Regulation Text
(a) Airplanes manufactured after March 29, 2002. Except as provided in paragraph (d) of this section, no person may operate a turbine-powered U.S.-registered airplane configured with six or more passenger seats, excluding any pilot seat, unless that airplane is equipped with an approved terrain awareness and warning system that as a minimum meets the requirements for Class B equipment in Technical Standard Order (TSO)-C151.
(b) Airplanes manufactured on or before March 29, 2002. Except as provided in paragraph (d) of this section, no person may operate a turbine-powered U.S.-registered airplane configured with six or more passenger seats, excluding any pilot seat, after March 29, 2005, unless that airplane is equipped with an approved terrain awareness and warning system that as a minimum meets the requirements for Class B equipment in Technical Standard Order (TSO)-C151.
(Approved by the Office of Management and Budget under control number 2120-0631)(c) Airplane Flight Manual. The Airplane Flight Manual shall contain appropriate procedures for—
(1) The use of the terrain awareness and warning system; and
(2) Proper flight crew reaction in response to the terrain awareness and warning system audio and visual warnings.
(d) Exceptions. Paragraphs (a) and (b) of this section do not apply to—
(1) Parachuting operations when conducted entirely within a 50 nautical mile radius of the airport from which such local flight operations began.
(2) Firefighting operations.
(3) Flight operations when incident to the aerial application of chemicals and other substances.
[Docket 29312, 65 FR 16755, Mar. 29, 2000]
Research Notes
Section 91.223 — Terrain Awareness and Warning System (TAWS) — requires TAWS on most turbine-powered aircraft with six or more passenger seats. TAWS prevents Controlled Flight Into Terrain (CFIT) — historically one of the largest fatal accident categories in aviation.
Scope (paragraph a): Required for turbine-powered airplanes with 6+ passenger seats (excluding any required crew seat). This covers most business jets, turboprops, and regional aircraft in commercial-equivalent configurations.
TAWS classes:
- Class A TAWS: Full functionality including terrain awareness, terrain alerts, and the famous 'TERRAIN, PULL UP' warning. Required by § 91.223 for the aircraft category specified.
- Class B TAWS: Reduced functionality, no terrain map display required. Permitted for smaller turbine aircraft.
The CFIT mitigation: Before TAWS, CFIT was a leading cause of fatal accidents in business aviation and Part 121. The introduction of GPWS and then TAWS dramatically reduced CFIT incidents. The technology compares the aircraft's GPS position and altitude to a terrain database and warns when the aircraft is approaching terrain.
TAWS NUI / 'NUISANCE' alerts: Pilots sometimes encounter false or marginal TAWS alerts during normal operations (steep approaches, terrain-following coastal approaches, etc.). The pilot's response should be to assume the warning is real and execute the appropriate escape maneuver. Investigation can occur after the safety event is resolved.
Reference: AC 23-18 / TSO-C151c on TAWS Class A/B; FAA Order 8900.1 Volume 4, Chapter 11.
Amendment History
Amendment History Coming Soon
Every time this regulation changes, we'll record it here — the date, what was amended, and a plain-English summary of what shifted.