Shallow Fog - Approach Ban

[ATRflyer]

Hi all,

Just wondering if anyone can help me out with this question. If there is a very shallow layer of fog over part of the runway and the airport is giving RVRs below CAT I minima; can anyone confirm that the approach ban does still apply, even if an aircraft were to call runway in sight early on in the CAT I ILS approach?

E.g. An aircraft 20 miles out can clearly see the runway threshold, all the approach lighting and the majority of the area around the airport, and calls visual. The aircraft is then cleared for a visual approach by ATC. Just want to confirm that the approach ban does still apply requiring at least CAT I minima (i.e. 550m in the touchdown zone); or is the minimum required touchdown zone RVR now 800m, since the aircraft called 'visual' early on in the ILS approach?

I presume the approach ban would still apply as RVR is always the main thing taken into account. Obviously you would either not commence an approach, or if you did; make a go-around at the outer marker unless the RVRs improved prior to reaching it. I am a little unsure though as to whether the minimum required touchdown zone RVR, in this example, would be 550m or 800m?

Many thanks,
All the best,

Atrflyer

[Farty Flaps]

If the rvr is as reported then lvp is in force. Therefore the option of a visual approach does not apply. Furthermore as you descend through decision you may find your vis not usable.
This was the case in man on sun Night. as we approached we could see the runway from 40 miles and clearly all the way to about 200 feet. Then it all went blurry. Hope this helps.

The preamble for lvp in your part A for cat 3 landings should include a section on the structure of fog which may expand on the reasons for this

[AirRabbit]

Hey ATRflyer:

I can only speak for the US. Under 14CFR part 91 rules (Takeoff and Landing under instrument flight rules), if the pilot has been cleared for an “IFR” approach, a CAT I ILS in this case, only the ATC controller can issue a clearance for a “visual approach.” There has to be sufficient visibility from the tower controller’s perspective for that to occur. As long as the runway of intended landing is, as in your example, reported to be “RVR below CAT I minima,” I don’t believe there is any way that ATC is going to clear the pilot for “a visual approach” regardless of what the pilot says is "visible." Of course the pilot may ask for and may be cleared for a “visual approach” to land on an alternate runway – but only IF the prevailing visibility at the airport would allow it and the visibility on the alternate runway is at or above “VFR” minimums. In your example case, I don’t think the controller would agree to this because the prevailing visibility probably doesn’t exist to issue such a clearance.

If the pilot, in your example, continues the ILS approach, on the IFR clearance issued, s/he would be legal to go all the way down final approach to decision height and determine if the requirements to go below DH are present. Those requirements are 1) the aircraft is continuously in a position from which a descent to a landing on the intended runway can be made a normal rate of descent using normal maneuvers (and if operating under part 121 or part 135) that descent rate will allow touchdown to occur with the touchdown zone of the runway of intended landing; 2) the flight visibility is not less than the visibility prescribed in the standard instrument approach being used, AND 3) at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot: a) the approach light system, except that the pilot may not descend below 100 feet above the touchdown zone elevation using the approach lights as a reference unless the red terminating bars or the red side row bars are also distinctly visible and identifiable; b) the threshold; c) the threshold markings; d) the threshold lights; e) the runway end identifier lights; f) the visual approach slope indicator; g) the touchdown zone or touchdown zone markings; h) the touchdown zone lights; i) the runway or runway markings; or j) the runway lights.

If these requirements cannot be met, the pilot is obligated to miss the approach.

Hope this helps you.

_______
AirRabbit

[JustaFew]

A few years ago, I was a witness for a case in which the exact scenario you described occurred. The commander was found guilty, given an absolute discharge, and fined £500 with costs.
Answer your question?

The case happened in England, Ireland may or may not be different.

[Dan Winterland]

Under JARs, if the RVR is below minima, an approach ban is in force.

Visibility in fog is all about slant visual range. You may see the lights on the approach down to very low levels - below DA/H is not a problem. But when you flare and start looking through the fog, the lights disappear. It's happened to me and it's scary!

[singleseater]

If wx reported below the applicable approach minima, then a visual approach is not available. Any request for same should be denied.

