[Rob P]

Interesting stuff here on what sounds to have been a fairly severe wake encounter

http://avherald.com/h?article=4a5e80f3&opt=0

Rob P

[PaulB]

I've thought about this before when flying under the approach path of an airport.

The Emirates 777 passed over us on approach to Birmingham. It looked mighty big and I did wonder at that time had we been a bit later whether its wake might have descended out of CAS to where we were. I guess with an A380, the likelihood is greater.

[Mike Tango]

ATC have to keep other IFR traffic, irrespective of size, a minimum of 1000' below with respect wake turbulence if required lateral/in trail distance not met if the other aircraft is an A380.

In the right place at the right time you could be 501' below in your PA28 or similar.

Or maybe that should be the wrong place at the wrong time.

[ganzic]

I was once crossing London City zone in a Mooney, approximately 1-2 minutes behind a turbo prop departure(Q400) at 90 degrees to his flight path.

My aircraft flipped up side down and hit my head on a pillar as the seat belt was not very tight. A bit more and I think I could have been knocked unconscious.

Lesson learned about turbulence the hard way....

The video on avherald is very good i think!

Code: Select allhttps://www.youtube.com/watch?v=KXlv16ETueU

[greghm]

But at 1000 feet separation it still has an effect then ? That is impressive.

[PaulB]

ATC have to keep other IFR traffic, irrespective of size, a minimum of 1000' below with respect wake turbulence if required lateral/in trail distance not met if the other aircraft is an A380.

In the right place at the right time you could be 501' below in your PA28 or similar.

Or maybe that should be the wrong place at the wrong time.

... so if an ATC unit working an A380 that that had placed 500' above the base of CAS could see a radar trace of another aircraft in the class G below that was likely to (unknowingly to the either aircraft) get tangled up in the super heavy's wake turbulence, is some duty of care not owed to that light aircraft?

[Lefty]

ATC have to keep other IFR traffic, irrespective of size, a minimum of 1000' below with respect wake turbulence if required lateral/in trail distance not met if the other aircraft is an A380.

In the right place at the right time you could be 501' below in your PA28 or similar.

Or maybe that should be the wrong place at the wrong time.

... so if an ATC unit working an A380 that that had placed 500' above the base of CAS could see a radar trace of another aircraft in the class G below that was likely to (unknowingly to the either aircraft) get tangled up in the super heavy's wake turbulence, is some duty of care not owed to that light aircraft?

I would suggest -yes. But the ATC might have limited scope to vector the heavy - and may not be talking to the unknown light aircraft. What then? To my way of thinking this requires a change to the rules to ensure that a heavy cannot be descended to less than 1000 ft above the base of CAS.

[PaulB]

Very true, but many airports have a listening squawk these days to facilitate quick identification of aircraft OCAS, or they may be wearing a squawk of a neighbouring unit.

Is it just the super-heacy category that might affect us in the (very) light category?

[kanga]

..

Is it just the super-heacy category that might affect us in the (very) light category?

being under, behind, or (if on ground) laterally near a 'heavy helo' (Chinook, Merlin, Sea King ..) can be very uncomfortable if in a light aircraft (fw, helo or gyro), static on ground or in flight. I have no idea how far vertically effect might be felt if both are well above ground and heavy above light. Can any ATCOs advise what norms are applied, if any ?

[Talkdownman]

..

Is it just the super-heacy category that might affect us in the (very) light category?

being under, behind, or (if on ground) laterally near a 'heavy helo' (Chinook, Merlin, Sea King ..) can be very uncomfortable if in a light aircraft (fw, helo or gyro), static on ground or in flight. I have no idea how far vertically effect might be felt if both are well above ground and heavy above light. Can any ATCOs advise what norms are applied, if any ?

See AIC P 003/2014 and DOC 8643 - Aircraft Type Designators

Chinook (H47), Merlin (EH10), Sea King (S61) are all in the ICAO Medium Wake Vortex Category. ISTR in the UK they fall within the UK 'Small' Category rather than Upper Medium or Lower Medium, but are still not to be messed with, they require serious separation from light aircraft. I recall that on final that's 4nm behind, and on departure it's two minutes. But never be afraid to request more (er...that is BEFORE lining up...)

[kanga]

Thanks. I still wonder how far vertically below a Chinook a passing lightish aircraft in S&L flight might be affected by the downwash. Has this ever been researched, does anyone know ?

[rikur_]

Thanks. I still wonder how far vertically below a Chinook a passing lightish aircraft in S&L flight might be affected by the downwash. Has this ever been researched, does anyone know ?

I've passed ~ quarter of a mile behind and slightly above a Chinook and that was lively enough.
At the time I'd only had something like 10 hours post PPL experience, and although I'd be taught about vortex separation on final approach, it had never specifically been highlighted to be about passing behind traffic (or if it had, I hadn't remembered it). The Chinook was converging perfectly from the right, and I remember thinking whether to descend below it or turn right to pass behind it .... at the time the thought of vortex never factored in making that decision.

[chevvron]

Thanks. I still wonder how far vertically below a Chinook a passing lightish aircraft in S&L flight might be affected by the downwash. Has this ever been researched, does anyone know ?

When the Chinook was being evaluated at Boscombe, I was shown some of the paperwork in order to write our own local 'vortex' requirements.
At one stage, a Chinook hovered near a windsock and literally blew it to pieces! Bear in mind at max auw they are very similar to a C130.

[Dave W]

Chinook MAUM (now) 55,000 lb (24,950 kg). On entry into Service the Mk.1 had a MAUM of 50,000 (22,700 kg).

C-130 MAUM 155,000 lb (70,300 kg)

The Chinook downwash is certainly significant, and I've seen one ground-taxying (so not full downwash present) lift the tail of a Jodel that was about 80m away with full back stick applied.

I must say, I'm very surprised that Chinook, Merlin and Sea King are in a UK 'Small' category. That seems very wrong and potentially hazardous.

Edit: Here's some video of a helicopter wake turbulence accident. The helo is a UH-60 Blackhawk variant MAUM 23,500 lb (10,660 kg). The Cirrus was flown by a student pilot, who survived. Time from UH-60 departure to Cirrus arrival seems to be around 30 seconds.

[mick w]

Maybe the fact that he was landing downwind , & the application of power , also added to this accident ?.