Clearance Delivery

First Post. I've been controlling for Vancouver FIR for about 10 hours now, and at this point I qualify to operate the Clearance Delivery position. Like in all of VATCAN's member FIRs, a controller starts out small and works his or her way up through a combination of training, practice, observation with an instructor, and passing grades on examinations.

So I'm authorized for Clearance Delivery. This means that when I'm online as that position, I'm known as CYVR_DEL (CYVR is the ICAO code for Vancouver International Airport) I could also log on as CYYJ_DEL for Clearance Delivery at Victoria International. You get the idea: typically, DEL is a position associated with a single airport. The primary job of DEL is to issue clearances to aircraft before they leave. This is, essentially, a route from one airport to another, or to a point in between, at a given altitude, and following a specific path. In really congested airspace, this is essential for getting aircraft to the right place without causing hazardous conflicts.

The components of the most basic clearance are as follows:

• C - Clearance limit. "Cleared to".
• R - Route. "via".
• A - Altitude (both initial, and final).
• F - Frequency.
  
• T - Transponder code.

For instance, I just looked on the wonderful website FlightAware (real-world aviation) at the flight Air Canada 552, which is an Airbus 319 flying from Vancouver to Los Angeles. If he was on VATSIM, and I were to issue a clearance to that pilot, he would contact me on the ground in Vancouver and say
"Vancouver Delivery, Air Canada Five Five Two request IFR clearance to Los Angeles". In front of me, on my computer, I'd bring up the flight plan that he had filed. I'd note the route that he'd requested (YVR SEA J5 SUMMA 4230N 12050W FRA J7 DERBB SADDE6) and the altitude of 39000 feet. I'd check this over and give him the following response (note the conformance with the CRAFT sequence listed above):
C: "Air Canada five five two, you are cleared to the Los Angeles Airport..."
R: "...via the Vancouver Four departure, flight planned route..."
A: "...maintain seven thousand. Expect flight level three niner zero, five minutes after departure..."
F: "... departure frequency one three two point three..."
T: "...squawk four seven zero zero"

To quickly step through each bit...

• Air Canada 552 is cleared all the way to LAX. I could, perhaps, clear him only as far as a middle point if it's a really long flight. This is most common in transoceanic flights, since it's even more critical to keep planes apart over the ocean...
• Just about all jet aircraft are cleared from Vancouver using the Vancouver 4 departure, which is a Standard Instrument Departure. SIDs are published descriptions for what pilots should do after takeoff. It's a lot harder to say "after takeoff, when you're 500 feet above the ground, turn right until you're heading 141°" than "cleared via the Richmond 9 departure". Richmond 9 is the SID typically given to turboprop aircraft at Vancouver. "Flight Planned Route" means that, once the SID has been executed, the rest of the flight is to proceed along the route defined by the pilot.
• The altitude stuff is actually included in the SID, which, if you read the chart, indicates that the pilot is to climb to 7000' and then expect the filed altitude (in this case FL390) 5 minutes after departure. It doesn't hurt to reiterate this for clarity over the radio...
• Why FL390 and not "39,000 feet"? It's something to do with altitudes, which has everything to do with barometric pressure settings. It'll be the subject of a future post. You use "Flight Levels" when you're talking about altitudes above 18,000 feet.
• the frequency given refers to the departure frequency, which is typically the frequency to switch to immediately after you take off. Since this is a very busy time in the cockpit, the delivery controller prepares the pilot with the frequency.
• "Squawk" is a funny thing. Most planes above a certain size, and all commercial aircraft, carry a transponder. This is a device that, basically, transmits a 4 digit code which is picked up and displayed on the radar scope of air traffic controllers, allowing the plane to have a unique identifier. Clearance Delivery assigns this code.
  

So there's a very basic overview to Clearance Delivery.