What is the ASI/Mach meter indication when there is a blocked static probe at a constant altitude?

When there is a blocked static probe at a constant altitude, the ASI (Airspeed Indicator) and Mach meter will not change their indications. This is because a blocked static system results in a situation where the static pressure does not change, regardless of the aircraft's speed.

As the aircraft climbs or descends, the static pressure would normally fluctuate and affect the ASI reading. However, with a blocked static probe, the instrument's reading remains constant at the altitude the blockage occurred, leading to a false indication. Thus, despite changes in the aircraft's true airspeed, the ASI and Mach meter maintain the appearance of stability in their readings, displaying exactly what was indicated at the time of blockage.

Dashed assumptions about fluctuations or variations in readings like over-reading or under-reading do not apply here since the blockage inhibits any responsive changes in pressure, hence the readings are frozen at one point. This is why the indication remains unchanged when viewed on the ASI or Mach meter.