What happens to the altimeter and airspeed indicator readings when the static pressure line is disconnected?

When the static pressure line is disconnected, the readings from the altimeter and airspeed indicator are significantly affected due to the loss of accurate static pressure input. The altimeter relies on static pressure to determine altitude; without it, the altimeter cannot accurately measure the atmospheric pressure outside the aircraft. As a result, it can indicate an altitude that is lower than actual altitude, leading to excessively low readings.

Similarly, the airspeed indicator is calibrated based on the difference between dynamic pressure (which is influenced by airspeed) and static pressure. If the static pressure line is disconnected, the airspeed indicator will not receive the correct static pressure reference, causing it to miscalculate the airspeed, which can lead to an erroneously low reading.

Thus, both instruments will give readings that do not reflect the true values, resulting in excessively low indications. This highlights the importance of the static pressure system in providing accurate data to these critical instruments.