[Hudson Bay]

Any approach made when the RVR is below Cat 1 minima is automatically reported to the CAA. It follows that you will be investigated!

[Captain Stable]

Sorry, Hudson Bay, that is not correct.

Firstly, such approaches are not "automatically" reported. Secondly, since the ATR is a Cat II-capable aircraft, it would look just a little silly to report the crew for carrying out something they are entitled to perform...

[ATRflyer]

Hi all,

Thanks very much for all your input. Just one final question regarding that JAR OPS requirement of Min RVR 800m for a visual approach. I presume this comes into play as soon as an aircraft operating on an IFR flight plan requests a visual approach?

Thanks again,
Atrflyer

[HEATHROW DIRECTOR]

ATRFlyer. Presumably this in the a/c ops manual? Unless the rules have changed quite recently, ATC cannot refuse a visual approach purely on the grounds of low RVR . The cloud base is the only criteria mentioned plus the ability of the pilot to complete the approach with visual reference.

[spekesoftly]

UK ATC will inform pilots when the RVR is below the 'Absolute Minima' for a visual approach. Should a pilot still elect to continue, ATC are required to report the facts, having advised the pilot accordingly.

ATC don't normally impose Wx related 'Approach Bans'. They do give pilots the facts, and are sometimes obliged by the regulations to warn pilots, on the R/T, of the consequences of continuing a particular action.

[HEATHROW DIRECTOR]

<<UK ATC will inform pilots when the RVR is below the 'Absolute Minima' for a visual approach.>>

Where does that that appears in any documentation? So far as I can see the "Absolute Minima" procedure refers only to instrument approaches and does not mention visual approaches. Therefore, once an aircraft passes 1000ft if the measured RVR drops below his minima but he reports that he has the runway in sight and can continue visually ATC a) has no option but to approve and b) there is no procedure for filing a report.

(Not trying to be awkward but this is an interesting discussion).

[spekesoftly]

Have a look at ATSIN No.19 (http://www.caa.co.uk/docs/33/ATS019.pdf). Scroll down to the Attachment - 'Calculation of Absolute Minima', para 6 - 'Visual Approaches'.

"A value of 800 metres RVR shall be used at all airports as the Absolute Minimum for visual approaches"

[HEATHROW DIRECTOR]

OK spekesoftly.... humble apologies. Now found it!

[ATRflyer]

Thanks for that Heathrow Director and spekesoftly.

Regards,
Atrflyer

[Hudson Bay]

Captain Stable I am not wrong!! You may have mis-understood me but I am not wrong! I will try to explain.

If a particular runway is designated CAT 1 and lets say the RVR is calculated at 550 metres (as published in the AIP which is the same as what is published in the Aerad plates) this RVR is known as "absolute minima" If the RVR is below 550 and an aircraft now commences an approach, after an initial warning ATC will pass the following message

" (Callsign) If you continue the approach and descend below 1000ft above aerodrome level, It is believed that you will be contravening UK legislation and I shall be required to report the facts, acknowledge".

No landing clearance will be given, only advice on traffic and wx conditions.

This absolute minima applies to any approach whether it be visual or instrument.

To conclude, if you pass 1000ft and the RVR reported is below the absolute minima for that runway you will be reported for breaking the law.

[HEATHROW DIRECTOR]

Hudlson Bay... I know what you're getting at but the confusion arose because your earlier statement: "Any approach made when the RVR is below Cat 1 minima is automatically reported to the CAA" is patently wrong!! Otherwise, how would thousands of Cat II and Cat III approaches be made?

[Hudson Bay]

OK HD I take your point. I was a bit brief in the first post!

Just to clear up another point from singleseater, ATC are NOT permitted to stop an aircraft making an approach due weather. They can for traffic reasons but they are not responsible for making sure minima is complied with. They just advise and report if the minima is broken. The decision to make an approach in specific weather conditions rests solely with the pilot whether it be legal or not.

[Max Angle]

My understanding (and that of our CAA approved ops. manual) is that:

You may commence an approach regardless of the reported RVR but may not continue beyond the OM or equivalent position unless if the RVR is below minima. ie. approach ban.

