Touchdown RVR failure on CAT II/III
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Jepp EASA AD Op has
RVR assessment systems:
CatIIIB No DH
At least one RVR value to be available on the AD
CatIIIB/A&II
On runways equipped with 2 or more RVR assessment units, one may be inoperative
CatIIIB No DH
At least one RVR value to be available on the AD
CatIIIB/A&II
On runways equipped with 2 or more RVR assessment units, one may be inoperative
Last edited by victorpapa; 5th Feb 2018 at 10:03. Reason: Typo
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TDZ is always controlling, MID and STOP END if reported and relevant. It then defines what is relevant ie >60kts. So the TDZ RVR has no speed limit before it is controlling ie it’s always controlling - I think we agree so far. However, if it’s not reported due to an unservicability then it cannot be controlling. There is no mention of replacing other reported RVRs, which themselves have alternative limits anyway.
The approach ban allows you to continue an approach below 1000’ no matter how low the RVR has fallen, assuming it was ok prior to 1000’. If you have sufficient visual reference you may land - the actual RVR at this point is irrelevant. Would this not be similar to a failure of the TDZ transmissiometer? So long as the MID and STOPEND are within limits (if relevant) you attempt the approach and if you have sufficient visual reference you may land, if not you goaround in the time-honoured fashion ?
That it was once written differently in your FCOM could be that your airline have chosen a more restrictive approach which is always allowed.
I do believe that many of the regulatory documents have scope for interpretation, hence the addition of AMC and GM sections. Unfortunately not so in this case.
The approach ban allows you to continue an approach below 1000’ no matter how low the RVR has fallen, assuming it was ok prior to 1000’. If you have sufficient visual reference you may land - the actual RVR at this point is irrelevant. Would this not be similar to a failure of the TDZ transmissiometer? So long as the MID and STOPEND are within limits (if relevant) you attempt the approach and if you have sufficient visual reference you may land, if not you goaround in the time-honoured fashion ?
That it was once written differently in your FCOM could be that your airline have chosen a more restrictive approach which is always allowed.
I do believe that many of the regulatory documents have scope for interpretation, hence the addition of AMC and GM sections. Unfortunately not so in this case.
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Intelligence
Is reading and understanding really so difficult?
Regulations state that TDZ RVR may be replaced by MID RVR if TDZ RVR is U/S.
Regulations also state the minimum required values for TDZ, MID and Stopend RVR.
Let's assume the real RVR values at a runway are 200, 150 and 75 metres.
Today, the TDZ RVR transmissometer is U/S, so there is no way that the pilots can obtain the knowledge that the TDZ RVR is really 200 m.
The (approach category D) aircraft wanting to start approach is Cat 3A capable, so needs 200 m TDZ RVR value.
Substituting TDZ with the value of the MID RVR means that the pilots have to regard available RVR's as 150, 150, 75. This means that known situation is BELOW LIMITS and approach is not allowed.
Don't need law references for this explanation, it is just a matter of knowing what the meaning of SUBSTITUTION is, go ask your English language teacher.
Regulations state that TDZ RVR may be replaced by MID RVR if TDZ RVR is U/S.
Regulations also state the minimum required values for TDZ, MID and Stopend RVR.
Let's assume the real RVR values at a runway are 200, 150 and 75 metres.
Today, the TDZ RVR transmissometer is U/S, so there is no way that the pilots can obtain the knowledge that the TDZ RVR is really 200 m.
The (approach category D) aircraft wanting to start approach is Cat 3A capable, so needs 200 m TDZ RVR value.
Substituting TDZ with the value of the MID RVR means that the pilots have to regard available RVR's as 150, 150, 75. This means that known situation is BELOW LIMITS and approach is not allowed.
Don't need law references for this explanation, it is just a matter of knowing what the meaning of SUBSTITUTION is, go ask your English language teacher.
EASA-OPS hasn’t stated that mid point can substitute touchdown RVR for several years. What it does say is that one transmissiometer may be inop (assuming you have multiple to start with) for cat 2-3A and just one on the airfield for cat 3B. Thoeretically you could land cat 3B on 18R in AMS with no working transmissiometer on that runway but an RVR reading from runway 27 that is above your minimum. Also, assuming you need 200/125/75 for a cat 3A approach, you could have inop/125/75 and legally continue to minima.
