter on the ground and the transponder should read the altimeter setting. But again most people don’t know this. It also breaks if your altimeter is also the encoder for the transponder…

Most people have 2 altimeters these days. If you want them to do the test, then just include it in the pre-take off checklist.

LSZH(work) LSZF (GA base), Switzerland

Airborne_Again wrote:

How do you calculate takeoff and landing performance without converting airfield altitude to pressure altitude?

I just use airfield elevation as pressure altitude in these graphs.

Some light aircraft POHs have tables. The ones I’ve seen have an entry every 1000ft at best. The difference between pressure altitude and actual altitude will be small compared to this rounding.

Some light aircraft POHs have little graphs on which you are supposed to draw lines. The graph is so small that the error of placing your pen, and the error of your lines not being 100% straight horizontal, is at least of the same order of magnitude as the difference between pressure altitude and actual altitude.

ELLX

Peter wrote:

Here ya go

And here to land

So you disregard the QNH. Very well.

lionel wrote:

Some light aircraft POHs have tables. The ones I’ve seen have an entry every 1000ft at best. The difference between pressure altitude and actual altitude will be small compared to this rounding.

Try that when the QNH is 980…

ESKC (Uppsala/Sundbro), Sweden

That data is from the POH which is FAA and CAA/EASA approved.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

That data is from the POH which is FAA and CAA/EASA approved.

I think AA meant you should translate pressure altitude with +27*(QNH-1013) to get DA for performance calculations

Airborne_Again wrote:

Try that when the QNH is 980

I think that is why 2500ft LTMA is in FTs instead of FLs, you don’t want to bust Class A while on circuit or on ground?
Tough when QNH is 980 I may have other major things to worry about

Last Edited by Ibra at 15 Jul 20:07
Paris/Essex, France/UK, United Kingdom

Actually, ATC will never assign a flight level below the transition level. So the lowest assignable flight level in controlled airspace becomes unusable if the lowest flight level of the airspace drops below the TA.

So any bust because of somebody flying at or below the TA, but above the FL of the airspace is completely irrelevant from a separation point of view.

Biggin Hill
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