Definition
An FAA Advisory Circular that provides operational and airworthiness guidance for conducting area navigation (RNAV) operations on U.S. terminal and en route procedures, including RNAV Standard Instrument Departures (SIDs), Standard Terminal Arrival Routes (STARs), and Q- and T-routes. It defines the equipment, training, and operating requirements an operator must meet to fly procedures designated 'RNAV 1' or 'RNAV 2.'
Plain English
It is the FAA's rulebook for using GPS-style navigation on departure, arrival, and en route routes. It tells pilots and operators what gear they need and how accurately they must stay on course to fly these routes legally.
Context Anchor
Seen in instrument procedure discussions, especially when an RNAV departure or route requires aircraft and operating practices that meet FAA guidance.
Derivation
An 'Advisory Circular' (AC) is the FAA's standard form of non-regulatory guidance. The number '90-100' identifies the subject series (90 = Air Traffic and General Operating Rules) and the specific document within it. Knowing it is an AC tells you it is official FAA guidance, not a regulation in itself, but compliance is typically required to gain authorization for the operation it describes.
Why Pilots Care
Following its guidance ensures compliance with RNAV equipment and procedure standards needed for IFR operations.
Intuition Check
AC 90-100 is not an electrical “AC” term and not a clearance. Here, “AC” means Advisory Circular: an FAA guidance document.
Example Sentence 1
Before accepting the RNAV departure, the crew confirmed their aircraft and training met the requirements of AC 90-100.
Example Sentence 2
AC 90-100 outlines the steps for conducting RNAV operations in terminal airspace.