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The Pilots Desk
US-FAA14 CFR 121.354

Terrain awareness and warning system

Read the official rule

This regulation requires all turbine-powered airplanes operated under Part 121 (scheduled air carriers) to have an approved Terrain Awareness and Warning System (TAWS) that meets TSO-C151 Class A standards, plus a terrain situational awareness display.

The compliance date depends on when the airplane was manufactured. Airplanes built after March 29, 2002, must have TAWS installed from the start. Older airplanes manufactured on or before that date had until March 29, 2005, to be retrofitted with the system.

Additionally, the Airplane Flight Manual must include procedures for using the TAWS and instructions on how flight crews should respond to its audio and visual warnings. This ensures pilots know how to properly react when the system alerts them to potential terrain conflicts, which is critical for preventing controlled flight into terrain (CFIT) accidents.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*

This is an original plain-English explanation for training and reference, not legal advice and not for navigation. Always rely on the current official rule linked above. Last reviewed June 20, 2026.