Regional Pressures
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Re: Regional Pressures
Pierre,
Your argument about several airfields in close proximity goes against the stabalishd procedures for operations within and under the London TMA. All aircraft ther use the "London QNH" which is the QNH from any suitable airfield within or below the TMA. The differences are according to the CAA not considdered to be significant.
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Farmer 1,
Can you elaborate on your statement: "Using it enables me to remember the Decision Height for every single airfield in the country"?
In my book, the decision height depends on the procedure, system minima and obstacle environment which are not the same for every airfield.
France does not have RPS and has terrain higher than the UK. Ireland does not have RPS and covers an area as big as England if one incluses SOTA and NOTA. Our nearest really remote area - Shanwick OCA does not have RPS. Why not?
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When landing Visually one can see the runway and obstacles - an altimeter is unnecessary. When flying the visual circuit, the altimeter enables one to fly at the published level. That could be done with the altimeter set to QFE, QNH, RPS or 1013 provided that the pilot flies at the appropriate level.
When flying IFR, all the obstacles published are AMSL even close to or on the aerodrome. Thus QNH provides better situational awareness. Until visual provided that the appropriate procedure is followed flying on QNH or QFE makes no difference. Once visual, refer to above comment regarding visual landing.
If however, one uses QFE and does not become visual, failure to reset the QNH at a very busy part of the flight is a) Dangerous and b) one of the most common cause of IR test failures.
I also think that using QNH for take-off, landing and circuit work improves situational awareness with regard to performance. For example take a PPL and get them to do a few circuits on QFE - they take-off at 0, downwind at 1000 and land at 0. No problem. Take them to an airfield 5000ft AMSL (with an altimeterb that could set the QFE). Again they take-off at 0, downwind at 1000 and land at 0.
Would it not be safer to have the PPL sit there and say "heck this airfield is high I better check the figures, lean the mixture and make a best performance take-off as per the POH.
QFE is used because of...........tradition. No other reason.
As Chilli says. Time to bin it.
Regards,
DFC
Your argument about several airfields in close proximity goes against the stabalishd procedures for operations within and under the London TMA. All aircraft ther use the "London QNH" which is the QNH from any suitable airfield within or below the TMA. The differences are according to the CAA not considdered to be significant.
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Farmer 1,
Can you elaborate on your statement: "Using it enables me to remember the Decision Height for every single airfield in the country"?
In my book, the decision height depends on the procedure, system minima and obstacle environment which are not the same for every airfield.
France does not have RPS and has terrain higher than the UK. Ireland does not have RPS and covers an area as big as England if one incluses SOTA and NOTA. Our nearest really remote area - Shanwick OCA does not have RPS. Why not?
--------
When landing Visually one can see the runway and obstacles - an altimeter is unnecessary. When flying the visual circuit, the altimeter enables one to fly at the published level. That could be done with the altimeter set to QFE, QNH, RPS or 1013 provided that the pilot flies at the appropriate level.
When flying IFR, all the obstacles published are AMSL even close to or on the aerodrome. Thus QNH provides better situational awareness. Until visual provided that the appropriate procedure is followed flying on QNH or QFE makes no difference. Once visual, refer to above comment regarding visual landing.
If however, one uses QFE and does not become visual, failure to reset the QNH at a very busy part of the flight is a) Dangerous and b) one of the most common cause of IR test failures.
I also think that using QNH for take-off, landing and circuit work improves situational awareness with regard to performance. For example take a PPL and get them to do a few circuits on QFE - they take-off at 0, downwind at 1000 and land at 0. No problem. Take them to an airfield 5000ft AMSL (with an altimeterb that could set the QFE). Again they take-off at 0, downwind at 1000 and land at 0.
Would it not be safer to have the PPL sit there and say "heck this airfield is high I better check the figures, lean the mixture and make a best performance take-off as per the POH.
QFE is used because of...........tradition. No other reason.
As Chilli says. Time to bin it.
Regards,
DFC
Re: Regional Pressures
QFE is used because of...........tradition. No other reason.
As Chilli says. Time to bin it.
As Chilli says. Time to bin it.
Aircraft flying relatively low in close proximity to a mil airfield will routinely be placed on QFE in order to make separation with vis/radar circuits easier - once away from the circuits the appropriate RPS(s) will be offered, if the crew would rather use a different setting (a QNH) they merely have to say so!
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Re: Regional Pressures
Regional QNH is still valuable for military low level let downs and fighter control type ops. It is used extensively within/below the North Sea MDAs where the nearest airfield can be 200+nm away. CM, find me an airfield off the West coast of Scotland where one can obtain an accurate QNH. Finally, if military pilots were to float around on airfield QNH at 420kts, in some areas they would spend their whole sortie tuning into various ATC agencies trying to ascertain the nearest correct pressure setting.
I understand RPS it is also extensively used by the oil industry helicopters.
QFE vs QNH, well there's always going to be 2 schools of thought. As an air taffic controller, I wish that we only used one pressure setting. As a Pilot, I don't care, as long as I remember which one I am using! It is not a difficult concept to grasp.
I understand RPS it is also extensively used by the oil industry helicopters.
QFE vs QNH, well there's always going to be 2 schools of thought. As an air taffic controller, I wish that we only used one pressure setting. As a Pilot, I don't care, as long as I remember which one I am using! It is not a difficult concept to grasp.
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Re: Regional Pressures
Canary Boy,
The reason why I say it is tradition is because the average RAF intake does not know very much about altimeter settings until they learn what the traditional system is. If the RAF had kept to the QNH system in the late 80s, the pilots qualified in the past 10 to 15 years many of whom ae now the QFIs would not know about QFE ops and would not be passing on the tradition.
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London Mil,
The reason as far as I am aware for the North Sea helis using a common altimeter setting is because very often they are IFR at or below the transition altitude (to stay out of icing). When things are busy on the defined tracks it is a great idea for IFR flights to have a common altimeter setting for separation purposes. There is also an advisory service provided to those flights. In fact I think that the place is so busy for ATC that no other flights are allowed at the moment over a large part of the area due to one of the radar heads being out of action.
Since the Mil are in such need of RPS, how many RPS areas are there in say Iraq, Saudi, Afganistan and other places round the world?
Would it not be better for military training to reflect the operational realities of operating in the back end of nowhere at short notice while under pressure?
As for having to call ATS for QNHs. That is old hat with data link technology available the nearest QNH can be available at the push of a button.
Terrain following radar and rad alts of course dont need RPS!
Regards,
DFC
The reason why I say it is tradition is because the average RAF intake does not know very much about altimeter settings until they learn what the traditional system is. If the RAF had kept to the QNH system in the late 80s, the pilots qualified in the past 10 to 15 years many of whom ae now the QFIs would not know about QFE ops and would not be passing on the tradition.
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London Mil,
The reason as far as I am aware for the North Sea helis using a common altimeter setting is because very often they are IFR at or below the transition altitude (to stay out of icing). When things are busy on the defined tracks it is a great idea for IFR flights to have a common altimeter setting for separation purposes. There is also an advisory service provided to those flights. In fact I think that the place is so busy for ATC that no other flights are allowed at the moment over a large part of the area due to one of the radar heads being out of action.
Since the Mil are in such need of RPS, how many RPS areas are there in say Iraq, Saudi, Afganistan and other places round the world?
Would it not be better for military training to reflect the operational realities of operating in the back end of nowhere at short notice while under pressure?
As for having to call ATS for QNHs. That is old hat with data link technology available the nearest QNH can be available at the push of a button.
Terrain following radar and rad alts of course dont need RPS!
Regards,
DFC
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DFC... Regional Pressure Settings provide a safe, low cost alternative, a fall back. Whilst you argue elegantly for the use of other pressure settings in various circumstances (he flatters), I don't see many convincing arguements for doing away with RPS altogether, other than that no one else in the world thought of the same good idea?
Leaving aside the merits of the argument for a moment, you will not believe what is on the Met Office's own website.
I quote...
"QNE is used to set the altimeter to the standard International Civil Aviation Organization atmosphere setting and assumes a sea-level pressure of 1013.2 hPa regardless of actual conditions. This setting is only used by aircraft cruising at high altitude and serves to ensure safe separation of aircraft.
QNH is used to set the altimeter to read the actual height above sea level in the local area, with the UK split into 20 different areas. All low-level aircraft use the QNH setting, including private aircraft, gliders, fast military jets and large commercial aircraft. The Met Office issues forecasts of all 20 QNH values every hour - coded FOQNH. Each forecast is for the lowest sea-level pressure value expected in the area during the hour".
[Note for the Uninitiated or the Easily Confused - ignore all above!!!!]
I quote...
"QNE is used to set the altimeter to the standard International Civil Aviation Organization atmosphere setting and assumes a sea-level pressure of 1013.2 hPa regardless of actual conditions. This setting is only used by aircraft cruising at high altitude and serves to ensure safe separation of aircraft.
QNH is used to set the altimeter to read the actual height above sea level in the local area, with the UK split into 20 different areas. All low-level aircraft use the QNH setting, including private aircraft, gliders, fast military jets and large commercial aircraft. The Met Office issues forecasts of all 20 QNH values every hour - coded FOQNH. Each forecast is for the lowest sea-level pressure value expected in the area during the hour".
[Note for the Uninitiated or the Easily Confused - ignore all above!!!!]
