777AV6R just to clarify my previous post when I said its's a certification requirement I meant the performance calculations for accelerated stop dinstances and landing distances are without reverse thrust by requirement. (At least that's what I think, please correct me if I'm wrong)
m&v Thanks for your point but what we were actually reffering to is the performance calculations mentioned above and all those in the FCOM's are without the use of reverse thrust.