PANSOPS 2

Alternate aerodrome

• An aerodrome to which an aircraft may proceed when it becomes either impossible or
  inadvisable to proceed to or to land at the aerodrome of intended landing where the necessary services and facilities are available, where aircraft performance requirements can be met and which is operational at the expected time of use.

• An alternate aerodrome at which an aircraft would be able to land should this become necessary shortly after take-off and it is not possible to use the aerodrome of departure.

• An alternate aerodrome at which an aircraft would be able to land in the event that a diversion becomes necessary while en route
  

• An alternate aerodrome at which an aircraft would be able to land should it become either
  impossible or inadvisable to land at the aerodrome of intended landing

Aerodrome elevation: The elevation of the highest point of the.....

Base turn: A turn executed by the aircraft during the...approach between the end of the outbound track and the beginning of the intermediate or final approach track. The tracks are not reciprocal.

Controlled airspace: An airspace of defined dimensions within which...service is provided in accordance with the airspace classification.

Initial Approach Segment

• That segment of an instrument approach procedure between the initial approach fix and the intermediate fix or, where applicable, the final approach fix or point.

• That segment of an instrument approach procedure between either the intermediate
  fix and the final approach fix or point, or between the end of a reversal, racetrack or dead reckoning track procedure and the final approach fix or point, as appropriate.

• That segment of an instrument approach procedure in which alignment and descent
  for landing are accomplished.

Intermediate approach segment

• That segment of an instrument approach procedure in which alignment and descent
  for landing are accomplished.

• That segment of an instrument approach procedure between the initial approach fix and the intermediate fix or, where applicable, the final approach fix or point.

• That segment of an instrument approach procedure between either the intermediate
  fix and the final approach fix or point, or between the end of a reversal, racetrack or dead reckoning track procedure and the final approach fix or point, as appropriate.

Final approach segment

• That segment of an instrument approach procedure in which alignment and descent
  for landing are accomplished.

• That segment of an instrument approach procedure between the initial approach fix and the intermediate fix or, where applicable, the final approach fix or point.

• That segment of an instrument approach procedure between either the intermediate
  fix and the final approach fix or point, or between the end of a reversal, racetrack or dead reckoning track procedure and the final approach fix or point, as appropriate.

Decision altitude (DA) or decision height (DH):

• A specified altitude or height in a 3D instrument approach operation at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.

• A specified altitude or height in a 2D instrument approach operation or circling approach operation below which descent must not be made without the required visual reference.

• The lowest altitude or the lowest height above the elevation of the relevant runway threshold or the aerodrome elevation as applicable, used in establishing
  compliance with appropriate obstacle clearance criteria.

Minimum descent altitude (MDA) or minimum descent height (MDH)

• A specified altitude or height in a 3D instrument approach operation at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.

• A specified altitude or height in a 2D instrument approach operation or circling approach operation below which descent must not be made without the required visual reference.

• The lowest altitude or the lowest height above the elevation of the relevant runway threshold or the aerodrome elevation as applicable, used in establishing
  compliance with appropriate obstacle clearance criteria.

Obstacle clearance altitude (OCA) or obstacle clearance height (OCH)

• A specified altitude or height in a 3D instrument approach operation at which a missed approach must be initiated if the required visual reference to continue the approach has not been established.

• A specified altitude or height in a 2D instrument approach operation or circling approach operation below which descent must not be made without the required visual reference.

• The lowest altitude or the lowest height above the elevation of the relevant runway threshold or the aerodrome elevation as applicable, used in establishing
  compliance with appropriate obstacle clearance criteria.