Definition
Instrument flight conducted with one or more primary flight instruments inoperative or unreliable, requiring the pilot to control the aircraft and navigate using the remaining functional instruments. Most commonly refers to flight without the attitude indicator and/or heading indicator, relying instead on the airspeed indicator, altimeter, vertical speed indicator, turn coordinator, and magnetic compass.
Plain English
Flying in clouds or low visibility when one or more of your main flight instruments has failed, so you have to keep the aircraft under control and on course using only the instruments that still work.
Context Anchor
Seen in instrument training, emergency procedures, and inadvertent IMC discussions when a pilot may have to keep control with incomplete instrument information.
Derivation
Partial means incomplete; panel refers to the instrument panel in front of the pilot. So a partial panel is literally an incomplete set of working panel instruments — you have some, but not all, of your normal flight references.
Why Pilots Care
Develops the skills needed to maintain control and complete a safe recovery or landing when primary instruments fail in actual instrument conditions.
Analogy
Like steering a car after the speedometer and compass have gone out—you still drive using the other gauges and careful attention.
Intuition Check
Partial panel does not mean the cockpit panel is physically broken or partly installed. It means the pilot has only part of the normal instrument information available and must fly using what is still reliable.
Example Sentence 1
After the vacuum pump failed in the clouds, she transitioned to partial panel instrument flight and used the turn coordinator and magnetic compass to hold heading until ATC could vector her to clear air.
Example Sentence 2
In partial panel instrument flight the student maintained altitude with the altimeter while referencing the airspeed indicator for pitch.