What configuration is indicated by the ASI reading if the ram air and drain hole are both blocked?

When the ram air intake and the drain hole of the atmospheric pressure sensor (such as that in an Airspeed Indicator, ASI) are both blocked, the instrument will continue to show a reading that remains consistent with the altitude at which the blockage occurred. This is because the ASI relies on the differential pressure between the static pressure (from the drain hole) and the dynamic pressure (from the ram air). If both inputs are blocked, the ASI becomes trapped, retaining the pressure differential that was present at the time of the blockage.

This means that as the aircraft maintains altitude, the ASI will display a speed consistent with that altitude. The instrument does not provide valid information about changes in speed or altitude, but rather continues to reflect what was true at the moment of blockage. Hence, the reading reflects a "frozen" airspeed that corresponds to a specific altitude rather than showing erratic or variable behavior. This situation can be dangerous, as pilots may not be aware that their airspeed is not truly representative of a current or safe flight condition.

In a blocked system, the other choices—indeterminate data, false readings with erratic behavior, or correct speed but not altitude—do not accurately describe the performance of the ASI