Fog

[lotus1]

With the currant weather conditions could some one tell me does airports like gatwick Heathrow charge airlines for the use of ILS System when this happens with aircraft nowadays with there Computer systems so advance does this happen?

[Groundloop]

Aircraft use the ILS for virtually all approaches at Heathrow and Gatwick regardless of weather. There is no extra charge.

[DaveReidUK]

They used to charge for it, but found that they needed detector vans because airlines claimed they hadn't used it even though they had. :O

Joking aside, MLS (microwave) and RNAV approaches are gradually supplanting ILS, though the latter will be around for a long time yet.

[Hotel Tango]

Currant weather can interfere with the beam though! :cool:

[kcockayne]

Raining dry grapes, is it ?

[RexBanner]

MLS (microwave) and RNAV approaches are gradually supplanting ILS, though the latter will be around for a long time yet.

If gradually supplanting ILS means at an absolute snail's pace then I'd tend to agree with you but, in reality, the only true statement there is the second. As you know, RNAV approaches are nowhere near as accurate in terms of altitude, which is why they have higher minima and decision altitudes. Additionally, funding for the MLS is rumoured to be about to be discontinued at Heathrow.

[HEATHROW DIRECTOR]

<<Currant weather can interfere with the beam though! >>

Really.... do tell.

[ShyTorque]

What is the raisin for asking?

[PAXboy]

To be serious for a moment - the reality that this fog shows up is the changing climate. Ignore, for a moment why it is changing.

We normally get fog in November, as the still warm land is covered by cold moist air. The fact that it happened in late December is a significant change. If happens like this for more years it helps to show how we have to be ready for the changing climate.

[Yellow Sun]

Err... I think that's the wrong way around:

Advection Fog. Forms when quite warm, moist and stable air is blown across a cooler surface (land or water). The air temperature falls until the dew point is reached and condensation occurs.

Typically occurs in the UK with a relatively warm SW airflow (nice long sea track to pick up moisture in the lower layers).

[RAT 5]

Use ILS in FOG = land therefore a landing fee. No ILS in a/c = divert = no landing fee at intended destination. However, airfield A has same landing fee in CAVOK, and even if you make a visual(are there still pilots who can do that????). I suspect airfields with an ILS charge more for landing than those without. Someone has to pay for it.

[PAXboy]

OK!! No worries about the manifest ways that fog can be generated. The point was that, whilst we have been used to fog from November onwards (on the roads as much as the airports, of course) I think it unusual to not have had serious fog until xmas.

[noflynomore]

my recollection for bad fog was spring and early summer rather than winter.

[PAXboy]

My recollections of fog were for Spring and Autumn when the seasons change. Hence my remark that FIRST big fog of the seasons arriving in late December - is unusual.

[Hotel Tango]

my recollection for bad fog was spring and early summer rather than winter.

I can recall many pea soupers from anywhere in late October to early December many many moons ago. Whatever, it certainly is not limited to Spring and early Summer.

[PAXboy]

Indeed. But I am used to hearing of fog, canx flights and crashes on motorways earlier than this time of year.

[Gonzo]

MLS is not supplanting ILS, in fact MLS will be dead and buried within a few years. It's not that funding is going to run out, it's that nobody manufactures the system any more, and the current one is about to reach it's end of life. The main benefits of MLS (smaller sensitive area in CAT II/III ops) have largely been replicated by the new 32-element array ILS localiser antenna on the market now anyway.

A standard RNAV GNSS (APV Baro VNAV) approach can't get to the same decision height as a CAT I ILS, so that won't do it either.

GBAS will, especially when CAT III certification is granted.

However, even new aircraft coming out of the factories now are noit fitted for GBAS, so ILS will be around for another 30 years at least.

[chevvron]

MLS is not supplanting ILS, in fact MLS will be dead and buried within a few years. It's not that funding is going to run out, it's that nobody manufactures the system any more, and the current one is about to reach it's end of life. The main benefits of MLS (smaller sensitive area in CAT II/III ops) have largely been replicated by the new 32-element array ILS localiser antenna on the market now anyway.

On my NATS Staff Course in 1986, we were told no new ILS' were to be commisoned after about 1992 and old ones would be phased out in favour of MLS'.
Based on this, we decided not to go for ILS at Farnborough but go straight for MLS. In the interim, until a 'rich' civil operator took over the airfield, we toyed with another much cheaper system called 'TLS', a transponder based precision guidance system which, as it had been approved by the FAA, the CAA said they would 'rubber stamp'.
As soon as it was installed, the CAA decided it would need 5 years of evaluation before they could approve it for IFR use!!
So Farnborough ended up with ILS after all, with some operators cleared to operate to less than Cat 1 minima ie RVR 300m.

[Denti]

GLS/GBAS could probably replace the ILS at some point. I have seen some trial approaches for CAT IIIb operation and it is a very impressive system. Currently only approved for CAT I though. Not to mention quite a bit cheaper than an ILS for every runway direction, especially for airports with several runways.