What is MEHT (minimum eye height over the threshold)? I can't find the definition and how to use it.
The MEHT (Minimum Eye Height over Threshold) is composed of two values: the EWH (the eye to wheel height) plus the WTH (wheel to threshold height). Both values are for the aircraft in the approach configuration and are not the dimensions as may be measured for a parked aircraft resting on the ground. The MEHT assumes that the pilot eye would follow the lower limit of the approach corridor which is defined by angle M = B minus 2 minutes of arc. You can see this in the image below: