The Mil and their use of QFE

[vintage ATCO]

Can someone explain what it is with the military and using QFE for everything (in the UK, obviously)? We transitted a Mil zone today (Class D not just MATZ) and were told to fly on QFE. We were below the cloud at 1500ft QNH. This immediately loses all reference to terrain and obstacles (unless you have two altimeters, we did), except for the airfield within the CTR which we were not inbound to. And how do they go on co-ordinating with each other? Must involve much arithmetic gymnastics, and for why? :confused:

On the way back we elected to climb to 3500ft IFR but again were put on the QFE (and an approx 500ft difference.)

I know the mil at one time were all QNH but went back to QFE. Now it seems all QFE rather than what we do in the civil world of QNH for intermediate approach and zone transits, and QFE for final approach and landing (and that's rare now at my unit.)

Seems odd but I am sure there must be an explanation. :D

[Chilli Monster]

Was it the higher or the lower of the Class 'D' airfields ;)

Believe me - you want to try taking handovers from them when you're next door! They've got the traffic on their QFE, you want it on QNH - b*****s muddle or what!

And out of interest - what service did they put you under as you transitted? Bet it wasn't what you expected?

Come on boys (and girls) in blue - isn't it time you realised you're in the same universe as the rest of the world and played accordingly?

[BEXIL160]

Come on boys (and girls) in blue - isn't it time you realised you're in the same universe as the rest of the world and played accordingly?

As I recall they tried to, at least for a while, in the late 1980s. Can't have been much of a success (for them) because they changed back pdq.

The RN at the time remained QFE based, as they are today. I can see some point in this. Not a lot of terain to miss at sea (one of the reasons I actually like flying over it, even single engined;) )

Rgds BEX

[A good headin]

We use QFE in and around our patterns at our aircrews request. Yes we did try using QNH in the mid nineties and confusion reigned.

If I was whazzing around at 380kts into radar patterns or visual circuits in my pointy plane the last thing I would want to be doing is messing around swapping pressure settings.

As a puddle jumper it is in your interest to join in the QFE game while transitting the busy Mil airspace and getting mixed up with the fast pointy jets. It makes co-ordination a lot easier if you are on QFE for us. Its always nice to sing from the same hymn sheet as they say. At the end of the day we are giving you a LARS to help you along safely and ensure you don't end up with a fast jet suppository.

[DFC]

"On the way back we elected to climb to 3500ft IFR"

QFE is just as bad (dangerous) as pilots who fly IFR above the transition altitude on a QNH. ;)

Regards,

DFC

[batty]

Do we know what the transition altitude was that day??...;) 3500ft may have been fine

[HEATHROW DIRECTOR]

<<Its always nice to sing from the same hymn sheet as they say.>>

PRECISELY - so why do Mil opt to be different to everyone else??

[A good headin]

Well for you guys everything bimbles around on the SAS or the good old QNH. As I said earlier, it's was the RAF pilots who decided to adopt QFE for all pattern flying,positioning into and visual circuit work. We don't really care what pressure you are on till you start getting mixed up with a of a load of fast jets whizzing around with pattern speeds higher than good old concordes.

At the end of the day as long as you get from A to B safely, with the correct separation standards and terrain clearance applied, we have done our job. It's nice to have co-operation as we go about our military task and thank you puddle jumpers for complying with what appears an alien concept. :D

[PPRuNe Radar]

Can't pointy ended pilots add or subtract then ?? :)

[stillin1]

Chill guys!!!
The Mil uk use QFE for circuit work and approaches cos it is easy - the altimeter reads zero, followed as by a little bump as you land. Outside of the MATZ / Military Radar Pattern we obey all the same conventions as the rest of the aviation community (QNH / SPS). Why do sums when you don't need to? What is difficult or wrong about the alt reading zero at touchdown? and If you are flying in / near a MATZ why not accept that you are being safely seperated from traffic that may be fast moving, rapidly changing height (forced landing patterns as just one example) flying many and various sized and speed circuits in many and various configurations - and already damned busy. Frequently we bash the pattern / circuit specifically to practicie emergency procedures (train hard - fight easy!!). We tried QNH and didn't find ANY benefit that outweighed the use of QFE. If in / near the MATZ -transit traffic (on QFE) will be told the Sector Safety Altitude if IMC, based on the QFE. As you reset QNH leaving the "service" - it's back to the deal you usually use vs SALT!
Think before using the big stick your carrying. Its a forum - just ask the Q (nicely):cool:

[A good headin]

OK, so there you go, the answer from the jockeys lips.

Mil Controllers serve both communties, that's our job. As long as everybody gets what they want, the fast pointy boys/C172 puddle jumpers don't hit each other, and everybody gets home safely, job done. Have a nice weekend and fly on what every pressure keeps you safe!:ok:

[HEATHROW DIRECTOR]

Now you can bet some loony will ask how military controllers can use 500 ft vertical inside a civil control zone!!!! Tee hee!!

