Does ATC care about the “Approach ban”
 

Hello .
For the purposes of clarifying the concept to someone reading this for the first time , “ approach ban “ is the ban of continuing an approach when an aircraft is passing 1000 ft AGL on approach , and the reported VIS/ RVR is less than the minimums of the procedure . If the reported RVR/ VIS is less than the minimum, then the crew should execute a missed approach
Something tells me that ATC ought not to care since different aircraft categories will have different minima for the same procedure . Also it is allowed to use converted meteorological visibity ( CMV ) , and ATC should not bother whether and which conversion factor has been used .
Can an ATC confirm this ?

Having flown a properly designed instrument approach, a pilot, at the minima's - and ONLY the pilot - is in the best position to assess the visibility between the aircraft and the touchdown zone and assess whether that visibility is suitable for them to continue the approach. Adding validity to this approach (please excuse the pun) airports across the globe have spent millions of dollars (or whatever the local currency is) to install lights facing up the intended approach path on final. Visibility sensing devices, no matter how highly developed, can never provide better information to a person who is not in the cockpit and, such, we should not prohibit pilots flying an approach to the minima's and making the appropriate decision about continuation of flight.

Gne

As an ATCO (retired), for many years I had no direct & official knowledge of what the legal limits for the pilots of an aircraft to continue an approach were. I had a general understanding of the pilots’ limits, but no official understanding & involvement (or policing) of the legislation. I simply provided the met’ data to the pilots & let them get on with doing their job - on the understanding that they knew what they were doing. During the latter part of my time, we were required to inform aircrew when conditions were below the limits for an approach, & to advise them that, if such an approach was made, we would be obliged to report the matter. I do not know if things have moved on & whether ATC now has the authority to forbid an approach “below limits”.

In the UK, the days of spieling off the ‘absolute minima’ and how we were required to report the pilot to the CAA if they continued the approach, are gone.

These days we just record the current RVR for each aircraft making an approach, in case the CAA wishes to look at it later.

That’s not what an approach ban is about. Read the first post again! The question is not wether the lights are visible at minima, but wether it is legal to continue the approach in the first place.

In the Uk that is entirely down to the crew, ATC have no policing rule for approach minima regarding the aircraft or crew capabilities. This includes the fact that flight plans can have the RVR minima in flight plan supplemental information. So if a vmc qualified pilot flying a basic spec non instrument C150 wanted to make an approach in CATIII conditions, the ATCO provides the services along the lines of what rodan and notwithstanding have said.

An ATCO who suspected something peculiar, and had the knowledge to recognise a peculiarity (not all will have that), might ask along the lines of confirm you want to make a X approach to Y? But if they ask and the pilot confirms their intentions as originally requested, then it’s game on, regardless of how the ATCO may feel about it.

Other countries may differ.

The approach minima will vary per type, crew recency, wind, weight, and technical state of the aircraft, it’s not just ‘the procedure minimum’. One flight you might be limited to 75m RVR, a defect might raise that to 550m on the next flight. Or a crosswind might preclude an autoland etc.

ATC will not be aware of all these variations. Either way, we as pilots are to make sure that we can legally continue the approach before the approach ban point.

I think that If the airport is not closed and there are no safety-related factors involved, ATC will clear aircraft to conduct the approach as usual.ATC’s responsibility is to provide separation and they do not take approach bans into consideration, nor do they prohibit pilots from making an approach.(due to weather} As for the pilots, it is their own decision whether to continue the approach or not.

(There is no prohibition on the commencement of an approach based on the reported RVR or VIS. The restriction applies only if the RVR or VIS is reported and applies to the continuation of the approach past a point where the aircraft is 1 000 ft above the aerodrome elevation)

It should be noted that CMV can't be used for LVO operations as per "AMC1 CAT.OP.MPA.305(a) Commencement and continuation of approach".

As mentioned previously, ATC are not aware of what restrictions apply to each individual aircraft as they vary due to crew and aircraft qualifications/ limitations. ATC are aware of what conditions need to be applied for the airfield to be capable of supporting the required operations such as CAT I/II/III etc and will report the measured RVRs. It is for the crew to apply the appropriate criteria for their approach in accordance with their Operations Manual.

