Turbulence from buildings.

[heli1]

There are plans to build a 50-60m high building, just to the right of a new 500m long FATO path at the heli museum at Weston super Mare ......about 100m away from the centre line but "blocking" the prevailing westerly wind.Its a big building and the helicopter consultant brought in from London by the local Council wonders if there is a turbulence issue? he knows all about the CAA and FATOs but not the effect of high buildings it seems.
Any practical experience or advice out there?

[Art of flight]

I would think the Met Office would be able to model this effect for you, ie give historic data for that location and forecast turbulence based on that.

[paco]

I'm guessing there would be some turbulence behind if it's blocking the prevailing wind. It will be a very similar effect to that in the lee of mountains.

phil

[CRAN]

They could do some computer simulations to identify the likely effects using modern computational fluid dynamics techniques. This approach is quite common for ship and oil rig evaluations.

PM me if you need more details.

CRAN

[Big Tudor]

Similar issue existed at Gatwick for years. Hangars to the south of the runway made for 'interesting' approaches to 26 when the wind was from the south. Hangars have now gone (I believe), along with the hangar effect.

[Cornish Jack]

Some years ago we did a weekend winching demo for a school fete in the N Midlands. Standard display - put 'survivor' in dinghy in middle of display line, standard circuit, double lift pickup, bow to the crowd line, transit upwind, 180 and downwind run past the crowd low level pull up steeply to a torque turn into wind with the usual rapid descent. Strongish wind and saw, but didn't take sufficient notice of, a building at the downwind end of the display line. Result?? ... more than usually rapid descent in distinctly downdrafting turbulence and an exploration of the upper reaches of the Whirlwind collective!!:eek: The audience, God bless them, applauded when we reappeared from behind the building. Winds over buildings - not good!:ooh:

[ShyTorque]

Tall buildings near FATOs?

Not been to Battersea heliport recently? It's now in between two very tall buildings.

[heli1]

Shy Torque.
Yes I wondered about Battersea but I suspect the middle of a city and surrounded by tall strucures is a little different from a wide open space exposed to the Atlantic winds with one big building for the wind to go over and around?
Computer simulations may be the best answer but i doubt the Council will want to spend the money .Thats why iwas looking for some practical experience.

[John Eacott]

This report (http://www.atsb.gov.au/publications/investigation_reports/2010/aair/ao-2010-008.aspx) from the ATSB may be of interest:

On 31 January 2010, an American Aircraft Corporation Grumman Traveller AA-5 aircraft, registered VH-ERP, was being operated on a visual flight rules private flight from Temora, New South Wales to Canberra, Australian Capital Territory. At about 1630 Eastern Daylight-saving Time, on late final approach to runway 12 at Canberra Aerodrome, and at an altitude of about 150 ft above ground level, the aircraft experienced severe turbulence that resulted in a brief loss of control. The pilot recovered control and landed on runway 12.

The investigation determined that it was probable that the severe turbulence was generated by a combination of the wind conditions on the day and the position of the two buildings located about 220 m and 290 m upwind from runway 12. In addition, there were no standard criteria for assessing the potential local wind effect of aerodrome building developments on aviation operations, and no national building codes for aerodrome developments that address the phenomena of building-induced turbulence.

The aerodrome operator had commissioned pre-construction wind impact assessments of the two buildings to the north of runway 12. These reports concluded that the buildings would not result in adverse wind effects on aircraft operations. This conclusion was based in part on the assessment that use of runway 12 was unlikely in northerly wind conditions. However, operations to that runway remained possible in those conditions without any alert to affected pilots about possible risk. By contrast the Canberra Aerodrome information in the En Route Supplement Australia alerted pilots of the possibility of severe turbulence during touchdown on runway 35 in strong westerly winds.

Subsequent to this occurrence, the Department of Infrastructure, Transport, Regional Development and Local Government established the National Airports Safety Advisory Group (NASAG). NASAG's role is to examine airport planning issues, including the potential local wind effects of buildings on aircraft operations, and to develop a set of universal guidelines and policy material for application at state and local levels. In addition, Airservices Australia is progressing the installation of wind shear detection technologies at several aerodromes. There is the potential that one of those installations could be at Canberra Aerodrome.