[vintage ATCO]

Well, thanks everybody. Thought I did ask the question nicely . . . . :hmm:

I'm still not convinced though but accept what you say. Just thought it would be good to do what the rest of us do. And how on earth you do inter-unit coordination . . . . . :confused: Still, I don't sit in front of a radar display these days. But if you want to see busy, I'll show you busy . . . . . :ok:

And as for 'puddle jumper' :mad:

[Whipping Boy's SATCO]

VA, having controled within a CTR where some ac were on QNH, others on QFE, ac in the hold were on QFE or SAS and an adjacent US mil airfield with interlocking patterns was on QNH (inches), I can say that the maths gets somewhat interesting.

HD, Is there such a thing as a "civil" CTR? I was under the impression that the majority were anything but civil. :O

[HEATHROW DIRECTOR]

<<HD, Is there such a thing as a "civil" CTR? I was under the impression that the majority were anything but civil. >>

Oh shame... must be because I've gone! Seriously, it used to amaze me that if we got two Heathrow inbounds 500 ft apart all the bells and red squares went off and it was off to the boss before our feet touched the floor... Yet, hand over a civil a/c to Northolt and they could gaily pop it 500 ft above or below any of their traffic quite legitimately...

[DFC]

Batty,

The transition altitude does not change day to day and (except where notified differently) is in general 3000ft in the UK including at Lyneham and Brize.

Regards,

DFC

[PPRuNe Radar]

Would it not be easier for pointy ended jockeys to learn about QNH Ops since that is what they will be forced to use when they undergo their IR and/or ATPL training at the taxpayers expense so they can get their job flying A340s for the Wooly Pully ;)

[cancel_mayday]

In the waste Russian airspace QFE is used by everyone: you'll never get altitudes from ATC - civil or mil - only heights. Pilots do maths, not us :=

[Harrier46]

Rather than the mil changing why not the civilians? Having experienced using both, QFE is (as said previously) much simpler. And sat at the runway threshold showing no altitude is (at least to me) logical. Try explaining QNH to the man in the street!

[whowhenwhy]

HD "Why do mil opt to be different to everyone else?"

If you look at JSP 552 (JSP 318A for those of us who can remember) and MATS Part 1 you will find few differences when they talk about the same stuff. Unfortunately, mil controllers tend to apply everything as per the book, whereas civil controllers sometimes tend to do otherwise. Specifically, ATSOCAS! (But lets not get into that again) As far as QFE/QNH is concerned, surely it's better to fly on a pressure setting that gives you a zero reading when you're on the runway? As others have said, it eases co-ordination problems when flying through or near to traffic patterns. As far as coordination with adjacent units is concerned, it's easy as long as you're used to doing those kinds of maths. Most controllers worth their salt will also have a guide made up in their head as to what separation is needed between certain altitudes/heights and differing pressures. Plus which, it's what we're trained to do, so it becomes second nature. :ok:

[stillin1]

P R
May I refer you back to my origional reply?
Your:
"Would it not be easier for pointy ended jockeys to learn about QNH Ops" comment was covered.
We do!!!!
As for the sarcstic bit that followed, I choose to refrain from comment since I'm in a good mood today. Chill - think gentle thoughts, then blast away at random :cool: :ok:

[Chilli Monster]

Harrier 46Rather than the mil changing why not the civilians? Having experienced using both, QFE is (as said previously) much simpler. And sat at the runway threshold showing no altitude is (at least to me) logical.

Shows how much flying you do outside the UK then. Say QFE to any non-UK European, or US pilot, and they'll look at you with a very quizzical expression.

The earth orbits the sun - not the other way round ;)

WhowhenwhyUnfortunately, mil controllers tend to apply everything as per the book, whereas civil controllers sometimes tend to do otherwise. Specifically, ATSOCAS! (But lets not get into that again)
People in glass houses shouldn't throw stones ;) (though I'm intrigued by the word 'unfortunately'). We do things by our book, you do it by yours - but who's book is right? And what is this attraction to to military of holding onto traffic until it's almost in someone else's overhead? I'm noticing that more and more these days. (sorry - off topic I know)
As far as QFE/QNH is concerned, surely it's better to fly on a pressure setting that gives you a zero reading when you're on the runway?

See my comment above. In the world of instrument flying you really don't care what the altimeter reads on landing. All you want to to know is:

a) MSA - Last time I looked spot heights were based on amsl, not some arbitrary airfield elevation. QNH is therefore more relevant than QFE when I'm working that out on a route

b) DA/MDA - after that you can see where you're going so you don't actually look at the altimeter. What it reads is therefore of no consequence. As an instrument go around will, in most cases, be based on QNH why would you want to complicate matters by transitioning from QFE to QNH in addition to the rest of the tasks that need to be carried out in a very short space of time in that scenario.

Still think the military is right and the rest of the world is wrong? I've not flown a QFE approach in the last 5-6 years - it's no hardship, believe me.

[M609]

After all, your MIL boys do manage very well on QNH abroad, it can't be too bad, since they keep coming back! :cool:

[DFC]

"Try explaining QNH to the man in the street"

See that hill over there - the map here says that it is 2500ft above sea level. When the altimeter reads 2500 or less with the sea level pressure set we will hit that hill.

