Originally Posted by
Capn Bloggs
then they shouldn't be used.
EXACTLY. But they are not misleading, you are expecting too much precision from the system.
The PAPI is a (1) VISUAL and (2) APPROACH aid. By the time you are over the fence, you should already be looking elsewhere and get a complete picture of the runway. You should be looking at touchdown zone markings and lights to get a complete picture. If you are on the PAPI you will be fine, the system will not make you crash. It's not a precision approach category, neither a visual flare aid, we’re not doing carrier landings here, it’s not that type of ”precision”. A PAPI is designed to put the aircaft on ie 3° glide 5NM out VISUALLY (using no GS or path indications on your instruments) and bring you close to the fence safely. Nothing more.
Capn Bloggs, everybody understands your ideas about main gear position on long body aircraft. But you make it sound like this simple light system is an automated landing system giving you sufficient protection all the way down to the runway. It’s not.
PS; it's a visual approach tool so legally, if you are cleared for an ILS... you're not even supposed to look at the PAPI, you visually transition from the glideslope indications to the set of runway lights (nothing stops you from using the PAPI, but it's your responsability).