Once past the OM if the RVR falls below minima the approach may be continued to MDA/DA/DH and IF required visual reference is established and maintained at that point you can land perfectly legally.

So basically once past the OM it's up to the commander and if you are visual at DH/DA you can land quite legally, a report may very well have to be filed but there is no proof that visual reference was not obtained and that the landing was illegal. If you were in a 2/3 crew aircraft you may well get reported, quite rightly, by the other crew members but they and you are the only ones who really know.

The situation is no different from ANY instrument approach, the tower may well be reporting a value much higher than minimum but due to the uneven nature of fog patches you may not see the runway at DA/DH so you go around. If you continue below DA and land you would have broken the law regardless of the reported vis.

In short, landing with reported vis. below the minima for the approach is NOT illegal, landing without the required visual reference at DA/DH most certainly is.

Our manual also has a note saying that visual approaches may not be conducted with the RVR less than 800m so in answer to orginal question my opinion is that if the reported RVR is less than 800m you can't start a visual approach. It is grey area though because once you have started one (inside OM?, what measure do we use? it's a visual after all) and the RVR falls below 800m what do you do?, if you can "maintain visual reference" there is no difference between that and the visual segment following an SRA or NDB that might terminate some way out at say 800ft. If you loose visual reference in either case you have to go-around and you could be well below MDA or DH when you do.

Anyone care to comment, can't find anything in my documents and manuals that covers it.

[cdb]

I agree with Max Angle, except that my (ATC) instructions don't refer to any outer marker, but to a height of 1000' above aerodrome level as Hudson Bay says.

[Spitoon]

I can't help thinking that the Absolute Minima thing is a red herring and simply confusing the issue. Absolute minima are an ATC thing and have no bearing on how
a pilot operates an aircraft. The absolute minimum is supposed to be the lowest minimum that any pilot can ever calculate, therefore it may be lower than the minimum in a particular Ops Manual or AIP plate. The idea is that if a pilot has calculated a minimum below the absolute minimum then he or she has made a mistake and ATC pass the message as a prompt to encourage the pilot to check that the minimum has been correctly calculated. The absolute minima procedure/message is not followed if Cat II/III approaches are available - usually indicated by LVPs being declared in force.

As to the original question, to me as a simple controller, it's all very straightforward. If the visibility at the time the approach is being made is at or above the minimum set out in the pilot's Ops Manual for a Cat I approach then the approach can be made. It really doesn't matter what's going on on the ground - LVPs or whatever. OK, I know there are some variables like whether the flight is operating to JAR-OPS and there's now this thing about the OM or equivalent position but as a controller I don't worry about them. Then there's some legislation about the approach ban that applies to all aircraft in the UK and UK registered aircraft wherever they are just to make the situation even more complex.

All this is only valid for the UK of course. And I don't think any other country has introduced anything as daft as the absolute minima procedure for ATC!

[ManaAdaSystem]

I agree with Max Angle, but if I remember correctly there are two countries in Europe where you cannot continue (even if you are) below 1000 AGL if reported RVR falls below minima. UK and Germany.

Or it used to be, maybe things have changed?

[keithl]

I'm familiar with the "Outer Marker or equivalent position" wording, but there are now so few Markers and no clarity about what an "equivalent position" is. Furthermore, the "Approach Ban" AIC only refers to "1000' aal".
As a result we now use 1000' aal and ignore all reference to Markers and "equivalent positions".
Any comments on that?

[Empty Cruise]

keithl,

Well, normally, the marker is used for GS check or as FAF - so the "equivalent position" would be your DME range used for that purpose.

The advantage of using that position (operationally speaking) - is that it's a position already in use - if you've done your GS check, you continue, if GS check not performed yet, you discontinue the approach. So simple even uncle Empty can do it :O

If you choose to operate using 1000 ft. AAL - you have to figure outr a new altitude on the altimeter - altough I don't know if some operators performed their "stabilised approach´-cut-off at 1000 ft. AAL - most use either 1000 ft. RadAlt or baro minima +1000 ft. (to keep it simple). If your operator uses 1000 AAL for that purpose, well, might as well use that...

