Touchdown RVR failure on CAT II/III
 

Hi all,

Asked a tricky question in the sim the other day. Your Planning a CAT II/III approach to an airfield, multiple RVRs normally available but ATC report touchdown RVR is unserviceable. Mid point and stop end reported 125/75.

Is there any regulation/guidance stating whether you can commence/continue the approach? Failed equipment chart says Multiple RVR available one may be inoperative but how can you assess the touchdown RVR and do you need to?

Company ops manual doesn’t cover it hence the confusion

Try EASA in case company manuals fail, in case operating in EU territory.
Try AMC7 SPA.LVO.100 Low visibility operations - EFFECT ON LANDING MINIMA OF TEMPORARILY FAILED OR DOWNGRADED EQUIPMENT which quotes:
"These instructions are intended for use both pre-flight and in-flight. It is however not expected that the pilot-in-command/commander would consult such instructions after passing 1000 ft above the aerodrome. If failures of ground aids are announced at such a late stage, the approach could be continued at the pilot-in- command/commander’s discretion. If failures are announced before such a late stage in the approach, their effect on the approach should be considered as described in Table 7, and the approach may have to be abandoned.

The following conditions should be applicable to the tables below:
(1) multiple failures of runway/FATO lights other than indicated in Table 7 are not acceptable;
(2) deficiencies of approach and runway/FATO lights are treated separately;
(3) for CAT II and CAT III operations, a combination of deficiencies in runway/FATO lights and RVR assessment equipment are not permitted; and
(4) failures other than ILS and MLS affect RVR only and not DH.

Table 7: Failed or downgraded equipment – affect on landing minima Operations with an LVO approval
...
RVR assessment systems | At least one RVR value to be available on the aerodrome | On runways equipped with two or more RVR assessment units, one may be inoperative
..."

There is guidance that touchdown RVR can be substituted by other readings but this should be in company manuals as Small cog said to ensure it is approved for your company.

That was my suspicion but I can’t seem to find anything. Do you have any idea where to look?

At every operator I flew for, there was a table of failed equipment and it’s effect on minima. If you’re EASA, it should be somewhere in chapter 8

It is but as I said above it states that one may be inoperative.

What’s your question, then :confused:

If TDZ RVR is inop, you just substitute it with the MID RVR value.

If you’re told about it below 1000’ you’re not expected to check the table - continue.
If you’re told about the failure above 1000’, consult the table, one may be inop - do you meet the minimum RVR for the remaining two, in this case 125m and 75m (if relevant of course) - if you meet those RVRs....continue
If you have sufficient visual reference at minimums - land

There are two answers there:

If you sustitue the TD for the mid point and the midpoint is less than 200 (our minima) you would go around outside the marker. If you just consult the table and assess that one of the three is inop then you would continue.

So I was hoping for some regulatory guidance on whether the touchdown RVR was required but I think I will have to ask for guidance to be put into our OMA.

Where the RVR is not available, RVR values may be derived by converting the reported visibility. For different country regulations refer to OM-C.but..not for CAT 11/111.

The touchdown zone RVR shall always be controlling. If reported and relevant, the midpoint and stopend RVR shall also be controlling. The minimum RVR value for the midpoint shall be 125 m or the RVR required for the touchdown zone if less, and 75 m for the stopend. Refer to OMA for "Landing on Wet or Contaminated Runways".

In this context, ‘Relevant’ means that part of the runway used during the high-speed phase of the landing down to a speed of approximately 60 kt (GM1 CAT.OP.MPA.305(f)).

So, in a nutshell, if there are multiple RVR reporting systems, one can fail (AMC7 SPA.LVO.100)

If you are below 1000 ft when ATC advise the failure you can continue and if the required visual ref is obtained, land.

In General:
Any restriction to RVR and/or visibility will be shown by a limiting letter (R or V), meaning that any given value followed by a letter must not be converted.
R: measured RVR.
V: visibility which cannot be converted.
Values without a letter can be converted.
Reported VIS shall be taken 1:1 as RVR identical value (no conversion allowed) if limiting suffix “R” is shown.
In general, a conversion of MET visibility into RVR is not allowed for Cat 2/3 approaches, for take-off minima, or if RVR is reported already.

The sim question is all about knowing the regulations in principle and then using common sense to apply them in a practical manner.

Hardly! You would need the midpoint RVR to be at or above your required touch down minima if TD was inop. You substitute the missing RVR intelligently. You don't simply say 2 out of 3 are working (but both below my TD minima) so continue!

The simple idea is that the approach should have a reasonable chance of success for a safe landing. Your logic of using the 2 reported RVR (both less than your TD minima) has little chance of success.
Have a read of http://aviation-safety.net/database/...?id=19651027-0 . We learned from accidents like that and introduced approach ban minima. Don't try to circumvent the rules - they are there for a reason.

Why in the world has anyone not produced a simple table that shows what's allowed and what isn't? Our illustrious aviation regulators simply do not want the responsibility. They'd rather keep things as is so they are open to interpretation. That keeps the airlines happy which is all they care about really.

I've just had an awkward sim session with a seasoned trainer completely at odds with everything I've been taught about RVRs at my previous gig and not a single legal document exists to clarify the disparity. What a stupid stupid position we find ourselves in in the year 2018.

What a stupid stupid position we find ourselves in in the year 2018.

Especially as it is legal territory. Approaching in LVO, beyond OM/1000', when you shouldn't is a violation subject to hefty reprisals. Before JAR in UKCAA land I know of one captain whose licence was suspended during investigation of landing below CAT 1 RVR. I know some Ops Manuals are written grey, deliberately, but this is 'law of the land' stuff. I wonder how all these 'non-employees' would fare in a show down with an XAA.

It's worth remembering, of course, that below 1000ft any change in RVR would be advisory. So if TDZ fails thereafter, one is not exactly losing much information anyway.

Not sure about that. If you can achieve 60kts at the midpoint instead of the endpoint, why is the RVR requirement 125m or more? It should be in line with the lowest RVR allowed which is 75m.

Can you provide a reference for this? The regs as I read them (EASA OPS) state what is required eg 200/125/75 it then goes on to say that one RVR can be inop, there is no caveat given that talks about intelligent substitution? Further, there is no AMC or GM that I can find that gives this info. There is a difference between opinion and rules, you always have the option of going-around if you don’t like it but this is a discussion of rules. I am quite happy to accept I’ve got it wrong if you can provide a reference?

My airline incorporated such a table into the QRH. For Cat III, it explicitly includes "Any one RVR may be temporarily inoperative"

Maybe the "seasoned trainer" needs to check with the standards people and find out their source documents for the new procedures...

In our case (South American operator) we did have a chart (they deleted it some months ago!) showing what equipment is required. As avenger said, TDZ RVR is always controlling for CAT II/III ops so in our case, if before commencing the approach, it would be a no-no.

Hi Too Few Stripes,
Sorry - I can't. Under Failed or Downgraded Equipment our FCOM used to say
"Touchdown zone RVR assessment system:
May be temporarily replaced with midpoint RVR if approved by the State
of the aerodrome. RVR may be reported by human observation."

However it still says "The touchdown zone RVR shall always be controlling.
If reported and relevant, the midpoint and stop end RVR shall also be controlling."

If you are allowed to commence an approach with Touchdown RVR missing (but mid point & stop end reported), how can you satisfy "touchdown RVR shall always be controlling" unless the reported mid point RVR => touchdown zone requirement?

Our Flight Deck QRH has...
 

TDZ May be temp replaced with​ MID RVR if​ approved by the state of​ A/D.