Definition
Flight time logged while a pilot is operating the aircraft solely by reference to instruments and is receiving instruction from an authorized flight instructor on board the aircraft. It is recorded in the pilot's logbook as both instrument time and dual (instructional) time.
Plain English
Time spent flying the airplane using only the cockpit instruments to know what the airplane is doing, while a flight instructor sits with you and teaches. It counts twice in the logbook: once as instrument flying and once as instruction received.
Context Anchor
Seen in training syllabi, lesson records, and logbook entries that track how much instructor-led instrument training a pilot has completed.
Derivation
"Dual" comes from the Latin duo, meaning two, and in aviation training has long meant flying with two people on board where one is the instructor. "Instrument time" refers to time controlling the aircraft by reference to the flight instruments rather than by looking outside. Combined, the term means instructional time flown on instruments.
Why Pilots Care
This time counts toward the minimum dual instruction required for an instrument rating and must be properly documented for certification.
Intuition Check
Dual does not mean two airplanes, and it does not mean two pilots both getting the same credit. Here, dual means instruction received from an instructor. Instrument does not mean a musical instrument; it means the aircraft instruments used to fly when outside visual references are not being used.
Example Sentence 1
On today's syllabus lesson, the student logged 1.2 hours of dual instrument time while practicing holding patterns under the hood.
Example Sentence 2
FAA requirements state that at least 20 hours of dual instrument time must be completed with a CFII before the instrument checkride.