freddoair
New Member
Hi All,
I hope this is in the right place for a question based on curiosity more than anything else.
I was wondering if Plane Finder assumes data to be invalid once a certain distance is reported, and it consequently doesn't use that data. Now for the why.
I'm quite close to the Pacific Ocean coast of Oz and frequently see aircraft out to beyond 400km, and those aircraft are reported in Plane Finder. Today, during a brief period of Tropospheric Ducting (or bending) to the north east of me (and over the ocean), I recorded planes beyond 600km (639km in one case) but they didn't appear in Plane Finder except for the dead reckoning course of dashed lines. Given that during such ducting (sometimes called tropospheric waveguide*) very strong signals can be received due to a very reduced pathloss, I believe the data was valid and I didn't see ghost aircraft.
*Atmospheric temperature normally changes linearly with changes in altitude. However, under certain meteorological conditions a sudden (step) change in temperature, known as a temperature inversion, can occur and this causes VHF/UHF radio waves to be trapped in the atmospheric duct that is formed, causing those waves to propagate great distances, sometimes thousands of kilometres.
Ray
I hope this is in the right place for a question based on curiosity more than anything else.
I was wondering if Plane Finder assumes data to be invalid once a certain distance is reported, and it consequently doesn't use that data. Now for the why.
I'm quite close to the Pacific Ocean coast of Oz and frequently see aircraft out to beyond 400km, and those aircraft are reported in Plane Finder. Today, during a brief period of Tropospheric Ducting (or bending) to the north east of me (and over the ocean), I recorded planes beyond 600km (639km in one case) but they didn't appear in Plane Finder except for the dead reckoning course of dashed lines. Given that during such ducting (sometimes called tropospheric waveguide*) very strong signals can be received due to a very reduced pathloss, I believe the data was valid and I didn't see ghost aircraft.
*Atmospheric temperature normally changes linearly with changes in altitude. However, under certain meteorological conditions a sudden (step) change in temperature, known as a temperature inversion, can occur and this causes VHF/UHF radio waves to be trapped in the atmospheric duct that is formed, causing those waves to propagate great distances, sometimes thousands of kilometres.
Ray
Last edited: