[UK-CONTEST] Aircraft Reflection Path Plot

[Rob Harrison]

Hi,

What you also have to know is regular long didtance flights can be up to an 
hour either side of their alloted times, and due to weather flights can take 
completely different tracks across the country, not due to our WX, but 
Atlantic WX, making the flight enter UK airspace in different positions. A 
classic is the SIA021 rarely seen down here, but recently has come in via 
southern Ireland and routing to Dover. Normally this flight goes via 
northern UK.

Don't ask me how I know, you'll get too many pages of answers, hi.

Bob G8HGN

----- Original Message ----- 
From: "Ray James" <gm4cxm at yahoo.co.uk>
To: "Ken Eastty" <ken.g3lvp at btinternet.com>; <uk-contest at contesting.com>
Sent: Tuesday, January 10, 2012 1:08 PM
Subject: Re: [UK-CONTEST] Aircraft Reflection Path Plot


Hi Ken,
Having checked the path plot between GB3ANG (IO86MN) and your location in 
IO81WV, air traffic between Manchester and EI would not be useful to you.
That path is too far south west of the mid-point which in your case is 
between Kendal and Settle.
The east/west Manchester/EI path is also "side-on" to you which is not the 
most favourable anyway.

They can produce reflections but of far shorter duration than those 
travelling in or close to the path your directing to.
Your actual mid-point towards ANG is very flight active, being on a regular 
flight path and should produce superb results.

However, the path plot between you and IO67UF identifies a mid-point in the 
Irish Sea triangulated between Whithorn, St Bees Head and the northern tip 
of GD.
This is definately not on a regulally used flight path so opportunities to 
hear the Isle of Skye beacon will be rare but not impossible.
Like a HF contester would plan ahead with greyline knowledge, propagation 
forecasts and more, this is an area were VHF+ contesters can optimise 
potential results.
Use of regular flight paths can give very good results, even by chance and 
without recourse to knowing when a reflection opportunity is available 
though it helps a lot to know so as not to waste time.
Use of rarely used flight paths opens up opportunities to work rarely worked 
or heard locations/multipliers. In your case, IO67.
Yesterday for example there were numerous opportunities.

05.55 DAL6 767-400 Detroit - Heathrow 33,000'
08.00 VIR206 747-400 San Francisco - Heathrow 37,000'
10.15 ICE542 757-400 Keflavik - Paris 39,000'
10.25 BAW48 747-400 Seattle - Heathrow 33,000'
16.25 BAW9 747-400 Heathrow Phoenix 31,350'
22.00 ICE455 757-200 Heathrow - Keflavik 38,000'
22.20 DHK972 767-300 East Midlands - Cincinnati 31,975'


In relation to the total UK/EU to/from North American air traffic in 24 
hours then that is a very small number and even the majority of those were 
in my opinion borderline cases but possible due to the wider beamwidth of a 
4m antenna over what I'm used to on the likes of 70cm, 23cm and 13cm. Only 
the first two were in what I would consider prime mid-point positions and 
there were a fair number of other G/GM flights that veered west of the 
Cumbrian coast that could possibly have produced an audible signal from the 
beacon and if not, certainly a visual trace using Spectran or other 
waterfall display of your receiver bandwidth.
The method I used to determine these possibilities is very easy.
Establish the mid-point using the SM7LCBpathplot software on his website.

Go to www.planefinder.net
Zero in on UK airspace and in particular the midpoint area you are 
interested in.
Click on the "Playback" icon.
Set a date from the calendar.
Set a start time.
Set the speed of playback. I usually use 120x normal.
When you see an aircraft approaching the mid-point circle (as indicated on 
the pathplot map) then hit the pause button to enable you to pause 
everything and click on the jet to identify everything about it including 
the height.

Range depends on numerous factors of which height and the size of a jet 
(area of reflection) are the most important.
You're 650km from GM8RBR's beacon. Something over 800km is the maximum I 
believe for a jet at 40,000' so you are very comfortably within that.
An SBS receiver would be useful for portable stations where no internet 
connection is possible but range would be a negative as I believe that even 
with a very effective 1,090MHz antenna there's a limit of about 400km.
That's fine for seeing traffic within 400km but it is important to know what 
is further away than that and coming closer so you're prepared for a maximum 
range contact (or CQ calls) on both inward and outward flights and not just 
outward.
As you say, the online resources are free and provide all the advance notice 
you need.

Good luck!

73 Ray GM4CXM








________________________________
 From: Ken Eastty <ken.g3lvp at btinternet.com>
To: uk-contest at contesting.com
Sent: Monday, 9 January 2012, 22:50
Subject: Re: [UK-CONTEST] Aircraft Reflection Path Plot


Aircraft Reflection Path Plot (Ray James) -

Thanks for that Ray, this is no doubt the mechanism which permits
reception of GB3ANG here (IO81WV) on 2 & 4m for most of the time
providing there's plenty of traffic in the airway between Manchester &
EI. It's a pity that the plots don't include the height at which an
aircraft would have to be flying for it to be 'seen' from both ends of
the path but I suppose that it only takes a few moments to calculate it.

So far I've not heard GM8RBR's new 10W beacon on Skye (IO67UF) on 70.1
Mc/s except via ms. The typical height of most airliners would seem to
be insufficient to act as a reflector over this path.

73...

Ken

G3LVP
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