AD 1.6 WAKE TURBULENCE AND JET BLAST

1.1 General
- 1.1.1 Wake turbulence is the term used to describe the effect of the rotating air masses (wake vortices) generated behind the wing tips of aircraft in flight. These vortices are two counter-rotating cylindrical air masses trailing aft from the aircraft and are particularly severe when generated by large and wide-bodied aircraft. The vortices are most dangerous to following aircraft during the take-off, initial climb, final approach and landing phases of flight. They tend to drift down, and when close to the ground move sideways (outwards) from the track of the generating aircraft.
- 1.1.2 Helicopters produce vortices when in flight and there is evidence that, per kilogram of gross mass, their vortices are more intense than those of fixed-wing aircraft. Helicopters should keep well clear of light aircraft when hovering or while air-taxiing.
- 1.1.3 Wake turbulence separation is provided by ATC to pilots whose aircraft may be affected by the phenomenon, except in the case of IFR aircraft making a visual approach or a VFR arrival behind a medium or heavy or A380. In these cases it is the pilot's responsibility to provide adequate spacing from preceding arriving or departing aircraft. In these circumstances ATC will make allowance for such pilot initiated manoeuvres when sequencing additional following aircraft. The spacing required is tabulated below and guidance material can be obtained from the CAA.
- 1.1.4 Whenever practicable, aerodrome controllers will advise pilots of the expected occurrence of hazards caused by turbulent wake by issuing a caution in the following form: "CAUTION -- WAKE TURBULENCE". The occurrence of turbulent wake hazards cannot be accurately predicted, and aerodrome controllers cannot assume responsibility for issuing advice of such hazards at all times, or for its accuracy.
- 1.1.5 If a pilot considers the wake turbulence separation standards inadequate, increased separation may be requested by specifying the spacing required.
- 1.1.6 If a controller considers the wake turbulence separation provided is inadequate, or that it need be applied for any situation not covered by a specific minimum, the pilot will be advised and an appropriate separation applied.
- 1.1.7 Notwithstanding the wake turbulence separation standards previously outlined, if pilots consider that the effect of wake turbulence can be nullified by ensuring that flight profiles do not cross, they may request and be granted exemption from these separations. ATC will advise the category or type of the other aircraft.
1.2 Weight Categories
- 1.2.1 For the purpose of assessing wake turbulence separation, aircraft are divided into the following weight categories:
  - (a) Heavy (H): Aircraft types of 136,000 kg MCTOW or more (example: C17, A330, B767, or any larger aircraft). Special wake turbulence separations apply to A380 aircraft.
  - (b) Medium (M): Aircraft types of less than 136,000 kg but more than 7000 kg MCTOW (example: SW4B/C, JS3A/32 and Beech 1900 or larger, up to and including B757 and A320 series). B757 aircraft will be categorised as a HEAVY (H) aircraft for the purpose of assessing wake turbulence to following aircraft or aircraft crossing behind.
  - (c) Light (L): Aircraft types of 7000 kg MCTOW or less (example: SW4A, JS31 and smaller). Seasprite (H2) aircraft will be categorised as a MEDIUM (M) aircraft for the purpose of assessing wake turbulence to following aircraft or aircraft crossing behind.
- 1.2.2 The wake turbulence category for each aircraft and helicopter type is listed in ICAO DOC 8643 (Aircraft Type Designators) and in the Airways IFIS website -- PLANNING INFO.

1.3 Distance Based Wake Turbulence Separation

1.3.1 The wake turbulence separation minima in Table AD 1.6-1 will be applied to aircraft in all phases of flight when:
- (a) an aircraft is operating directly behind (0.5NM laterally) another aircraft at the same level or less than 1000ft below (this includes reciprocal track aircraft after passing); or
- (b) an aircraft is crossing behind another aircraft at the same level or less than 1000ft below; or
- (c) both aircraft are using the same runway, or parallel runways separated by less than 760m.

Table AD 1.6-1
Distance Based Wake Turbulence Separation Minima
Leading aircraft	Aircraft following or crossing behind	Minimum distance
A380	A380	4NM
	Non A380 HEAVY	6NM
	MEDIUM	7NM
	LIGHT	8NM
HEAVY	HEAVY	4NM
	MEDIUM	5NM
	LIGHT	6NM
MEDIUM	LIGHT	5NM

1.3.2 Whenever the distance between an aircraft, at the same level or less than 1000ft below and following an aircraft of heavier wake turbulence category, is less than the equivalent of 2 minutes flying time, ATC will issue a caution of possible wake turbulence.

1.4 Time Based Wake Turbulence Separation:

1.4.1 Minimum time separations are applied between:
- (a) aircraft using the same runway or grass strip; or
- (b) parallel runways or grass strips less than 760m apart; or
- (c) where there is a possibility that the projected flight paths will cross at the same altitude or less than 1000ft below.

