r.j
How do you arrive at 1800kgs for the -800 NG ??
FFR+ Alt fuel = CMR
Depending upon the flying time, and landing weight to No.1 div, your CMR could be under 1.8
Ryanair no.1 div from Prestwick is Glasgow. 23nm as the crow flies. Depending upon actual routing, flying time could be less than 10 minutes if landing on rw 05.
Having said that, anything under 2.0 MT and still airborne is likely to concentrate the mind !!