Current QNH?
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Current QNH?
A question to fellow controllers around the world.
What means of updating altimeter/QNH are being used in your country/at your unit? Do you have a display showing actual altimeter/QNH values for setting altimeters available in your unit? If not, what kind of routine is used for letting pilots know the actual QNH, and what is the update frequency for the values?
Thank you for any replies in advance!
What means of updating altimeter/QNH are being used in your country/at your unit? Do you have a display showing actual altimeter/QNH values for setting altimeters available in your unit? If not, what kind of routine is used for letting pilots know the actual QNH, and what is the update frequency for the values?
Thank you for any replies in advance!
A question to fellow controllers around the world.
What means of updating altimeter/QNH are being used in your country/at your unit? Do you have a display showing actual altimeter/QNH values for setting altimeters available in your unit? If not, what kind of routine is used for letting pilots know the actual QNH, and what is the update frequency for the values?
Thank you for any replies in advance!
What means of updating altimeter/QNH are being used in your country/at your unit? Do you have a display showing actual altimeter/QNH values for setting altimeters available in your unit? If not, what kind of routine is used for letting pilots know the actual QNH, and what is the update frequency for the values?
Thank you for any replies in advance!
I think not.
Avoid imitations
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Seems like a reasonable question to me. Sounds like the lockdown is getting to some....
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A question to fellow controllers around the world.
What means of updating altimeter/QNH are being used in your country/at your unit? Do you have a display showing actual altimeter/QNH values for setting altimeters available in your unit? If not, what kind of routine is used for letting pilots know the actual QNH, and what is the update frequency for the values?
Thank you for any replies in advance!
What means of updating altimeter/QNH are being used in your country/at your unit? Do you have a display showing actual altimeter/QNH values for setting altimeters available in your unit? If not, what kind of routine is used for letting pilots know the actual QNH, and what is the update frequency for the values?
Thank you for any replies in advance!
As soon as the QNH or QFE moves up or down by 1hPa, our met page alerts and if it’s a QNH change then we pass that to aircraft via RT.
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QNH/QFE with the option for an inHg-setting, for the US pilots if they require it.
Normally without any decimals, if we want to see that, it can be selected.... but the system does the rounding down just fine for us.
Should start blinking with changes, but that does not work... so we'll just keep an eye on it. Latest QNH is put on the strips when given, so rather straight forward.
Normally without any decimals, if we want to see that, it can be selected.... but the system does the rounding down just fine for us.
Should start blinking with changes, but that does not work... so we'll just keep an eye on it. Latest QNH is put on the strips when given, so rather straight forward.
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If it's the QNH/QFE, the decimal is always rounded down... so 1013.9 is given as 1013.
Oh, and the 1 hPa = appx. 30 feet.... that is only at ground level, due to the way an altimeter is set up, at 30.000 feet 1 hPa is roughly 70 feet. Which is the reason vertical separation is 2000 feet above FL290 (but is reduced in RVSM airspace with requirements on the altimeters of the aircraft flying there)
Only half a speed-brake
QNH/QFE, the decimal is always rounded down... so 1013.9 is given as 1013.
Going deeper, if the value as displayed in single digits decimals fluctuates between x.9 and x+1.0 what is the filtering logic? So you do not have to issue a new report for every instant change. Genuine geeky question.
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But yes, if it keeps flipping between 1013 and 1014 (because it's flipping the decimal 3,9 and 4,0), you'd have to pass it. But those situations are relatively rare.... at least where I work.
Only half a speed-brake
Things getting lost in translation, thanks for the insights provided.
As a regular (weekly basis) visitor to QFE run ATS theatres with a QNH built machine it becomes second nature and a good tool to have in the box. Not to mention some back-office calculations or the annual assessments of technical competence.
As a regular (weekly basis) visitor to QFE run ATS theatres with a QNH built machine it becomes second nature and a good tool to have in the box. Not to mention some back-office calculations or the annual assessments of technical competence.
Last edited by FlightDetent; 18th May 2020 at 16:10.
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It's a shame you cannot give "upvotes" here, really appreciate the reply.
I just went through the observers course... they've found out we could handle the observing from the tower, and moved the meteorologist.... (actually they fired the observer many years ago, because the meteorologist could do that)... and since the system is automated, and certified to operate without anyone doing anything anymore.... We're only supposed to poke it if anything is really wrong...
I just went through the observers course... they've found out we could handle the observing from the tower, and moved the meteorologist.... (actually they fired the observer many years ago, because the meteorologist could do that)... and since the system is automated, and certified to operate without anyone doing anything anymore.... We're only supposed to poke it if anything is really wrong...
I understand that the QNH for an airfield can be read directly from an instrument at the airfield.
When a Regional QNH (UK) is given how is that determined and obtained by approach controllers?
PPL
When a Regional QNH (UK) is given how is that determined and obtained by approach controllers?
PPL
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Rounding algorithm?? For what?
If it's the QNH/QFE, the decimal is always rounded down... so 1013.9 is given as 1013.
Oh, and the 1 hPa = appx. 30 feet.... that is only at ground level, due to the way an altimeter is set up, at 30.000 feet 1 hPa is roughly 70 feet. Which is the reason vertical separation is 2000 feet above FL290 (but is reduced in RVSM airspace with requirements on the altimeters of the aircraft flying there)
If it's the QNH/QFE, the decimal is always rounded down... so 1013.9 is given as 1013.
Oh, and the 1 hPa = appx. 30 feet.... that is only at ground level, due to the way an altimeter is set up, at 30.000 feet 1 hPa is roughly 70 feet. Which is the reason vertical separation is 2000 feet above FL290 (but is reduced in RVSM airspace with requirements on the altimeters of the aircraft flying there)
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In practice the Met Office disseminate Regional Pressure Settings as their forecast for the current hour and the next hour - originally via Afpex, most of us see them nowadays on the Met Office Aviation Met site.