See that airfield over there - the map here says that it is 625ft above sea level. When the altimeter reads 625ft we will hit that runway.

Most common cause of initial IR rating test failure is pilots failing to reset QNH in the missed approach having made an approach using QFE - UK CAA.

It's an altimeter not a heightameter! :D

Regards,

DFC

[stillin1]

Doh!
OK Mr man-in-the -street:

See that runway, in fact any runway, anywhere any time? Well with QFE set - when the altimeter reads zero you will be landing on it.
See that hill just over there? The nice man / lady in ATC or the little book of Approach Plates I carry that tells me how to get to the runway also tells me a height not to fly below so that I can be sure to miss that hill.
When we fly away from the airfield but stay quite near the ground I will set the QNH on the altimeter so that I know how high I am in relation to the sea level cos that is the datum height my maps use to show me how high the hills are. But just like the QFE thingy - we'll need to change it every now and then cos the pressure over the country changes you know.
And if we go high, no matter where we are we set SPS so that we can all miss one another.
Easy isn't it? - no matter where I go or how busy I am I know that the runway = zero on the altimeter with the QFE set and there are only the other two thingys to remember when you arn't quite as busy.
Now would you like to be patronised about any thing else?:E

[Chilli Monster]

There's always one that falls into the trap ;)
in fact any runway, anywhere any time? Well with QFE set - when the altimeter reads zero you will be landing on it.
.
Not so hypothetical question. If the QNH was the same as the standard (1013) what would the QFE be at:

a) Las Vegas McCarran (2181 ft amsl)?

b) Big Bear City (6748 ft amsl)?

There are others around the world - they're just two that I have the figures in my head for.

As an addition to the question - can you physically set that QFE on your altimeter?
the little book of Approach Plates I carry that tells me how to get to the runway also tells me a height not to fly below so that I can be sure to miss that hill.
All the plates I've used show MSA, not MSH, but happy to be corrected if the Mil produce the latter.

[HEATHROW DIRECTOR]

<<Not so hypothetical question. If the QNH was the same as the standard (1013) what would the QFE be at:

a) Las Vegas McCarran (2181 ft amsl)?

b) Big Bear City (6748 ft amsl)?>>

Sounds like a QNE question to me..........

[stillin1]

If I can't set the QFE (altimeter mb sub-scale limited I presume) I'll set QNH and get on with it! - just like I did in both Big Bear and McCarran. I am both flexible and a realist.:cool: It ain't a pi**ing contest, it's a forum. I can & do work both procedures - I just prefer QFE.
Your right about the MSA thing - for that I take off my shoes and socks and do the difficult sums before the approach (and set QNH on the other altimeter). Its only a trap if you don't know the way out:p Now the Russian thingy was a real bag of metered worms
:yuk:
We could keep this going for weeks!

[BEXIL160]

Ahhhh QNE!

Have actually used it... once. Extremely low pressure up in Aberdeen (942mb?).

A further question. The RAF isn't the only air force to drive fast pointy things around the sky. What do other air arms use? How many use QFE (or would have any idea what you are talking about)?

Rgds BEX

[Whipping Boy's SATCO]

How many of us (in the UK) fly around the visual cct with QNH set?

Similarly, how many of us transit underneath a TMA with the local airfield's QFE set?

How many of us have tried to set the Kabul (6870ft AMSL) QFE?

Why do we have a mixed transition altitude in the UK (mostly 3000ft but 6000ft under a number of TMAs)?

What does it matter as long as everyone knows what datum they are flying relative to and the controllers can do their maths when mixing 2 or more pressure settings?

Personally, I think the mixed use of pressure settings can be a recipe for disaster. However, surely we can just bite the bullet and get on with it.

PS. How many feet equate to one millibar at 35000ft when the temp is ISA -10deg Celcius. Anyone who uses the 30ft rule will be in for a shock.

[stillin1]

Whipping Boy's SATCO
Well said that man:cool:

[ILS 119.5]

I think you'll find also that SID's use flight levels and altitudes for the initial climbing levels. If there was a high transition altitude then in the initial climb from take off through the TA would involve three changes of pressure settings, which would increase workload.
I assume that the mil use QFE because they like it and the controllers can provide some separation. Don't forget that anyone bashing circuits at a civilian airfield will use QFE.
If the mil want to transit civil CAS then they will be instructed to fly QNH for separation purposes. I find it far easier, with less workload to use QNH, 1013.25 and airfield elevation.

[ILS 119.5]

If you are flying at 35000ft then you should be flying at a flight level of 35 with all the other a/c in the area flying on 1013.25. minus 10 degrees is irrelevent. I agree with all using the same datum, however radar cannot determine the datum a/c are flying to. It is easier for the controller to have all the a/c flying on the same pressure setting to ensure separation.
Please keep safety first.

[HEATHROW DIRECTOR]

<<I think the mixed use of pressure settings can be a recipe for disaster. However, surely we can just bite the bullet and get on with it.>>

Hopefully not the attitude of professional controllers! If something is that dangerous it needs fixing.

