PPRuNe Forums > Wannabes Forums > Professional Pilot Training (includes ground studies) > Collision avoidance math? PDA View Full Version : Collision avoidance math? flydaddy31st Jan 2005, 18:41Hi all, Somebody give me a shove with the simplist way of calculating impact times. IE. 2 aircraft head on at 550 k see each other at 4 kilometers, now calculate how long until impact. I realise I need to convert 4 kilometers to NM by multiplying by .54 but from there I go blank. At one point I could do this but now cannot. Please help a mental blocked getting annoyed oldtimer. Thanks. Happy Landings Flydaddy. reynoldsno131st Jan 2005, 18:524km = 2.16nm Aircraft closing speed = 550 x 2 = 1100nm/hr Time to impact = 2.16/1100 = .002 hr or (.002 x 3600) = 7.07 sec flydaddy31st Jan 2005, 19:06Thanks for the response, Just one last question, where does the 3600 come from? Thanks again. Happy Landings. Flydaddy reynoldsno131st Jan 2005, 19:11Number of seconds in one hour ........ :ok: flydaddy31st Jan 2005, 19:12See, TOTAL block. Thanks again. Happy Landings. Flydaddy.