Air traffic controllers called to AOPA’s attention an apparent misunderstanding of phraseology involving RNAV instrument departures that has led to unwelcome surprises.
The issue was reported by air traffic control personnel in Florida, though it could happen at any airport where a published RNAV standard instrument departure procedure (RNAV SID) includes a route with multiple waypoints.
The procedures used at many large airports with parallel runways route traffic through distinct waypoints used with specific runways. ATC issues takeoff clearances that are phrased like this example: “RNAV to GOHOM, wind xxx/xx, Runway 36L, cleared for takeoff.”
This does not mean that ATC expects the pilot to fly direct to GOHOM in this example. Rather, ATC expects pilots to fly the procedure as published, as explained in detail in the Aeronautical Information Manual, Chapter 5, Section 2-8 (b)(2):
“The purpose of the advisory is to remind pilots to verify the correct procedure is programmed in the FMS [flight management system] before takeoff. Pilots must immediately advise ATC if a different RNAV SID is entered in the aircraft's FMC [flight management console]. When this advisory is absent, pilots are still required to fly the assigned SID as published.”
The AIM notes that the SID transition is not restated because the clearance is a clearance to fly a published route, and aircraft cleared to use an RNAV SID that begins with a vector to a waypoint will be assigned a heading before departure.