NormalSpeed From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 11 months 3 days 13 hours ago) and read 3433 times:
The clearance limit in the IFR clearance is the point to where the flight is cleared to. For example, if the controller clears you to the destination airport, then you know that you are cleared to fly all the way there. Sometimes, the controller will clear you to an intermediate fix, to hold until a clearance to proceed is recieved. The reason for this is traffic sequencing. And, in the event of a lost comm, then you know where to hold and when to leave that fix (because when you are cleared to an intermediate fix, the controller gives you an EFC, or expect further clearance time). Sometimes, the controller will clear you to an intermediate fix, and then give you further clearance while you are enroute to that fix.
A controller will rarely specify the entire route in the IFR cleareance.
Mb339 From Italy, joined Jun 2001, 238 posts, RR: 3
Reply 4, posted (12 years 11 months 2 days 16 hours ago) and read 3343 times:
Thanks for your replays, but I have another question.
Here a clearance example:
AZA200, cleared to LIMC, Compton 3G departure, then Strumble, climb initially to 6000 feet, squawk 3451.
I suppose that the ATC says nothing about a new route once the aircraft is airborne, when the plane is over Strumble, the flight is automatically cleared to reach LIMC via the flight planned route, isn't it?
NormalSpeed From , joined Dec 1969, posts, RR:
Reply 5, posted (12 years 11 months 2 days 12 hours ago) and read 3318 times:
"AZA200, cleared to LIMC, Compton 3G departure, then Strumble, climb initially to 6000 feet, squawk 3451.
I suppose that the ATC says nothing about a new route once the aircraft is airborne, when the plane is over Strumble, the flight is automatically cleared to reach LIMC via the flight planned route, isn't it?"
I would assume so. However, I'm not sure how things work over in Europe - I only know the US methods for that. But it would seem if you were only cleared to Strumble, the controller would have specified that in the clearance limit. "AZA200, cleared to Strumble, Compton 3G departure..."
An amended clearance in the US would go something like this:
"N1234A, cleared to the Las Vegas airport, Sevier1 departure, Milford (VOR), then as filed. Climb and maintain 12,000, contact departure on [whatever frequency], squawk 2398."
(An amended clearance is when the controller changes, or amends, your filed route of flight.)
B747skipper From , joined Dec 1969, posts, RR:
Reply 6, posted (12 years 11 months 2 days 6 hours ago) and read 3301 times:
Dear Mmb339 -
Issue of a departure clearance is very much like you describe it, and the route and levels to be flown are as filed on the "paper document" of which the crew receives a copy, as part of their "CFP" computer flight plan...
Like others mention here, this is a rather simple thing in the USA/Canada airspace, as well as in EU airspace... in some areas of the rest of the world, this can create a few problems... I have flown in the whole entire world, and am extremely familiar with some problems...
As an example your departure clearance has "cleared to...", generally your destination... some routes I have flown, present further problems... suppose you operate from Roma, to Johannesburg... Initially, you fly the departure, enter into the Malta airspace, no problem... then Malta ATC asks an estimate for "SARKY", a waypoint on the route which is the boundary of Malta and Tripoli airspace... The reason Malta ATC asks your estimate, is so that they can make a phone call (or type a telex on AFTN lines) to advise Tripoli ATC that "Flight XYZ123, estimates SARKY at 22:13, FL 330..."
Between Roma and Malta, never a problem, good communications (and radar often available) but what of Tripoli... maybe Malta was unable to advise Tripoli of your estimated time and flight level to enter their airspace, their only responsibility is to "feed the traffic" at appropriate levels, and separated or, "metered" so that planes are separated by 15 or 20 minutes as they would require in Tripoli's airspace...
Suppose Malta is not succesful to advise Tripoli... the result is, to enter Tripoli airspace, it is better to call them by radio, some 10 minutes in advance, and give them your estimate, and flight level... If no contact with Tripoli, well... hope for the best... but even if the clearance "limit" is your destination Johannesburg, in practice, your "practical" clearance limit maybe the next boundary entry checkpoint, unless you want this 747 to get to tangle with some Lybian jet fighters eager to practice interceptions...
Knowledge of routes and applicable communication procedures for the route are paramount for international flights. It is never a problem in Europe, in North America and Atlantic routes, which are well regulated and controlled with excellent communications, but with many parts of Africa, of Asia and some areas of South America present real problems, and only route familiarity and experience of flight crews are compensating for poor communications...
One such complicated area is the Turkish boundary with Nicosia airpace, which is also claimed by the North Cyprus Turkish sector, people who refuse to communicate with each other... and throw in the communications with Damascus or Beirut control which is nearby...