What might cause an increase in indicated airspeed while descending through IMC without a corresponding change in ground speed?

An increase in indicated airspeed while descending through Instrument Meteorological Conditions (IMC) can be attributed to a blocked static port. The static port provides ambient atmospheric pressure information to the altimeter, vertical speed indicator, and airspeed indicator. If the static port becomes obstructed, the airspeed indicator may not be able to accurately measure the true pressure differential, which can lead to erroneous readings of airspeed.

In the case of a blocked static port during a descent, as the aircraft descends, the ambient pressure decreases. If the static pressure source is blocked, the instrument will not respond correctly to this change, causing the indicated airspeed to show an increase even though the ground speed remains constant. This is due to the incorrect pressure data being translated into an inflated airspeed reading.

Understanding the impact of a blocked static port is crucial for instrument pilots because it can lead to misinterpretation of airspeed, which is vital for maintaining control of the aircraft during critical flight phases.