Which of the following is NOT included in the required equipment for VFR day flight?

In VFR (Visual Flight Rules) day flight, specific equipment is mandated for safe operation. Among these, an airspeed indicator, landing gear position lights, and anti-collision lights are all essential components. The airspeed indicator provides crucial information about the aircraft's speed relative to the surrounding air, which is vital for performance and control. Landing gear position lights give visual confirmation of whether the landing gear is extended or retracted, enhancing safety during takeoff and landing. Anti-collision lights, such as strobe lights, are important for increasing the visibility of the aircraft to other pilots, which is particularly critical in preventing mid-air collisions.

In contrast, the temperature gauge, while it may be useful for monitoring engine performance and ensuring the aircraft operates within safe limits, is not a required piece of equipment for VFR day flight. Therefore, it is accurately identified as not being included in the mandatory equipment list, distinguishing it from the other options that are essential for VFR operations.