IFR
Abbreviation with 2 meanings
| Stands for | Instrument flight rules |
|---|---|
| Meanings | 2 |
| Categories | Transportation & Travel, Medical |
| Also written | iFR |
IFR has two meanings. It stands for Instrument flight rules (aviation) or Instantaneous wave-free ratio (cardiology).
Meanings of IFR at a glance
| # | IFR stands for | Context |
|---|---|---|
| 1 | Instrument flight rules | Transportation & Travel › Aviation |
| 2 | Instantaneous wave-free ratio | Medical › Cardiology |
1. Instrument flight rules
Transportation & Travel · Aviation Abbreviations
Regulations under which a pilot flies by reference to cockpit instruments and follows ATC clearances instead of navigating by outside visual cues. An instrument rating and an IFR flight plan are required to fly in clouds or low visibility, and airliners file IFR regardless of the weather.
Example: We filed IFR to Denver because ceilings along the Front Range were forecast to drop below 1,000 feet.
Contrasted with VFR. Pilots loosely say "IFR conditions," though the formal term for the weather is IMC. Under IFR in controlled airspace, ATC is responsible for separating the aircraft from other IFR traffic. A long-running pilot joke expands IFR as "I follow roads," a nod to visual pilots who navigate by highways.
2. Instantaneous wave-free ratio (iFR)
Medical · Cardiology Abbreviations
Resting pressure-wire index measured during a window of diastole when coronary resistance is naturally lowest, avoiding the need for adenosine. A value of 0.89 or lower is considered significant.
Example: iFR across the circumflex lesion 0.93, so the stenosis was deferred and treated medically.
The DEFINE-FLAIR and iFR-SWEDEHEART trials (2017) found iFR-guided PCI noninferior to FFR guidance at one year, with fewer side effects during measurement. Other resting indices, such as the resting full-cycle ratio, are used in a similar way. Written with a lowercase i.
Related abbreviations
More aviation abbreviations
- IAS – Indicated airspeed
- IATA – International Air Transport Association
- ICAO – International Civil Aviation Organization
- IFE – In-flight entertainment
- ILS – Instrument landing system
- IMC – Instrument meteorological conditions
- IR – Instrument rating
- LAANC – Low Altitude Authorization and Notification Capability
See all 142 aviation abbreviations →
More cardiology abbreviations
- IABP – Intra-aortic balloon pump
- ICD – Implantable cardioverter-defibrillator
- ICM – Ischemic cardiomyopathy
- IE – Infective endocarditis
- IHD – Ischemic heart disease
- ILR – Implantable loop recorder
- ISR – In-stent restenosis
- IVC – Inferior vena cava
See all 229 cardiology abbreviations →
This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.