Papi / Vasi
I'm hoping one of you learned folk can point me in the right direction. I've searched the web but can't find the technical information I'm looking for.
I'm trying to find out at what point (DME / Altitude) PAPI and VASI, etc. becomes critical to flight safety.
Is there a maximum and / or minimum distance from TDZ that the aids are designed to be effective at?
Under what circumstances are these aids beneficial to flight safety? Obviously, they are of no use in IMC conditions. In a non instrument VMC approach where are they factored into the safety margins? I presume during night approaches where the paths may have obstacles.
Grateful for any pointers.
Cheers,
2close