Minimum eye Height over threshold is the Threshold Crossing height from pilots eye to the ground (its a self explanatory definition but)
To put it in a simple way,
Aircraft like A320 have a minimum wheel clearance of 20 feet(from Wheel to threshold)....1
From pilots eye to wheel is know in the FCOM which is 24ft in A320.....2
MEHT is basically Point 1 + Point 2 which is 45 feet
if the MEHT/TCH is less than 45ft the aircraft will not have adequate clearance
hence the A320 in that case cannot use PAPI.
Last edited by planeboy_777; 14th Jun 2012 at 07:24.