QFE, QFF and QNH
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Looking these up and found they are supposed to be (i think) all refer to the same in that when you request these from ATC at the airfield you’re landing at, they are the altitude of the airfield ASL, is this right? if so why would i want to know this?
Because if you do not get the right pressure to use as a reference you will go into the ground if using the barometric altimeter wrongly.
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Transition altitude is FL140 in Korea.
Pretty High , I think in USA is 11.000 ft right ? By the way it can not be a transition altitude, this one (140 FL) must be the transition level. Transition altitude is given in thousands of feet while Transition altitude is given as a Flight Level.
Do you mind to check ? Thanks
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Transition altitude is given in thousands of feet while Transition altitude is given as a Flight Level.
tsss tsss
Transition altitude is given in thousands of feet while Transition level is given as a Flight Level
worse moment to make a typo -
Pretty High , I think in USA is 11.000 ft right ? By the way it can not be a transition altitude, this one (140 FL) must be the transition level. Transition altitude is given in thousands of feet while Transition altitude is given as a Flight Level.
Do you mind to check ? Thanks
It’s 18,000 ft in the USA - FL180.
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Sorry to slightly necro this thread, but I’m having some troubles with this.
I never paid attention to it honestly. But lately I have, and I don’t seem to get a match between baro and radar altimeters. Flying to one side of the airfield, over sea, I request any of the three and dial them in into the altimeter. Radar and barometric are off by a big margin (say 18k vs 17k or 100 vs 800). So… anything I’m missing here? All switches seem to be in the right position. I understand the radar altimeter has a warm up period? But that can’t be it because it’s been on for a long time before testing it.
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If I’m correct, RADAR and barometric altimeter will only show the exact same altitude when flying in ISA (at sea level: 15 degrees Celcius with a lapse rate of 1.98 degrees/1000ft, 1013.25hPa with 27hPa/1000 feet, 0% relative humidity, …), when right above the field’s ARP, and with airfield’s QFE set. Any diversion from these values will result in a different readout, even if it’s just a few feet.
As you’ll most likely never fly in ISA weather, that’s where the difference usually comes from.
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Sorry to slightly necro this thread, but I’m having some troubles with this.
I never paid attention to it honestly. But lately I have, and I don’t seem to get a match between baro and radar altimeters. Flying to one side of the airfield, over sea, I request any of the three and dial them in into the altimeter. Radar and barometric are off by a big margin (say 18k vs 17k or 100 vs 800). So… anything I’m missing here? All switches seem to be in the right position. I understand the radar altimeter has a warm up period? But that can’t be it because it’s been on for a long time before testing it.
In theory if you put QNH value into the altimeter it will turn the barometric altimeter into a true altimeter (or QFE for true height above aerodrome). The problem with BMS’s default weather is that the atmosphere doesn’t match the design of the altimeter very well. The only thing that the QNH/QFE values guarantee is that the altimeter will read elevation or zero respectively at the aerodrome. Altitudes different from the parking spot rely on an estimate of how the air pressure will decrease at higher altitudes. This relationship is built into the design of the instrument.
Weather in real life and the design of the instrument are usually very good matches. An error of 100’ would be cause for concern at all but the highest altitudes. You’ll find if you load real weather into BMS with the .fsmap files from a real world weather source the altimeter will be much more accurate than not using real world weather data.
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Hey mates
reading all these questions and comments on when and how to use correct altimeter settings I would like to add some (maybe) minor points just out of my experience as a former airline pilot flying international…
whatever there might be the local or national TA/TL - ATC will just use the terms “ALTITUDE” (“xy flight, climb/descent ALTITUDE 6000 ft”) and “FL” (“xy flight, climb/descent FLIGHT LEVEL 250”) to seperate and differentiate between the usage of local QNH and standard altimeter setting (1013.2 or 29.92)
They usually will never use the Q-codes….Due to the fact that all published instrument charts show their altitude information in respect to local elevation above MSL (also those of the surrunding mountain peaks or obstacles etc) it is necessary to fly those approaches with the local QNH set to the appropriate value (received from ATC or ATIS or similar ) - and not to QFE or leaving the “Kollsman window” setting at 1013.2 respectively 29.92
Regarding my quote taken …
@Eagle-Eye:……The issue was one aircraft being at 18,000ft (on local QNH, e.g. 29.12 InHg) and another at FL190 on standard setting (29.92 InHg). In this case, after a quick glance at the numbers, you would expect them to have 1000ft vertical separation, while they are actually only separated by about 200ft.
Note that flying at these altitudes you will not fly in an uncontrolled area!
So according to the local air pressure (and temperature influences) ATC will NOT provide someone with a clearance to fly at 18000 ft while some other guy will get a clearance to fly at FL 190 in the same region ! As already pointed out there will be some “altitudes left out” and not been given just due to that very effect of minimized separation! Some countries will just “lift up” their lowest usable FL accordingly…fly safe
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They usually will never use the Q-codes….
Whenever you’re expected to cruise at an altitude or height, you should know the QNH/QFE value though, so ATC will have to inform pilots flying below TRL at least once what the QNH/QFE is. As you well know, ICAO (FAA may be different, but I doubt it) phraseology for that is “descend to 4000ft, QNH 1015” or “cross CTR at 1500ft or below, QNH 1001”, so tower, approach and lower ACC ATC use it all the time.
Unless I misunderstood this part, and you meant they would never say “descend to 4000ft QNH” or something similar?
