And Stopways? Is grass OK?
Stopways only apply to the accelerate - stop case. They are not included in the LDA.
Grass is OK for a stopway when the aircraft for which it is intended can use grass and it is maintained to the required standard.
i.e. in general a grass stopway would for example be OK for say a Kingair (certified to operate from grass) but not for a citation (prohibited from operating from grass).
I would caution against using the unfactored flight manual data for landing in anything other than a "Land Immediately" situation - eg uncontained fire, smoke in the cockpit or similar. In these situations the high probability of an over-run is easily balanced by the urgent requirement to get back on the ground.
Any other reason for return or diversion could not justify the high risk of an over-run and therefore appropriate factors including those applicable to overspeed at the threshold need to be applied.
Regards,
DFC