What do ice pellets encountered during flight indicate?

Ice pellets, also known as sleet, typically form when warm air overrides a layer of cold air near the surface. This situation creates conditions where precipitation falls as rain, but it freezes into pellets as it passes through the colder air. Therefore, encountering ice pellets during flight is an indication that warm air is present above the cold air at lower altitudes, suggesting that a warm front is about to pass through the area.

The presence of ice pellets signifies that the warm front is likely approaching; hence, this is the correct answer. Just before the warm front passes, conditions can be characterized by temperature inversions where warmer air precedes it, resulting in the formation of ice pellets as the precipitation falls through the cold air layer. This aligns with meteorological principles surrounding front dynamics and precipitation types.