Thursday, August 21, 2008

Wake Turbulance - How was it for you??

Over 9 months ago a resident expressed their concern in a email to London City Airport at what they felt were wake turbulances travelling over the river Thames onto the banks of housing developments in West Thamesmead. This phenomena occurred just seconds after a jet had passed to land in from the east.

Robert Grafton, the London City Airport Environmental Officer initially tried to explain the phenomena 0f an extremely loud noise shooting across the Thames, and the incidence of mini tornados hitting trees and making them shake violently on the river banks as being something to do with the 'bird scaring' tactics used on the run way almost a mile away. Of course, why wouldn't we have thought of that lame explanation!?

However this is a serious issue, and the airport as usual is in complete denial of anything that is negative as a result of their activities. Since more jets are being introduced - wake turbulance sound and movement is now becoming a weekly feature of life in West Thamesmead - perhaps it is for those at the other end of the runway too. The vortex sound now hits blocks of flats - so just how long it will be before structural damage occurs is anyones guess - not long by the frequency of the vortexes it seems.

After Robert Grafton finally accepted that the phenomena described was wake turbulance almost a year ago, he made the usual hollow claims that come from that airport that he would investigate further and discuss this with the airlines. In the meantime the resident also had it confirmed by the CAA that the experience described was indeed wake turbulance. So you can imagine the surprise and awe that the environmental officers junior at the airport - finally responded to that resident yesterday, after month upon month of asking them for an answer.The statement from Rob Grafton's junior?

"With regard to wake turbulence, we have never had any evidence of wake turbulence affecting properties in the vicinity of London City Airport . Furthermore, it is unlikely for wake turbulence to occur due to the increase angle of aircraft during take-off and landing. However, if you believe that wake turbulence is occurring on your property, we welcome further factual evidence on this point."

No evidence? We're not surprised really with their usual obstructive and behaviour of denial and lack of ability to collect evidence themselves! LCA, after almost a year of waiting for an investigation into the issue now want the residents to collect the sound and images of wake turbulance travelling across the river and hitting the blocks of flats! Any offers? Usual 'community
responsible' airport then!

Strange how the text books say something quite different to the juniors comments here about the incidence of wake turbulance from aircraft! It will be interesting to see what the authorities make of LCAs usual pass the buck on this serious issue and of the lack of noise readings for 7 years - and we are pursuing every avenue.

So it's business as usual at LCA - denial, denial and try to bury bad or costly news. They've even alledgedly started telling callers to the airport that there are no objecters (over 800 - an unpredented amount - not including 800 signatures on petitions all submitted to Newham and available to see at their offices) to the expansion....oh dear they really do have a problem with dealing with reality. Still the PR regime has to come up with something for it's money!

Wikipedia Extract
Wake turbulence is turbulence that forms behind an aircraft as it passes through the air. This turbulence includes various components, the most important of which are wingtip vortices and jetwash. Jetwash refers simply to the rapidly moving gasses expelled from a jet engine; it is extremely turbulent, but of short duration. Wingtip vortices, on the other hand, are much more stable and can remain in the air for up to three minutes after the passage of an aircraft. Wingtip vortices make up the primary and most dangerous component of wake turbulence.
Wake turbulence is especially hazardous during the
landing and take off phases of flight, for three reasons. The first is that during take-off and landing, aircraft operate at low speeds and high angle of attack. This flight attitude maximizes the formation of dangerous wingtip vortices. Secondly, takeoff and landing are the times when a plane is operating closest to its stall speed and to the ground - meaning there is little margin for recovery in the event of encountering another aircraft's wake turbulence. Thirdly, these phases of flight put aircraft closest together and along the same flightpath, maximizing the chance of encountering the phenomenon.
Wake turbulence can occasionally, under the right conditions, be heard by ground observers. On a still day, heavy jets flying low and slow on landing approach may produce wake turbulence that is heard as a dull roar/whistle. Often, it is first noticed some seconds after the direct noise of the passing aircraft has diminished. The sound then gets louder, sometimes becoming as loud as was the original direct sound of the aircraft. Nevertheless, being highly directional, wake turbulence sound is easily perceived as originating a considerable distance behind the aircraft, its apparent source moving across the sky just as the aircraft did. It can persist for 30 seconds or more, continually changing timbre, sometimes with swishing and cracking notes, until it finally dies away