Wake turbulence

[Old Koreelah]

While waiting at Sydney airport for my flight I'm taking in the amazing sights. They're really pumping the big jets out; take-offs from 34R have been as close as 49 seconds apart! These big aircraft are all following the same impressive steep climb path and turning right to avoid the CBD. They must be passing thru the wake of previous big jets. What happened to the 3-minute rule to allow wake turbulence to disperse?

 

 

[shags_j]

Time between departures depends on acft wake turbulence category. And really only applied when a higher category tamed of in front of a smaller one. Two mediums (738, a320 etc)there is none. Have to heavy use distance.

 

I'm not a tower controller though so maybe they have more detailed charts

 

 

[facthunter]

The PIC has to accept it but would rarely refuse these days. If there is significant cross wind, the turbulent air blows off track. You make a track reference to the ground by maintaining runway centre or any other specified track, and the turbulence moves with the body of air. The turbulence lasts longer in some atmospheric conditions than others.. You should always be aware of the risks when flying in the wake of other aircraft. Slow, heavy and high wing loading aircraft are the worst. Nev

 

 

[rhysmcc]

There is no wake turn standard between 2 medium aircraft (i.e. b737 a320), a medium following a heavy (a330 b767) then 2 minutes is required OR 5 NM (from airborne), same with a light behind the medium. This is assuming they are both departing from the same taxiway, otherwise 3 minutes is required.

 

49 seconds seems too close, I find they take longer then that just to roll down the runway and get airborne, if big jets means heavy, you need at least 4 NM, which is about 1.5 minutes pushing traffic.

 

 

[facthunter]

I don't know the logic behind that. A medium sized aircraft doing a 45 degree bank turn may cut it's own wake and nearly go on it's back.. You are better to be upwind and above. Nev

 

 

[Guest ozzie]

Wake turbulence is more of a problem with aircraft on approach to landing. All dirtied up with flap and gear tend to make more wake than cleaned up and climbing where it tends to fall pretty quick.

 

 

[facthunter]

Larger aircraft use a fair bit of flap for take-off and noise abatement climb keeps them slow. You are right about the landing situation but don't discount other slow speed situations. Most larger aircraft are not far above their minimum manoeuver speed in the circuit, especially in turns. Nev

 

 

[shags_j]

Wake turbulence is just one of those things. I've had aircraft at FL340 and above complain about wake turbulence from an aircraft 20 mile ahead.