Aerial cartwheelin flights of raptors, particularly eagles, are spectacular interactions in which birds lock feet and fall earthward while cartwheeling about a common axis. This is traditionally seen as courtship behaviour, despite the fact that injuries and some fatalities have been reported. We solicited unpublished accounts from 20 raptor biologists world-wide and reviewed published evidence for the courtship interpretation among 39 species of large and small falconiforms. In 82% of 107 cases in which detailed observations were available whirling flights were aggressive interactions between territorial birds and intruders. Cartwheeling also occurs as play behaviour and as aggression during parent-offspring conflicts. Cartwheeling in Fish Eagles Haliaeetus vocifer was confirmed as mainly intra-sexual aggression by T. Liversedge (pers.comm), who induced over 200 cartwheeling events in 5 years by providing fish on territorial pairs' boundaries. Cartwheeling during courtship is described between presumed paired birds in three species of Haliaeetus eagles, and one valture (11% of 107). However, only in one report is unequivocal evidence provided that the birds were paired. We conclude that whirling interactions are mainly aggressive encounters and suggest that observer-expectant bias and other factors may have led to a general misinterpretation of cartwheeling as courtship.