Approach Ban

[RTN11]

The approach ban states (extracted from the AIP):

4.9.1 The requirements for the commencement and continuation of an approach (approach ban) applicable to all CAT operations is given in CAT.OP.MPA.305

4.9.2 The approach ban requirements for public transport operations, aerial work and private operations are defined in Articles 107,
108 and 109 of the Air Navigation Order 2009. The ‘specified’ minima are detailed below and reflect EASA Ops.

4.9.3 An aircraft may commence an instrument approach regardless of the reported RVR/Visibility but the approach shall not be
continued below 1,000 ft above the aerodrome if the relevant RVR/Visibility for that runway is at the time less than the specified
minimum for landing.

4.9.4 If after passing 1,000 ft in accordance with paragraph 4.9.3, the reported RVR/Visibility falls below the applicable minimum, the approach may be continued to DA(H) or MDA(H)

4.9.5 The approach may be continued below DA/H or MDA/H and the landing may be completed provided that the required visual reference is established at the DA/H or MDA/H and is maintained.

4.9.6 The touchdown zone Runway Visual Range (RVR) shall always be controlling.

Just looking at 4.9.5, in the case where the reported RVR is below your minima, lets say 300m RVR in fog where you require 550m. If you are still above the 1000' cut off, but can clearly see through the fog and have all the require visual references from that point, are you in any way allowed to overrule the reported RVR and continue the approach, or is it a case of go around at 1000' if the RVR is still reported below your minma?

[dawsonj1]

I would say almost certainly no. The 550m or whatever the RVR required to shoot the approach below 1000ft AAL must be attained from the controller prior otherwise aren't they obliged to then start quoting some legal statement over the radio saying something like "you are in breach of ...." ?

Also, chances are if RVR is below minima, your not going to have the required cues at 1000ft. Not saying it's impossible but personally I would be wanting an updated reading before continuing to the CAT I minima.

[RTN11]

Yeah, I thought as much.

I have had the exact situation fairly recently, at night, reasonably shallow fog, runway lights were as clear as day, could see the whole lot, but tower giving an RVR of 300m.

We went around above 1000' and ended up diverting, but just studying a wee bit now and it's running through my head that if you clearly have visual reference is there any way of getting around the ban?

[dawsonj1]

I get what your saying, but with shallow fog at the airfield, you may well have the cues from a distance but then descend into it, perhaps below decision altitude/height and now you may lose those cues at a much more critical height above the ground. I think in this scenario the approach ban exists to protect us. If you were to continue and something happens, the operating crew would have a hard job justifying continuing unless there were some overriding safety issues involved of course that made it safer to continue and land.

I would be surprised if you found anything written down in a controlling document that could be interpreted to say you could get around it in the described situation.

[JeroenC]

Think about it. RVR IS 300 m at 2 m above the ground (measuring station height). Just because the layer might be 3 m thick looking vertically through it from above, once in the layer you'll be looking at maybe a 3000 m "thick" layer, and are fully "IMC".

[dixi188]

Had exactly this situation at Southend many years ago. RVR from firemen was below limits but Captain could see the lights so continued. We had to go around from about 10 ft. when all visual reference was lost.

[Jwscud]

The minimum RVR for a visual approach is 800m precisely for this situation.

You may be able to see the runway, but the world is going to disappear at 100ft which is a particularly dangerous place to be if flying visually.