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From FAA land...a few scenarios/conditions to consider...there are others in the document...if one of 2 may be inoperative, it appears the touchdown one must be op for II and III...
(1) Other Than CAT II/III. In all operations other than CAT II/III, (including non-precision, approach procedures with vertical guidance (APV), and CAT I precision
operations), the touchdown RVR VS data is controlling when installed and operational. If the touchdown RVR VS is inoperative, some operators may be authorized, via OpSpecs, MSpecs, or
an LOA, to substitute an operative mid-point RVR VS for visibility minima greater than or equal to 1,800 RVR. Refer to OpSpec/MSpec/LOA C052 (Straight-In Non-Precision, APV, and
Category I Precision Approach and Landing Minima—All Airports) for current RVR operational requirements.
(3) CAT II. Touchdown and rollout RVR VSs are an FAA system requirement for runways that are 8,000 feet or less. Touchdown, mid-point, and rollout RVR VSs are an FAA
system requirement for runways in excess of 8,000 feet, but AFS-400 may approve CAT II operations on a runway with only two RVR sensors (a touchdown zone (TDZ) and either a
mid-point or rollout RVR sensor) on a case-by-case basis. All CAT II operations less than 1,600 RVR require touchdown and a second RVR VS (either mid-point or rollout). The
touchdown RVR data is required and controlling for all CAT II operations. Where installed, mid-point and rollout RVR VSs provide advisory visibility information to pilots. CAT II
runways require associated RVR systems. Refer to OpSpec/MSpec/LOA C059 (Category II Instrument Approach and Landing Operations (Optional): 14 CFR Parts 91, 121, 125, 125M,
135, and 91K Operators) for current RVR operational requirements.
(5) CAT III. All CAT III operations require touchdown, mid-point, and rollout sensors of an RVR reporting system. AFS-400 may approve CAT III operations on a runway with only
two RVR sensors (a TDZ and either a mid-point or rollout RVR sensor) on a case-by-case basis. CAT III runways require associated RVR systems. Refer to OpSpec/MSpec/LOA C060
(Category III Instrument Approach and Landing Operations) for current RVR operational requirements.
https://www.faa.gov/documentLibrary/...r/6560.10C.pdf
(1) Other Than CAT II/III. In all operations other than CAT II/III, (including non-precision, approach procedures with vertical guidance (APV), and CAT I precision
operations), the touchdown RVR VS data is controlling when installed and operational. If the touchdown RVR VS is inoperative, some operators may be authorized, via OpSpecs, MSpecs, or
an LOA, to substitute an operative mid-point RVR VS for visibility minima greater than or equal to 1,800 RVR. Refer to OpSpec/MSpec/LOA C052 (Straight-In Non-Precision, APV, and
Category I Precision Approach and Landing Minima—All Airports) for current RVR operational requirements.
(3) CAT II. Touchdown and rollout RVR VSs are an FAA system requirement for runways that are 8,000 feet or less. Touchdown, mid-point, and rollout RVR VSs are an FAA
system requirement for runways in excess of 8,000 feet, but AFS-400 may approve CAT II operations on a runway with only two RVR sensors (a touchdown zone (TDZ) and either a
mid-point or rollout RVR sensor) on a case-by-case basis. All CAT II operations less than 1,600 RVR require touchdown and a second RVR VS (either mid-point or rollout). The
touchdown RVR data is required and controlling for all CAT II operations. Where installed, mid-point and rollout RVR VSs provide advisory visibility information to pilots. CAT II
runways require associated RVR systems. Refer to OpSpec/MSpec/LOA C059 (Category II Instrument Approach and Landing Operations (Optional): 14 CFR Parts 91, 121, 125, 125M,
135, and 91K Operators) for current RVR operational requirements.