But - you delay your cut-off point (at most airports), thereby increasing the chance that you'll have to discontinue the approach i.s.o. going down to DA/H to take a look ;) - especially relevant in the circumstances described above.

To remain on thread - if you are carrying out an approach (JAR-OPS 1 operators, that is) and the RVR drops below approach minima (visual or otherwise) - your ops manual will prohibit you from continuing the approach. ATC (and through them, possibly, the CAA) will only be a circumstantial factor.

I think the reason why people focus on the ATC bit is that it seems much more powerfull when somebody speaks the words "You can't do that!" as opposed to knowing that the same words are written by your DFO in a book somewhere in the ships library :(

My 2 eurocents worth - brgds fm
Empty

[brain fade]

RVR passed after the 4 miles point are advisory only. At least in the UK.

I know this as I am just back from the sim and this point featured several times.

[wiggy]

Guys
At the risk of sounding a bit like "it's God here" can we be a bit less authoritative about what "we" do in the UK - I suspect some of what "we" do is governed by Company Ops manuals.

FWIW, in the UK, for precision approaches my operator uses 1000' agl as the control height ( no mention of 4 miles/ markers), and RVR deterioration or improvements after passing that point must be ignored.......( so if it drops below minima you do not have to go around.

Standing by to be flamed.........

[BizJetJock]

Heathrow Director,
To pick up on one of your earlier points, all landings below Cat 1 minima are reported to the CAA, who then wade through them checking against the list of approved Cat II/III operators.
A friend of mine had an interesting time a few years back when the CAA reported him to the FAA for landing below minima, because they didn't check which runway at LHR he had landed on. The "in use" runway was below 550m, but the departure runway was above and ATC were quite happy for him to approach and land on that. Sadly all that the CAA picked up on was that the landing runway was below minima. Wonderful people:mad:

[HEATHROW DIRECTOR]

<<To pick up on one of your earlier points, all landings below Cat 1 minima are reported to the CAA,>>

OK BizJetJock, perhaps you can tell me how it's done. Having worked as a Heathrow controller most of my life I have to say that I was not aware such action was taken. Just the number of Cat II and Cat III landings which take place at Heathrow and other large airports during bad weather suggests that the paperwork involved would be mountainous.

With the usual proviso that things might have changed since I retired, I am not aware of any ATC involvement in such arrangements - we would have been too busy! At this time of the year Heathrow is below Cat 1 quite frequently and hundreds upon hundreds of flights operate below Cat 1.

[BizJetJock]

Hi Heathrow Director,
Whilst not having any direct knowledge of the system, I would guess that since there is a record of all landings (for BAA to charge their ever so tiny fees!) and presumably a log of the RVR's then it is relatively easy for BAA to have a clerk or a computer correlate these and send them off. This would not require any action by the controllers, and would also explain how my friend came to be pulled up because a clerk/computer assumed that all landings took place on the "landing" runway:rolleyes:

[MANTHRUST]

Back to the original post, the question of patchy shallow fog should be considered on a practical basis.
I`ve landed at LGW on 26R with reported RVRs below minima for CAT 1 ILS to 26L. On landing the fog was very low and very patchy, had 26L been in use LVP`s would have been in force.
Why ban approaches in such a scenario just because the auto RVR meter indicates a low value! why can`t the tower controller be given some discretion.
In the USA the rules are even tighter, you may continue passed the marker but if at decision height the RVR is below limits you must go around what`s happened to common sense here?
Fog is often patchy and the best person to decide if a landing can be safely achieved is the Captain at decision height.
( Airbus may beg to differ)

[Spitoon]

To pick up on one of your earlier points, all landings below Cat 1 minima are reported to the CAA Not strictly true as I recall. It was all landings carried out whilst RVRs were reported (commonly in vis conditions <1500m). It was something that the airport authority had to do so at a big airport like LHR ATC may not have had any active involvement beyond recording the RVR (which they would probably do anyway).

But it hasn't been done for several years to my knowledge.


