| Topic: | Re:Re:How accurate is heathrow webtrak? | |
| Posted by: | Claudia Jachtmann | |
| Date/Time: | 05/12/07 14:03:00 |
| hi, here are some inputs from other people interested in webtrak and losely associated with and consulting for airport watch organisations (i did not manage so far to get anything from BAA, but probably not been getting to the right place yet for such a query) i quote below : VERY simply put: WEBTRAK is an edited version of the radar data which is supplied to the airports by NATS plus, probably, data from their own secondary surveillance radar. I suspect that it's edited twice: once, very lightly, by NATS themselves but only to remove any "sensitive" flights, and again by Heathrow's own Noise & Track Monitoring System (GEMS, writen by Lochard, an Australian outfit for what its worth.) I'm extrapolating a bit from practice at Luton (which uses a different NTK system and, at present, does NOT permit public access to it a la WEBTRAK). At Luton the supplementary data from secondary surveillance radar includes the "transponder codes" which are sent by every commercial aircraft these days: a bit of kit automatically sends data such as aircraft registration, flight number, heading, height, rate of climb or descent - pretty much everything except the pilot's inside leg measurement. At Luton their NTK software can filter the streams of data and, if they want, exclude data from aircraft not relevant to Luton's operations. And, though it won't be an issue for Heathrow, the smallest of the biz-jets and light aircraft do NOT have transponders which send loads of data (known to the anoraks as "Mode C". If your correspondent would like to contact me directly I could talk to her about devices: on the lines of that which Steve Charlish described at the Noise seminar, which would let the Heathrow folk see the radar tracks for themselves: clever little boxes which plug into a PC and, using that Mode C data, plot the flight tracks - and, for Heathrow at least, they'd show EVERYTHING except the odd helicopter. I've recently bought one of the clever little boxes, which is why I sound a bit like an anorak (but I'm not really! |