(5) CAT III. All CAT III operations require touchdown, mid-point, and rollout sensors of an RVR reporting system. AFS-400 may approve CAT III operations on a runway with only
two RVR sensors (a TDZ and either a mid-point or rollout RVR sensor) on a case-by-case basis. CAT III runways require associated RVR systems. Refer to OpSpec/MSpec/LOA C060
(Category III Instrument Approach and Landing Operations) for current RVR operational requirements.
https://www.faa.gov/documentLibrary/...r/6560.10C.pdf
Last edited by underfire; 5th Feb 2018 at 21:50.
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EMIT
WOW - could you be any more condescending?
Apparently ‘reading and understanding’ is difficult! EASA-OPS makes no mention of substituting the RVRs. Zero, nil, nada, my English teacher isn’t required for this one! The FAA do specifically mention it, but this thread has consistently mentioned EASA.
While we’re on it, and only because of your pomposity, can I point out that the minimum midpoint RVR for landing is 125m not 150m as you use in your example. The fact you mention cat D aircraft one can only assume you believe the midpoint RVR requirement is tied to your minimum for takeoff, cat D 150 cat C 125. CAT.OP.MPA.305
WOW - could you be any more condescending?
Apparently ‘reading and understanding’ is difficult! EASA-OPS makes no mention of substituting the RVRs. Zero, nil, nada, my English teacher isn’t required for this one! The FAA do specifically mention it, but this thread has consistently mentioned EASA.
While we’re on it, and only because of your pomposity, can I point out that the minimum midpoint RVR for landing is 125m not 150m as you use in your example. The fact you mention cat D aircraft one can only assume you believe the midpoint RVR requirement is tied to your minimum for takeoff, cat D 150 cat C 125. CAT.OP.MPA.305
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Answer
Stripes / Not meant to be condescending. In the first couple of answers there were remarks about substitution and then there were strange ways that substitution seemed to be implemented by some posters.
I think #11 (Goldenrivett) already dealt with that mis-interpretation of substitution.
Reading and understanding ought not be difficult; what is difficult is FINDING things in EASA rules. An example is the reference in #3 – it leads properly to the AMC and GM book of EASA, but that is only part of the whole complex of rules. The issue date seems to be 25 oct 2012 (but the first page literally states “Initial issue” ) – so, is this a current reference or not?
The initial check I made was with my company regulations for the situation as described by the OP.
Those rules state literally – The touchdown zone RVR (may be replaced by midpoint RVR if touchdown not available) is always controlling. If reported and relevant, the midpoint and stop-end RVR are also controlling. … etcetera …
Now, as you correctly pointed out, EASA rules nowhere mention the substitution of one RVR with another one.
However, EASA does state that all Low Visibility Operations are subject to Special Approval. The company seeking a Special Approval must present their Operations Manual to the national authority for authorization – with that approval, that OM becomes the law for the company pilots.
What we, as pilots, cannot check is whether the inclusion of the substitution rule is a sort of unintentional leftover from previous rules, and not weeded out by the authority during their inspection, or whether it is an intentional amplification of the meagre wording in the EU rules.
Using Air Ops Easy Access lumps all the books together, but what a load of electronic paper to rummage through. Of course, search function, but what if you are looking for “low temperature correction” , they call it “temperature compensation”, “substitute” or “replace”? Tedious!
With all these caveats it is hard to give a definitive answer to the OP, he really should get his company to check it with their national authority.
Your reasoning in #22, second paragraph, about the similarity with the situation where an RVR drops below limits after you have descended below 1.000 HAT seems correct, but actually it is not from a statistical risk standpoint, such as regulators regard.
The time from 1.000 ft HAT until touchdown is around a minute and a half. Only one aircraft is in that position at any one time. The crew is bound by required visual reference rules. The risk for just that one aircraft to do look and see in case one RVR drops below limits is acceptable.
Suppose you are number 1 of the 200 aircraft bound to land at that airport. All the other aircraft behind you get the message about the RVR below limits before they reach 1.000 ft HAT.
With your reasoning about similarity of situation, all the other 199 aircraft would also go for a look-see and that exactly is the risk that the authorities do not find acceptable.
