Attention should be drawn by all controllers to the dangers associated with turbulence caused by aircraft wake vortices. Previously not a concern in the simulator environment, modern software can now accurately simulate these dangers.
This policy shows the UK's existing wake turbulence separation arrangements and implement aspects of Amendment 9 to ICAO Doc 4444 PANS-ATM. Therefore, this policy is applicable to both the United Kingdom (CAA) and Ireland (ICAO).
It incorporates the ICAO PANS-ATM requirements relating to aircraft in the SUPER wake turbulence category, and states the aircraft wake turbulence categories that are used by ANSPs in the UK and Ireland to determine the required wake turbulence separation minima when sequencing aircraft in the approach and departure phase.
ICAO uses the term ‘wake turbulence’ to describe the effect of the rotating air masses generated behind the wing tips of aircraft in preference to the term ‘wake vortex’ which describes the nature of the air masses.
Wake turbulence separation minima are based on a grouping of aircraft types into categories, generally according to their maximum certificated take-off mass (MCTOM).
The United Kingdom conforms, in general, to the ICAO standards on wake turbulence. However, experience at those UK aerodromes where an air traffic control (ATC) service is provided and wake turbulence separation minima are applied, has shown that certain modifications to the relationship between the maximum certificated take-off mass of an aircraft and the wake turbulence separation are advisable for the safety of operations.
Since 1982 the differences between the UK and ICAO criteria have been:
In 1997 a further modification was made for the purpose of wake turbulence separation in the approach phase at London Heathrow, London Gatwick, London Stansted and Manchester and London Luton in 1999, by dividing the MEDIUM category for landing aircraft into UPPER and LOWER MEDIUM.
In light of the safe operational experience over the years since 1997 it was decided in 2010 to extend this categorisation to all UK aerodromes where an air traffic control (ATC) service is provided and wake turbulence separation minima are applied.
Differences between the ICAO and UK wake turbulence categories do not affect the composition of flight plans, which should be completed in accordance with ICAO Doc 4444 PANS-ATM and UK AIP ENR 1.10. The aircraft’s wake turbulence category should be entered on the flight plan (item 9) as J, H, M or L according to the ICAO wake turbulence categories.
The UK UPPER MEDIUM and LOWER MEDIUM categories are considered to form the MEDIUM wake turbulence category and is not split for wake turbulence separation on departure.
UPPER MEDIUM, LOWER MEDIUM and SMALL are UK categories only, and are not to be entered onto the flight plan under item 9.
| Wake Turbulence Category | ICAO (KG) | UK Departures (KG) | UK Arrivals (KG) |
|---|---|---|---|
| J - Super | ≥ 136,000 | ≥ 136,000 | ≥ 136,000 |
| H - Heavy | ≥ 136,000 | ≥ 136,000 | ≥ 136,000 |
| M - Medium | > 7,000 & < 136,000 | > 40,000 & < 136,000 | n/a |
| M - Upper Medium (UK only) |
n/a | n/a | > 104,000 & < 136,000 |
| M - Lower Medium (UK only) |
n/a | n/a | > 40,000 & ≤ 104,000 |
| L - Small (UK only) |
n/a | > 17,000 & ≤ 40,000 | > 17,000 & ≤ 40,000 |
| L - Light | ≤ 7,000 | ≤ 17,000 | ≤ 17,000 |
For the purposes of separation in the approach phase at UK aerodromes the B757, B707 and DC8 will be treated as Upper Medium.
IL62 and VC10 are RECAT-EU Lower Heavy but have a higher MTOW than UM and so have been removed from the above list*
| Wake Turbulence Category | ICAO (KG) | UK Departures (KG) | UK Arrivals (KG) |
|---|---|---|---|
| M - Medium | > 7,000 & < 136,000 | > 40,000 & < 136,000 | n/a |
| M - Upper Medium (UK only) |
n/a | n/a | > 104,000 & < 136,000 |
| M - Lower Medium (UK only) |
n/a | n/a | > 40,000 & ≤ 104,000 |
| L - Small (UK only) |
n/a | > 17,000 & ≤ 40,000 | > 17,000 & ≤ 40,000 |
| L - Light | ≤ 7,000 | ≤ 17,000 | ≤ 17,000 |
Certain aircraft have wake turbulence generation and resistance characteristics which differ from those which would be expected based upon their MCTOM alone, and this affects their categorisation.