[Edit below]
And another thing, MANTHRUST, the reason that the rigid rules are in place in some parts of the world today is because when pilots were allowed to make the judgement they go it wrong more often than the authorities - and the passengers - could tolerate.

[HEATHROW DIRECTOR]

<<LHR ATC may not have had any active involvement beyond recording the RVR (which they would probably do anyway). >>

Yet again I have to hope that somebody in current practice can help, but during my time at Heathrow ATC certainly did not record the IRVR and I'm sure it wasn't automaticallly recorded. Heck, it would change by the second, let alone the minute!

[Spitoon]

Sorry, HD, but I'm pretty sure that the AGI IRVR system records data that it measures. And, yes, there can be loads of it! At the likes of LHR I guess this would all be within the ATE's domain.

[HEATHROW DIRECTOR]

OK many thanks Spitoon.. I learn something new every day!

[spekesoftly]

It's always been my understanding that IRVR readings are automatically recorded. It was once explained to me, many moons ago, that this is a CAA requirement, and that the data had to be available for cross-checking by their 'AWOPS Department', should they so desire.


I'm pretty sure that the AGI IRVR system records data that it measures

Yes, the AGIVIS 2000 website confirms this:-

"The information is also entered onto a magnetic cartridge recorder and page printer for archiving and legal record purposes."

[alf5071h]

MANTHRUST, “Why ban approaches in such a scenario just because the auto RVR meter indicates a low value!”
”Fog is often patchy and the best person to decide if a landing can be safely achieved is the Captain at decision height."

The reasons against change are because the scenarios are unpredictable, often with misleading visual cues. Furthermore human judgement is often flawed or the perceptual system confused. The RVR system was developed to overcome disparities in visibility measurement; I flew on many of the flight trials in various fog conditions. By far the most challenging were the periods of fog formation or dispersal, most often associated with Cat 1 becoming Cat 2, or Cat 3 improving to Cat 2.

When ‘shallow’ fog forms there are successive periods of layering and subduction; each layer associated with different visual ranges, vertical extent, water content, etc. The conventional view of shallow fog is a single layer, thus over flying at height you can see down through it to the runway, but during an approach the visibility reduces as the aircraft enters the layer. This effect alone has cause many accidents.

In reality a shallow fog layer may have many layers and the visual effects are similar to entering and exiting many stratus layers, which alternately reduce and brighten the approach lights and have similar effect on the slant visual range. Thus, the far point of visibility can oscillate towards or away from you; it is very disconcerting.

When fog begins to clear, often from a stable homogeneous deep layer (that is why Cat 3 conditions are more predictable), the clearance pattern is similar to the formation of small cumulus clouds. Even where the sun burns through the fog some areas remain thick and dense with greatly reduced visibilities. Flying through these ‘cumulus’ causes rapid changes in visual range, approach light intensity, and ambient light level.

Don’t mess with the unstable periods of fog formation or dispersal. Cat 2 (RVR) is one operation where you can make a valid decision to land and then find that you are wrong before you get to the threshold.
--------------------
Unless specifically authorized everything else is forbidden.

[jonathang]

Hudson Bay

If a particular runway is designated CAT 1 and lets say the RVR is calculated at 550 metres (as published in the AIP which is the same as what is published in the Aerad plates) this RVR is known as "absolute minima" If the RVR is below 550 and an aircraft now commences an approach, after an initial warning ATC will pass the following message

" (Callsign) If you continue the approach and descend below 1000ft above aerodrome level, It is believed that you will be contravening UK legislation and I shall be required to report the facts, acknowledge".

No landing clearance will be given, only advice on traffic and wx conditions.

This absolute minima applies to any approach whether it be visual or instrument.

To conclude, if you pass 1000ft and the RVR reported is below the absolute minima for that runway you will be reported for breaking the law.


Would this approach ban speech be given if the RVR dropped below minima once established on the approach but before the 1000ft AGL check?

After passing 1000ft AGL if the RVR dropped below minima and the pilot continued to DA/MDA made visual contact. Would you still refuse the clearance to land and if so what RT phraseology would be used to indicate that it is safe to land?

My understanding was we could continue to land after passing 1000ft AGL assuming adequate visual reference is maintained at DA/MDA?