ILS 119.5 wrote: "If you are flying at 35000ft then you should be flying at a flight level of 35"

I think not, but I (think I) know what he means.

[whowhenwhy]

ILS 119.5. WB's SATCO is alluding to other airspace users who use a regional pressure setting to maneouvre up to say 45 000'. In this instance, when coordinating with said users, finding that the 30' per millibar assumption is wrong has come as quite a shock and no-one is quite sure exactly what to do about it.

As far as the QFE/QNH issue is concerned, I think people are starting to get a little confused. We use QFE in the instrument and visual circuits and for aircraft flying close to, or through, these patterns. Outside this, ac should be flying on a RPS below the TA and the SAS above.

Chilli, aside from the differences of necessity due to mil vs cvi ops, there aren't that many key differences between "your" book and "ours." They would all have come from the same root document in the dark mists of time. But why would you change from QFE to QNH on a missed approach? Maybe yes if you were flying away from the airfield after the approach, staying below the TA, but certainly not if you were going back around for another go.

[Whipping Boy's SATCO]

My 35000 ft comment was aimed at some elements of the mil who fly at this sort of level on the RPS!!

Regarding my "biting the bullet" statement, maybe it was not the best choice of words. What I meant to say was that there may be perfectly valid reasons for operators to fly on different pressures. We should be able to manage their expectations and deal with the issues.

[Chilli Monster]

But why would you change from QFE to QNH on a missed approach?

1) All civil holds (which missed approaches often end up in) are flown on QNH / Standard depending on whether above or below TA.

2) After a missed approach you'll often have briefed the plan that you may be going somewhere else, at MSA - hence QNH required

3) All missed approaches are required to be "terrain safe" (obviously). Approach plates show MSA, not MSH (as stated before) therefore datum required is QNH

DFC's post is quite correct when he points out the single biggest fail on Instrument Rating tests flown on QFE is failing to reset QNH on the missed approach - hence flying the approach QNH takes out that possibility.

Re (1 & 3) above it's worth remembering of course that, unlike the military, not all airfields with IAP's have radar. Therefore an RVA chart is not applicable from which a controller can put you on QFE and keep you 'terrain safe' according to his chart / video map. Terrain clearance is still the responsibility of the pilot fully in that scenario hence the use of QNH as the 'safe' datum

[peatair]

It is nonsense and, in my view dangerously confusing, to use QFE for anything other than final approach. Indeed, most civil operators long since ceased to use it even for that.

[ILS 119.5]

HD

Yeah sorry FL350, too used to doing approach. Have not done area since 85.

Also for any a/c to fly up to 45000' why use a regional pressure setting? I think that the rules of the air state that above a certain level all a/c must fly on 1013.25. Please correct me if I am wrong.

[whowhenwhy]

Unless under the control of ATC, HM Ships or ASACS!!!!! Say, if they were in the block surface to 45 000'? That's the problem!

Chilli. Good points. Some down to civ/mil differences and of course I am viewing QFE/QNH from a purely mil point of view. I can certainly see the benefits from a human factors point of view, but still like the idea of seeing 0 when I'm on the runway. Maybe I'm just old and resistant to change?? Unlike my NATS brethren who have their destinations and who are all far from being resistant to change (sorry going off thread now!). :ok:

[KPax]

If you don't like the service we are providing at Class 'D' airfields then we can offer you a re route. Keeps you away from us, and perhaps will stop you commenting on things that are outwith our control. We do our best within the rules, as said before if you don't want to fly on the QFE then stay away from the airspace.

[ILS 119.5]

WWW

In the UK there is no such block of airspace which extends from the surface up to 45,000 ft. Everything above FL245 is Controlled Airspace. Also if you were flying at 24,500 ft on the regional pressure then there is a danger that you could be above FL245 and entered CAS illegally.

[Whipping Boy's SATCO]

ILS 119.5, you're absolutely wrong. There are blocks (very big ones at that), which go from 5000ft to 55000ft (promulgated in the AIP) with class G below. If one is cleared into these blocks, there is nothing that would necessarily stop you goinng from 55 grand down to sea level. that

[Giles Wembley-Hogg]

I think that maybe the time has come for a review of the altimeter setting procedures used by military ATC in the UK. This thread already highlights some areas where the current procedures do not seem to be best practice or are liable to cause confusion.

As an example (and by know means wishing to cause embarrassment to stillin1) he mentions on page 1 of the thread that transit traffic in IMC will be told the Sector Safety Altitude based on the QFE. Surely this should be refered to as the Sector Safety Height? Whilst I think I know what he was getting at, it shows that confussion can easily arise (especially for simple minded pilots like myself).

A statement by whowhenwhy saying that traffic outside the pattern should be on an RPS when below TA is also illuminating. My dusty old MATS part 1 says that RPS should be used "at, or below 3000' amsl when outside controlled airspace and not in the vicinity of an aerodrome". Now, it seems to me that you have to be in the vicinity of an aerodrome in order to receive a LARS, otherwise there would be no radio/radar contact or the pilot would be outside of the operational area of the unit and hence the sevice would have been refused. Furthermore, if you have just transitted a zone (under QFE) I do not see how the next pressure setting given can be the RPS. How can you transit a zone and then not be in the vicinity of an aerodrome?