There is some evidence that, per KG of gross mass, the wake turbulence generated by a helicopter is more intense than that of a fixed-wing aircraft. Consequently, in the UK, all helicopters with a MCTOM of 7,000 KG or more and 40,000 KG or less are classified as SMALL for the purposes of providing wake turbulence separation on approach and departure.
| Leading Aircraft | Following Aircraft | Wake Tubulence Seperation Minima Distance (NM) | |
|---|---|---|---|
| ICAO | UK | ||
| SUPER | SUPER | # | # |
| SUPER SUPER SUPER SUPER SUPER |
HEAVY UPPER MEDIUM LOWER MEDIIM SMALL LIGHT |
5 7* 7* n/a 8 |
5 7* 7* 7 8 |
| HEAVY HEAVY HEAVY HEAVY HEAVY HEAVY |
SUPER HEAVY UPPER MEDIUM LOWER MEDIUM SMALL LIGHT |
# 4 5* 5* n/a 6 |
# 4 5 5 6 7 |
| UPPER MEDIUM UPPER MEDIUM UPPER MEDIUM UPPER MEDIUM UPPER MEDIUM UPPER MEDIUM |
SUPER HEAVY UPPER MEDIUM LOWER MEDIUM SMALL LIGHT |
# # n/a n/a n/a 5 |
# # 3 4 4 6 |
| LOWER MEDIUM LOWER MEDIUM LOWER MEDIUM LOWER MEDIUM LOWER MEDIUM LOWER MEDIUM |
SUPER HEAVY UPPER MEDIUM LOWER MEDIUM SMALL LIGHT |
# # n/a n/a n/a 5 |
# # 3 4 4 6 |
| SMALL SMALL SMALL SMALL SMALL SMALL |
SUPER HEAVY UPPER MEDIUM LOWER MEDIUM SMALL LIGHT |
n/a n/a n/a n/a n/a n/a |
# # # # 3 4 |
| LIGHT LIGHT LIGHT LIGHT LIGHT LIGHT |
SUPER HEAVY UPPER MEDIUM LOWER MEDIUM SMALL LIGHT |
# # # # # # |
# # # # # # |
Unless alternative wake turbulence separation criteria have been approved for use, the UK wake turbulence separation minima specified above are to be applied when:
The UK does not split the MEDIUM wake turbulence category for the purposes of wake turbulence separation on departure.
| Leading Aircraft | Following Aircraft | Minimum Wake Turbulence Separation at the Time Aircraft are Airborne | |
|---|---|---|---|
| SUPER | SUPER | Departing from the same position or from a parallel runway separated by less than 2500ft |
No wake turbulence separation minima required |
| SUPER | HEAVY | 2 minutes | |
| MEDIUM SMALL LIGHT |
3 minutes | ||
| HEAVY | HEAVY | 4NM or time equivalent | |
| HEAVY | MEDIUM SMALL LIGHT |
2 minutes | |
| MEDIUM or SMALL | LIGHT | 2 minutes | |
| Leading Aircraft | Following Aircraft | Minimum Wake Turbulence Separation at the Time Aircraft are Airborne | |
|---|---|---|---|
| SUPER | SUPER | Departing from an intermediate point on the same runway or from an intermediate point of a a parallel runway separated by less than 2500ft |
No wake turbulence separation minima required |
| SUPER | HEAVY | 3 minutes | |
| MEDIUM SMALL LIGHT |
4 minutes | ||
| HEAVY (full length takeoff) | HEAVY | 4NM or time equivalent | |
| HEAVY | MEDIUM SMALL LIGHT |
3 minutes | |
| MEDIUM or SMALL (full length takeoff) |
LIGHT | 3 minutes | |
Unless alternative wake turbulence separation criteria have been approved for use, the UK wake turbulence separation minima specified above apply when the aircraft are using:
Wake turbulence separation minima on departure are applied by ATC by determining airborne times between successive aircraft. Take-off clearance may be issued with an allowance for the anticipated take-off run on the runway. This may result in a take-off clearance being issued at less than the prescribed time interval. However, the airborne time interval will reflect a difference of at least the required time separation.
Pilots do, on occasion, request departure clearance before the minimum time separation has elapsed. On those occasions ATC will apply the minima as prescribed in this policy, irrespective of the request for reduced separation. It is important for pilots to note that ATC does not have the discretion to reduce separation minima.
Where the separation minima required for IFR purposes is greater than the recommended separation for wake turbulence, the IFR minima will apply.
The separation criteria listed are the minima and when applied by ATC may be increased at the discretion of the controller, or at the request of the pilot. It is important to note that a pilot request for increased separation must be made before entering a runway or commencing final approach. Requests made on the runway or final approach may result in a departure delay and/or an avoidable missed approach.
Aircraft carrying out a touch-and-go or low approach shall be considered as making a departure from an intermediate point on the runway.
AFIS means flight information service for aerodrome traffic and as such provides advice and information useful for the safe and efficient conduct of flights in the vicinity of an aerodrome. Whilst the responsibility for wake turbulence avoidance rests entirely with the pilot-in-command, AFIS shall, to the extent practicable, provide a warning of the expected occurrence of hazards caused by turbulent wake to:
AFIS units will use the ICAO wake turbulence categories in applying the criteria above.
The occurrence of wake turbulence hazards cannot be accurately predicted and AFIS units cannot assume responsibility for the issuance of information on such hazards at all times, nor for its accuracy.