Yes CMV is not applicable to LVO approaches but pretty much any NPA can make use of it. The Approach ban is applicable to any approach, and using the CMV in NPAs may actually help you get around the ban in marginal conditions

There are even ILS with some unusually high RVR where using CMV can be handy. They're not all 550m!

Exactly. In the new EASA regulations, you can not use CMV in LVOs, which are defined to be landing operations which less than 550m RVR. So any ILS with RVR minima more than this value, should be able to make use of CMV

Is it not prohibited to use CMV if RVR is being reported? Then it won't help at all on those marginal days, unless you're "lucky" and only met vis is reported.

We don't know what your minimums are, you do.

I would like to also offer a concept called "duty of care" although it goes by other names.

For ATC it might mean if a controller knows something a pilot should know, but the controller is not certain, he/she should pass on that information.

In the above, that would certainly include, RVR, reported cloud base, previous pilot reports, and so on. But not, in my opinion, the approach minimums. These are published and available through paper or electronic displays.

In Australia, years ago, the Federal Government exercised Operational Control over all IFR flights and made ATC the responsible agency. We could, and did, close airspace and airports due to weather minimums, close approaches due to below minimums reports and order pilots to divert, and to where, when we calculated that they had insufficient fuel. (Yes, we monitored their fuel states!)

I believe, back then, the majority of pilots actually trusted the Government system. It was impartial, eliminated peer or company pressure on pilots, was based entirely on met reports including from ATC Tower controllers. (They were and still are all qualified weather observers, hence we do not have to broadcast the METAR as our ATIS)

Anyway, the Feds gave Operational Control to the companies, they promptly gave it to the PIC. But we still can be dragged through the courts if we forget our "duty of care"!

As an ex-controller, long out of operational positions, back in my day we generally knew about the approach ban but, to an extent at least, didn't care.

The equivocation comes from the fact that knowing whether a particular operator or type might be able to make an approach or not could help planning where to put traffic in marginal conditions. Knowing the RVR that would enable an aircraft to make or continue an approach was sometimes helpful also to understand who might want to start an approach when the weather update arrived. I'll be honest, too, that there were occasions when an inbound was five or six miles out and the RVR dropped I might be otherwise engaged for a few moments and unable to pass the new values until the aircraft was inside four miles. But, of course, all of this is just war stories from years ago, at an airport where the ILS was only Cat I at one end, it wasn't that busy and there were a fair few aircraft which were not fully equipped for AWO - times have changed in many, many ways - but I think the basic principles remain, pilot flies the aircraft and worries about whether he/she can start or continue the approach and the controller advises when the pilot can give it a go if they are permitted. But I must mention that I found the shifts where such things were going on to be some of the most satisfying.

Having said all that, I did have some involvement with the UK's foray into blurring these boundaries with the absurd 'absolute minima' procedure which, if nothing else, made it clear to everyone how many factors are involved in getting aircraft onto the ground in poor weather.

Flying out of London on a foggy day recently I heard a bizjet inbound to Luton being given the RVRs (can’t remember exactly what they were but definitely below CAT1) and he was asked if he was able to make an approach. He answered in the affirmative. Then about a minute later he asked for the RVRs again and was told the same figures. At this point he reported that he couldn’t make an approach after all…

Strictly speaking what he did was perhaps within the realm of the approach ban ….. you see according to the approach ban you can commence the approach regardless of the reported VIS/RVR . Passing 1000 ft AAL (or in the final approach segment if the minima are above 1000 ft AAL ) , if the reported RVR is below minimum then you ought to execute a missed approach . ( and to complete the whole concept , after passing the 1000 ft AAL mark , if reported RVR/VIS is below minima , you can continue the approach to the minima ) . In the story above if the reported RVR was given before 1000 ft AAL , he could continue down to the 1000 ft AAL mark . The second RVR report which was given after the pilot requested it , could have been at the 1000 ft AAL mark .

I’m well aware of the above. In this case the aircraft was nowhere near starting the approach. I think it was more a case of them being told what the RVRs were and then saying they could make an approach before actually checking what their minima were. Shortly afterwards, they asked for the RVRs again, were told the same numbers again, but this time they said they couldn’t start an approach. They were nowhere near 1000’.

Now that Enhanced Flight Vision Systems (EFVS) are used by some operators to land below the CAT I minima, it’s even harder to second guess a pilot’s minima.