Separation in the Vicinity of Aerodromes

Air Regulations · Chapter 6 · DGCA CPL and ATPL

How ATC spaces aircraft in the busy air around an airport, and when your own eyes can take over from the clock.

Remember

Departures: 1 minute if tracks diverge by 45°, 2 minutes if the leader is 40 kt faster, 5 minutes if the follower climbs through the leader's level.
Behind a straight-in arrival, departures in any direction may go until 5 minutes before it lands, or until 3 minutes if diverging 45°.
Visual approach visibility: 2800 m for Cat A and B, 3200 m for C, 3600 m for D, 5 km for a circling runway; the pilot owns terrain clearance.
You get an EAT when the delay is 10 minutes or longer, and a new one whenever it moves by 5 minutes or more.
On final, a mean tail-wind change of 2 kt is significant; head-wind 10 kt and cross-wind 5 kt.

How does ATC space traffic near an airport?

The big picture

Four jobs near the aerodrome. Tap a box with + to open it.

Near the aerodrome departures and arrivals How ATC separates departing and arriving aircraft close to the aerodrome, when those minima may be reduced, and what information it passes to them.
- Departure from departure Minimum time between successive take-offs: 1, 2 or 5 minutes, depending on track divergence, speed difference and whether the follower climbs through the leader's level.
  - 1 minute tracks diverge 45° or more Just one minute between departures if their tracks split by 45° or more straight after take-off, because they are then side by side apart.
  - 2 minutes leader 40 kt or more faster Two minutes between departures on the same track if the first one is at least 40 kt faster.
  - 5 minutes follower climbs through Five minutes, with no vertical separation, when a departure will climb through the level of a preceding departure on the same track.
  - Clearance contents heading, track, level, rate, SID Direction of take-off and turn, heading or track, level to maintain, when to change level.
- Departure before an arrival When a take-off clearance depends on an arriving aircraft's position, the release depends on the type of approach and the direction of the departure.
  - Complete instrument approach Departures go in any direction until the arrival starts its procedure or base turn; after that only 45 degrees off the reciprocal, at least 3 minutes before the arrival.
    - Any direction until procedure or base turn A departure may take off in any direction up to the moment the arriving aircraft starts its procedure turn or base turn onto final.
    - Diverging 45° until 3 min before threshold After the turn has started, a take-off at least 45 degrees off the reciprocal of the approach may go until 3 minutes before the arrival is over the instrument runway.
  - Straight-in approach Departures go in any direction until 5 minutes before the arrival is over the runway; diverging 45 degrees until 3 minutes before, or until it crosses a designated fix.
    - Any direction until 5 min before threshold Take-off in any direction is allowed until 5 minutes before the straight-in arrival is estimated over the instrument runway.
    - Diverging 45° until 3 min, or the fix A take-off at least 45 degrees off the reciprocal may go until 3 minutes before the arrival is over the runway, or before it crosses a designated fix.
- Eyes reduce the gap Close to an aerodrome the minima can be cut, if the controller or the pilots can see the aircraft and keep them apart by eye.
  - Tower sees both continuously The tower controller can keep aircraft apart by eye, as long as the controller can see each of them the whole time.
  - Crews see each other and keep their spacing Each aircraft is continuously visible to the other crews, and the pilots report they can maintain their own separation.
  - Follower sees leader reports it in sight The crew behind can see the aircraft ahead and keep their own distance from it.
  - Own separation in VMC daylight, Class D and E At or below 10,000 ft (3050 m), on the pilot's request, with the other pilot's agreement.
- Arrivals Arrivals normally follow a STAR and are told the approach type and runway early; ATC also passes delay times and information at first contact and on final.
  - Visual approach visibility by category An IFR flight completes part or all of the approach by visual reference to terrain. Ground visibility must be at least 2800 m (Cat A/B), 3200 m (Cat C) or 3600 m (Cat D).
  - Expected approach time delay of 10 min or more An EAT is worked out for an arrival delayed 10 minutes or more and sent as soon as practicable, preferably before descent from cruising level starts.
  - First contact approach, runway, weather In this order: the approach type and runway in use, the weather, the runway surface, and any changes to the lights and nav aids used for approach and landing.
  - Start of final wind, shear, RVR, runway traffic At the start of final approach ATC passes significant changes in mean surface wind, the latest wind shear or turbulence, and the current visibility or RVR.
    - Mean wind change head 10, tail 2, cross 5 kt When the wind is held as components, significant changes are 10 kt head-wind, 2 kt tail-wind and 5 kt cross-wind.
    - Latest wind shear or turbulence As final approach begins, you are told of any fresh report of wind shear or turbulence on final.
    - Visibility or RVR change The visibility right now in the direction you are landing, or the latest RVR figures and which way they are trending, if possible.
    - Unauthorised runway traffic During final approach, a sudden hazard such as unauthorised traffic on the runway is passed to the aircraft without delay.

Takeaway: Departures are spaced from each other and from arrivals; eyes can shrink the gap; arrivals get visual approaches, EATs and final-approach information.

How far apart must two departures be?

Departures

Three cases, three numbers. The condition earns the number.

Memory hook: 1, 2, 5: turn away, run away, climb through.

Takeaway: 1 minute if tracks diverge by 45° or more, 2 minutes if the leader is 40 kt faster, 5 minutes if the follower climbs through.

Can this departure go before the arrival lands?

Release a departure

Read each case and press the stamp that applies.

This lesson is part of the Core plan. See plans

How does the window close as a straight-in arrival nears?

Release window

Read the time line from left to right as the arrival flies towards the runway.

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What weather changes must ATC pass to a departure?

Departure updates

Every card is something approach control passes without delay. Tap a card.

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What do you need for a visual approach?

Visual approach

An IFR flight finishing its approach by looking at the ground. Find your category.

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Can you be given a visual approach?

Visual approach?

An IFR arrival, runway in sight. Answer in order.

This lesson is part of the Exam-Ready plan. See plans

What are you told on arrival and on final?

Told on arrival

In order, from first contact to short final.

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How many minutes, and how much visibility, near the aerodrome?

Timing near the field

Four views: departure gaps, the release window, visual-approach visibility and the EAT.

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When may separation near an aerodrome be reduced?

Closer near the field

Three ways to go below the minima, and VMC own separation. Tap + to open each.

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Numbers to know

Numbers

The figures examiners like, in one list.

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Pairs that catch students out

Don't mix up

Look-alike rules side by side, and how to tell them apart.

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Test yourself

Ten questions from this chapter.

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