I fly in the South East of England where a lot of the airspace above me has its lower level defined as an altitude. The last setting I want to use is RPS which is the lowest FORECAST QNH and hence could put me closer to my work colleagues above me than I want to be on a day off!

As a parting thought, the controllers at Seaton TWR use QFE for circuit/landing traffic and QNH for transit traffic as do many other units around the country, so this type of operation is not without precendent and help and advice should be readily available.

As always, just my view.

G W-H

[DFC]

The more I think about this subject, the more I discover that the UK altimeter setting procedures are absolute rubbish. Some examples;

The general transition altitude is well below the highest terrain.

Looking at Brize as an example -

The Transition Altitude is 3000ft but the top of the CTR is defined as an altitude of 3500ft.

The top of a MATZ is 3000ft above the appropriate airfield which in all cases puts it more than 3000ft AMSL thus aircraft passing over the MATS are required (for safety sake) if IFR to fly at a Flight level that keeps them above the fast moving jets that are using QFE. Does the pilot use RPS to assess separation (NO TMA, CTR or other CAS) or does he call the mill ATC unit for QNH only to be given the QFE?............The biggest danger in aviation is not knowing what is going to happen to the flight!

I am amazed that there are not more incidents relating to altimeter setting..........however I could safely say that there are several each day that go unreported or even unnoticed!!

ILS119.5..............have a look at a danger area of the big variety - all have an upper height AMSL. As far as I am aware the ACC use the RPS to separate flights crossing above i.e. use the RPS to determine a minimum FL..........however aircraft operating within the danger area could be using the QFE of an aerodrome within it!!!!!

---

KPax,

Perhaps you should review the separation provided in Class D between a VFR flight (transit or otherwise) and any other flight - none. Thus QNH or QFE for a VFR transit aircraft makes little difference because all you do is give traffic info and the pilot does the manoeuvering as required to avoid traffic and maintain VMC............I have received a clearance from you guys to fly VFR at 1500ft QFE when your actual was Overcast 1000ft.....because your circuit was active............not what we would call a good idea :)

As for IFR - If your field elevation is 500ft and the circuit is 1000ft then you simply want the IFR flights to be not lower than 2500ft on your QNH without giving traffic info!

All very simple for someone to put into local procedures which is always safer than making it up on the fly!

---

Giles,

The definition of "In the vicinity of an Aerodrome" is;

Within, entering or leaving the aerodrome traffic circuit.

In other words - the ATZ!

The limits to LARS coverage is based on radar performance, airspace issues, adjacent units, local requirements and last but not least - the CAA limit on the distance at which controllers can provide a radar service without holding an Area Radar rating.

Regards,

DFC

[LXGB]

Hi Giles,
Drifting off topic a bit, but in response to your...

"I fly in the South East of England where a lot of the airspace above me has its lower level defined as an altitude. The last setting I want to use is RPS which is the lowest FORECAST QNH and hence could put me closer to my work colleagues above me than I want to be on a day off!"

I routinely provide a service to traffic transiting under airspace with lower limits defined as an altitude. I won't pass this traffic the RPS, I'll pass the pressure datum the airspace is based on. I would be surprised if you were given any other pressure if operating close to the limits of said airspace.

Best Regards,
LXGB

[KPax]

The Vis cct is 1000' QFE, SPC 1500' QFE, RTC 2000' QFE, Procedure Pattern height (NDB, TAC) 2500' QFE. We try our best using the premise that if you are VFR and you are not visual with IFR traffic then we will separate you. We very rarely have problems and our procedures appear to work very well receiving not many complaints at all. As stated before if you don't feel comfortable with what we are doing then go west with Bristol or east with Brize.

[LordSven]

Wow what a hot topic! At my RAF civil manned unit we still have QGHs and Spiral Descents!! All Mil IAPs are flown on QFE, which seems to make sense to me as under a high workload, the man in the hot seat in the sky (who is after all our raison d'etre) doesn't have to think about whether he's about to hit the floor or not. Correct me if I'm wrong, but I believe both civil and mil IAPs give both altitudes and heights on approach plates, so the pilot can in fact please himself. The ATCO, I think, should, and generally does, carry out any correction required for separation, as he/she already does on low pressure days between highest Alt and lowest FL.
As for separation, we can only apply 500' between mil flights. Civ vs civ or civ vs mil get MATS1 standard separation.
And I also believe I'm correct in saying that MATS1 states that all a/c are to be given QFE before commencing Final Apch, unless the pilot has stated, or it is known that the pilot/operator lands QNH.
Hope I haven't left myself open to a broadside.......
:D

[DFC]

KPax,

Bit hard for a VFR flight to be visual with an IFR flight that is in cloud. However, provided the VFR flight remains outside cloud then the IFR flight who is inside that cloud is separated (segregated) from the VFR flight........if they are both in VMC then see and avoid applies in Class D with traffic info from ATC to help.

