ATC clearance limits

[tubthumper]

This may seem a bit pedantic to some, but here goes....

MATS 1 says we shall clear an aircraft all the way to its aerodrome of first intended landing when its planned route will keep it in controlled or advisory airspace etc.

A clearance limit must be given by specifying either a reporting point, an airspace boundary, or an aerodrome.

If the destination aerodrome is outside controlled/advisory airspace, how do we, as ATCOs, know where to clear the aircraft to? I keep finding myself with IFR departures going to places I've never even heard of, never mind Knowing if they have their own control zone or not.

I would value other folks' opinions and views on the matter.:ok:

[Spitoon]

You'll have to be a bit more specific.

Are you at an aerodrome? If so, does it have any airspace around it? And is that airspace connected to any other airspace?

Is the clearance one that has been issued by another agency and you are just passing on?

Where are these places that you've never heard of?

If you're at a centre, you're only clearing it through your area of responsibility so it's not really the same question.

Once you've answered some of these questions people may be able to give you the book answer and, perhaps, explain what happens in practice and why.

[Lock n' Load]

You clear it to...
a) destination aerodrome if inside controlled or advisory airspace, or
b) leave controlled airspace, or
c) an international FIR boundary.

[tubthumper]

Fair point, perhaps I was a bit too vague.

I'm talking specifically about aircraft departing from an aerodrome in class D airspace straight into the UK airways structure. However, the destination may very well be some small airfield in the open FIR. My point, all be it a bit poorly made, was that if I know his destination is outside controlled and advisory airspace, how will I know what his clearance limit should be?

It might be a bit pedantic, but MATS 1 does make it clear that the clearance limit is mandatory.:O

[Legs11]

further evidence that MATS part 1 is not written for the benefit of those working outside controlled airspace:confused:

[Lock n' Load]

I thought I already told you but....
Here was the situation at EGPH when I worked there, with Loganair SF34s going to Inverness. During the week they'd file via and fly via an advisory route.

"LOGxxxB, cleared to Inverness, Grice 3C departure, squawk xxxx."

At the weekend, they'd go direct.

"LOGxxxB, cleared to leave controlled airspace north of Grice, Grice 3C departure, squawk xxxx."

[5milesbaby]

I think I get the gist of the question but do not have the answer.

If you are sat in Gatwick tower with a Global Express for example that wants to depart to some outback place no-one knows in South Africa, how can you give a clearance limit? How can you clear the aircraft to destination when you have no idea if the destination is inside CAS, or 50 miles outside, "BOKKY" rp being the last point inside?

Alternatively how can any ATCO giving a clearance to Southampton from an airfield south of the UK know that NEDUL is the clearance limit?

I have a feeling that the clearance limit is in the SID if one is given, and that subsequent ATCO's enroute give further limits, although I believe that the UK is one of the only places to give the full extent of routings that we do.

Thats my guess - NEXT!!

[Goldfish Jack]

Well from some place in South Africa, aka Cape Town, and it is sometimes is in the outback I can tell you that (!), ICAO ATM says: PARA 4.5.2.: "When a flight plan specifies that the first portion of a flight will be subject to ATC, and that the subsequent portion will be uncontrolled, the aircraft shall normally be cleared to the point at which the controlled flight terminates."

But, of course, where does the flight leave controlled airspace you say? Further on, para 4.5.7.1 says "If an aircraft has been cleared to an intermediate point in adjacent controlled airspace, the appropriate ATC unit will then be responsible for issuing, as soon as practicable, an amended clearance to the destination erodrome. When the destination aerodrome is outside of controlled airspace, the ATC unit responsible for the last controlled airsapce through which an aircraft will pass shall issue the appropriate clearance for the flight to the limit of that controlled airspace.

So I suppose the whole thing goes about successfully co-ordinating the flight ahead of its time, with the next ATCC...

[tubthumper]

5milesbaby, thanks. That's exactly the point I was trying to make. In which case, like you say, if the aircraft is departing from an airfield in controlled airspace on a published SID, is the SID a sufficient clearance limit?

[MrApproach]

In Australia we do the same as Tubthumper, that is clear an aircraft to it's destination. I think what is intended is that we (ATC) are "accepting" the pilots planned route and levels at that point in his flight. Bearing in mind that flight plans may be continuously amended by ATC as the aircraft flies along, the Tower has only initiated the process. As far as leaving controlled airspace, or leaving and re-entering, the Australian AIP makes it quite clear what the pilot's responsibilities are. Having said that I travelled on a US DC10 into Cairns, Nth Queensland once and the pilots were given a clearance limit. Not only did they not understand what it meant they assured me that Honolulu Tower had cleared them all the Cairns, Australia!

Sorry that should read "all the way to Cairns, Australia"