Thank You,

Johnny

[THICKO]

Hi Wiggy,

>>FWIW, in the UK, for precision approaches my operator uses 1000' agl as the control height ( no mention of 4 miles/ markers), and RVR deterioration or improvements after passing that point must be ignored.......( so if it drops below minima you do not have to go around.<<

My operators Ops Manual only refers to RVR deteriororations at/after the relevant point (usually 1000' AGL) It doesn't really make sense (practically or commercially) to ignore improvements after that point.

Cheers,

THICKO

[wiggy]

Hi Thicko

I take your point , but as far as "my" ops manual is concerned RVRs passed below 1000' are ignored, and since that's what the boss says......( I guess it's to prevent "a can we, can't we?" conversation at not a lot of feet if you get a subsequent equipment malfunction)
Rgds

[HEATHROW DIRECTOR]

Just a thought... all this talk about the 1,000 ft "point"... I presume that this has all come in during the last 2-3 years? I worked at Heathrow thousands of times in LVPs and I've seen hundreds of aircraft carrry out missed approaches from below 1,000 ft (and well inside 4 miles) when the RVR has dropped below their minima. Just recently I was told about the pilot of a large private jet asking ATC if he could "have a go" even though the RVR was below his minima. The controller, having already obtained the pilots' minima, emphatically responded with the RVR reading. The response was "roger" and the aircraft continued holding...

Surely, the various rules regarding starting or continuing approaches in poor visibility are framed with safety in mind? It would be a great shame if, under commercial presure, things went back to the "old days" when people were regularly "having a go".. and occasionally ending up strewn down the runway. If the final decision is left to the captain and not based on the RVR system there must always be the temptation to descend that little bit further...........

[wiggy]

The "1000' point" is not new with our lot, it goes back at least 15 years ( Major UK/LHR operator).

[Hudson Bay]

I'm not sure what we are debating any more!

I think it is very clear what the regulations are.

If an aircraft continues past the 1000 ft point when the RVR is below the absolute minima for that runway he WILL be reported and action will be taken for a breach of law. It does not matter how capable your aircraft is, whether it be Cat 1, Cat 2, Cat 3.........

If the RVR falls below the required amount after the aircraft passes the 1000ft point a clearance to land will still be issued.

No clearance will be issued if the RVR is below the absolute minima when the aircraft is before the 1000ft point.

As for the wording of the controller if an aircraft continues, only traffic information and wind direction and speed will be passed.

[spekesoftly]

If an aircraft continues past the 1000 ft point when the RVR is below the absolute minima for that runway he WILL be reported and action will be taken for a breach of law. It does not matter how capable your aircraft is, whether it be Cat 1, Cat 2, Cat 3.........

There are no UK CAA published 'Absolute Minima' for CAT II/III approaches.

[jonathang]

Thanks Hudson Bay,

That concurs with my understanding.

With the ANO only in consideration the rules are very clear. Once you take JAR OPS into consideration, opens up grey areas.

Cheers

[Hudson Bay]

Spekesoftly.

I don't think you understand.

Absolute minima has nothing to do with Cat 1, Cat 2 etc. Absolute minima is connected to the landing runway. Each runway in the UK has an absolute minima. As controllers you should know what that minima is for your landing runway. If an aircraft passes the 1000 ft point when the RVR is below the absolute minima it is your duty to report this to the CAA.

eg. The absolute minima for 06R at MAN is 550 metres. If an aircraft passes the 1000 ft point when the RVR is 500 metres, he WILL be reported. Simple and clear. No landing clearance will be issued, only the advice mentioned above.

[bookworm]

Absolute minima has nothing to do with Cat 1, Cat 2 etc. Absolute minima is connected to the landing runway. Each runway in the UK has an absolute minima. As controllers you should know what that minima is for your landing runway. If an aircraft passes the 1000 ft point when the RVR is below the absolute minima it is your duty to report this to the CAA.

This directly contradicts the advice to ATC in ATSIN no 19, which says:

There is no requirement to calculate Absolute Minima for Category II/III approaches, nor to pass a warning to pilots conducting such approaches, for which specific procedures for use by the flight crew will have been approved.