If you are using radar of course the info provided to you via SSR is always referenced to 1013.2 Thus provided that you decide to put QFE or QNH into the processor, you will get the appropriate readout to judge separation by regardless of what we set on our altimeter!!!

If we have an uncomfortable experience (safety) in any airspace we report the matter and then next time expect a more comfortable experience! ;)

---

Lord Seven,

Please advise QTH as I would love to come and do a speechless, compass and gyro U/S flameout descent.....haven't done one in decades!!! :D

In class D separation is only provided between IFR-IFR-Special VFR. VFR flights are not separated from anything and nothing is separated from VFR!!!.........Basically, the only thing that the mil gain from having class D is that it removes the option from the VFR flight to corss without bothering to call which can happen in a MATZ.

Regards,

DFC

[Itsrainingagain]

And how on earth you do inter-unit coordination

Good old fashioned maths!!!:confused:

[KPax]

'If the VFR ac is VMC and the IFR is IMC then as long as the VFR is clear of cloud then hthey are separate' not sure what the ATCEB would say to that. 1000' QFE is our separation standard for Mil against Civ, only in exceptional circumstances and if the Civ pilot is happy do we reduce to 500'. The bottom line is if the VFR is not visual with the IFR then he must avoid.

[HEATHROW DIRECTOR]

<<However, provided the VFR flight remains outside cloud then the IFR flight who is inside that cloud is separated (segregated) from the VFR flight>>

I don't recall seeing this in any manual. Please quote the reference DFC..

[Giles Wembley-Hogg]

DFC

I am not sure about your definition of "in the vicinity". Heathrow have been using "reduced separation in the vicinity of an aerodrome" for years and since their ATZ would not extend much past the ends of the runways, does this mean that their operation has been illegal?????!!

LXGB

I have been passed the RPS on a number of occasions by a unit not a million miles away from Middle Wallop as I was heading in the direction of the TMA, but I always ask for the QNH instead anyway.

Back to QFE for a second. It is worth bearing in mind that the EGPWS must be over-ridden for QFE operations on the Boeings that I fly. Just one of those little things that add to the workload when we conduct QFE operations.

Regards

G W-H

[PPRuNeUser0172]

As a Mil Type currently operating in a Cold part of the world (near a Lake) where QNH reigns, I can say that I prefer it to QFE ops, all this hoop about what the altimeter reads when you hit the runway, IT DOESNT MATTER!!!!! who the hell looks at the altimeter below 200 either on a precision/non precision approach (assuming you are visual) or an a VFR approach?? After all, the height you fly circuits/radar patterns at is just a number, it doesnt matter what that number is. QFE is outdated and unnecessary and having seen and operated under both regimes I would like to see it got rid of. The rest of the civvy world operate on QNH and there is no reason why the RAF/mil guys need to operate on QFE.

I know the counter to this argument is that it isnt difficult to add/subtract before the blunties beat me to it, but if we dont need to do mental gymnastics in the radar pattern then why bother. I would much prefer to just look out the window and remind myself how cool my job is. (assuming it is not IMC)

Get rid of it I say, although I know that for most in the Military it would be like the HM the Queen saying that she wants to be referred to as 'Lil. Did someone say "Jehova";)

DS

[Whipping Boy's SATCO]

One final observation - UK military controllers use QFE 'cos that's what the pilots say they want. Maybe this thread should continue on the mil pilots forum?

[bookworm]

ILS 119.5. WB's SATCO is alluding to other airspace users who use a regional pressure setting to maneouvre up to say 45 000'. In this instance, when coordinating with said users, finding that the 30' per millibar assumption is wrong has come as quite a shock and no-one is quite sure exactly what to do about it.

Can I take issue with this one? From an altimetry point of view, the 30 ft per millibar assumption holds nicely, because the difference between altimeter settings is millibars at or close to sea level.

We presumably agree that if you have an aircraft at 1,000 ft on an altimeter setting of 1013, it will be about 300 ft below an aircraft 1,000 ft on an altimeter setting of 1003.

If you have an aircraft at 45,000 ft on an altimeter setting of 1013, it will still be about 300 ft below an aircraft 45,000 ft on an altimeter setting of 1003.

The first aircraft is 45,000 ft above the 1013 mbar surface, the second is 45,000 ft above the 1003 mbar surface. The difference between the 1013 and 1003 mbar surfaces is about 300 ft.

[Immelmann]

Some eastern countries, like Ukraine, had their procedures quite a long time based on QFE.
They are adopting to QNH nowadays. Will the british military adopt, too?
I doubt it. Why? Because it has always been like this!

During my military time we just accepted the QFE for landing in Britain.
British military jockeys came on the radio in old Germany:

"Request all infos for QFE" The empire?;)

[LXGB]

Agree with WB's SATCO. Good idea to cross-link this thread to the Mil Aircrew forum if possible. See what the
"customers" think!

LXGB

[ILS 119.5]

Can't say too mich but I am argueing with my fleet manager at the moment and will be first thing in the morning as to whether we fly over the pond tomorrow on regional qnh or 1013.25!!

Regardless, I will fly on a FL.

