Separation Near Aerodromes

When a take-off clearance depends on an arriving aircraft, the approach type, arrival position, departure direction and remaining time to the instrument runway determine whether the departure can be released.

Complete instrument approach

Straight-in approach

Near an aerodrome, normal separation may be reduced only when continuing visual evidence lets the controller or pilots maintain a safe relationship. Wake turbulence and any locally published runway minimum still apply.

Reduction in separation minima near an aerodrome

1. The aerodrome controller can provide adequate separation because every aircraft is continuously visible to the controller.
2. Each aircraft is continuously visible to the crews of the other aircraft, and the pilots report that they can maintain their own separation.
3. When one aircraft follows another, the succeeding crew reports the preceding aircraft in sight and confirms that separation can be maintained.

Essential local traffic

Essential local traffic includes an aircraft, vehicle or person on or near the runway, and traffic in the take-off, climb-out or final-approach area, that may constitute a collision hazard to an arriving or departing aircraft. Known essential local traffic is passed to affected crews without delay, with enough position and movement information for the hazard to be understood.

Reduced runway separation categories

These values are used only where the competent ATS authority has authorised a reduced runway separation procedure and the applicable AIP publishes it. The distance is measured from the succeeding aircraft's threshold or take-off position to the point passed by the preceding aircraft, as required by the operation.

How the runway distances are used

Conditions for using a reduced runway minimum

Reduced runway separation is not applied to a departing aircraft behind a preceding landing aircraft. The controller must first satisfy the normal runway-occupancy requirement for that sequence.

An aircraft cannot use separation intelligently without current operational information. Approach control passes material changes promptly, while the crew is still able to adjust the departure or arrival safely.

Meteorological conditions for departing aircraft

Significant changes in take-off or climb-out weather are transmitted without delay unless the aircraft is known to have received them. The list includes surface wind direction or speed, visibility, RVR, air temperature for turbine aircraft, thunderstorm or cumulonimbus, moderate or severe turbulence, wind shear, hail, moderate or severe icing, severe squall line, freezing precipitation, severe mountain waves, sandstorm, dust storm, blowing snow, tornado and waterspout.

Operational status of visual or non-visual aids

Changes in the operational status of visual or non-visual aids essential for take-off and climb are transmitted without delay, unless already received. Essential local traffic information is passed whenever it affects the departure.

Procedures for arriving aircraft

Arrival sequencing begins with the applicable STAR, approach and runway information, then becomes more specific as the aircraft descends.

General arrival setup

Where a STAR is established, an arriving aircraft should normally be cleared to follow the appropriate STAR. The aircraft is told the expected approach type and runway in use as early as possible. After coordination with approach control, the area control centre may clear the first arrival for an approach instead of sending it to a holding fix.

What makes an approach visual

A visual approach is an approach by an IFR flight in which part or all of the instrument approach procedure is not completed and the approach is flown with visual reference to terrain. The pilot may request it or the controller may initiate it. A controller should not initiate one when there is reason to believe that the crew is unfamiliar with the aerodrome or surrounding terrain, and considers traffic and weather before offering it.

Direct base or final may be cleared when there is reasonable assurance that the visual approach and landing can be completed. Separation is still provided between the visually approaching aircraft and other arriving or departing traffic.

Instrument approach

The approach control unit specifies the instrument approach procedure to be flown. The crew may request an alternative procedure and, when circumstances permit, ATC clears it accordingly.

A pilot-requested visual approach uses the runway in sight and continuing visual reference to terrain, but Bali adds measurable visibility and ceiling safeguards for the Indian operating context.

Visual approach by the flight crew

The crew requests the visual approach with the runway in sight, maintains visual reference to terrain and gives its position with the request. Acceptance does not remove the stated visibility, ceiling or traffic-separation conditions.

Ground visibility threshold

Ceiling or pilot assurance

In addition to the visibility condition, either the reported ceiling is at or above the beginning level of the initial approach segment, or the pilot reports at that level or during the instrument approach that conditions give reasonable assurance that a visual approach and landing can be completed. The pilot should include a position report when requesting the visual approach.

When visual conditions deteriorate

The pilot immediately advises ATC if weather deteriorates so terrain cannot be kept in sight, if following the preceding aircraft cannot continue, or if additional spacing is required. ATC then restores an appropriate separation or instrument instruction. The pilot may request an alternative instrument approach, which is cleared when circumstances permit.

A specific visual-separation clearance is different from merely flying in visual weather. It transfers a defined task for a limited part of the flight while ATC preserves the surrounding controlled-traffic system.

Conditions for the clearance

1. The aircraft requests the arrangement.
2. The pilot of the other aircraft agrees.
3. The appropriate ATS authority authorises the procedure.
4. The controlled flights operate in Class D or E airspace in VMC during daylight.
5. The clearance applies to a specified climb or descent segment at or below 3,050 m (10,000 ft).

Protection if VMC cannot continue

When there is a possibility that VMC will become impracticable, ATC provides alternative instructions for the IFR flight. If conditions deteriorate, the pilot informs ATC before entering IMC and follows those alternative instructions. Essential traffic information is passed whenever the two controlled flights become essential traffic to each other.

Time information lets the crew plan fuel, descent and holding. EAT concerns leaving the approach holding fix to complete the approach, while onward clearance time concerns leaving a different fix where the aircraft is being held.

Expected approach time

EAT is the time at which ATC expects an arriving aircraft, after delay, to leave the holding fix to complete its approach for landing. It is not a landing time.

Onward clearance time

If an aircraft is held en route or at a location or aid other than the initial approach fix, it is given an expected onward clearance time as soon as practicable. This is the time at which it can expect to leave the fix where it is held. The crew is also told if further holding is expected at a later fix.

Timed approaches

When authorised, timed approaches allow successive aircraft to start approaches at planned intervals. ATC specifies a recognisable point on the inbound path, such as a VOR radial or DME distance, and gives each aircraft the time at which to pass it inbound. The instruction is issued early enough for speed or track adjustment, and all applicable air and runway separation minima continue to apply.

Arrival information becomes more immediate as the aircraft approaches the runway. The initial package supports planning, the final-approach update protects the landing decision, and sudden hazards are passed without delay.

As early as practicable after first contact

An item already received need not be repeated. If an aircraft must fly a different instrument approach or use a different runway from the one first stated, the crew is advised without delay.

At the commencement of final approach

During final approach

The controller transmits without delay a sudden hazard such as unauthorised runway traffic, significant wind variation expressed as minimum and maximum values, significant runway-surface change, a change in the status of required visual or non-visual aids, and an observed RVR or representative-visibility change.

The operational flow