Also keep in mind that those minimum seperation values usually apply to a/c flying (tracking) in the same direction (000°-179°) or (180°-359°) - [RVSM is just the same but with lower values] - meaning: a/c flying opposite have to have twice that (already mentioned) separation !
It’s the other way around.
There are some exceptions due to airway structure, e.g. France, but in general the rule is: north- or eastbound = odd FL, south- or westbound = even FL (NEODD SWEVEN in short)
So traffic flying same direction (e.g. westbound) will fly at EVEN flight levels (200 - 220 - 240 - …) while opposite traffic (in this case eastbound) will fly ODD flight levels (190 - 210 - 230 - …). Same direction traffic thus has 2000ft separation, opposite direction traffic only has 1000ft separation.
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Hey Eagle-Eye
sorry - I made a mistake concerning the separation - got your comment wrong and confused it myself! Your statement is true (with the calculated separation being only 200 ft) BUT - as I stated - this will not happen due to ATC advised FL or minimum usable FL respectively max usable Alt !
Concerning the Q-word - I meant they don’t use the whole Q-group and yes, they need to give you when crossing from FL toward Altitudes the current local QNH but the word “Altitude” or “FL” is/should be added and - by the way - the little word “to” as a filler is to be avoided due to possible misunderstandings with the number 2
But again: I’m sorry for putting it wrong with the separation between ODD/EVEN same / opposite FL … and I CORRECTED MY POST !
Thanks for pointing it out
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the little word “to” as a filler is to be avoided due to possible misunderstandings with the number 2
There can indeed be confusion, but whenever given altitudes above 20,000ft, you’re most likely to be using FL anyway, and the way you stress the to/two is (or should be) slightly different.
Also, there’s a difference between “descend to 1000ft” and “descend 1000ft”. The first means you need to descend to 1000ft AMSL, regardless of initial altitude. The second (although in reality not often used as such, to my knowledge) means you need to substract 1000ft from your current altitude. E.g. at FL350, “descend 1000ft” would mean the same as “descend FL340” (here, I don’t use the “to”, as there can be no confusion)
At least, that’s how I’ve been taught for ICAO/Belgium. FAA, CAA or other ICAO countries may have different local procedures…
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I was under the impression that you should always get from ATC instructions to a specific altitude/FL, and never relative instructions - always ‘descend to 1000 ft’ rather than ‘descend 1000 ft’. Even when not using ‘to’ in the instruction, they should always tell you where to be, rather than how to get there. At least for altitude, anyway.
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The second (although in reality not often used as such, to my knowledge) means you need to substract 1000ft from your current altitude.
In 4500+ hours of flight, I’ve ever never heard it!(?)
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I’ve never in my life heard a relative descend, as Blu3wolf (and deejay that was faster responding than me :p) points out, and if I ever got it I would definitely confirm the level they want me to descend to.
According to the British, that are always very pedantic with their RT, the correct way to clear to an altitude is “descend/climb TO ALTITUDE xxxx feet” to avoid any confusion, while the clearance to a flight level would be given as “descend/climb flight level xxx” (without the TO)
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According to the British, that are always very pedantic with their RT, the correct way to clear to an altitude is “descend/climb TO ALTITUDE xxxx feet” to avoid any confusion, while the clearance to a flight level would be given as “descend/climb flight level xxx” (without the TO)
It is really only out of laziness that ATC would not say “TO xxxx”. We even say “climb/descend TO Flight level xxx”. This reduces any risk of ambiguity. The big one is an aircraft assigned two thousand feet. It is lazy to simply say “ABC climb two thousand”. The proper phraseology is “ABC climb TO two thousand” etc. It comes up every day at work [emoji6]
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It is really only out of laziness that ATC would not say “TO xxxx”. We even say “climb/descend TO Flight level xxx”. This reduces any risk of ambiguity. The big one is an aircraft assigned two thousand feet. It is lazy to simply say “ABC climb two thousand”. The proper phraseology is “ABC climb TO two thousand” etc. It comes up every day at work [emoji6]
“sportstar five two eight two, Climb two two thousand feet” is ambiguous - although worked out easily enough, it causes momentary confusion. “sportstar five two eight two climb and maintain two thousand feet” is not ambiguous.
Of course, the sportstar would be doing pretty well to make it to two two thousand feet XD
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According to the British, that are always very pedantic with their RT, the correct way to clear to an altitude is “descend/climb TO ALTITUDE xxxx feet” to avoid any confusion, while the clearance to a flight level would be given as “descend/climb flight level xxx” (without the TO)
British are CAA-regulated, though, using CAP413 instead of ICAO DOC 4444/9432 as their “ATC Bible”/phraseology manual. Never read a CAP413 myself, but I know there are some differences from the ICAO Docs, and FAA is yet another thing.
I just checked the currently active ICAO DOC 4444 and 9432 (both dated 2007.01.01), and Skybrary phraseology database to be sure. The only correct phraseology nowadays is “climb/descend to (altitude/height/flight level)”. Makes me wonder, though, as I had my basic training in 2010-2011, and I still have my course material in which ‘relative descents’ are a real thing, and we actually used the phraseology during our sim runs.
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In the end all these books are thrown out of the window anyway (at least by me :p) and as Snpusher says, lazyness takes over.
Even though 4444 sets a standard that should be used worldwide, if you move across a border within the very same region, you will appreciate different phraseologies. I just cited the British ATC as they sound the most organised of all the places I frequent (even though, as I said, their RT comes up as a little bit pedantic to me).