[ADIS5000]

Bookworm,

I have recently done a limited amount of research on the 30ft or not height difference per mb and I can confirm that WBS is correct. The 30ft per millibar difference is only valid up to (very approx) 20 - 23,000ish ft. At 35,000ft the difference can easily be 70ft per millibar! Ring your local Met man for confirmation.

Regards, ADIS

[bookworm]

The 30ft per millibar difference is only valid up to (very approx) 20 - 23,000ish ft. At 35,000ft the difference can easily be 70ft per millibar!

What you write above is quite correct, but it's not the point. The level difference between the 250 mbar level and the 249 mbar level is actually about 100 ft. But that's irrelevant when it comes to separating traffic on different altimeter settings. If you change the altimeter subscale setting by 1 mbar, the difference in altitude indicated by the altimeter is 30 ft, because you're changing the reference level by about 30 ft, and the altimeter simply measures the altitude difference from that reference level.

Try it out at FL350 some time.

[Whipping Boy's SATCO]

bookworm, let us take an example:

The calculations below show actual feet/mb for various altitudes assuming ISA:

Zero ft 30 ft per mb
5000 ft 30 ft per mb
10000 ft 31.45 ft per mb
20000 ft 36.25 ft per mb
30000 ft 40.84 ft per mb
40000 ft 47.84 ft per mb
50000 ft 52.75 ft per mb
60000 ft 62.96 ft per mb


If an aircraft is flying at 20000 ft on an RPS of 1033 (20
mbs x 36.25) the aircraft is 725ft lower than an aircraft at FL200. This differs from our traditional assumtion that, using 30ft/mb, the first aircraft would only be 600ft lower.

If we then use this example in an ATC coordination scenario, we may find that ATC would agree for an aircraft not to be below 21600ft RPS to ensure standard separation against traffic at FL200. Under the 30ft/mb assumption this would be OK as 21600ft would equate to 21000ft 1013.2mbs. However, taking into account the 36.25ft/mb accurate equation, in this particular circumstance the aircraft on RPS would actually be at the equivalent of 20 875 ft 1013.2 mbs thus creating actual separation between the 2 aircraft of 875ft. This, in ATC separation parlance, is not enough.

If we take the argument up to the 35000ft territory and are in airspace where the temperature bit of ISA is significantly different from the assumed, then the problem gets significantly more acute.

[CAP670]

....the CAA limit on the distance at which controllers can provide a radar service without holding an Area Radar rating.

DFC - not so any longer!

For at least two years now, the only restriction on the maximum range that a civil radar service can be provided using an Approach Radar ticket is radar coverage, adjacent airspace arrangements and the procedures written into the unit's MATS Part 2 ('Controllers' Order Book').

On the subject of QNH vs QFE, why would Brit mil aircrew 'want it' when US mil & Canadian mil appear to be able to function without???

Surely, if you fly an SRA you're given the threshold elevation and advisory altitudes i.e. QNH-based check altitudes, if you fly an ILS you simply follow the glidepath and the approach plate will give you check heights (altitudes) at the FAF and in tabulated form against ranges from touchdown, and if you fly a PAR you just do what the nice talkdown controller tells you to do over the earphones.

As for publishing a CTR with an upper limit defined as an altitude of 3500' when the TA is 3000', or an AIAA with an upper limit of altitude 5000', (note: altitude and so based on QNH) this really is a load of complete and utter bo:mad:s; next time I'm near the Brize CTR I'll ask Zone for the QNE...

:\ :\

[bookworm]

The calculations below show actual feet/mb for various altitudes assuming ISA:

Zero ft 30 ft per mb
5000 ft 30 ft per mb
10000 ft 31.45 ft per mb
20000 ft 36.25 ft per mb
30000 ft 40.84 ft per mb
40000 ft 47.84 ft per mb
50000 ft 52.75 ft per mb
60000 ft 62.96 ft per mb

What is your source for these numbers, or the basis of your calculations, please, WBS?

[Whipping Boy's SATCO]

bookworm, I cannot put my hands on the source of the table, i will keep looking. In the meantime, the attached make interesting reading.


http://www.auf.asn.au/meteorology/section1a.html

http://www.auf.asn.au/groundschool/umodule3.html

[bookworm]

WBS

I'm confused by your table of numbers. If you're attempting to work out the change in level corresponding to a change in pressure as a function of level in the ISA, then they're incorrect.

The variation is much higher -- some approximate numbers are shown in the pressure gradient (http://www.auf.asn.au/meteorology/section1a.html#pressure_gradient) section of the reference you quoted. Even those are broad averages.

I previously used 100 ft/mbar in the mid-300s, which comes from the knowledge that the 250 mbar level is conventionally FL340, and the 200 mbar level is conventionally FL390, so that's an average of 100 ft/mbar.

Maybe you're using the average gradient between sea level and the level indicated?

If that's what the numbers are meant to be, then I can only reiterate that it's not relevant, for the reasons that I've tried to set out.

If I try to put it another way, you need to realise that changing the altimeter setting by 1 mbar is not the same as moving the aircraft up or down by one mbar of pressure in the atmosphere. When you change the altimeter setting, you shift the reference level, at which the altimeter would read zero.

