I remember one time, during my training with an instructor, that I was landing at an airport. The instructor told me to ignore the VASI indicators as it was calibrated for the larger airplanes. Flying in a C172, I found that remark odd as I was under the impression that all VASI or PAPI would accommodate the C172 configuration.

I didn’t think much of it until today, a few years later, after reading an accident synopsis that indicated using the APAPI was a contributing factor to the accident.

There are three types …