Wake Turbulence
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Wake Turbulence
I'm interested to hear about how your local airport's ATC (especially in the Uk) integrates you into their traffic pattern with regard to wake turbulence.
For example. You are cleared to approach and land directly onto your apron remaining north of the runway at all times (your apron is around 300m north of the runway centreline). There is a 737 departing the main runway as you arrive. Would your ATC unit ask you to
a) Hold off for 2 minutes due wake turbulence from the departure.
b) Clear you in remaining north of the runway and issue you with a "caution wake turbulence" message or
c) clear you in with no mention of the potential wake turbulence as you are routing direct and not crossing the runway?
d) treat you like a fixed wing and insist that you make the approach to the runway.
For example. You are cleared to approach and land directly onto your apron remaining north of the runway at all times (your apron is around 300m north of the runway centreline). There is a 737 departing the main runway as you arrive. Would your ATC unit ask you to
a) Hold off for 2 minutes due wake turbulence from the departure.
b) Clear you in remaining north of the runway and issue you with a "caution wake turbulence" message or
c) clear you in with no mention of the potential wake turbulence as you are routing direct and not crossing the runway?
d) treat you like a fixed wing and insist that you make the approach to the runway.
Canada - (b) cleared to land remaining north of active runway, but with no "caution wake turbulence" message.
On departure same conditions they may hold you for wake turbulence, but you can "waive" that (you must ask for it - it isn't offered) because the 737 is not considered a "heavy".
On departure same conditions they may hold you for wake turbulence, but you can "waive" that (you must ask for it - it isn't offered) because the 737 is not considered a "heavy".
When we operated out of Liverpool airport, ATC would always tell us of wake turbulence when at the take off point, and recommend the recommended interval before take off. Knowing that a) it wouldn't really affect us, and b) I would very quickly be clear of any turbulence, I would just reply "Roger. Ready for departure" and they would be happy to let us go. I've never felt any turbulence from fixed wing aircraft.
The latest CAP493, dealing with the revised separation criteria post Airbus 380, only mentions helicopters in regard to the problems caused by rotor downwash to other aircraft. It only refers ATC to helicopters landing after other helicopters that there might be a turbulence problem.
I've always been of the opinion(possibly wrongly) that the high speed of our "wings" leaves us unaffected.
The latest CAP493, dealing with the revised separation criteria post Airbus 380, only mentions helicopters in regard to the problems caused by rotor downwash to other aircraft. It only refers ATC to helicopters landing after other helicopters that there might be a turbulence problem.
I've always been of the opinion(possibly wrongly) that the high speed of our "wings" leaves us unaffected.
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It depends a lot on which ATC bod is on whether they will let you anywhere near fixed wing, but if they are feeling brave they just advise you of the wake turbulence and the recommended spacing.
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I've always been of the opinion(possibly wrongly) that the high speed of our "wings" leaves us unaffected.
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I've always been of the opinion(possibly wrongly) that the high speed of our "wings" leaves us unaffected.
Yeah, you'll get a bump, no big deal. You'll eat far worse turbulence flying in mountains - stuff that would destroy an airplane. Helicopter pilots here always ask to waive turbulence -they'll even request it behind a heavy on the offchance that the controller is asleep and might give it to them. Oddly, ATC only seems to care about holding you for takeoff, never for landing.
I share Mighty Gem's opinion that it is the high-aspect ratio of the helicopter blade plus the rotational speed that minimizes the consequences to a helicopter compared to an airplane.
I share Mighty Gem's opinion that it is the high-aspect ratio of the helicopter blade plus the rotational speed that minimizes the consequences to a helicopter compared to an airplane.
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Wake vortex
Gentleman may I urge all the pilots who feel less vulnerable to Wake vortex in a helicopter to revise their views and maybe operations urgently.
I operate out of a airport with a large mix of types from 152's through turbo props to Medium and heavy cat jets.
Be in no doubt that if you fly/hover taxi through the wake vortex of a medium/heavy you will know all about it. BRIEFLY!!!
Read up on the proper practices, and here are some basic principles by which I have operated amongst these machines without upset for a good number of years.
1,If crossing or passing behind a machine on departure or approach always fly OVER its flight path.
2, If following a machine on approach or Take Off always fly above its track and always UPwind of its track, a few Metres offset makes all the difference.
3, If lifting or landing after a landing or departing aircraft always lift/land well before rotation point or past touchdown point of that aircraft. again always only fly/hover upwind of the app/dep track.
Always visualise where the wind is coming from and Keep upwind in the clean air!! If you cannot insure this then wait the appropriate 1 ,2 or 3 mins, re-check your systems, advise the passengers why and before you know it its time to go. Your family, your passengers and your helicopter will really appreciate it!!
I have flown heavy jets and have been unpleasantly surprised by the impact of wake turbulence, same with Helicopters. Get this near the ground and it will kill you!!
I operate out of a airport with a large mix of types from 152's through turbo props to Medium and heavy cat jets.
Be in no doubt that if you fly/hover taxi through the wake vortex of a medium/heavy you will know all about it. BRIEFLY!!!
Read up on the proper practices, and here are some basic principles by which I have operated amongst these machines without upset for a good number of years.
1,If crossing or passing behind a machine on departure or approach always fly OVER its flight path.
2, If following a machine on approach or Take Off always fly above its track and always UPwind of its track, a few Metres offset makes all the difference.
3, If lifting or landing after a landing or departing aircraft always lift/land well before rotation point or past touchdown point of that aircraft. again always only fly/hover upwind of the app/dep track.
Always visualise where the wind is coming from and Keep upwind in the clean air!! If you cannot insure this then wait the appropriate 1 ,2 or 3 mins, re-check your systems, advise the passengers why and before you know it its time to go. Your family, your passengers and your helicopter will really appreciate it!!
I have flown heavy jets and have been unpleasantly surprised by the impact of wake turbulence, same with Helicopters. Get this near the ground and it will kill you!!
Last edited by Heli-phile; 11th Jun 2009 at 01:57. Reason: typo's
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Flying in and out of Rush Green (which is inside Luton's outer marker, dead on the centre line), Luton are usually pretty good about warning us of wake turbulence. On the way out, you'd have the get the timing wrong with very exact precision, but on the way in, if there's something heavy whizzing overhead, they'll sometimes ask you to orbit a little way out to let the vortex dissipate.
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malabo
Turbulence and Wake are two different things. I fail to understand how a rotor disk which has one half in rapidly up moving air, and the other half in rapidly down moving air, is going to fail to flip upside down very rapidly, regardless of how fast it's rotors are moving. I'm guessing you have never seen video footage of such an event?
I've taken off in a 747 behind another 747, and had full aileron control just to prevent the roll upon encountering the preceding aircraft's wake. It is true that I was taking off exactly along his takeoff profile, but it is also true that I had the inertia of 340 tonnes behind me, so I had a lot more time to react than a lightweight aircraft such as a helicopter.
A helicopter will generally not fly through a plane's wake, because of the totally different takeoff profiles. A helicopter's approach to land is far steeper than a plane's, and wake descends, so you are even more unlikely to experience problems on landing.
Hit a full blown wake vortex low down in a helicopter, and you are unlikely to survive to tell the tale.
Turbulence and Wake are two different things. I fail to understand how a rotor disk which has one half in rapidly up moving air, and the other half in rapidly down moving air, is going to fail to flip upside down very rapidly, regardless of how fast it's rotors are moving. I'm guessing you have never seen video footage of such an event?
I've taken off in a 747 behind another 747, and had full aileron control just to prevent the roll upon encountering the preceding aircraft's wake. It is true that I was taking off exactly along his takeoff profile, but it is also true that I had the inertia of 340 tonnes behind me, so I had a lot more time to react than a lightweight aircraft such as a helicopter.
A helicopter will generally not fly through a plane's wake, because of the totally different takeoff profiles. A helicopter's approach to land is far steeper than a plane's, and wake descends, so you are even more unlikely to experience problems on landing.
Hit a full blown wake vortex low down in a helicopter, and you are unlikely to survive to tell the tale.
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Yeah, you'll get a bump, no big deal
