Parallel Operations guidance addition to the ATC Manual

May, 10, 2021 by

In the version 21.1.0 update of the Infinite Flight ATC Manual we got new guidance added to cover parallel operations. Let’s have a look.

6.10.7 — Controllers must ensure that aircraft continue to meet the IFR separation criteria (see 6.2.2 above) until they are established on the LOC (see 6.13.2 below). Once established, the IFR separation criteria no longer need to be applied between aircraft aligned with parallel runways.

Key “new” portion is that “IFR separation criteria no longer need to be applied with parallel runways”. Why do they not need to be applied? Here is the explanation.

6.10.8 — During parallel operations, lateral separation will always be lost first, therefore during the intercept, only vertical separation can be relied upon.

You can’t ensure the separation.

If Controllers identify two or more aircraft that will end up being “parallel” during the final approach, there are two steps that should be followed to ensure the separation requirement above is met:

  • ensure that all aircraft involved are LEVEL at the altitude you intend on clearing them at for the approach, separated by 1000ft as a minimum (ideally before the base turn)
  • vector all aircraft so that they intercept the LOC in-line with each other. This will mean that no aircraft has begun to descend on the G/S (which could compromise vertical separation), until all the aircraft are established on the LOC

Finally, here is the example provided in the Manual.

In the following image (see below), both aircraft are level for the intercept (one at 3000ft and the other at 4000ft). In the example on the left, the aircraft will be established on the LOC before the G/S is met. However in the example on the right, the aircraft have not intercepted the LOC in-line with each other and thus the aircraft that was at 4000ft has already met the G/S and begun their descent. Subsequently, the vertical separation is lost before both aircraft are established on the LOC!

Image – Parallel Operations

Kyle Boas is the Founder of the IFATC Education Group. He is an IFATC Supervisor and Infinite Flight Appeals team member. — More