What is the standard reference reading when an aircraft is in level flight in the VSI?

• A. Zero VSI (no vertical movement)
• B. One VSI
• C. Negative one VSI
• D. Two VSI

Answer: (A)

The Vertical Speed Indicator measures how fast you’re moving up or down, i.e., your rate of climb or descent in feet per minute. In level flight, there is no change in altitude, so the vertical speed is zero. That’s why the standard reference reading is zero on the VSI. Real-world effects like gusts or instrument lag can cause a brief excursion away from zero, but the steady-state value for level flight remains zero. Any nonzero reading means the aircraft is climbing or descending, not level, so the zero reading best represents level flight.