1.4.2 The minimum separations applied between arriving flights are provided in Table AD 1.6-2.

Table AD 1.6-2
Time Based Wake Turbulence Separation Minima --
Arriving Flights Same Direction Runway
Leading aircraft	Following aircraft	Minimum time
A380	A380	2 minutes
	Non A380 HEAVY	2 minutes
	MEDIUM	3 minutes
	LIGHT	4 minutes
HEAVY	HEAVY	2 minutes
	MEDIUM	2 minutes
	LIGHT	3 minutes
MEDIUM	LIGHT	3 minutes

1.4.3 The minimum separations applied between departing flights are provided in Table AD 1.6-3.

Table AD 1.6-3
Time Based Wake Turbulence Separation Minima --
Departing Flights Same Direction Runway
Leading aircraft	Following aircraft	Minimum spacing at time aircraft are airborne
Leading aircraft	Following aircraft	Departure from same take-off position	Departure from intermediate take-off position
A380	A380	2 minutes	3 minutes
	Non A380 HEAVY	2 minutes	3 minutes
	MEDIUM	3 minutes	4 minutes
	LIGHT	3 minutes	4 minutes
HEAVY	HEAVY	2 minutes	3 minutes
	MEDIUM	2 minutes	3 minutes
	LIGHT	2 minutes	3 minutes
LIGHT	LIGHT	2 minutes	3 minutes

1.4.4 In the case of parallel runways and/or grass strips where the departing thresholds are not laterally aligned, a succeeding departure from a forward threshold is deemed to be departing from an intermediate take-off position.
1.4.5 Where the possibility exists of a departing aircraft of higher performance overtaking a departing aircraft of lower performance, wake turbulence separation will be applied as if the higher performance aircraft is the leading aircraft.

1.4.6 The minimum time separations applied between arriving and departing aircraft, if the flight path of the following aircraft will cross the projected flight path of the leading aircraft (e.g. when an arriving aircraft is operating onto a runway using a displaced landing threshold) are provided in Table AD 1.6-4.

Table AD 1.6-4
Time Based Wake Turbulence Separation Minima --
Arriving and Departing Flights Same Direction Runway
Leading aircraft	Following aircraft	Minimum spacing at time aircraft are airborne or have touched down
A380 ARRIVAL	HEAVY DEPARTURE	3 minutes
	MEDIUM DEPARTURE	3 minutes
	LIGHT DEPARTURE	3 minutes
HEAVY ARRIVAL	MEDIUM DEPARTURE	2 minutes
HEAVY ARRIVAL	LIGHT DEPARTURE	2 minutes
MEDIUM ARRIVAL	LIGHT DEPARTURE	2 minutes
A380 DEPARTURE	HEAVY ARRIVAL	3 minutes
	MEDIUM ARRIVAL	3 minutes
	LIGHT ARRIVAL	3 minutes
HEAVY DEPARTURE	MEDIUM ARRIVAL	2 minutes
HEAVY DEPARTURE	LIGHT ARRIVAL	2 minutes
MEDIUM DEPARTURE	LIGHT ARRIVAL	2 minutes

1.5 Time Based Wake Turbulence Separation:

1.5.1 Minimum time separations are applied between aircraft operating from:
- (a) an opposite direction using the same runway or grass strip; or
- (b) parallel runways or grass strips less than 760m apart; or
- (c) where there is a possibility that the projected flight paths will cross at the same altitude or less than 1000ft below.

1.5.2 The minimum separations applied between arriving flights are provided in Table AD 1.6-5. 2 minutes

Table AD 1.6-5
Time Based Wake Turbulence Separation Minima --
Arriving and Departing Flights Opposite Direction Runway
Leading aircraft taking off or landing or low or missed approach	Following aircraft arriving or departing	Minimum spacing at time aircraft are airborne or have touched down
A380	A380
	Non A380 HEAVY	3 minutes
	MEDIUM	3 minutes
	LIGHT	3 minutes
HEAVY	HEAVY	2 minutes
	MEDIUM	2 minutes
	LIGHT	2 minutes
MEDIUM	LIGHT	2 minutes

1.6 Time Based Wake Turbulence Separation:

1.6.1 The minimum time separations applied between arriving and departing aircraft, for operations on crossing or non-intersecting runways or where flight paths intersect, are provided in table AD 1.6 - 6.
1.6.2 These separations apply to take-off clearances or the time a landing aircraft crosses the threshold versus the time the leading aircraft crosses the intersection.
1.6.3 If the leading aircraft lands prior to the intersection no wake turbulence separation is applied.

1.6.4 If a departing aircraft commences its take-off run from past the intersection no wake turbulence separation is applied provided that, in the case of two departing aircraft, their projected flight paths do not cross at the same altitude or less than 1000ft below.

Table AD 1.6 - 6
Time Based Wake Turbulence Separation Minima --
Crossing or Non-Intersecting Runways with Crossing Flight Paths
Leading aircraft	Aircraft crossing behind	Minimum spacing
A380	HEAVY	3 minutes
	MEDIUM	3 minutes
	LIGHT	3 minutes
HEAVY	HEAVY	2 minutes
	MEDIUM	2 minutes
	LIGHT	2 minutes
MEDIUM	LIGHT	2 minutes

2 JET BLAST AND PROPELLER SLIPSTREAM
- 2.1 General
  - 2.1.1 Pilots are cautioned of the hazards caused by jet blast and propeller slipstream to taxiing aircraft, to aircraft taking off or landing, and to vehicles and personnel operating on the aerodrome.
  - 2.1.2 Jet blast and propeller slipstream can produce localised wind velocities of sufficient strength to cause damage to other aircraft, vehicles and personnel.