Setting aerodrome QFE/QNH on arrival
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Setting aerodrome QFE/QNH on arrival
When are you supposed to set aerodrome QNH on arrival to an airfield. My instructor told me it was within so many miles or so many minutes of the airfield, which ever is sooner. Typically I can't remember these numbers.
Also setting QFE, I know you should only set it when you have the airfield in sight, but are there mile/minute limitations too? I don't recall this, but don't think there is - but I honestly can't remember
Thanks guys
Also setting QFE, I know you should only set it when you have the airfield in sight, but are there mile/minute limitations too? I don't recall this, but don't think there is - but I honestly can't remember
Thanks guys
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I don't think that there's any hard and fast rule on when to go to or from QNH or QFE.
Personally, I usually set QNH before take off (if I'm intending to leave the circuit). This eases the cockpit workload. If I'm staying in the circuit I set the QFE and leave that set.
So far as setting QFE on my return to an airfield is concerned, I usually make my initial call at what I consider to be an appropriate distance out (usually about 5 or 10 minutes, unless there are airspace restrictions which cause me to call earlier). I will get the QFE during that call and I'll set it at the same time as I start my top of descent checks.
None of the instructors I've ever flown with have commented on this practice so I assume it to meet with approval.
Any other views anyone?
Pronto
Personally, I usually set QNH before take off (if I'm intending to leave the circuit). This eases the cockpit workload. If I'm staying in the circuit I set the QFE and leave that set.
So far as setting QFE on my return to an airfield is concerned, I usually make my initial call at what I consider to be an appropriate distance out (usually about 5 or 10 minutes, unless there are airspace restrictions which cause me to call earlier). I will get the QFE during that call and I'll set it at the same time as I start my top of descent checks.
None of the instructors I've ever flown with have commented on this practice so I assume it to meet with approval.
Any other views anyone?
Pronto
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Well,for me I change to the destination airport QNH when I`m switching to their radio station.
For example,leaving london info,to contact Southend..I`ll quickly check the ATIS and scribble down the QNH/QFE,airport information,set the QNH..then make my call to Southend,contact them with "information echo" or whatever the ATIS is at,pass my message,get my instructions..get into visual range of the airport,then set the QFE a minute or two before entering the circuit.
As for distance / time,I always make my call about 10 miles out minimum,roughly 5 minutes I guess,if not more.
Gives me plenty of time to mangage the workload,get a picture of the situation,better situational awareness..generally making things nice and slick
For example,leaving london info,to contact Southend..I`ll quickly check the ATIS and scribble down the QNH/QFE,airport information,set the QNH..then make my call to Southend,contact them with "information echo" or whatever the ATIS is at,pass my message,get my instructions..get into visual range of the airport,then set the QFE a minute or two before entering the circuit.
As for distance / time,I always make my call about 10 miles out minimum,roughly 5 minutes I guess,if not more.
Gives me plenty of time to mangage the workload,get a picture of the situation,better situational awareness..generally making things nice and slick
If you're flying below the transition altitude (i.e. not using flight levels), is there any good reason for not setting your destination's QNH immediately you get it from either the ATIS or their approach frequency?
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There seems to be some confusion between QNH and QFE creeping into this thread.
QFE is the barometric setting which causes the aircraft altimeter to read zero when the aircraft is on the ground at the aerodrome to which the QFE relates. Aircraft elevations when QFE is set are reported as "height". It is usual - in the UK - to land and take off with QFE set. A few years ago the RAF experimented with the US system where aircraft operated only on QNH (but with QFE available on request).
QNH is the barometric setting which causes the aircraft altimeter to show the aircraft height above sea level. This is the setting usually used for cross country flying below the transition level as it also shows your height above the chart datum. When QNH is set, aircraft elevation is reported as "altitude".
If flying above the transition level (in the UK generally 3,000 feet amsl) pilots flying in accordance with the Instrument Flight Rules are required, and pilots flying VFR are advised, to use QNE. This is a standard setting of 1013.25 hPa. Aircraft elevation is reported as "flight level".
For further discussion see Thom vol 3 at pages 113 onwards.
Pronto
QFE is the barometric setting which causes the aircraft altimeter to read zero when the aircraft is on the ground at the aerodrome to which the QFE relates. Aircraft elevations when QFE is set are reported as "height". It is usual - in the UK - to land and take off with QFE set. A few years ago the RAF experimented with the US system where aircraft operated only on QNH (but with QFE available on request).
QNH is the barometric setting which causes the aircraft altimeter to show the aircraft height above sea level. This is the setting usually used for cross country flying below the transition level as it also shows your height above the chart datum. When QNH is set, aircraft elevation is reported as "altitude".
If flying above the transition level (in the UK generally 3,000 feet amsl) pilots flying in accordance with the Instrument Flight Rules are required, and pilots flying VFR are advised, to use QNE. This is a standard setting of 1013.25 hPa. Aircraft elevation is reported as "flight level".
For further discussion see Thom vol 3 at pages 113 onwards.
Pronto
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Pronto
Can't see any confusion between the two settings here.
If you are referring to my last posting, allowing for field elevation when flying on QNH simply entails understanding that if you are flying at 1500' (QNH) over an airfield with a 500' threshold elevation, then you are 1,000 agl and will touch down at 500' altitude, zero height.
Furthermore many commercial pilots might take issue with your assertion that it is normal to land on QFE in the UK.
You'll also find that many flight schools, such as OATS teach QNH only, inline with airline SOPS.
In the USA (as this is a global website) the altimeter setting used is QNH, although it is not called that as they have no QFE to differentiate from.
If anyone in a low lying area wonders why this is, try winding on the difference between Big Bear or Aspen (circa 7000 agl!) Also, the transition in the USA is 18,000' to standardise and take the Rockies and others into account.