Wording can be misleading – EASA OPS states that when 2 or more RVR’s are available on a runway, then one may be U/S. With this wording you do not get the idea that Cat 3 runways, in principle always have three RVR’s and only in exceptional cases would one be classified Cat 3 with only two RVR transmissometers (perhaps very short runways?). If the original runway only has two RVR positions, is it a TDZ and MID, or a TDZ and Stop-end? If TDZ and MID, then the opposite RWY would not have a TDZ RVR. If it is a TDZ and a Stop-end, and the TDZ is U/S, Stop-end 75, wow, what a problem if your required TDZ RVR is 200 m, or even 300 m? Would an XAA dare to say, hey, Stop-end is above limits, let all those 200 aircraft inbound just have a look see?
In my post I did not confuse T/O and landing minima, I only mentioned RVR 200 as limit for landing, as per OP post, the mid and end RVR were just example of values.
The problem of the OP is exactly for aircraft with a rather high TDZ RVR requirement, my aircraft with 75/75/75 for both take-off and landing is not so complicated (if all systems are go).
I think #11 (Goldenrivett) already dealt with that mis-interpretation of substitution.
Reading and understanding ought not be difficult; what is difficult is FINDING things in EASA rules. An example is the reference in #3 – it leads properly to the AMC and GM book of EASA, but that is only part of the whole complex of rules. The issue date seems to be 25 oct 2012 (but the first page literally states “Initial issue” ) – so, is this a current reference or not?
The initial check I made was with my company regulations for the situation as described by the OP.
Those rules state literally – The touchdown zone RVR (may be replaced by midpoint RVR if touchdown not available) is always controlling. If reported and relevant, the midpoint and stop-end RVR are also controlling. … etcetera …
Now, as you correctly pointed out, EASA rules nowhere mention the substitution of one RVR with another one.
However, EASA does state that all Low Visibility Operations are subject to Special Approval. The company seeking a Special Approval must present their Operations Manual to the national authority for authorization – with that approval, that OM becomes the law for the company pilots.
What we, as pilots, cannot check is whether the inclusion of the substitution rule is a sort of unintentional leftover from previous rules, and not weeded out by the authority during their inspection, or whether it is an intentional amplification of the meagre wording in the EU rules.
Using Air Ops Easy Access lumps all the books together, but what a load of electronic paper to rummage through. Of course, search function, but what if you are looking for “low temperature correction” , they call it “temperature compensation”, “substitute” or “replace”? Tedious!
With all these caveats it is hard to give a definitive answer to the OP, he really should get his company to check it with their national authority.
Your reasoning in #22, second paragraph, about the similarity with the situation where an RVR drops below limits after you have descended below 1.000 HAT seems correct, but actually it is not from a statistical risk standpoint, such as regulators regard.
The time from 1.000 ft HAT until touchdown is around a minute and a half. Only one aircraft is in that position at any one time. The crew is bound by required visual reference rules. The risk for just that one aircraft to do look and see in case one RVR drops below limits is acceptable.
Suppose you are number 1 of the 200 aircraft bound to land at that airport. All the other aircraft behind you get the message about the RVR below limits before they reach 1.000 ft HAT.
With your reasoning about similarity of situation, all the other 199 aircraft would also go for a look-see and that exactly is the risk that the authorities do not find acceptable.
Wording can be misleading – EASA OPS states that when 2 or more RVR’s are available on a runway, then one may be U/S. With this wording you do not get the idea that Cat 3 runways, in principle always have three RVR’s and only in exceptional cases would one be classified Cat 3 with only two RVR transmissometers (perhaps very short runways?). If the original runway only has two RVR positions, is it a TDZ and MID, or a TDZ and Stop-end? If TDZ and MID, then the opposite RWY would not have a TDZ RVR. If it is a TDZ and a Stop-end, and the TDZ is U/S, Stop-end 75, wow, what a problem if your required TDZ RVR is 200 m, or even 300 m? Would an XAA dare to say, hey, Stop-end is above limits, let all those 200 aircraft inbound just have a look see?
In my post I did not confuse T/O and landing minima, I only mentioned RVR 200 as limit for landing, as per OP post, the mid and end RVR were just example of values.
The problem of the OP is exactly for aircraft with a rather high TDZ RVR requirement, my aircraft with 75/75/75 for both take-off and landing is not so complicated (if all systems are go).
