3 ms·
That's from primary radar. Those altitude readings are unreliable at that range.
by confluence 13y ago
That's from primary radar. Those altitude readings are unreliable at that range.
- yock 13y agoCan you expound on that? Does it have to do with atmospheric curving of the radar beam?
- confluence 13y ago> The use of primary radar requires a great deal of signal power, because objects further from the antenna will reflect or send back a weak signal. At longer distances from the antenna, radar becomes unreliable as a way to determine aircraft position with only reflected signals. http://www.wisegeek.com/what-is-a-primary-radar.htm http://www.wisegeek.com/what-is-a-primary-radar.htm
- digikata 13y agoI think it has to do with electromagnetic ducting or other clutter effects: http://www.radartutorial.eu/07.waves/wa17.en.html http://www.radartutorial.eu/07.waves/wa17.en.html If the last effect on the page were in effect, you might get a return, know it's relative bearing well, it's range a little less well, and it's altitude not very well at all.
- Nacraile 13y agoRadar derives altitude from measurements of distance and elevation angle. The greater the distance, the less sensitive elevation angle is to vertical displacement (simple trigonometry), and hence signal:error decreases.
- apaprocki 13y agoInvestigators flew the same exact flight path in another 777 and it should have been apparent if primary radar misreported altitude +/- such a large margin at the distances observed. If they observed primary radar lose no accuracy at that distance, why judge the 45k as inaccurate?
- superuser2 13y agoYou are assuming that the altitude reading would always be off by (close to) the same amount.