Wingtip vortex: a hazard to ground-based objects?
 

Watching a 747 landing at Gatwick arrive a couple of hundred feet over the London-Brighton railway today I wondered whether the wingtip vortex from such aircraft could ever pose a danger to people/objects on the ground?

If you do a search, a PIA took some tiles off a roof at MAN on departure, but that is fairly unusual....

MAN flight path
 

We live on the flight path for Manchester airport, I don't know how low the aircraft are as they pass but they are gear down as they fly over and can cast a shadow in to my bedroom.

In certain conditions we can clearly hear the vortex generated and occasionally actually see them in the air. They are an incredible phenomenon.

When they touch they can pull debris and loose tiles up but I'd be very surprised if they could hurt anyone or cause significant damage.

Mind you they do seriously freak our cats out if they're outside when it happens!

Ju

I imagine,

that if a few tiles off the roof flew around and wacked somebody in the face, that could be a bit dangerous and harmful.

Randy

Fair call. But its not really like iy happens in the Wizard of Oz, anything lifted doesn't go very high or very far as the vortex gets broken up very easily as it travels over the ground.

A tile falling of the roof could hurt but only in the same way as anything else dropping off a roof.

Ju

I was in Dubai for the airshow last year and landing aircraft came close to the hotel at around 600-700 ft (info from nav box) and the vortices were enough to move paper / empty glasses around and kick up any dust on the roof.

I think it's very unlikely wing tip vortices would pose a direct risk to ground objects. They are a risk to other aircraft in close proximity which are effectively being supported by the air as they fly through it, the turbulent airflow can throw an aircraft around quite a bit and possibly risks affecting the amount of lift produced by that aircrafts wings. But to an object that is being supported by the ground rather than lift created by flying through the air the effects will be much milder. I doubt it would pose any more risk than a strong wind.

There have been stories of overflying aircraft dislodging roof tiles. I don't think anything has ever been proven (tiles do sometimes just fall off even on houses not directly under flight paths) and I suspect that even if the overflying aircraft are a factor they will certainly not be the only one, i.e. the tiles may well have been loose anyway and would just have easily come off on a windy day. If wing tip vortices are causing tiles to dislodge I suppose you could argue that this is risk to people on the ground they might fall on.

There was a flight safety film, quite a few years ago I'm afraid, that showed the effect of wing-tip vortices close to the ground and a stationary helicopter on the ground at the Marshalling Point - quite a bit of blade sail. A further sequence showed a vortex leaving the wing, as an aircraft touched down, and rolling across the airfield as its energy dissipated. Does anyone know if the film still around?

Roof damage to properties located under runway approaches does occasionally happen. I believe Heathrow has an insurance scheme in place to cover such events which are often caused by a combination of certain weather conditions and type of aircraft, normally by B757 or larger. Other busy airports may have similar schemes.

A few years back, Mrs Zooker and I sat in the garden drinking white wine late on a very warm summer evening, when a B757 took off from the local A/D. Passing overhead at about 2000ft QNH, it caused our apple and plum trees to shake violently.

NASA wing vortex tests
 

I know this probably isnt the video FantomZorbin was talking about but it certainly shows the power of some of the vortices especially from larger aircraft.

(Apologies for slight thread drift)

YouTube - C-5A Wing Vortice tests at NASA Langley Research Center

They make the trees move and create a bit of a strong gust in the beer garden at The Green Man under the LHR 27L approach. When there is no road traffic, you can hear them too.

:}

They certainly make a very dramatic noise as they whipcrack over our heads here at the end of the runway @ Liverpool - I've often wondered what would happen if one touched down on a roof...It's also surprising how far behind the aircraft they run as well - shows how much turbulence an airliner can make - and at Liverpool it's generally Easyjet & Ryanair planes so it's not as if they're particularly large craft either...