Low vis proc Vs fuel debate?

[alosaurus]

More and more airlines are going down the road of trying to force pilots to carry minimum fuel.
-In the crew room last week a skipper was telling me he had a call from our fleet manager,asking him why he had carried the JAA recommended 30 mins low vis fuel allowance(four pax had to be offloaded)
-Skipper advised that low vis procedures were expected (forecast)at ETA.
-High paid help responds that it is not LVPs which are relevant,but whether conditions at destination will be cat 2 (ie at our landing minima).

Questions
-Is there any technical increase in LVP arrival,departure rates (cat 1 Vs cat 2).
-What are the practical effects of say 600m vs 350M on arrival/departure rates.

Any info would help reduce my fuel diversion rate;thanx in advance.
:rolleyes:

[Warped Factor]

alosaurus,

Questions
-Is there any technical increase in LVP arrival,departure rates (cat 1 Vs cat 2).
-What are the practical effects of say 600m vs 350M on arrival/departure rates.

I'm not sure about your first question. The low viz procedures in use at the airport I work at (and which is the same for all the London airports) kicks in at certain weather minima (IRVR less than 600m, and/or, cloud ceiling 200ft or less) irrespective of the ILS category.

If the weather is somewhere just above the low vis minima, whilst not requiring low vis spacing inbound it is more than likely the tower will want an increase in spacing with a consequent reduction in the landing rate.

As for your second,the answer is probably not a great deal. If anything a reduction at the worse end of the scale.

The minimum spacing into EGLL in LVP's is generaly 6nm which roughly equates to an arrival rate of 24-26 per hour, obviously well down on the usual rates.

What probably is of interest to you is that in LVP's our (London TMA) traffic managers are aiming to contain airborne holding to 20mins. If it slips up to 30mins they are meant to take action to get it back down to 20mins.

So, in theory, once you get to the stack in LVP's you shouldn't have to hold for more than 30mins. 20mins if we've got it right.

WF.

[ 13 December 2001: Message edited by: Warped Factor ]

[Spotter]

We normally use 6nm spacing between inbounds. In LVP's this increases to at least 15nm. Believe me these spacings are just enough to safely get a departure away between 2 inbounds.

Without any inbound traffic, departures would be virtually unaffected.

Without any departures inbound spacing would be around 10nm.

Recently we were holding due to traffic volume without any weather problems. Within 5 mins of entering the hold one aircraft was starting to get itchy about having to divert due to fuel limits.

Before anyone jumps down my throat about company fuel policies & cost & profitability etc just stop for a minute & think. Isn't our number one priority safety? OK so a diversion is no big deal, just a bit of co-ordination to do & away you go.

Let's go back to the above scenario. One of the aircraft on approach develops a problem. At this point whinging about diverting because of your poor fuel planning is really not going to impress. Long haul I could have some sympathy, but on a UK domestic flight this is inexcusable.

Now we all make decisions which turn out with hindsight to have been crap. Hopefully we go on to learn from them & avoid the same mistake again.

Perhaps by reading this you might avoid actually having to make the mistake in order to learn something from it.

There are plenty of reasons why the airport that you fly in & out of all the time with minimal delay might suddenly change without any warning whatsoever.

In the event of radar failure you could go from being 30 miles from touchdown to having to take up the hold number 5 for a procedural ILS approach with 50 minutes to go to your EAT.

Any one of the aircraft ahead of you in the sequence has the capability to block the runway. Is it really worth having to divert just for the sake of 15 minutes in the hold?

Your own aircraft is not immune to technical problems. Do you really want fuel worries as well as finding that you can't get 3 greens?

Please stop to think through the possible consequences of not taking that extra 1/2 hour of fuel. Across your company how many diversions does it take to wipe out the cost saving? You are ultimately responsible for the safety of your aircraft. I am there to help with that, but you also have a responsibility not to KNOWINGLY make my job more difficult than it has to be.

I hope when you read this it is taken in the spirit it is intended. It is certainly not a dig at pilots.

[1261]

Our situation at EDI is the same as that described by FIS above, except that in poor weather most pilots want to backtrack for departure. Depending on the wind, that can mean 25Nm gaps for arrivals - bear in mind that from the Tweed hold to touchdown is around 35Nm (track), and you see the problem.

We're all aware of the commercial pressures that you guys are under - believe me we are under a similar pressure from BAA to shift the traffic.

I would point out, however, that it's none of my business how much fuel you carry. If you want to divert to Glasgow, it's no skin off my neck - it most circumstances it takes one phone call and you're off to 119.1. Marvellous! Notwithstanding that, unless you declare an emergency, you wait your turn in the queue.

When this situation arises at EDI it's always the same airlines who don't have enough fuel to hold. In fact it's usually only one airline that ever diverts - I won't name them but it might not be who you think!

[cossack]

I'll give you a few bits from the Manchester procedures...

LVP alert: When IRVR is 800m and forecast to deteriorate or the cloud ceiling is 300ft and forecast to deteriorate, reconfiguration to single runway operations is to commence. No effect on movement rates.

LVP cloud: Cloud ceiling 200ft or less, IRVR 600m or greater.
Presently we can continue to depart aircraft that have already crossed 24R, from 24L, but will be reconfiguring to a single runway operation. Not available on the 6's due CAT 1 ILS. Inbounds will be switched to 06L straight away. Runway entry at the full-length point only from CAT3 hold (longer taxy time), all exits available. Reduction in movement rates - arrival spacing 8 miles. Landing clearance ideally given by 3 miles but must be given by 2 miles from touchdown. Practically 60+ on dual ops to nearer 40 per hour.

