New tower approach calls
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Bumping an old thread just to clear up something that I think I understand. Could you check my statements below and tell me if I’ve understood it correctly?
Regional QNH is what you should be using below transition level, ie 14000’. This is known as “Altimeter” setting. So, I get cleared above 14000’ and altitude is then reported as Flight Level. Once above 14000’, do I then set my Altimeter to the Standard (which I understand as a sort of Global average pressure at sea level) of 1013mbar?
Am I right in saying that this is not the same as Force QNH? Force QNH is what you’d use when below transition level but over airspace where you can’t get local QNH/Altimeter settings, such as over enemy territory?
I understand what QFE is, but why or when would that be used?
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Yep, above 14k in Korea go standard.
QFE is Field Elevation, basically the pressure at any given field will resolve to your altimeter reading zero when on the ground.
Force QNH? No idea Harry…
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Yep, above 14k in Korea go standard.
QFE is Field Elevation, basically the pressure at any given field will resolve to your altimeter reading zero when on the ground.
Force QNH? No idea Harry…
I remember being told that over enemy airspace, you obviously can’t radio a weather station/tower to get a local QNH so a force QNH was to be used. If I remember right, it was lowest regional QNH of the day.
This is a very old video, but I found this on YouTube and I know understand FL a lot better. It makes much more sense now. FL are fixed altitudes from a fixed ‘standard’ pressure of 1013.2mb. Only when you drop below the national transition level, do you start using local QNH values.
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Yep, force QNH is comparable to Regional QNH. Except with Regional you have the lowest QNH value for a FIR or smaller fixed aera and Force QNH is calculated from the same principle (lowest QNH) of some reporting stations for a specific area in which the force is going to operate.
The question is how do they get the different QNH since you can’t really predict pressure settings precisely, you must observe it.
Anyway, Regional QNH is more a civilian thing for a known area with cooperating reporting stations, Force QNH is the same over a dynamic area where a force is going to operate
Both case take the lowest QNH value observed in their own areaIn BMS we don"t really have regional QNH, we only use local QNH
We don’t have Force QNH either … yetSo basically for now, under the TL: local QNH and above the TA: 1013.2hPa or 29.92inHg
In BMS Korea TA and TL are equal: TA: 14000feet, TL:FL140
In some countries TL will be assigned by ATC depending on the delta Pressure from standardAnd here’s a trick to get QNH on the ground without asking ATC:
Check the chart, note the field elevation
Rotate the alt pressure setting on the altimeter until the altitude displays the fiel elevation and the setting in the pressure windows is the QNH
Do the same with 0000 on altimeter and the setting in the pressure window is the QFE -
I meant to add, QFE is also useful when you’re in trouble, for example in a flamed out jet running on emergency power. You’ll have no radar altimeter and knowing QFE for the field you’re going to attempt to land at, you can then use your altimeter readout to have a better idea when to flare on landing - you’ve enough on your plate without having to remember field elevations, etc.
See here -
When I crash down, the altimeter reads zero. Ignore the fact it went all to pot please…
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QFE is almost no more used in military aviation (except by the funking french and their bad habits ;)) … it has been proven as accident-prone.
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QFE is almost no more used in military aviation (except by the funking french and their bad habits ;)) … it has been proven as accident-prone.
Might QFE be used at airshows where all the flying is done above the base? Or would that all be done with RAD ALT?
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Might QFE be used at airshows where all the flying is done above the base? Or would that all be done with RAD ALT?
Airshow is a good place for QFE indeed. RAD ALT … no way (did you noticed that RAD ALT have some attitude limitations? )
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Airshow is a good place for QFE indeed. RAD ALT … no way (did you noticed that RAD ALT have some attitude limitations? )
Yeah, up to 1500 AGL, but I figured RAD ALT might be good for precise height measurement for the show stuff, then they might use QFE between 1500 and TL.
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Last airshow involvement I had, what they did was to set the altimeter so that the numbers matched what was practiced to the location of the show…and that could/can/does vary depending on where you practice and conditions of the day - at each location. And what is to be performed during the show. But in any…er…event…the setting was done so that the altitude numbers presented during the show points stayed the same. So airshows are a very special case, and have very little to do with general flight operations.
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Heh heh DJ. American here, so I am curious as to what the metric system countries do for things like airspeed (do you do knots), range (nm), etc. Do you have to just put up with Yanks sticking to the old measures or do real foreign pilots use old measures as well.
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We basically do the same as you
altitude in feet,
airspeed in knots
distance in Nautical miles,
visibility in meters
Fuel is made mostly in liters or Kg I presume for larger Ac
Main difference is pressure I’d say, we do hPa, you yanks do inHg
and we all speak english in the air
The french are again the exception on that one, they don’t say One two they say Unité deux
As far as flying units, the real difference is Russia they’re all meters, km/hour, ….
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Last airshow involvement I had, what they did was to set the altimeter so that the numbers matched what was practiced to the location of the show…and that could/can/does vary depending on where you practice and conditions of the day - at each location. And what is to be performed during the show. But in any…er…event…the setting was done so that the altitude numbers presented during the show points stayed the same. So airshows are a very special case, and have very little to do with general flight operations.
So thats a yes, QFE.
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Yeah, up to 1500 AGL, but I figured RAD ALT might be good for precise height measurement for the show stuff, then they might use QFE between 1500 and TL.
I said aTTItude limitations, not altitude.
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I said aTTItude limitations, not altitude.
There’s nothing wrong with my attitude! Kidding. Woops, my bad. Obviously I haven’t noticed RTFM for me then…
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@Red:
As far as flying units, the real difference is Russia they’re all meters, km/hour, ….
The joys of Su-27 Flanker 1.5 (and later Flanker 2.0) of having to convert Kmh-1 to knots on the fly in my head to get any idea of what was going…oh and also learning a bit of cyrillic so i knew what master mode I was in!