If the ram air is blocked but the drain hole is open, what will the ASI indicate?

When the ram air is blocked but the drain hole remains open, the airspeed indicator (ASI) would show zero. This situation occurs because the ASI relies on differential pressure between static (ambient) pressure and the pressure created by ram air entering the system. When the ram air intake is blocked, the system cannot detect any dynamic pressure relative to the static pressure, which effectively means that the airspeed cannot be registered.

In this case, while the drain hole is open and allows for the escape of any accumulated water or moisture, it does not help in resolving the blockage at the ram air input. Therefore, the ASI cannot measure the airflow accurately and will register an indication of zero airspeed.

Options indicating any other reading, such as indicating altitude or fluctuating, do not reflect the fundamental operation of the ASI under such conditions, where the blockage essentially negates any airflow measurement resulting in a reading of zero.