LARS vertical limits

[FullyFlapped]

Anyone know what the vertical limit is for LARS services ?

An on a completely unrelated subject, at FL100 over Carlisle on Thursday, I could hear an aircraft talking to Cambridge ... does anyone know what met conditions are optimum for this sort of thing ?

Cheers,

FF :ok:

[PPRuNe Radar]

Generally FL95. Local restrictions may apply but will be notified.

[Keef]

VHF Radio horizon... (HF is very different):

Under normal conditions (whatever that is), the radio horizon in nautical miles is 4/3 times the square root of the height in feet.

If you are at 10,000 feet, your radio horizon is 133 nm. If the other bloke is at 3600 feet, his horizon is 90nm. Between you, you have a theoretical range of 223nm.

Signal strength drops off with distance, so he'll be faint if he's a long way away.

Atmospheric conditions can do strange things to that - I've contacted amateurs in Northern Sweden, around 1,000 nm away, on VHF with an antenna at 40 feet at my end. That doesn't happen often.

Some VHF ATC stations operate "bandboxed" - covering more than one frequency. Sometimes they retransmit the signal they are hearing - so what you think is someone far away is actually that signal being retransmitted by the local London Info.

[Pierre Argh]

Forget the maths, the answer is defined....

LARS = Lower Airspace Radar Service.

Lower Airspace (in the UK) = up to FL100

Simple answer for upper limit (unless regulated airspace gets in the way)

Lower limit is not defined, but obviously you need to be in cover. Service may be limited at low level and RAS (available for IFR flights only) may take terrain clearance issues into account, establishing a safe minimum altitude below which that service is not available

(All subejct to locally specific limitations... but this is the basic principle)

[FullyFlapped]

Thanks all ...

FF :ok:

[aluminium persuader]

Above FL100 London Mil will work you unless they're extremely busy. The bigger/faster/higher you are the more interested they are.

[Pierre Argh]

AP

True to a point... but at FL100 or above it's not called LARS, nor strangely MARS? Probably because LARS was a concept introduced in the 70s when transit services were only available from area radar units, but it was recognised that there was a growing need for a service "down among the weeds"... and as most airfields now had, or were getting radar, they were volunteered.

(PS: London (Mil) is no longer called London (Mil) anymore, since the move to Swanwick... hard to keep up, isn't it?)

[London Mil]

Pierre, thanks for telling me that niether I, nor the 140 people I work with, still exist. Maybe we should all go home and forget the entire East side of England and a fair amount of the North Sea? Furthrmore, frequency 135.275 as indicated in the AIP (ENR Page 1-6-4-1) must also be a complete work of fiction and I will write, immediately, to the CAA informing them that their docs need amending.

To be correct, military middle air services are currently available from 3 units - ScATCC(Mil), Swanwick(Mil) and London(Mil). The delineation is, roughly, ScATCC North of Newcastle, London East of the "Alpha's" and Swanwick everything else. Our little lot at West Drayton (which includes an insignificant organisation known as D&D) wil move to Swanwick at the end of 2007. Until that date, and possible beyond, I suspect that London (Mil) still exists.

Keep up:p

[Pierre Argh]

Ahhh my Sarcasm alarm has sounded.... Mr Mil please accept a sincere apology someone based largely on the West Side, for what was an honest late-night oversight.

However... on a private flying forum I think the question of Military Middle Airspace Service may be irrelevant; and there is at least one more unit that routinely provides service above FL100... Plymouth (Mil) and maybe Brize still do?...but I wouldn't want to get into point scoring?

One question, how on earth did you find another 139 people who actually work at West Drayton? ...keep up the good work.

[London Mil]

Good question, well phrased. I was merely correcting an inaccurate statement.

Spooky that Proone is occasionally misleading............