over estimation


Is it normal for Dump 1090 mutability to over estimate the distance from the tracking station, i.e reported 271 miles and as calculated by as the crow flies 159 miles.


Please give an example of the coordinates involved and where you are seeing the distance.


MLAT calculations on done by the MLAT servers.
They estimate the location of MLAT only devices best on the best information they receive.
This is limited by the internal clock on the receiver(normally inside the dongle).
My radarcape provides a much better clock(8-10 times better than a regular USB dongle), however, there need to be others for the triangulation to work well(There aren’t that many in my area).

Non-MLAT locations should be accurate to 10 or so metres(30ft) at the time of reception.

SBAS(WAAS/EGNOS etc) and GBAS(Limited to a few ariports) will improve the accuracy.
Things will get better with Galileo. It should provide Globally accurate positions, especially at high latitudes.