View Full Version : LVP and CAT1
8th Aug 2012, 13:17
What is wrong with this:
I am approaching an airfield as the weather bombs, and we go around from CAT1 minima. The ATIS then starts to say LVP in force, but still RVR1100m and F003. I am told to wait 20 min for CAT2 to come up. 2 aircraft arrive and they hear only that LVP is in place, and do successful (presumably CAT2?) approaches. I start the approach and stupidly ask, to be told still no CAT2. We go around from CAT1 minima again and divert.
Can anyone tell me:
- Does LVP assure CAT2 is available, or can LVP be announced and in force before the CAT2 is available? (ie can you have LVP with CAT1 only)
- Is there any requirement in Asia for the Tower/ATIS to tell you if CAT2 is operating, separate to LVP?
8th Aug 2012, 14:39
LVP's can be in force for CAT II, CAT I or even non precision approaches. What it does is it affects how the airport is managed, spacing between aircraft, ground movements, etc. It doesn't depend on what approaches are available.
Approach or radar will tell you what approach to expect. If they said it was CAT I only, then that's what you have to plan against.
Out of interest, why had you gone round twice? Was the ATIS lying? 1100m and F/300 is good enough for a VOR approach!
I don't know about UK, let alone Asia, but if can take at least 20 minutes for a full LVP to be enforced, often involving aircraft moving to other stands if they infringe the zone, as at LGW.
8th Aug 2012, 16:06
The problem with LVPs is that they mean different things to different people. I don't think there is any harmonised or standardised definition of what LVPs are.
I am Europe-based but what LVPs mean is that some measures have been put in place to protect operations that can take place in the prevailing weather conditions. There is an assumption that where a cat II/III approach is available and LVPs are declared to be in force, then the ILS will be protected to support cat II/III operations. Certainly in most pilots' minds this seems to be the case. At airports I have done ATC at - all in the UK - this was very definitely the case because the regulator did not accept anything different. And it's probably a valid assumption in most parts of the world and at most airports.
Be aware also, it's not really an ATC thing - technically it is for the aerodrome operator to manage LVPs.
Just to give you an idea of some of the difficulties, some airports introduce special procedures and restrictions for ground handlers and other ground-based activities when the weather deteriorates below certain criteria (although not as low as cat I minima) so that the necessary protection required can be introduced more quickly if/when it is needed. These restrictions are commonly referred to as LVPs and there has been at least once incident where a handler told an inbound crew that LVPs were on when the ILS very definitely was not suitably protected for cat II/III. As I recall, the aircraft was well down the approach before the true situation became clear to the crew.
9th Aug 2012, 03:37
So from the above its seems like:
- LVP is operation doesnt mean LVO
- But LVP in operation frequently implies LVO allowed, esp in Europe
- The controllers should tell you what approach to expect (but do they?)
In the above situation, the 1100m F003 was actually rapidly decreasing to 700m VV001. My first approach was B002 with about 850m (from looking out the window). 2 other aircraft were then cleared the ILS. But the fact they heard LVP in operation meant that they assumed that CAT2 was in place. In reality it was not. There was no mention of CAT2. From my experience 3 mins behind them, I think they went to 100ft, since at 200ft there was nothing to see anymore....
9th Aug 2012, 05:13
Right, finally getting to the bottom of this:
Getting to Grips with CATII (section 3.3.2) says:
Unless LVP are reported active by ATIS, clearance to carry out a CAT II or CAT III approach must be requested from ATC, who will check the status of the ILS and lighting and protect the sensitive areas from incursion by aircraft or vehicles. Such an approach may not be undertaken until the clearance has been received.
Getting to Grips with CATII (section 5.10.2 - ATC clearance) says:
Clearance to carry out a CAT II or III approach must be requested from ATC, who will activate the Low Visibility Procedures, i.e. prepare the airfield and assure appropriate aircraft separation. Such an approach may not be undertaken until the clearance has been received.
So Airbus itself isnt clear. Do you need to request CAT2 under LVP or not? :confused:
My understanding is that you are 'technically' required to request a CATII or III approach because of increased spacing requirements etc although once the airfield actually drops below CATI weathe, and CATII/III is operative this is a moot point.
Need an ATC comment, perhaps? It sounds as if ATC at that airfield were remarkably slow to notice the weather deterioration. LVP/CATII should have been in force well before your approach unless the weather was un-forecast and there were no obvious trends.
Sir George Cayley
9th Aug 2012, 12:19
The ILS radiates a signal regardless of weather conditions. An ILS installation that is approved for CAT lll approach operations is de facto also of the appropriate integrity for CAT ll and CAT l.
Coming from the other direction an ILS certified for CAT l will more than likely not have the integrity to facilitate lower minima.
On the airfield certain lights have to be available for ILS approaches from the full 900m coded 5 bar with Supps and TDZ. CAT l lighting is less extensive; all of this is spelt out in our favourite bed time read - CAP168. There's also a description of Low Visibility Procedures (LVPs) required in order to mount Low Visibility Operations (LVOs)
Once the weather starts to deteriorate (not a surprise cos it was in the TAFs) ATC should ask Ops to commence safeguarding. This should be in place before the RVR hits the trigger point for LVOs to start.
Once safeguarded ATC should then take measures to ensure continuity of electricity supply and look for the "LVP available" tell tale.
I've never come across a situation where ATC have been involved in permitting different types of approach. If the ATIS declares LVPs in force it's up to each crew to refer to SOPS and decide if they can commence an approach.
It may be different abroad but that's been my experience of operating at UK airports.
20th Aug 2012, 16:08
There is only one official LVP definition by ICAO, for EUR region in ICAO DOC 013 :
Low Visibility Procedures (LVP): Specific procedures applied at an aerodrome for the purpose of ensuring safe operations during Lower than Standard Category I, Other than Standard Category II, Category II and III approaches and/or departure operations in RVR conditions less than a value 550 m.
20th Aug 2012, 16:28
ICAO has define LVO in PANS ATM (DOC4444) as :
7.12 PROCEDURES FOR LOW VISIBILITY OPERATIONS
7.12.1 Control of aerodrome surface traffic in conditions of low visibility
Note.— These procedures apply whenever conditions are such that all or part of the manoeuvring area cannot be visually monitored from the control tower.
Additional requirements which apply when category II/III approaches are being conducted are specified in Section 7.12.2.
LVO means that ATCOs can no more rely on their outside sightseeing to apply aerodrome control service and shall work with a kind of procedural orgnisation depited in the ICAO SMGCS manual ( SMR is an adjunct, not a replacement for visual sightseing : ICAO ATS Manual)
Then the "additional requirement" correspond more or less to the Low visibility procedures as published in ICAO DOC 013.
The ICAO LVP Project team is updating this document to introduce new type of approaches ( "better than", "Less than..") and the use of A-SMGCS. The next step will be to expand the EUR document to a PANS Level and suppress a lot of inconsistencies that still exist to day between different documents.
PS/ Decision to launch LVP is an ATC role. Then depending to the airport organisation,some contingencies are in ATC or Airport hands (including Met )