take note of the times they fly past every day... you'll find its usually almost good enough to set your watch by.... then one day, be ready in ambush mode, so as soon as its visible, its in the view finder!
Thats how I used to take photos when I was living in the N.T.... I was near RAAF base Tindall, at 14:23
15-50 seconds) two F/A-18's would fly over at around 900-1100ft, every other day.
So I'd be ready and waiting with the BIGma 170-500 APO on my nikon...
best way to do it..