| Topic: | Re:How accurate is heathrow webtrak? | |
| Posted by: | Richard Jennings | |
| Date/Time: | 14/11/07 02:42:00 |
| "I have noticed an unidentified flight transit (yellow) that suddenly appears at 18:45:50 over the M4 by Syon Lane." I noticed several such flights amongst that evening's data on WebTrak. They are all heading NNE at around 15,000 feet but gradually losing altitude. I wondered if they were heading for Luton or some other airport. The reason why it suddenly appeared is possibly because everything above 16500 ft is excluded from WebTrak. In answer to Claudia's points: - the flight paths on WebTrak are based on actual radar tracks, not timetables. - the original tracks are processed to exclude most non-Heathrow flights, and to distinguish between arriving and departing flights. - WebTrak shows aircraft positions at intervals of between 4 and 10 seconds of recorded time, depending on the speed of replay. Some smoothing of the tracks may occur because of this. - There seems to be some distortion at the largest scales, for example some planes taking off from Heathrow appear to follow an oddly curved path just after take-off. - Landings and take-offs appear to happen about 150 metres north of the runway on the map. (The normal flight paths over Chiswick and Putney also seem to be 150 metres north of the paths I plotted at http://tinyurl.com/2nsnqj using Google Earth, but that may just be my inaccuracy.) Tim said "I want to see how it records the three in a row that woke me up at 4.30 am." [on Monday] The data is now available. Actually it was five in a row, so at least you slept through two of them. For the record, the planes were as follows (all 747s, times are when passing Chiswick): 04:30 BA026 from Hong Kong 04:33 CX251 from Hong Kong 04:36 BA032 from Hong Kong 04:38 BA012 from Singapore 04:41 BA074 from Lagos |