LVP - CAT II | CAT II etc.

[HB-UAE]

Hi everyone,

I've just had a very energetic discussion about vertical visibility. If you were to have a cloud sitting right over the beginning of your landing runway, visibility is RVR values all 1500m or more, but you have a vertical visibility at the THR of your RWY of 200ft, what would this mean to you?

I'm really looking forward to hearing your answers.

Thanks

HB-UAE

[kenparry]

First, I think you need to clarify your question. Under whose rules are you operating? What type aircraft?

Presumably ILS, as you are talking about LVP. AFAIK vertical visibility is not measured, so cannot be reported.

If the RVR is 1500+, then under JAR-OPS there is no approach ban for a Cat I ILS (RVR required typically 550m) so you can make an approach. If you see nothing at DH you go around. What's the problem?

[Artificial Horizon]

Answer really depends on when the airfield deems it appropriate to activate 'LVP's'. At my home base LVP's are started when either the RVR reduces below 600m or the cloud base reduces below 400' AGL (due to the tower being so high up!!). Until LVP's are in force then CAT 1 all the way, if LVP's are in force with a cloud base of 200' then I would opt for a CAT II/III approach to avoid an unwanted go-around. If in you example the 200' cloud base is truely only over the approach runway it may take a few go-arounds from CAT I for ATC to start LVP's, of course nothing to stop you asking for it as well.

[GlueBall]

Universal standard for a CAT-I approach at DH [typically 200 feet AGL] if you can see the approach lights, but not the threshold just yet, you may continue the descent over the lights to 100 feet, at which point you must see the runway or execute a go-round.

CAT-II DH 100'
CAT-IIIa Alert Height 50'
CAT-IIIb Alert Height 20'
Radar altitude height as measured from extended landing gear to ground.

[wiggy]

"Universal Standard"? there's no such thing, ultimately it depends on your own Ops Manual. No mention of 100 feet in ours.

[Clandestino]

If you were to have a cloud sitting right over the beginning of your landing runway, visibility is RVR values all 1500m or more, but you have a vertical visibility at the THR of your RWY of 200ft, what would this mean to you?

Nothing meaningful, I'm afraid.

If LVP CAT II are active, then it would be CAT II. If not, ceiling and VV are not considered limiting for commencing CAT I approach and we'd do cat I.

[Mansfield]

The presence of a vertical visibility observation would indicate an obscuration, and the lack of a ceiling. But ceiling isn't controlling, so the RVR would still be the critical factor. While vertical visibility is an estimate based on looking up into nothing, RVR is a measure of seeing conditions with respect to all of the visual aids, particularly runway lighting. Quote from the FAA Air Carrier Inspector's Handbook:

RVR is an instrumentally-derived value that reflects an artificially created seeing condition on or near the portion of the runway associated with the RVR report. This artificially created seeing-condition is achieved by using high intensity runway edge, TDZ, and centerline lights.

[GlueBall]

wiggy: Just curious: What exactly must you see at DH [CAT-I, 200'] according to your ops manual in order to continue the approach?

Are you saying that if you only see the familiar approach lights, but not the threshold/pavement at DH 200' that you must go-around?

[FE Hoppy]

3. Visual reference. A pilot may not continue an approach below the Category I decision height, determined in accordance with subparagraph (c)2. above, unless at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot:
(i) Elements of the approach light system;
(ii) The threshold;
(iii) The threshold markings;
(iv) The threshold lights;
(v) The threshold identification lights;
(vi) The visual glide slope indicator;
(vii) The touchdown zone or touchdown zone markings;
(viii) The touchdown zone lights; or
(ix) Runway edge lights.

Your company ops manual may be more restrictive.

[411A]

"Universal Standard"? there's no such thing, ultimately it depends on your own Ops Manual. No mention of 100 feet in ours.

Standard for TERPS ops, different for PansOps.

[Henry VIII]

EU-OPS 1.405 Commencement and
continuation of approach

(a) The commander or the pilot to whom
conduct of the flight has been delegated may
commence an instrument approach regardless of the
reported RVR/Visibility but the approach shall not
be continued beyond the outer marker, or equivalent
position, if the reported RVR/visibility is less than

the applicable minima. (See
[EU-OPS 1.192].)
(b) Where RVR is not available, RVR values
may be derived by converting the reported visibility
in accordance with Appendix 1 to EU-OPS 1.430,
sub-paragraph (h).
(c) If, after passing the outer marker or
equivalent position in accordance with (a) above, the
reported RVR/visibility falls below the applicable
minimum, the approach may be continued to DA/H
or MDA/H.
(d) Where no outer marker or equivalent
position exists, the commander or the pilot to whom
conduct of the flight has been delegated shall make
the decision to continue or abandon the approach
before descending below 1 000 ft above the
aerodrome on the final approach segment.

If the
MDA/H is at or above 1 000 ft above the
aerodrome, the operator shall establish a height,
for each approach procedure, below which the
approach shall not be continued if the
RVR/visibility is less than the applicable minima.
(e) The approach may be continued below
DA/H or MDA/H and the landing may be completed
provided that the required visual reference is
established at the DA/H or MDA/H and is
maintained.
(f) The touch-down zone RVR is always
controlling. If reported and relevant, the mid point
and stop end RVR are also controlling. The
minimum RVR value for the mid-point is 125 m or
the RVR required for the touch-down zone if less,
and 75 m for the stop-end. For aeroplanes equipped
with a roll-out guidance or control system, the
minimum RVR value for the mid-point is 75 m.
Note. “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 knots.