DUBAI RECAT Seperation behind a Heavy

[ssietbunny]

Hello Everyone,

I have been flying into Dubai in a 738 for a while now. Over a period of time now, due to increased traffic, the seperation between aircrafts have further reduced than what is mentioned in ICAO Seperation minima.

For eg. During approach , a 737/320 behind a A380
ICAO Minima 7 miles.
Dubai recat minima is 5 miles.

A 737/320 behind a 777
ICAO Minima 5 milesDubai Recat minima is 4 miles
I have been hit by wake on finals quite a few times by a 777 . , despite keeping having a continuos decent and being higher than preceding aircraft, sometimes due to longer vectoring, calm or direct head or tailwinds it becomes a challenge .

1. Do you guys feel it's justified for to have such lower seperation minima ? IMHO with stressed work environment, red eye flights, for most airlines, it's a disaster waiting to happen.

2. Following are the points i have learnt to avoid being hit by a wake in arrivals,
1. I attempt to keep a 3 degree path angle above the preceding aircraft .
2. Continuous vnav planned descent from tod.
3. Avoid the use of rudder and over controlling ailerons,when at low altitude struggling with a with a wake.
Your experiences and points welcome .

[Little One]

Just to clarify, the RECAT separation minima is actually an ICAO Minima and not a Dubai Sep.

ICAO Doc 4444 allows for the application of two different types of Wake Turbulence Categories and Groupings.

4.9.1 Wake turbulence categories and groups of aircraft
4.9.1.1 Except as provided for in 4.9.1.2, wake turbulence separation minima shall be based on a grouping of
aircraft types into four categories according to the maximum certificated take-off mass as follows:
a) SUPER (J) — aircraft types specified as such in Doc 8643, Aircraft Type Designators;
b) HEAVY (H) — aircraft types of 136 000 kg or more, with the exception of aircraft types listed in Doc 8643 in
the SUPER (J) category;
c) MEDIUM (M) — aircraft types less than 136 000 kg but more than 7 000 kg; and
d) LIGHT (L) — aircraft types of 7 000 kg or less.
Note.— The wake turbulence category for each aircraft type is contained in Doc 8643, Aircraft Type Designators.
4.9.1.2 When approved by the appropriate ATS authority, wake turbulence separation minima may be applied
utilizing wake turbulence groups and shall be based on wake generation and resistance characteristics of the aircraft.
These depend primarily on maximum certificated take-off mass, wing characteristics and speeds. The group designators
are described as follows:
a) GROUP A — aircraft types of 136 000 kg or more, and a wing span less than or equal to 80 m but greater than
74.68 m;
b) GROUP B — aircraft types of 136 000 kg or more, and a wing span less than or equal to 74.68 m but greater than
53.34 m;
c) GROUP C — aircraft types of 136 000 kg or more, and a wing span less than or equal to 53.34 m but greater than
38.1 m;
d) GROUP D — aircraft types less than 136 000 kg but more than 18 600 kg, and a wing span greater than 32 m;
e) GROUP E — aircraft types less than 136 000 kg but more than 18 600 kg, and a wing span less than or equal to
32 m but greater than 27.43 m;
f) GROUP F — aircraft types less than 136 000 kg but more than 18 600 kg, and a wing span less than or equal to
27.43 m;
g) GROUP G — aircraft types of 18 600 kg or less (without wing span criterion).
Note 1.— Information on the wake turbulence group for each aircraft type is contained in Doc 8643, Aircraft Type
Designators.
Note 2.— Guidance on the implementation of wake turbulence separation between wake turbulence groups can be
found in the Manual on Implementation of Wake Turbulence Separation Minima (Doc 10122).
https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/1450x1320/wake_892428182572c5b8bc1be71ef881b5f204b36d67.jpg

The Spacing that is being applied by Dubai is technically all ICAO Spacing. There are usually conditions where the RECAT spacing may be suspended and the revision to "Legacy" spacing put in place, and these include if there are a certain number of moderate to severe wake encounter reports.