Difference between TERPS & PANS-OPS?
Two documents that describe how to design instrument approach procedures.
In short they are very similar from a pilot’s practical operating view – you fly the approach as published. There are, however some differences such as maximum distance from the airport during circling approach.
TERPS = United States Standard for Terminal Instrument Procedures published as a joint venture by the Inter Agency Chartering Committee (Defence and Civil Gov Agencies). TERPS contains some notes about items not meeting ICAO standards. Additional details can be found in AIP USA Diff section.
PANS-OPS = Procedures for Air Navigation Services has two volumes:
Vol 1 Flight Procedures (of interest to pilots)
Vol 2 Construction of Visual and Instrument Flight Procedures (for those that design procedures and detail seekers).
From a practical view you will see that the US tends to stick to the TERPS book while you can find some rather scary approaches based on PANS-OPS but with various notes about deviations.
Domestic Jeppesen manuals have details from TERPS while the international include PANS-OPS information.
I am also curious about the Greek TERPS circle?