MID and RO/SE RVR "if reported and relevant"

[Microburst2002]

Hi

I can't find in the books what are the requirements of RVR reporting for CAT 1,2 and 3 approaches.

How should "if reported and relevant" be read?

I have the notion that for CAT 1 and 2 only TDZ RVR is required but that CAT 3 requires all 3 RVRs (TDZ, MID and RO/SE).

Thanks

[TOGA Tap]

If the landing distance does not require full length and stop-end is never reached during landing it is "not relevant'

[7478ti]

For US operations and US Operators, see FAA AC120-29A and AC120-28D.

For a particular operator, see their FCOM and approved Op-Specs Part C.

[Intruder]

FAA Notice 8900-234, 8/30/2013 (Cat II) has new RVR requirements for OpSpec C059:The midpoint RVR report (if available) and the rollout RVR report are now required and controlling. The lowest allowable midpoint RVR is 600 RVR and the lowest rollout RVR is 300 RVR. These requirements are shown in a new Table 2.

FAA Notice 8900-235, 8/30/2013 (Cat III) has RVR requirements for OpSpec C060:All RVR reports are required and controlling, except as specified in subparagraphs d(2), d(3), and d(4) below.
Note: TDZ and mid RVR reports must be no lower than the approach chart minima to conduct any CAT III operation.

[172_driver]

I have the notion that for CAT 1 and 2 only TDZ RVR is required but that CAT 3 requires all 3 RVRs (TDZ, MID and RO/SE).



As I take it, the regulation makes no difference between CAT 1, 2 and 3.

Unless a particular airport has some weird weather pattern giving odd RVR readings (such as 600/100/100) it would be unlikely MID or SE would limit you on a CAT 1. On a CAT 2 a bit more likely, perhaps. On a CAT 3 it could happen, such as 200/100/100.


CAT.OP.MPA.305 Commencement and continuation of approach

(f) 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. For aircraft equipped with a rollout guidance or control system, the minimum RVR value for the midpoint shall be 75 m.

Was that what you were alluding to?

Edited to add: EASA regulations

[nick14]

Whatever is reported has to be within limits, if they report only touchdown then that is all that is required. I believe that (not certain) to have a CAT III system approved you need to have multiple RVR reporting systems (certainly required for 125M TO).

There are a few weird places, RIX being one, where they used to have a CAT III ILS and therefore MRVR but since downgraded to CAT I but still give you all three on approach in poor weather. As they report all three you must have 550/125/75.

[FlightDetent]

I seem to remember value of 70 kt being significant, anyone? The idea is that after you're down to 70 or below, only 75 is required.

In the RIX example then 550/75/75 is enough, if you can calculate to be below 70 knots within the first 1/3rd.

[dirk85]

GM1 CAT.OP.MPA.305(f) Commencement and continuation of approach

EXPLANATION OF THE TERM ‘RELEVANT’
‘Relevant’ in this context means that part of the runway used during the high-speed phase of the landing down to a speed of approximately 60 kt.

[7478ti]

Intruder is correct in that these are some additional appropriate recent policy references to consider, ...but note that Op-Specs still are the controlling document for a particular carrier.

Note that "Policy" (of an authority) as for Orders or Notices is not necessarily a "rule" and they may not necessarily be applied to a particular carrier or situation (as would be an actual FAR such as 91.175 or 121.651), ...and even Advisory Circulars can sometimes have alternate means of compliance (I can cite many examples), or delayed or revised updating of compliance of [Automated] Op-Specs, or a different means of compliance, or even alternate compliance (especially relief from "Notices" and "Orders", which typically are targeted to and pertain to direction of "FAA employees" as to being instructions (e.g., to POIs/CMO/APMs... inspectors), and not necessarily applying to the general public (except as indirect information). Bottom line is that the operator's actual approved signed Op-Specs rule here, and variances from both Orders, Notices, and even ACs can exist (and even differences from rules, if there are "exemptions" or "deviations" legally approved).

Regarding "relevant RVR" the language was originally addressed in AC120-29A and AC120-28D (with historical precedent as far back to AC120-28B (Dec 1, 1977) ...to cover situations such as two versus three transmissometer runway installations (8000' ft runway length breakpoint), temporarily inoperative RVR components, and later recognizing short landing distances of some aircraft types like the DHC-8 (with HUD) that could often accomplish an entire landing (or takeoff) within the relevant portion of just one installed transmissometer. The criteria here for short field length aircraft was keyed to conservatively slowing to a "safe taxi speed" considering mu and normal breaking, as well as non-normal events, ...and for takeoff, the distance for the entire takeoff, including any potential entire RTO at the relevant mu, if a stop was required.

[Microburst2002]

thank u guys

All useful answers.

Nick wrote
Whatever is reported has to be within limits, if they report only touchdown then that is all that is required. I believe that (not certain) to have a CAT III system approved you need to have multiple RVR reporting systems (certainly required for 125M TO).

There are a few weird places, RIX being one, where they used to have a CAT III ILS and therefore MRVR but since downgraded to CAT I but still give you all three on approach in poor weather. As they report all three you must have 550/125/75.


Which is just what I "suspected". Whatever they give you, you must comply with. What I would like to see is in what document it is stated the relation between a runways Cat 1,2 and 3 capability and the number of reported RVRs. For instance: is it required to have the 3 RVRs for cat 3?

Thanks 172 and 747, as well. In fact, in my airline the MID RVR requirements are different

I was aware of the 60 kt rule, which rises a few questions of its own, like how it is computed, etc... Some say that you can land in a 300/250/<50 if you select a high autobrake setting so that the SE RVR becomes irrelevant.