Air traffic services & airspace

A. If you are not airborne by 0920 the clearance is cancelled and a new one is needed

The expiry time is the time after which the clearance is automatically cancelled if the flight has not started. Miss it and you need a new clearance - you do not need a new flight plan.

C. Immediately a significant change occurs

The ATIS is updated as soon as a significant change occurs, and each new broadcast gets the next code letter so pilots can confirm they have the current one.

A. The pilot takes back responsibility for his own navigation

Vectoring has ended and the pilot navigates again, usually back to the route. The flight is still controlled. If the vectors took you off your route, ATC will also give you your position.

B. Prior to taxiing for take-off

Before taxiing for take-off the aircraft is given, in order: runway, surface wind, QNH, air temperature (turbine aircraft), visibility or RVR if relevant, and the correct time.

A. 250 kt IAS

The speed limit is 250 kt IAS below 10,000 ft AMSL. In Class C it applies to VFR flights; in Classes D to G it applies to IFR and VFR alike. It is indicated airspeed, not true.

A. Controlled traffic to which ATC separation applies but which, in relation to a particular flight, is not or will not be separated by the minima

Essential traffic is controlled traffic that should be separated but, in relation to your flight, is not or will not be. Because of that, ATC must pass it to you as essential traffic information.

A. Aircraft identification, position, time, level, next position and time over, ensuing significant point

Identification, position, time, flight level or altitude, next position with its time, then the ensuing significant point. Type and fuel are not part of it.

B. The number and type of aircraft and the wake turbulence category

Item 9: number of aircraft (if more than one), type designator and wake turbulence category. The departure aerodrome is Item 13 and the cruising level is part of Item 15.

A. Taxi out onto the runway and take off in one continuous movement

An immediate take-off clearance may be given before the aircraft enters the runway. Once you accept it, you line up and take off in one continuous movement - so accept it only if you are ready.

B. The appropriate ATS unit

The ATS unit sets the transition level from the QNH and passes it to aircraft. The transition altitude, by contrast, is published by the State.

A. IFR is separated from IFR and from VFR; VFR is separated from IFR and receives traffic information on other VFR

Class C: IFR separated from all traffic; VFR separated from IFR only, and given traffic information about other VFR. "IFR separated from IFR only" is Class D.

A. Earth

The definition says "a specified limit above the earth". The control zone is the one that extends upwards from the surface of the earth.

A. Flight information service and alerting service are provided

FIR = flight information and alerting service. These are the minimum services, available everywhere; ATC comes on top of them only in controlled airspace.

A. The radar position of the aircraft is seen and identified on the situation display

Radar contact: the controller sees your radar position and has identified it. From then on, surveillance services can be provided.

B. True airspeed (or Mach number where prescribed)

Item 15 cruising speed is true airspeed, in knots (N0450) or km/h (K0830), or true Mach number where the ATS authority prescribes it.

A. Aircraft threatened by grave and imminent danger and requiring immediate assistance

Distress is grave and imminent danger needing immediate help. A safety concern that does not need immediate assistance is urgency.

B. 4000 ft

AIP India states that no transition altitude is less than 4000 ft.

B. At least one hour before the expected arrival of an aircraft

Lights may be switched off only if they can be back in operation at least one hour before an aircraft is expected.

A. 200 m (700 ft)

A control area starts above the ground - never lower than 200 m (700 ft). It is the control zone that runs from the surface upwards, around an aerodrome.

A. 4

Four: Delhi, Mumbai, Kolkata and Chennai, one for each Indian FIR, coordinated by the Airports Authority of India.

B. Class B

Class B: IFR and VFR, everyone separated from everyone. Class A allows IFR only. In Class C, VFR flights are not separated from each other - they only get traffic information on other VFR.

A. Participating IFR flights receive an air traffic advisory service, and all flights receive flight information service if requested

Class F is uncontrolled. IFR flights taking part get advisory service, and every flight can have flight information service on request - but nobody is separated by ATC.

A. Class E airspace

In Class E (and F and G), VFR flights do not need continuous two-way radio. Classes A to D need it for every flight - and Class A does not allow VFR at all.

A. Class A and Class B

All flights are separated from each other only in Class A (IFR only) and Class B (IFR and VFR). From Class C down, at least some pairs of flights receive traffic information instead of separation.

