RVR substitution in LVOs.

[sparkman]

Could any one with the spare time please remind me of the rules in the UK about the substitution of RVRs during Cat 2 and 3 approaches. What I mean is, if the T/D zone is U/S can we substitute it with the Mid Point and vice versa?

Many thanks.

[Thunderbug]

My company (UK) has the following guidance:

TDN Zone RVR assessment system u/s

CAT2, CAT3A, CAT3B - May be temporarily replaced with midpoint RVR. RVR may be reported by human observation.

T'bug

[sparkman]

Many thanks for that but I don't suppose you have any references for that dp you?

[Thunderbug]

Sorry - Only ref is "JAR-OPS PART 1"

We use company manuals that are derived from the relevant bits of JAR OPS.

[Del Prado]

A little off topic but how do you guys feel about making an approach/landing when RVR below 600 metres but safeguarding not yet complete (ie Low Vis Procedures not in force)?

[Che Guevara]

Substitution of the touch down zone RVR with mid point may be temporarily replaced with midpoint RVR if approved by the state of the airport.
RVR may be reported by human observation.

That is what we use (international operator).
Not sure what the UK says, I am interested to find out if it is different however.

[Thunderbug]

Del Prado

If they won't give LVP protection I can only fly to CAT1 limits. Either Barometic DA or Radio DH (If published). Usually this is an RVR of 550m.


Che Guevara

There is a post-script which states:

The Unserviceable Facilities tables reflect company, UK & JAA policy. They do not guarantee that any non-JAA state will necessarily offer a CATII or CATIII approach with the defects listed. Where specific rules exist they are published in a seperate manual or Airfield booklet

We also publsihed specific restrictions for operations in the US & Canada.
In the example above for the USA, Mid-point RVR may be substituted for TDZ only on CATI and Non precision approaches. For Canada it is as per JAA.


T'Bug

[Del Prado]

Thanks Thunderbug, so if the RVR was 400 would you commence an approach down to minima or sit in the hold and wait it out?

[Thunderbug]

If they can't give me Low vis protections, then my controlling RVR is CAT1 minima (550m) and with RVR 400m, I am subject to an approach ban and cannot legally continue below 1000'AAL.

Options would depend on circumstances, i.e fuel endurance, wx forecast, etc.

(or they could pull their finger out and give me the low vis protection! )

T'bug

[Che Guevara]

Thunderbug,
Thanks for the information. The post-script mentioned is not in our OMA because although we tend to use JAR OPS, we are not officially a JAR OPS operator (Middle East). We are therefore in a position that we have to look it up in AIP or an airfield booklet etc.

Thanks again for the clarification re. JAR and UK CAA etc.....makes it a bit easier for us.

Cheers

[mcdhu]

There is 1 important point which has not been made yet if you are considering
substituting the Mid for the Tdz Rvr. If you do that, the value on the Mid must be the one you require for the Tdz ie you are only substituting the machine, not the value.

Cheers,
mcdhu

[SIDSTAR]

And for LVO takeoff, the reported RVR (if too low) may be replaced by pilot assessment - count the lights (as long as you know what their spacing is). RVR is only an approximation of the vis along the runway as IRVR is measured by transmissometers that legally are required to be about 100 m from the runway centreline. As we all know who operate in Europe, fog is anything but uniform in its density.

Bring back the guy on top of the truck doing a manual RVR check!

[Thunderbug]

SidStar

Yep, the assesment from the flightdeck rule can be very useful. In MUC last year as we lined up for an evening departure on RW26R the tower said "RVR 300m". Only thing was that we could see the other end of the runway. The heat from the runway was keeping it clear, but the transmissiometer (RVR measuring device) was sat in the patchy fog that was forming over the grass beside the runway.

T'bug