Definition
An attitude instrument flying technique in which, for any given maneuver or flight condition, certain instruments are designated as primary (showing the most direct indication of a specific performance result that must be held constant) while others are designated as supporting (backing up and corroborating the primary indication). The primary instrument for pitch, bank, and power changes depending on the phase of flight, and the pilot uses the supporting instruments to confirm what the primary is showing and to detect trends.
Plain English
A way of flying by instruments where, for each thing you need to control (pitch, bank, and power), you pick one instrument as the main one to watch and others as backups that confirm what the main one is telling you. Which instrument is the main one changes depending on what the airplane is doing.
Context Anchor
Used during attitude instrument flying, especially when learning how to scan an electronic flight display without giving every indication equal attention all the time.
Derivation
Primary comes from the Latin primus, meaning 'first' — the instrument you look at first for that piece of information. Supporting comes from Latin supportare, 'to carry from below' — the instruments that hold up and confirm what the primary one shows.
Why Pilots Care
This structured assignment of instrument roles lowers workload and prevents fixation on less precise instruments, leading to smoother and more accurate control.
Grounding Statement
In this method, “primary” means main reference for the moment, and “supporting” means used to back up and verify that reference.
Intuition Check
Do not assume “primary” means the same instrument is always most important. In this method, the primary instrument changes depending on what the pilot is controlling at that moment.
Example Sentence 1
In straight-and-level flight, the altimeter is the primary instrument for pitch, and the attitude indicator and vertical speed indicator are the supporting instruments.
Example Sentence 2
During a constant airspeed climb the airspeed indicator becomes the primary pitch instrument with the altimeter and vertical speed indicator serving supporting roles.