Instruments and equipment for operations under IFR or over-the-top

This regulation specifies additional equipment required for Part 121 air carrier operations when flying under instrument flight rules (IFR) or over-the-top of clouds. These requirements come on top of the basic equipment mandated in earlier sections.

The airplane must have:

• Heated pitot system: An airspeed indicator with a heated pitot tube (or equivalent anti-icing protection) to prevent ice from blocking the pitot system and causing airspeed indication failure
• Sensitive altimeter: A precision altimeter capable of accurate altitude readings for instrument flight
• Proper instrument lighting: Lighting that illuminates all required instruments, switches, and controls adequately for the crew to read them easily, without glare or reflections that could interfere with the pilots' vision. The lighting must be adjustable in intensity unless fixed lighting is proven satisfactory

These requirements ensure pilots can maintain safe flight references and situational awareness when operating without visual ground contact.

*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.*