What type of light is essential for IFR night operation according to GRABCARD?

In the context of IFR (Instrument Flight Rules) operations at night, the landing light is crucial due to its function of enhancing visibility during critical phases of flight, particularly during the approach and landing. The landing light provides pilots with a clearer view of the runway environment and surrounding obstacles, which is essential in low visibility situations that often accompany night operations.

While navigation lights, anti-collision lights, and strobe lights contribute to the overall safety and visibility of the aircraft, they do not directly assist the pilot in landing the aircraft. Navigation lights are mainly for the identification of the aircraft's position and direction to other airspace users. Anti-collision lights and strobe lights serve to make the aircraft more visible to others in the air and on the ground but do not enhance the pilot's forward visibility as effectively as landing lights do during approach and landing phases.

Thus, in the context of GRABCARD, which stands for the required equipment for IFR flight specifically at night, the landing light stands out as the most essential type of light for ensuring safe operations during these conditions.