What might indicate a rapid decay of N1 during flight?

A rapid decay of N1 during flight typically indicates a loss of engine performance, which can manifest as a loss of power and a decrease in airspeed. The N1 is a measure of the rotational speed of the engine's low-pressure compressor, and a significant drop in this value suggests that the engine is not producing the thrust necessary to maintain the aircraft's speed. When this situation occurs, pilots may experience a corresponding decrease in the aircraft's airspeed, making it a critical factor to watch for during operations.

In contrast, increased airspeed, stable oil pressure, and an accurate flight path do not necessarily correlate with a rapid decay of N1. Increased airspeed could imply that the engine is functioning properly and generating thrust, while stable oil pressure remains indicative of healthy engine operation. An accurate flight path, on the other hand, suggests that the aircraft is operating within expected parameters and does not indicate any potential engine performance issues. Thus, the correct indication of a rapid decay of N1 during flight is the loss of power and airspeed.