Vtoss and Vy
Vtoss is the Take Off Safety Speed and is the slowest speed at which a rate of climb of 100 ft/min can be maintained and is applicable between TDP and 200 feet ATS (Above the Take Off Surface)
Vy is Best Rate of Climb speed and is applicable for the climb segment between 200' and 1000' ATS during which the min RoC is 150'/min.
This climb profile is set out in the Cat A certification and is an artificial template against which all certified aircraft are measured. Sometime you may need to climb to MSA at Vtoss if you are in an extremely obstacle-rich environment like a city full of sky-scrapers - and cranes!
G
Last edited by Geoffersincornwall; 30th Jan 2013 at 10:49.
Reason: addiions