[spekesoftly]

Hudson Bay,

I don't think you understand.

A runway may have a number of different Absolute Minima RVR values, for different approaches - Cat1 ILS, NDB, SRA etc. (In the case you mention, the Absolute Minima RVR value for a Visual Approach to RW 06R at MAN is 800 metres, for example. Should a pilot attempt a visual approach when the RVR is less than 800m, then ATC are required to WARN, using precisely worded phraseology, and if ignored, to subsequently REPORT the facts.

However, the 'ATC Absolute Minima Procedure' does not apply to CAT II/III Approaches, as bookworm's quote from a CAA document clearly states.

Please have another look at the LINK (http://www.caa.co.uk/docs/33/ATS019.pdf) I posted earlier.

[Captain Stable]

Hudson Bay, can you come up with any JAR OPS or MATS references for your contentions?

[Hudson Bay]

Sorry Spekesoftly you are incorrect. I think you may have to read a little more.

AIC 7/25 (Pink 79)

"Each ATC unit has calculated the minimum RVR values, for EACH TYPE OF INSTRUMENT APPROACH available at that airfield, below which pilots should not continue an instrument approach below 1000ft above aerodrome level"

No exemptions except those granted by the CAA to airlines that do not have to comply with the 1000ft barrier.

Does anybody know which airlines do not have to comply with this 1000ft barrier?

[brimstone]

H B - The AIC doesn't say "airlines", it says "flights". This presumably means particular flights maybe military, which are perhaps concerned with security, national emergency or whatever and which are granted exemption on a one-off basis. Don't really know.

You really are wrong in your interpretation of Absolute Minima but I don't blame you. The AIC if read in isolation would lead to any reasonable person drawing the conclusion which you have. It really needs to be read in association with the Supplementary Instruction in the MATS Part 1 which details the ATC procedure referred to in the Pink AIC.

Just to quote a bit of it "Operators who are approved to make Cat II or III approaches are required to undergo specific approval for their operations. It has been decided that the passing of minima, as detailed in this SI, will not apply to Cat II or III approaches. However the procedure will be applied when the performance of an ILS is downgraded and it is capable of providing only Cat I guidance or localiser only approaches."

Just re-read the SI and it says that "Military flights, including those operating as General Air Traffic are excluded from this procedure".

[Hudson Bay]

Ok. It says flights not Airlines.

I am not privy to the SI in the MATS so I cannot comment on that. I do have access to my company manuals and AIC's and I know what they state and that is where my information comes from.

I guess in all walks of life their are always different takes on issues such as this.

[javelin]

Specific example.

We returned to BHX last year, at night. Now the location of their IRVR detectors is awful - just to the right of 15, in a dip, first to catch the fog.

We saw the airfield from 20 miles out, they were giving RVR's below Cat 1, rwy 15 in use, centre line lights out due work in progress.

We are Cat 3 but now can't conduct Cat 3 landing because of no centre line lights.

Decide to continue until the 4 mile point (our approach limit for RVR) then enter the hold if below Cat 1.

It was, we held. Other operators were making autolands, their ops manuals may have been different.

ATC asked us to go up a thousand to let someone take off from 33, our cunning plan was hatched ! 33 was localiser only, 900m RVR from memory was needed, we asked for immediate vectors for 33 as we knew the RVR would improve. It did but was dropping fast as we approached 4 miles, we were above Cat 1 RVR at 4 miles ( never lost sight of the runway throughout), then it dropped below, he asked for our intentions, we said continue.

The controller then came out with a whole long statement about being below state minima and there were no known obstructions to prevent our landing - we landed.

We queried the statement as we taxied in and he said it was for the tape recorder and was to protect the controller in the event of an incident.

To conclude - we landed when the RVR was below the minima for the runway, however we had crossed our 4 mile mark and were entitled to continue to our MDA which we did. We never lost sight of the runway so we were legal - complicated isn't it ;)

[Hudson Bay]

brimstone

I thought these procedures were brought in because of General Aviation traffic breaking the rules in the first place. Can't see why the rules don't apply to them.

