Low Visibility Procedures-A Question
 

At the BAA Airfield I am most associated with, we have Low Vis procedures to implement when the weather gets grotty. This is then broadcast on the ATIS. OKay so far .
However, we only have a CAT 1 ILS. Ergo:
1. How does this impact on Aircraft Operations i.e. what difference does this make "on the flight deck?
2. Shouldn't we forget about doing this and get real as I can't see the necessity with CAT 1 operations?::confused:

LVPs are there to protect whatever operations go on in poor weather. Bear in mind that aircraft can depart in some very poor visibilities (down to 200 m if the runway lighting is good enough as I recall). The LVPs will include safeguards to minimise the risk of runway incursions or an aircraft getting lost on the taxiways in fog and running into another aircraft or an obstruction.

Sorry Spitoon-I wasn't making things clear enough. I know the safeguards are there to protect the runway. I am very much aware of runway incursions BUT what is the impact of Safeguards to Flight Crew-especially under CAT 1 approaches only?
should I perhaps be posting this elsewhere:confused:

Low visibility procedures also require traffic flow rates to be reduced to limit aircraft movement on the ground, particularly where taxiway lighting is limited, so expect delays whether Cat I or Cat III equipped.

Remember that part of the procedures is to protect the ILS critical areas during CAT I, II, and III approaches, which as you know safeguards the pilots from receiving erronous signals.

Mike

Ed Set,

I hear you - what are the implications of LVP's on a CAT I airfield...

At the CAT I airport I used to work at, we never had LVP's, as we were informed that LVP's are only applicable at a CAT II or better equipped airport.

My understanding of this is: How can you sustain LVP's if you do not have Hold/Stop bars, inadequate approach lighting, and probably no taxiway or runway centreline lights. I may be wrong, but in all the CAT I airports I have been at, none have had any of the above equipment. That is just my take on the LVP & CAT I situ.

At my airport now - which is CAT II (used to be CAT IIIa, but was downgraded due to legalities regarding the lack of individually selectable stopbars/holdbars), there are 3 phases of LVP's. Phase 3 is for the worst wx, and there we are only allowed 2 movements at any given time, and if the GMR is u/s, then only 1 at a time.

Cheers
URC

I work at a CatI airport with stop bars,taxiway lights, ctrline lights and adequate approach lighting.
Lvps restrict access by vehicles to the rwy, limit the number of a/c we can have on the move at anyone time, increase pushback restrictions put the AFS on wx standby and increase the spacing between inbounds so that the rwy has been vacated before following a/c reach 4 nm on the approach.

What it means on the flight deck is that atc will not be expecting a/c to do anything expeditious. We`ll put you on the localiser a bit further out and be prepared for you to make a slower approach than normal so we`ll make an effort not to impose any speed control. We`ll probably give you instructions to follow in the event of a go-around but the biggest difference at a CatI airfield is you won`t have as pretty a view!!

Take ABZ. Cat 1 airfield. I am allowed to depart down to 400m without LVP's in force. With LVP's in force, I am allowed to depart in 125m. I have done it too!

No brainer....

Ed set
1) I can depart! On arrivals - Despite having only cat 1 equipment, I am authorised to autoland my aircraft using a cat1 DH/A. As such, knowing when there is less likelyhood of signal disturbance is useful.

2) Sorry dude, I disagree.

That's interesting Cough. I presume those are the JAR-OPS rules. But I think the CAA has - for the last few years - insisted upon LVPs and certain minimum runway lighting if the airport wanted to operate in RVRs of less than 400m

Ed Set,

I think that the most important part of safeguarding, associated with LVPs, which would interest pilots at your Cat1 unit is whether the standby generators have been switched on.

Correct me if I'm wrong but I believe that even at Cat1 equipped airfields, LVPs cannot be declared until all the safeguarding procedures are complete. These can include removing work parties from the manouvering area, blocking off runway access points which don't have stop-bars, lighting inspections etc, but perhaps most importantly - starting up the airfield generators.

The airfield lighting and, in some cases the ILS and other facilities, will run on the generators and instantly fail to mains power if the generators fail. This allows Cough and his mates to hurtle down ABZ's incredibly short runway at 120kts+ in 125m vis, secure in the knowledge that the lights aren't suddenly going to go out!

letMfly

Apart from the obvious advantages in safeguarding facilities like the ILS (especially with E145s!), I think Cough hit the nail on the head with the significant reduction in departure minima when LVPs are in force. I for one wasn't aware of this difference.

If that isn't reason enought for doing it (i.e. keeping stuff moving even if it is just departures at that low viz level), then I dunno what is.

Good 'ole CAP 168 requires a 1-second changeover but there's another way, which we employ at LGW.

We've created a ring main around the aerodrome that feeds the various sub-stations. We also have 2 x 33kvA inlets from different parts of the National Grid, feeding the ring. This is considered sufficiently robust by the CAA that we don't need to fire up the gennies when we start LVPs, providing it's all in place. If there's a break in the ring, then we have to be prepared to start the generators if we want to go into LVPs.

Here's another puzzle for you. When we're Northern Runway, we're purely visual approach off a SRA, terminating at 2 miles. So why do we have LVPs for Northern Runway ops? There's no ILS to protect and only minimal lighting, side lights only on the runway. It's because some companies can depart in 200m IRVR. We can still derive IRVR using a mixture of the transmissometers and Northern Runway side lighting intensity. We provide safeguarding to ensure no physical intrusion is made into the Northern Runway Cleared & Graded Area under such conditions.

Complicated, isn't it?

Cheers,

The Odd One

Cough
 

At last-an answer as to why we declare LVPs. I too wasn't aware of the ability to depart with a lower minima.
Obviously we don't declare LVPs are in force until all safeguarding has been completed AND as you say, the standby generators are up and running.
When next I hear you dashing off in 125 metres (cos I can't see you in that sort of vis) at least I'll know who you are now-and more importantly WHY you can depart.
Many thanks guys-you've made an old man very happy:ok: