What will happen to the VSI when using an alternate static source?

What will happen to the VSI when using an alternate static source?

• A. It will indicate a steady descent
• B. It will indicate a steady climb
• C. There will be a momentary climb, then normal indication
• D. It will show no change

Answer: (C)

When using an alternate static source, the vertical speed indicator (VSI) often experiences a momentary climb before normal indications resume. This occurs due to the differences in static pressure that can be experienced when switching from the primary static port to an alternate source. The alternate static source may be located in a different area of the aircraft, and if this area has a varying pressure compared to the primary static source, it can lead to a temporary erroneous indication on the VSI. Once the initial pressure change is accounted for, the VSI will stabilize, providing the normal indication based on the actual vertical speed of the aircraft. This is an important consideration for pilots to remember, as understanding the behavior of the VSI during such a transition can aid in correctly interpreting instrument readings during flight. In summary, due to the nature of static pressure changes, the VSI's initial momentary climb followed by normalization is a key element of this scenario.

When using an alternate static source, the vertical speed indicator (VSI) often experiences a momentary climb before normal indications resume. This occurs due to the differences in static pressure that can be experienced when switching from the primary static port to an alternate source. The alternate static source may be located in a different area of the aircraft, and if this area has a varying pressure compared to the primary static source, it can lead to a temporary erroneous indication on the VSI.

Once the initial pressure change is accounted for, the VSI will stabilize, providing the normal indication based on the actual vertical speed of the aircraft. This is an important consideration for pilots to remember, as understanding the behavior of the VSI during such a transition can aid in correctly interpreting instrument readings during flight. In summary, due to the nature of static pressure changes, the VSI's initial momentary climb followed by normalization is a key element of this scenario.