Javelin

You make a good point and it illustrate's the differences in what is written in company manuals.

Our company allows us to designate any point down the approach as long as it is before the 1000 ft point.

[spekesoftly]

Hudson Bay,

I thought these procedures were brought in because of General Aviation traffic breaking the rules in the first place. Can't see why the rules don't apply to them.

Understandably perhaps, I suggest you are confusing the generic term 'General Aviation', with 'General Air Traffic' (GAT) - which has a specific (AIP) definition. (more reading required!)

The existing legislation does apply to both Public Transport and civil non Public Transport flights.

It does not apply to Military Flights, be they operating as GAT or OAT (Operational Air Traffic).

[Empty Cruise]

Watsyors,

The FAF/FAP is not a JAR-OPS requirement.

The term used is "....outer marker (or equivalent position) If no such position exists, the decision to continue or discontinue the approach shall be made before passing 1000 ft. AAL".

So - using the FAP (9 miles/3000 ft. in some cases) as the cutoff could leave you between the FAP and the OM equivalent position (most often the DME GS check) with RVRs below required approach minima - and thinking that you were allowed to continue. Not adviseable, in my humble opinion.

...but always willing to be proved wrong :ok:

Brgds
Empty

[Hudson Bay]

Ok guys lets not point score here.

Never heard the term General Air Traffic and I've been flying for over 20 years. I assumed and gave you the benifit of the doubt that you meant General Aviation.

My guess is that General Air Traffic is what it says. Just that. Maybe you could tell all? Is it an ATC term?

As for absolute minima, it would never affect the majority of flight deck as they never go below minima anyway.

[keithl]

Hudson, try this (http://www.eurocontrol.int/mil/public/standard_page/hogi.html) Its not an AIP reference, but it does indicate the difference between OAT and GAT.

Furthermore, I confim Empty Cruise's statement that FAF/FAP is not a JAR requirement.

Furthermore, the appropriate AIC (latest 7/2005) only refers to 1000ft Above Aerodrome Level. No reference to Markers, Fixes or anything else. That AIC also contains the full required spiel as reported by Javelin.

[Captain Stable]

On a point of order that 1000ft is QNH l assume ?Not at Denver, Colorado Springs, Telluride, Nairobi or a few hundred other places I could name. The references to the 1,000 ft point are above the threshold of the landing runway.

[Bumz_Rush]

We operate gulfstream aircraft in Russia, and almost all approach procedures are based on QFE.

We are a JAR charter operation.

There is almost no JAR guidance in the check list or operations manual for QFE operations, apart from the Glf operating manual, and QRH. Howver these are biased towards an 18000ft TL, and not 3000 ft as we are often using.

So we change all the height references in the FMS from QNH to QFE, and fly with the inputted data.

Remember we are given levels and heights in Metres...

The radar vector to GS intercept is often 1000ft AGL.....

Fun is not the word I used last night...

Bumz

[Captain Stable]

You don't need to operate on QFE to know where the 1000' point is.

For example, when making an approach to Bristol, it is @ 1622' MSL.

I hope this makes things clear for you.

[ssg]

Interesting topic...

Part 91 Corporate in the US seems a little easier...

I can shoot the ILS no matter what is reported.
At 200 feet, I need to be able to see the lights and then...
at 100 feet I need to be able to see the 'runway environent'

While the regs are not subject to interpretation, to shoot approaches to say 100 indef and 600 RVR it comes down to 'what the pilot saw' if you make it in. :)

-SSG

There are those who can, and those who bitch about those who can.

[alf5071h]

ssg That was the case in UK / Europe several years ago (general aviation).

Those who thought they could, but couldn’t, and did, crashed. Thus, new regulations were introduced to provide constrains on those who thought they could, but now they cannot . . . legally.

[keithl]

Wotsyors:
well, if you know a jaa operator working on QFE I`d like to know which one.
Well, we use QFE and we're a UK based JAA operator. Or don't you count helicopters?!

And I don't think there's anything grey about 1000ft aal, which we also go by. In response to "Below absolute minima, state your intentions", we say "continuing to 1000ft" and hope for an improvement meantime.