The SPEED pushbutton is used to do what?

• A. Engage HDG hold
• B. Engage ALT hold
• C. Engage CLB or DES mode
• D. Engage NAV mode

Answer: (C)

The SPEED pushbutton switches the autopilot/flight director into a vertical mode that follows a climb or descent speed target. When you push it during a climb, it engages CLB mode, which makes the aircraft hold the climb speed dictated by the flight plan or a captain-selected target. When used for descent, it engages DES mode to hold the published descent speed. This keeps you on the intended speed profile during transitions, independent of heading or altitude hold or NAV guidance. In short, this button activates the climb or descent speed guidance, rather than controlling heading, altitude, or navigation directly.