What happens to the ASI if both the ram air and the drain hole are blocked?

When both the ram air source and the drain hole of the Airspeed Indicator (ASI) are blocked, the ASI will not function properly as it relies on differential pressure between the static and dynamic atmospheres to indicate airspeed. However, in this situation, the ASI will still reflect the static pressure, which corresponds to the altitude in terms of the indicated airspeed.

As the aircraft ascends or descends, the atmospheric pressure changes, but the ASI will not account for these changes due to the blocked ram air. The instrument will essentially stabilize and show a reading that corresponds to the static pressure at that altitude. Thus, while the reading may not be trustworthy for actual airspeed calculations, it will provide an indication that may be misleadingly interpreted as altitude in terms of airspeed.

It is important for pilots to understand that even though the ASI might display a reading during such a malfunction, that reading is not reliable for navigation or speed assessments and shouldn't be trusted for flight maneuvers.