LVP vis: IRVR less than 600m.
Single runway operation. Entry to the runway at full-length only, from CAT3 hold (longer taxy time). 24R exit at BD and A only. 06L exit at JB ang J only. Landing clearance ideally given by 3 miles but must be given by 2 miles from touchdown. Arrival spacing of 10 miles gives movement rate of about 30 per hour.

Block system: IRVR less than 400m. Only one aircraft is permiited to be moving within a taxyway block i.e. between two lit stopbars. An aircraft holding at a stopbar is considered to be moving. In this situation the number of aircraft that can be accommodated on the ground is less than the runway can accommodate. Therefore a further reduction in landing rate will occur. Inbound spacing may be increased to 12 miles or more. Movement rate will therefore reduce to 24 per hour or less.

I hope this helps.

alosaurus - drop me an email if you want to have a look around. You'll be made very welcome!

[Gonzo]

At Heathrow:

Basically it's either Cat 1 or Cat 3 from our point of view.

As soon as the viz drops down to 600m, then we're into LVPs. 6 mile spacing on arrivals, and on departures what would have been a 'wheels up' split now has to wait until No.1 gets past the far end localiser aerial. However, the departure rate drops significantly because of the ability of Ground to shift traffic using only a surface movement radar that is really very poor, especially in heavy fog and heavy rain (doh!!!). And of course, Multiple line ups are not allowed, because we can't see you!

The difference between 600m and 350m?
The only one I can think of is the arriving aircraft will be able to vacate the runway and Localiser Sensitive Area quicker due to the greater visability, and thus go arounds are less likely.

Gonzo.

[HalesAndPace]

Tell fleet manager to put his ideas in writing so that you can forward them to CAA!!! :D

[alosaurus]

Some good info there guys-thanks.
FIS-Totally agree with your reasoning.My last sentance was intended to stir a response(I posted this in the questions forum and got next to nothing).I needed some hard facts regarding movement rates so that when the phone call comes,as it probably will this winter,I can educate our Fleet Manager.I have always carried 30 mins extra fuel when LVPs are forecast;in the absence of quality information though some pilots will defer to management.Oddly enough the last time I came into your forum it was to discuss a diversion.Good WX day,took more than 20 mins extra fuel,Ryanair burst a tyre and blocked Manch 24R-if I had been carrying 30 mins of fuel it would have saved the company >£1,000.It is,however,in our ops manual that we carry only enough fuel for one approach,a go around and immediate diversion(CAVOK days).If all aircraft approching Manchester that day had been operating on a minimum fuel basis there would have been chaos.Fortunately few of us ever KNOWINGLY make any of our jobs more difficult than they already are and do carry some extra fuel.

1261-Do they fly to Paris and BHX in 145s?

Cossack-Nice to hear from you again.Interesting that there are effectively three categories of LVP,this kind of info helps to establish our fuel requirements on a more scientific basis.I am returning from AMS at 10:35 on 17/12/01 (Mon)to check in for a positioning flight BA1606 at 12:15,could you fit me in between those two?

HalesAndPace-Our management are not yet able to write,they have just found out how to read though,and do "KNOW WHERE I LIVE"(maybe I should edit some of this...nah.

To check my understanding then,is it fair to say that if LVPs are in force(and the vis is less than 600M)arrival rates will roughly be halved (more than 60 to less than 30)? :)

[cossack]

alosaurus

No problem. Phone the Tower Supervisor, he'll be expecting your call. We'll make sure the AMS gets in OK and the CDG gets delayed a bit! :D I'm sure the French will take care of that for us! :D

At MAN, 60+ was the overall rate not just arrival! We aim for about 32 arrivals per hour in normal ops and 15 per hour in less than 600m but more than 400m. Below 400m its about 12 per hour.

BIG difference!
See you Monday :)

[Gonzo]

alosaurus,

I think halving the movement rate is a good rule of thumb.

Gonzo.

[1261]

Alosaurus; you may speculate about the airline in question, but I couldn't possibly comment :)

All of the above seems to be pretty standard MATS Pt1 stuff as far as the minima and procedures are concerned; what will surely vary is the limitation imposed by the infrastructure at a particular airfield. Therefore it is important to consider the specifics of the destination, rather than just a blanket set of figures.

[alosaurus]

1261-The 60 reducing to less than 30 example related WFs post (EGLL).I was looking for ballpark reductions in movement rates to quote to our high paid help.Have to agree though some destinations(like EDI/easterly day in the AM rush) may demand more than the standard half hour.
Bad news,our hot of the press ops manual revision says:-
"ATC DELAYS MAY CONTINUE AFTER CAT 2 TRAFFIC FLOW RESTRICTIONS HAVE BEEN REMOVED AND YET THE CONDITIONS ARE STILL CAT 2.ALLOW AT LEAST AN ADDITIONAL 30 MINS HOLDING FUEL FOR DELAYS TO THE TERMINAL AREA"
-How can you lift CAT 2 flow restrictions when conditions are still CAT 2??????
-The mention of CAT 2 flow restrictions suggests that the implications of 600M vis on flow rate is not fully appreciated.
Looks like I may have to try and scrounge a copy of the relevant MATS part 1 from the tower tomorrow. :rolleyes:

[Warped Factor]

alosaurus,

Was going to e-mail you some stuff but no address available.

If you want, drop me an e-mail address to the one in my profile.

WF.

[alosaurus]

WF and Cossack thanx for the additional info I'll let you know how it goes. <img src="wink.gif" border="0">