What exactly is an ATC clearance and how is it requested?

Question

What exactly does it mean to get an ATC clearance?

I’m asking the question because I read point 8015 of the Standardised European Rules of the Air (SERAs), which states that ATC clearances are requested by submitting a flight plan. I always thought that this was done by a radio-request when asking for start-up (at least for IFR-flights)...

And what does it exactly mean to get certain ATC instructions during the flight (for example in the case of vectoring)? Are these amendments to the initial clearance or do I mix something up?

Answer 1

I realize that the question was asking about EASA, but perhaps an FAA perspective will increase understanding. The FAA Pilot Controller glossary defines clearance as:

AIR TRAFFIC CONTROL CLEARANCE [ICAO]− Authorization for an aircraft to proceed under conditions specified by an air traffic control unit.

Note 1: For convenience, the term air traffic control clearance is frequently abbreviated to clearance when used in appropriate contexts.

Note 2: The abbreviated term clearance may be prefixed by the words taxi, takeoff, departure, en route, approach or landing to indicate the particular portion of flight to which the air traffic control clearance relates.

In short, clearance is permission, and is generally associated with operating under IFR in controlled airspace.

I will disregard taxiing at a tower controlled field because it can be done under IFR or VFR. Additionally, I have heard compelling arguments that you are not “cleared” to taxi, but are given taxi “instructions”. (Ground controllers will never use the word “cleared” when telling you to taxi).

But that is a separate discussion...

The process begins with filing an IFR flight plan. This notifies ATC of your intentions, and gives them time to enter your request into the system.

The actual clearance is issued when you call them, (radio at towered field, land line at uncontrolled field) field and put your clearance “on request”. When you call, ATC will issue the clearance. It will be either what you filed for, or it may contain amendments.

In the clearance you may be told to expect radar vectors. This then becomes part of your clearance. However, vectors assigned as needed during flight for traffic separation aren’t generally considered an amendment to the clearance. Think of them more as a temporary detour around something.

For example, if ATC needs to amend your clearance they will tell you specifically that they have an amendment, and ask when you are ready to copy. The amendment will generally be a rerouting that you are expected to follow on your own, and may also include a different altitude.

If given a vector, however, the expectation is that is it a temporary heading needed by ATC to provide traffic separation. Once the need for positive ATC control is past they will clear you to resume your own navigation along your flight planned route.

Answer 2

An ATC clearance cover a wide variety of approved requests by air traffic control. The basics are it’s granting permission to a pilot by that controlling agency to fly through airspace or conduct a flight by a filed flight plan under the control of that agency or to move an aircraft on the ground through a controlled movement area on the surface of an airport.

ATC clearance are granted as I said by the appropriate controlling agency. Typically an ATC request is made using two items: The callsign of the aircraft making the request and the specific request.

Examples:

“Savannah Ground, Cessna six tree tree seven X-ray on the ramp at Signature, request taxi VFR with Information Charlie.”

“Portland Clearance Delivery, Lear two fife seven tree Victor at Flightcraft, ready to copy IFR to Centennial with Information Papa.”

In both cases, the flight crew identified who they were and what they were requesting. ATC will respond with both the callsign of the aircraft and the specifics of the clearance they are granting.

Examples:

“Cessna six tree tree seven X-ray, Savannah Gound, Taxi to runway one niner via Bravo, hold short of Runway two eight.”

“Lear two fife seven tree Victor, Cleaed to Centennial via Whamy Four departure, Kimberley transition, then as filed. Climb and maintain one fife thousand, expect flight level four one zero one zero minutes after departure. Departure frequency on one one eight point one, squak fife four four seven. Contact Portland Ground on one two one point niner when ready to taxi.”

Once this has been done ATC has now granted the clearance. Pilots are generally expected to read back clearances to verify they understand and will comply with the specifics.

Answer 3

As Carlo so well put it, ATC clearance are given for many different reasons and scenarios. Even an aircraft flying VFR or one not on a flight plan will need to get ATC clearance to do many things such as:

• Entering and being in a movement area.
• Especially entering or being on a runway or taxiway.
• Takeoff and land at an airfield with an operating control tower.
• Flying IFR.
• Flying in Class A, B, and some Special Use Airspaces.
• Even flying in Class C & D airspaces since maintaining two-way communication could be interpreted as having clearance.
• Approaching the airport either on an Instrument Approach Procedure or joining the traffic pattern at a towered airfield.
• Etc.

In the US, you can request clearances simply by utilizing radios (NavCom, CPDLC, et.), telephones, Ground Communication Outlets, transponder codes, maneuvering to receive light-gun signals, etc. Filing a flight plan will notify ATC of your intent to request a clearance and the details of your intentions. It will set expectations for/of both you and ATC. You will still have to request and receive your clearance through the aforementioned ways. Although a flight plan is not mandatory (but recommended, none the less) for VFR flight in the US. Filing, or the lack there of, of a flight plan does not preclude requesting and receiving clearance in the above mentioned situations.

Where it is mandatory, it will still be mandatory without a flight plan. And, the flight plan itself is not considered the request nor the receipt. Although Pre-Departure Clearance and Automated Digital Departure Clearance procedures and systems make it possible to request and receive clearances without actually talking to ATC. In the future, the two-way digital link of ADS-b might make it possible to receive clearances and separation instructions digitally through those devices as well.