So in your example, your aircraft at 20,000 ft on the RPS of 1033 is 20,000 ft above the 1033 mbar level. Your aircraft at FL200 is 20,000 ft above the 1013 mbar level. The vertical distance between them is therefore the level difference between the 1033 mbar level and the 1013 mbar level, and that's about 20 mbar x 30 ft/mbar = 600 ft because the 1033 mbar level and the 1013 mbar level are both close to sea level.

If you were to measure the actual pressure outside the FL200 aircraft, it would be about 435 mbar. If you were to measure the actual pressure outside the 20,000 ft on 1033 aircraft, it would be about 446 mbar. There would only be 11 mbar difference in pressure between them, even though their altimeter settings are 20 mbar apart.

[A good headin]

HD says <Now you can bet some loony will ask how military controllers can use 500 ft vertical inside a civil control zone!!!! Tee hee!!>

Looks like HD has shown a typical civil controllers lack of understanding of the military task.

Shame, so I'll throw my tuppence worth in and say we use RVS in 'CTZs' because our limited airspace requires such controlling skills. Indeed, we are good enough to wheel and deal OAT/GA traffic in very limited space, we have too. We do seek the civil pilots permission to apply RVS and if they are happy they get a good view of a fast jet and the pleasure of flying on QFE too!!


I will also go further and say that unlike HD's 'routine' job as a LHR Director, where evreything either comes off BOV,BPK,BIG or LAM and does the same thing day in day out. The Mil Controller has to cope with a far more dynamic, fast moving,unpredictable traffic flow from all points of the compass, with conflictors and the odd lack of SSR day. I would like HD to try recovering 13 Tornados (pattern speed of Concorde, remember?) with a number of emergencies, fuel priorities and the weather going downhill quickly in limited airspace. Throw a few transits in the way and 500' RVS is a luxury that Mil Controllers need to achieve their task.

Hope this loon has answered the question.



:O

[Chilli Monster]

With arrogance like that prevalent thank god they don't get civil licences automatically!

[DFC]

Ah yes Northolt is absolutely awash with fast jets arriving unanounced from all directions with fuel emergencies! :D

As for using 500ft separation in places other than Heathrow Zone - simple - because JSP whatever says it can be done.

However just because it says it can be done does not make it safe. If 500ft separation was safe in civil operations we would have double the capacity in the airways!

Similarly one has to question the safety of the altimeter setting procedures in current use.

Regards,

DFC

[Canary Boy]

:{ Let's not allow a good bit of banter to cloud the issue. Mil pilots want to fly on QFE in the vicinity of the aerodrome. As mentioned earlier QNH was tried (posed no problems to ATC) but the aircrew didn't like it. If the primary customer is using QFE, it makes sense to me that all traffic likely to mix it should also use QFE. Procedures are very clear cut, well tried and tested and all Mil controllers are fantastic at sums! (I should know ;) )
Whilst A Good Headin might have gone a tad OTT, his/her sentiment is not a million miles wide of the mark - in very busy, constantly changing scenarios, the procedures really do work! :8

[fly bhoy]

AGH says <where evreything either comes off BOV,BPK,BIG or LAM>

Looks like AGH has shown a typical military controllers lack of understanding of the civil task.

Surely they all come off either BOV, OCK, BIG or LAM?!? Much harder i'm sure!!;) :ok:

FB:ok:

[fireflybob]

Having spent circa 2,000 hrs in the back of the simulator, training and checking, and having seen both QFE and QNH ops I know which I prefer - definitely QNH - as has been said by Chilli Monster the number of missed approaches I have seen where QFE is used and we get an alt bust due to not/late setting of QNH.

Stateside they dont even call it QNH - its THE altimeter setting.

Lastly, reminds of going into Crete on a nice weather day and we were about number three in the visual approach "queue" to join right base RW 27. The Greek ATCO was working like a one armed paper hanger with arrival and departure tracks the same and much traffic - no radar, all separation based on DME. In the middle of all the RT chat Danair who had been cleared for a visual asks for the QFE - the controller replies in rather exasperated voice "Danair, the QFE is 3 millibars less than the QNH!" - I could hardly control my laughter - you had to be there to appreciate it!

[A good headin]

I do enjoy a bit of banter with civvy controllers and they usually get me back when they flash their pay chits at the end of the month. CB sums up the original question/answer nicely,thnks. Feel free to abuse me with your paychits as the end of the month is upon us! :ok:

[Last call for Mr..]

Lord Sven, Thank you for some sanity amongst all this blah. This country is not Canada or the Ukraine, or even Holland where you could land with a negative value on your QNH set altimeter. The Military choose to use QFE for recovery and the Civvies QNH. There is no need for a review, because we are all able to do maths or we wouldn't be in the jobs we are. Bookworm, you are quite correct. Move on!!!!!!:{ :{ :{ :{

Oh yeah, and lets not get onto the subject of Millibars, Inches, Metres and Feet!:\\ :uhoh: :{ :ugh:

[Canary Boy]

:hmm: Just a thought - of the replies posted from aircrew - how many are military?