B. Terminal control area (TMA)

That is the definition of a terminal control area. A control zone starts from the surface around an aerodrome; a TMA is a control area, so it starts from a specified limit above the earth.

C. Both of these

"ATS unit" is a generic term that covers ATC units (area control centre, approach control office, aerodrome control tower), flight information centres and ATS reporting offices.

B. Aerodrome control service

Aerodrome control service is the ATC service for aerodrome traffic - everything on the manoeuvring area and aircraft in the vicinity of the aerodrome.

A. The point to which an aircraft is granted an ATC clearance

The clearance limit is a point - the fix, reporting point or aerodrome up to which you are cleared. The time after which a clearance lapses is its expiry time.

A. Alert phase (ALERFA)

Unlawful interference is one of the triggers for the alert phase, along with failing to land within 5 minutes of the expected time after being cleared to land.

C. 5 NM

At least 9.3 km (5 NM). A control zone may include two or more aerodromes that are close together.

A. Give advice and information useful for the safe and efficient conduct of flights

FIS gives advice and information - weather, facilities, known traffic and hazards. It does not separate aircraft; that is ATC.

A. Arriving or departing controlled flights

Approach control handles arriving and departing controlled flights. The tower handles aerodrome traffic; area control handles en-route traffic.

A. Aircraft identification

Item 7 is the aircraft identification - the call sign, or the registration. Flight rules are Item 8 and aircraft type is Item 9.

B. Prior to taxiing for take-off

Before taxiing for take-off, ATC passes the runway, surface wind, QNH, temperature (turbine aircraft), visibility or RVR if relevant, and the correct time.

A. A transmission made where two-way communication cannot be established but the called station is believed able to receive it

You make a blind transmission when you cannot hear the ground but believe they can hear you - for example after a receiver failure.

C. GG

AIS messages, including those concerning NOTAMs and SNOWTAMs, carry priority indicator GG. SS is distress and DD is urgency.

A. A

Series A: international distribution, duration more than 2 hours. Series B covers 30 minutes to 2 hours.

A. Has crossed the end of the runway in use or has started a turn

The runway must be clear: the departing aircraft has crossed the end of the runway or started a turn, or all preceding landing aircraft have cleared the runway.

A. The manoeuvring area and the aprons

Movement area = manoeuvring area (runways and taxiways) plus aprons. The manoeuvring area excludes the aprons.

A. Alert phase

Uncertainty - doubt exists. Alert - apprehension exists. Distress - reasonable certainty of grave and imminent danger requiring immediate assistance.

A. Remotely Piloted Aircraft System

A remotely piloted aircraft (RPA) is an unmanned aircraft flown from a remote pilot station. The whole set - aircraft, station and command-and-control link - is the RPAS.

A. 1 and 3

Changing from IFR to VFR is the pilot's decision, not a clearance: he notifies ATS specifically that the IFR flight is cancelled and passes the changes to his current flight plan. Nothing happens automatically, and no clearance is requested.

A. An air traffic control unit, flight information centre or air traffic services reporting office

All three are ATS units: an ATC unit (area control centre, approach control office or aerodrome tower), a flight information centre, and an ATS reporting office.

A. Provided by ATC

A visual approach is still an IFR flight. ATC keeps separating it from other arriving and departing aircraft; only for successive visual approaches, once the pilot reports the aircraft ahead in sight, may he be told to maintain his own separation from it.

A. Informs ATS that he is cancelling his IFR flight

Changing to VFR is the pilot's call: he notifies the ATS unit specifically that the IFR flight is cancelled, and passes the changes to the flight plan. No clearance is asked for, and special VFR is something else entirely.

A. Not applicable

Classes A and B carry no speed limitation. The 250 kt IAS limit below 10,000 ft applies in Class C (to VFR) and in Classes D to G.

A. No - except that when an IFR flight is vectored, ATC must keep it at the prescribed obstacle clearance

ATC service prevents collisions between aircraft, and on the manoeuvring area between aircraft and obstructions. Terrain clearance is the pilot's - except when ATC vectors an IFR flight, when the controller must keep the prescribed obstacle clearance until the pilot resumes own navigation.