Shallow Fog - Approach Ban
Thread Starter
Join Date: Nov 2004
Location: Europe
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
Shallow Fog - Approach Ban
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
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
Last edited by ATRflyer; 23rd Nov 2005 at 18:38.
Join Date: Sep 2003
Location: here and there but mostly lgw
Posts: 166
Likes: 0
Received 0 Likes
on
0 Posts
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
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
Join Date: Apr 2005
Location: Southeast USA
Posts: 801
Likes: 0
Received 0 Likes
on
0 Posts
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
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
Join Date: Oct 2002
Location: frozen norff
Posts: 215
Likes: 0
Received 0 Likes
on
0 Posts
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.
Answer your question?
The case happened in England, Ireland may or may not be different.
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!
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!
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
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...
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...
Thread Starter
Join Date: Nov 2004
Location: Europe
Posts: 24
Likes: 0
Received 0 Likes
on
0 Posts
Thanks
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
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
Join Date: Oct 2000
Location: Berkshire, UK
Age: 79
Posts: 8,268
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
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.
Join Date: Oct 2000
Location: Berkshire, UK
Age: 79
Posts: 8,268
Likes: 0
Received 0 Likes
on
0 Posts
<<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).
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).
Have a look at ATSIN No.19. 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"
"A value of 800 metres RVR shall be used at all airports as the Absolute Minimum for visual approaches"
Last edited by spekesoftly; 23rd Nov 2005 at 16:04.
Join Date: Jun 2000
Location: UK
Posts: 450
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Last edited by Hudson Bay; 24th Nov 2005 at 11:18.
Join Date: Oct 2000
Location: Berkshire, UK
Age: 79
Posts: 8,268
Likes: 0
Received 0 Likes
on
0 Posts
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?
Join Date: Jun 2000
Location: UK
Posts: 450
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
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.
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.
Last edited by Max Angle; 24th Nov 2005 at 14:14.