Definition
Controls on a Radio Magnetic Indicator (RMI) that allow the pilot to select which navigation source — typically a VOR or an ADF (NDB) — drives each of the two bearing pointers on the instrument face. Each switch independently assigns a navaid type to its corresponding pointer, so the pilot can display bearings to two different stations at once.
Plain English
Small selector switches on the RMI that let the pilot choose what each of the two needles on the instrument is pointing to. One switch controls one needle, the other switch controls the other needle.
Context Anchor
Seen on or near an RMI display when setting up which source each bearing pointer will show.
Derivation
Pointer comes from point, meaning to indicate a direction. Function means the job something is assigned to do. In this term, the switch assigns the pointer its job: which navigation source it will follow.
Why Pilots Care
Allows quick selection of available navigation aids so the pilot can maintain accurate bearing information without changing instruments.
Intuition Check
Do not assume the pointer function switches move the pointers directly. They select the source feeding each pointer; the RMI then moves the pointer based on that selected signal.
Example Sentence 1
Before tracking inbound to the NDB, the pilot set the pointer function switches so that the single bar needle showed VOR and the double bar needle showed ADF.
Example Sentence 2
During the en route phase, both pointer function switches were placed in VOR mode to track the airway.