I noticed today that my home-grown ‘antenna range overlay’ was drawing an extremely bizarre shape. When I went to look at the raw data, I noticed at least one case of what looks like bad data – coming from flight ACA1150:
http://flightaware.com/live/flight/ACA1150/history/20150828/1810Z/CYYC/CYYZ
My own data looks even worse than this i.e. jumping from one hemisphere to another (!). I have never noticed this before. Equipment problem on the aircraft?