Can't see any confusion between the two settings here.
If you are referring to my last posting, allowing for field elevation when flying on QNH simply entails understanding that if you are flying at 1500' (QNH) over an airfield with a 500' threshold elevation, then you are 1,000 agl and will touch down at 500' altitude, zero height.
Furthermore many commercial pilots might take issue with your assertion that it is normal to land on QFE in the UK.
You'll also find that many flight schools, such as OATS teach QNH only, inline with airline SOPS.
In the USA (as this is a global website) the altimeter setting used is QNH, although it is not called that as they have no QFE to differentiate from.
If anyone in a low lying area wonders why this is, try winding on the difference between Big Bear or Aspen (circa 7000 agl!) Also, the transition in the USA is 18,000' to standardise and take the Rockies and others into account.
If flying above the transition level (in the UK generally 3,000 feet amsl) pilots flying in accordance with the Instrument Flight Rules are required, and pilots flying VFR are advised, to use QNE. This is a standard setting of 1013.25 hPa. Aircraft elevation is reported as "flight level".
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If I'm planning to land at the airfield, I set its QNH as soon as I get it, or as soon as I go below transition altitude, whichever is later.
If I'm arriving in nice VMC, I set QFE when I have the field in sight. If I'm arriving IFR/in IMC, I land on QNH because things get a tad busy on a missed approach, and forgetting to reset QNH from QFE can be embarrassing.
I used to use QFE for IFR approaches, and eventually convinced myself that QNH is preferable. It also means no "conversion" needed when flying in the USA.
You pays yer landing fees, and you makes yer choices.
If I'm arriving in nice VMC, I set QFE when I have the field in sight. If I'm arriving IFR/in IMC, I land on QNH because things get a tad busy on a missed approach, and forgetting to reset QNH from QFE can be embarrassing.
I used to use QFE for IFR approaches, and eventually convinced myself that QNH is preferable. It also means no "conversion" needed when flying in the USA.
You pays yer landing fees, and you makes yer choices.
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Just to further confuse the issue,
I was taught that QFE is the setting which causes the aircraft altimeter to read zero when the aircraft is above the height of the highest obstacle on the airfield....
My altimeter usually reads about -34 feet when sat on the ground at Blackpool on QFE.
As for the original thread, I usually change the pressure settings as I receive them from the different frequencies - at take off I'll have QFE from the AFIS or Tower and change to QNH when handed over to approach to depart the zone.
On the way back into the zone I'll change back to the Tower frequency and change from QNH to QFE.
That way I always remember if I'm changing frequency, I probably need to change pressure setting.
QFE is the barometric setting which causes the aircraft altimeter to read zero when the aircraft is on the ground at the aerodrome to which the QFE relates.
My altimeter usually reads about -34 feet when sat on the ground at Blackpool on QFE.
As for the original thread, I usually change the pressure settings as I receive them from the different frequencies - at take off I'll have QFE from the AFIS or Tower and change to QNH when handed over to approach to depart the zone.
On the way back into the zone I'll change back to the Tower frequency and change from QNH to QFE.
That way I always remember if I'm changing frequency, I probably need to change pressure setting.
I was taught that QFE is the setting which causes the aircraft altimeter to read zero when the aircraft is above the height of the highest obstacle on the airfield....
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Rotorhorn,
Of course you set everything as soon as you're given it. We rotary pilots don't have enough hands to write things down do we?
So long as you remember whether you're on QNH or QFE, who really cares? I've flown here and set QFE; I've flown in the US and remembered airfield elevation; same thing really. What does it matter so long as you're comfortable with it and remember which you're doing. Though it's probably a good thing to always do it the same way, or one day you'll forget.
Of course you set everything as soon as you're given it. We rotary pilots don't have enough hands to write things down do we?
So long as you remember whether you're on QNH or QFE, who really cares? I've flown here and set QFE; I've flown in the US and remembered airfield elevation; same thing really. What does it matter so long as you're comfortable with it and remember which you're doing. Though it's probably a good thing to always do it the same way, or one day you'll forget.
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MATS PT 1 states that ATC should pass the QFE (unless it is known that an operator uses QNH) at a convenient time before the aircraft is on final approach or before joining the visual circuit to land.
It does not really matter which you select and when, but I would advise that when flying in Controlled Airspace you ensure that you are flying in compliance with your clearance. This is particuarly important at airfields where they may be a number of mbs difference between QNH and QFE.
It does not really matter which you select and when, but I would advise that when flying in Controlled Airspace you ensure that you are flying in compliance with your clearance. This is particuarly important at airfields where they may be a number of mbs difference between QNH and QFE.
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Rotorhorn
Bookworm is quite right, the standard QFE will be based on the highest point of the airfield surface.
So you might be 34ft below that (although remembering Blackpool in the distant past, I can't recall too many big dips - maybe a few big dippers !) or it might just be altimeter calibration. (isn't a difference of +/- 50 feet allowed between 2 altimeters when flying IFR?)
Bookworm is quite right, the standard QFE will be based on the highest point of the airfield surface.
So you might be 34ft below that (although remembering Blackpool in the distant past, I can't recall too many big dips - maybe a few big dippers !
) or it might just be altimeter calibration. (isn't a difference of +/- 50 feet allowed between 2 altimeters when flying IFR?)
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Final 3 Greens
Also not quite right, the airfield elevation which the QFE is based on is the highest point on the landing area.
the standard QFE will be based on the highest point of the airfield surface.
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our south east airfields tend to be flat anyway
Having done all my basic training at Elstree, I can only do greasers on runways, that have a hump in the middle & a downslope at both ends!