FAR Explainers
14 CFR Part 91 for instrument pilots.
The FAR sections the Instrument ACS expects you to know — each broken down with eCFR links, plain-English explanations, edge cases, and oral-exam scenarios.
- 91.103
Preflight Action
What the PIC must determine before any flight (weather, runway lengths, alternates, fuel).
- 91.155
Basic VFR Weather Minimums
Cloud clearances and visibility by airspace class (relevant for IFR vs VFR contrasts on the oral).
- 91.167
IFR Fuel Requirements
Required fuel to destination, alternate, and 45 minutes thereafter.
- 91.169
IFR Flight Plan: Information Required (Alternate)
When an alternate is required and what minimums it must meet (1-2-3 rule + alternate minimums).
- 91.171
VOR Equipment Check
Required VOR accuracy checks for IFR operations (30 days, ±4°/±6°).
- 91.173
ATC Clearance and Flight Plan Required
ATC clearance and IFR flight plan filing requirements.
- 91.175
Takeoff and Landing Under IFR
Visual references required to descend below DA/MDA; takeoff minimums for Part 91.
- 91.177
Minimum Altitudes for IFR Operations
MEA, MOCA, and obstacle clearance requirements.
- 91.181
Course to Be Flown
Center of airway/route requirements.
- 91.183
IFR Communications
Required IFR position reports and ATC communication.
- 91.185
IFR Operations: Two-Way Radio Communications Failure
Lost-comm procedures: route, altitude, leave-clearance-limit timing (A-V-E-F / M-E-A).
- 91.187
Operation Under IFR in Controlled Airspace: Malfunction Reports
When a pilot must report navigation/communication malfunctions to ATC.
- 91.189
Category II and III Operations: General Operating Rules
Cat II/III approach operating rules (mostly Part 121/135 but cited on oral).
- 91.205
Powered Civil Aircraft With Standard Category U.S. Airworthiness Certificates: Instrument and Equipment Requirements
ATOMATOFLAMES (VFR day) + FLAPS (VFR night) + GRABCARD (IFR) equipment lists.
- 91.211
Supplemental Oxygen
Oxygen requirements above 12,500 / 14,000 / 15,000 MSL.
- 91.215
ATC Transponder and Altitude Reporting Equipment
Where Mode C transponders are required.