Definition
A set of FAA regulations governing flight conducted primarily by reference to cockpit instruments rather than outside visual references. IFR flight requires an IFR-rated pilot, an appropriately equipped aircraft, an ATC clearance, and operation within the air traffic control system. IFR is required when weather conditions are below VFR minimums and is also used by choice in controlled airspace regardless of weather.
Plain English
The rules that apply when a pilot flies using cockpit instruments instead of looking outside, with air traffic control directing the flight from start to finish.
Context Anchor
Seen in instrument training, weather decisions, flight plans, clearances, and instrument procedure discussions.
Derivation
IFR is made from the first letters of instrument flight rule. Instrument comes from an older word meaning a tool; in aviation, it means the cockpit tools that show the aircraft’s attitude, altitude, speed, heading, and other flight information.
Why Pilots Care
IFR is what allows flight in clouds, low visibility, and busy controlled airspace. Operating IFR means the pilot is bound to a clearance, must follow ATC instructions, and must fly published procedures precisely. Knowing whether you are IFR or VFR determines what rules, minimums, and equipment requirements apply.
Intuition Check
IFR does not simply mean “flying in bad weather.” You can be in clear skies and still be operating under IFR if the flight is filed, cleared, and flown under those rules.
Example Sentence 1
We filed IFR for the trip because a layer of clouds was forecast along the route.
Example Sentence 2
Under IFR the crew flew the published approach procedure using only the instruments on the panel.