Which FAA exams test 14 CFR 91.123?

This regulation is tested on the following FAA exams: PAR, IRA, CAX, ATP. These include the FAA Private Pilot (PAR), FAA Instrument Rating (IRA), FAA Commercial Pilot (CAX).

Part 91General Operating and Flight Rules

14 CFR 91.123 — Compliance with ATC Clearances and Instructions

Pilots must comply with ATC clearances and instructions when operating in controlled airspace, unless an emergency requires deviation.

Regulation Text

When an ATC clearance has been obtained, no pilot in command may deviate from that clearance unless an amended clearance is obtained, an emergency exists, or the deviation is in response to a traffic alert and collision avoidance system resolution advisory. Each pilot in command who deviates from an ATC clearance or instruction shall notify ATC of that deviation as soon as possible.

Note: This is an excerpt. Refer to the full regulation in eCFR for the complete text.

Plain-English Explanation

When ATC gives you a clearance, you must follow it. The only exceptions are emergencies, TCAS resolution advisories, or getting an amended clearance. If you do deviate, tell ATC as soon as possible. Note the difference between clearances (specific authorizations) and instructions (general directions). This regulation works with 91.3 — you have emergency authority, but you must communicate. The FAA may ask for a written report within 48 hours.