AirLaw - Air Ops - Approach

The different approach segments

Arrival: Transition from enroute to the IAF.

Initial: From the IAF to the IF

Intermediate: From the IF to the FAF / FAP
Speed and config should be adjusted read for final. OC reduces from 1,000ft to 500ft

Final:
FAP is for Precision Approach
FAF is for non-PA
Alignment and descent for landing is made.


Missed approach:
Has the same segments
Initial, starts at MAPt end at Start of Climb SOC.
Intermediate starts at SOC ends at 50m OC. (less than 15° turns)

and final: 50m OC end when new approach, hold or return to route is started.

What is an instrument approach question:

an instrument approach is a series of predetermined manoeuvrers by reference to instruments, With specified protection from obstacles, from the IAF or where applicable from the beginning of a defined arrival route.

To a point where landing can be completed, or if landing not completed, to a position… Missed approach.

Aircraft Approach Categories

A 91kt, E 166+ kt
ABCDE ICAO categories

OCH / OCA & relationship with PA and N-PA

OCH/A is the lowest height or altitude above X that obstacle clearance is provided.

For Precision Approaches, the datum for height is the threshold of that runway,
for Non-PA it is the airfield elevation

To get OCA from OCH

PA: OCH + Runway Threshold Elevation = OCA
NPA: OCH + Airfield elevation = OCA.

OR if the Runway is 7ft below the aerodrome, then OCH + RW Threshold.


Circling appoach is OCH + Aerodrome elevation = OCA.

Continuation of approach below MDA/H provided the visual reference for the type of the approach is maintained:

NPA / Type A / CAT1:
1 visual reference is enough

CAT II:
3 consecutive lights

CAT III A
3 consecutive lights maintained

CAT III B: fail operation with DH = 1 centre light.

CAT IIIB - No DH, no visual ref required

What is OCA?

The lowest altitude above the (Reference (PA = Runway threshold, NPA = Airfield), at which a missed approach shall be initiated, to maintain obstacle clearance.

Straight in approach:

where possible, track aliged with runway, for a nonPA, it could be 30° either side. (Departure is 15°)

DA vs MDA (DH vs MDH)

DA / DH -
position in a precision approach, at which missed approach must be initiated if required visual references are not established.

MDA / MDH - Min descent Alt/height
point in a non-pa, below which descent must not be made without visual ref.

DA/MDA are always above OCA as they are OCA + Operational factors

Circling Approach:

• once the runway environment is in sight, it should be kept in sight, while circling at MDA for circling.
  
  Descent below MDA should not be made until:
  threshold in sight, visual ref established and maintained, OC is maintained and landing is made.

• Turn from the approach runway to the circle to land should be 45°.
  
  

• Lost visual on circling approach:

  • Turn to landing runway & climb

  • proceed on the original instrument approaches runway missed approach procedure.

A circling approach is a manoeuvrer that allows the aircraft to land on a runway that is not aligned with the final approach path. Once the runway is in sight, pilots must maintain visual contact while circling at the Minimum Descent Altitude (MDA). Descent below the MDA is only permitted when the runway threshold is visible, visual references are established, obstacle clearance is ensured, and preparations for landing are finalised. If visual contacts are lost during the circling approach, pilots are instructed to turn toward the landing runway and execute a climb, subsequently following the missed approach procedure associated with the original instrument approach for that runway.

Design considerations for instrument approach:

• terrain

• type of operations

• aircraft to be using

Max interception angle between initial and intermediate segments?

PA = 90°
NonPA = 120°

Procedure Turn:

Turn made away from the track, then a turn back, to fly the reciprocal of the original track.

Racetrack Turn:

Procedure to reduce altitude, during initial approach

Base Turn:

For instrument proceudres, a specified outbound track followd by a turn to the approach track, the outbound and return are not reciprocal.

Optimum angles for approach procedures:

Optimum..
Glide path = 3°
5.2 % Gradient

and a 3.5 Flight path angle (velocity vector angle compared to surface)

Accuracy of Fixs

ILS - has 4s - 2.4 or 1.4%
VOR - Has 5s - 5 or 4.5%
NDB - Has 6s 6.9 or 6.2%

MAPt

When you are at MAPt, the MAP must be initiated.

A go around after the MAPt is a baulked landing go around (different to missed approach).

DME Fix Accuracy Question

DME 0.25NM ± 1.25%

TAR - terminal area radar 0.8
Enroute surveillance radar 1.7

You expect the DME to be best at measuring distance

MAPt 2D vs 3D approach:

For a 3D approach, the MAPt = DA
For a 2D approach, the MAPt = MAPt

On a 2D you fly down to MDA, level off until the MAPt position, if no visual, you go around.

For 3D you continuously fly to DA, no VIS = go around.

Protected Areas:

• Most straight segments have primary and secondary areas.

• full OC is provided in primary area

• for the secondary the OC is reduced from the inner to the edge.

• Where no track guidance is provided during a turn, the total width is considered primary.

• 
  

ILS different DHs

ILS CAT I = Baro = DH 200ft+
ILS CAT II = RAD ALT = 100 to 200ft
ILS CAT III = RAD ALT , with DH less than 100ft or no DH requirement.

ILS Protection Area:

Not deviate more than half scale deflection.