▁or ▁night ▁flying ▁over ▁a ▁feature less ▁terrain ▁with ▁a ▁clearly ▁defined ▁pattern ▁of ▁ground ▁lights ▁and ▁a ▁dark , ▁star less ▁sky . ▁ ▁Ve ction ▁▁ ▁This ▁is ▁when ▁the ▁brain ▁perce ives ▁peri pher al ▁motion , ▁without ▁sufficient ▁other ▁c ues , ▁as ▁applying ▁to ▁itself . ▁Consider ▁the ▁example ▁of ▁being ▁in ▁a ▁car ▁in ▁lan es ▁of ▁traffic , ▁when ▁cars ▁in ▁the ▁adjacent ▁l ane ▁start ▁cre eping ▁slowly ▁forward . ▁This ▁can ▁produce ▁the ▁per ception ▁of ▁actually ▁moving ▁backwards , ▁particularly ▁if ▁the ▁whe els ▁of ▁the ▁other ▁cars ▁are ▁not ▁visible . ▁A ▁similar ▁ill usion ▁can ▁happen ▁while ▁tax i ing ▁an ▁aircraft . ▁ ▁Re pe ating ▁pattern ▁▁ ▁This ▁is ▁when ▁an ▁aircraft ▁is ▁moving ▁at ▁very ▁low ▁alt itude ▁over ▁a ▁surface ▁that ▁has ▁a ▁regular ▁repeating ▁pattern , ▁for ▁example ▁r ipp les ▁on ▁water . ▁The ▁pilot ' s ▁eyes ▁can ▁mis inter pret ▁the ▁alt itude ▁if ▁each ▁eye ▁lines ▁up ▁different ▁parts ▁of ▁the ▁pattern ▁rather ▁than ▁both ▁eyes ▁l ining ▁up ▁on ▁the ▁same ▁part . ▁This ▁leads ▁to ▁a ▁large ▁error ▁in ▁alt itude ▁per ception , ▁and ▁any ▁descent ▁can ▁result ▁in ▁impact ▁with ▁the ▁surface . ▁This ▁ill usion ▁is ▁of ▁particular ▁danger ▁to ▁hel ic opter ▁pil ots ▁operating ▁at ▁a ▁few ▁metres ▁alt itude ▁over ▁calm ▁water . ▁ ▁Ex amples ▁▁▁ ▁Air ▁India ▁Fl ight ▁ 8 5 5 , ▁the ▁le ans ▁ ▁Flash ▁Airlines ▁Fl ight