Author Topic: ATOM station avoid direct overhead transit.  (Read 311 times)


ATOM station avoid direct overhead transit.
« on: May 02, 2022, 04:05:30 pm »
My apologies if this has been discussed before.
For the last 12 months I have had an ATOM station installed and it works well. I have noticed that when I am flying I have a tendency to use ATOM stations as waypoints and fly direct from one to another. This also allows me to get a clear result on the Vector software when I am checking the performance of my Pilotaware. However there is a slight downside to this behaviour. When sitting in the garden I have noticed that there seem to be an increase in the number of aircraft transiting overhead the ATOM station. I don't mind but a couple of neighbours have commented on the increase but not yet made the connection with the aerials strapped to the side of our greenhouse..
I have also noticed that this increase in transits will increase the density of aircraft in the vicinity of the ATOM station and could result in a very slight increase in the chance of an airprox which is the very thing the PAW is intended to avoid.
When I was doing IR/IMC training my instructor always recommended that if I was using an VOR or NDB I should fly 0.5 miles to the right of the beacon. That meant there was a good chance of separation and an increased prospect of spotting any aircraft that was flying through the beacon overhead. So unless anyone can see a snag that I have not spotted could I suggest that we all try to fly 0.5 miles right of the ATOM beacon rather than direct through the overhead. (It will also keep my neighbours happy but they won't know why!)


Re: ATOM station avoid direct overhead transit.
« Reply #1 on: May 02, 2022, 10:00:44 pm »
Surely the whole point of having satellite navigation is not having to tie navigation to ground-based signal sources? ATOM ground station location takes no role in my flight planning.


Re: ATOM station avoid direct overhead transit.
« Reply #2 on: May 03, 2022, 05:42:36 am »
What a bizarre concept. Surely you’ll get a better Vector picture of the overall performance of your PAW installation by not tracking to or from ATOM stations.


Re: ATOM station avoid direct overhead transit.
« Reply #3 on: May 05, 2022, 06:12:38 pm »
Hi Peter K,

The occasional use of a ‘non-airfield’ ATOM site as a waypoint at an appropriate height above ground level is unlikely to cause major disruption or disturbance. I fully appreciate your concerns, however, about potential nuisance to neighbours which could be caused by pilots deliberately using such sites (especially in domestic premises) as waypoints on a regular basis, especially at low level - and this should certainly be discouraged except where used at an appropriate altitude in accordance with the terms of the ANO.

In reality, however, I suspect that this practice is relatively rare, and there is certainly NO advantage to be achieved by flying close to known ATOM sites in an attempt to generate or improve your reported radiation pattern. In fact, exactly the opposite principle applies!

If you were to set up a linear route directly overhead a series of ATOM stations all in a straight line, the resulting polar diagram would (assuming no other in-range stations and that your antennas have clear coverage all round with no significant obscuration) simply show coverage in a straight line in your 12 and 6 o'clock as you approach and then fly away from each station, but nothing whatsoever either side of the fore/aft line. Similarly, flying a perfect circle around a single ATOM station would (in theory) produce a report along a single bearing from the Aircraft, (3, or 9 o’clock depending on direction of orbit), with maximum range equivalent to the radius of the circle around the ATOM antenna.

If users want to see the maximum coverage from their aircraft, they need to fly ‘past’ as many ATOM stations as practicable, whilst keeping as FAR away from each as will still achieve a report from as many points as possible around their aircraft. Failure to do this will simply produce a diagram showing coverage at relatively short range - or nothing at all if you are outside reception range from all of the stations. To achieve maximum exposure, the route should ideally also be flown in both directions, to expose both sides of your aircraft to the receiving stations along your route. In practice, however, simply flying a decent length route through an area with multiple ground stations will normally ensure a fairly accurate and realistic range / obscuration report from Vector, the accuracy of which will build up and improve over time (assuming fairly regular flights).

I have, for example, just re-checked the coverage from my own flexwing (405A14) using the Vector Tool on the PilotAware website after last weekend’s flight to and from Popham (from East Fortune - east of Edinburgh). The polar diagrams for each separate transmission mode - in my case PilotAware, Flarm and ADSB - have been created from a combination of reports from previous flights (since 8th April) plus those from the 60 to 70+ separate ATOM stations ‘passed’ during each of last weekend’s flights to and from Popham (I haven’t flown since). The high number of stations reporting and the significantly varying bearing and range from each, of course, helps to maximise reliability in the resulting polar diagrams (though accurate reports can also be obtained from significantly less stations).

For anyone who isn’t aware of the Vector analysis tool, you can look at my results (or those for your own aircraft) by inserting the relevant information in the Vector analysis tool available via the following link....

Hope this helps clarify the situation...

Best Regards
Peter R