Protection during LVP approach

[FourTrails]

Yesterday I was making a CATIIIA approach into UK airport where LVP's where in force. Could some of you kind ATC folk please advise within what range from touchdown the type of protection you are required to provide.

Yesterday, when at 10 DME another aircraft was cleared to enter & takeoff which had been at the CATII/III holding point. This caused noticable upsets on the Localiser and when we got to 4 DME a vehicle was cleared to cross the runway at the upwind end just infront of the LOC antenna. Landing clearance was issued at 3.3 DME.

Thanks

[The Greaser]

2 nautical miles is my guess.

[NudgingSteel]

Different airports have slightly different figures, worked out I guess according to local issues with equipment etc, but the requirement to give landing clearance or go-around instructions by 2 DME is common. (Other guidance might say, for example, a departure must be rolling before the next inbound reaches 6 miles in order to achieve the above).
All ATC procedures relating to LVP ops are pretty rigorous and relate to protection of the ILS for the autoland in the very final phase of approach, whilst also allowing for some traffic flow (albeit very reduced rate).
If the incident mentioned caused concern or a problem, you should certainly file an ASR in order that the procedures can be re-evaluated if necessary. Otherwise if you get the chance to visit the ATC unit, go and have a coffee and a chat; amazing how much useful stuff crops up like this.....

[Standard Noise]

All ATC units specify in their MATS part II what the criteria are for landings in LVP/CATIII conditions and there may well be differences from unit to unit.
At BRS, we have to give a dep. his take off clearance before the next arrival reaches 6nm from touchdown. The dep aircraft must be airborne and have passed the localiser aerial, before the arrival reaches 3nm from touchdown.
This also allows for vehicle movements, as long as the Localiser Sensitive Area (LSA) is vacated before an arriving aircraft gets to 3nm.
We have to issue a landing clearance before the arrival reaches 3nm from touchdown, otherwise, it's a go around situation.

But that's just us, we're picky like that.
It's possible, the rules are the same at the unit you mention.

[flower]

Our procedures are similar to Bristol but differ in that the Take off roll should have commenced by the time an inbound aircraft is 8nm from Touchdown to allow for the outbound to have cleared the ILS antenna by the time the inbound reaches 3 miles from touchdown

[Vlad the Impaler]

At Stansted in LVPs the departure MUST be airborne and overhead the Loc aerial by the time the inbound is at 2NM.

[terrain safe]

At some units the AC can be told to continue approach and expect late landing clearance at 1 mile, but this is only used when things go a bit wrong. By 1 mile or try again....:( :( :(

[ASD]

This may differ from unit to unit agreed.

We have a CAT IIIB ILS and we will not allow a departure if the arriving a/c is within 12nm from touchdown. The chances of a go-around is extremely good in LVP's! As you can imagine this causes a bit of a nightmare for the Approach controller having to sequence traffic with 12 nm spacing on final approach.

We dont allow any vehicle movements in LVP's.

So FourTrails if you were flying into our Airport you wouldnt have had these concerns.

[benedictus]

At Glasgow any departure has to be cleared for take off by the time an inbound is at 6 miles, landing clearance is to be given at 2 miles or a/c told to expect late landing clearance, at 1 mile landing clearance or go around to be given

[nibog]

Not sure whether there is a specific reg dealing with it but..

Any vehicle or aircraft crossing in front of the LOC antenna disrupts the signal. This is especially importand in Reduced Visibility. In my facility guidelines are being published at the moment.

Don't knoe the applicable distance yet, but I expect it will be along the lines of 'Aircraft or Vehicles will NOT be permitted to cross active RWY if ILS inbound is within XX NM'

Landing Clearance usually within 2NM - Less if advised in advance.

[TheOddOne]

ASD,

We dont allow any vehicle movements in LVP's.

So how do you do runway inspections? How do you escort a/c that get lost in the fog? I don't know if you have surface movement radar, but if you do, how do you check out ghosts? How do you check out facilities that show a back-indication of a fault?

Our MATS Part II requires Airfield Ops to mount patrols to ensure that other aircraft and vehicles don't stray anywhere near the Localiser Sensitive Area and in fact we can be as busy on the airfield during LVPs as in Ops Normal. The restrictions are that we have to ask for specific routing instead of being able to freerange when driving closer than a given line to the LSA. Any driver that normally can freerange can ask for a specific route during LVPs.

We too have the 'LSA must be free of a/c and vehicles and landing clearance given at 2 miles' deal. This seems to be pretty standard, but there are interesting variations in some of hte other detail, such as the distance of an inbound when an outbound is over the Localizer aerial.

Another intersting point that cropped up a couple of years ago was the introduction of a Sensitive Area for the Glideslope. This has a curious shape and limits activities on an adjacent taxiway which we have to barrier off to prevent incursion.

Cheers,
TheOddOne

[ASD]

I should rephrase, Vehicles are allowed to operate in LVP's when they absolutely have to... otherwise we keep them off until LVP's have been cancelled.

How can tower visually assure that the runway is clear when you have vehicles all about in LVP's and you cant see anything...

I have had vehicles that have ignored stop bars in the past!!!! If they can do that, they can infringe in the LSA.

We do have ASMI which is mostly unreliable and can only be used for monitoring anyways.

Personally, I rather keep the vehicles away. Maybe its also becuase we only usually get LVPs in the early morning and it doesnt last for too long.