Narrative:

After departing runway xx from ZZZ; we received an unexpected increase in airspeed with the nose set to approximately 12 degrees pitch up. At 1;000 feet; I had the pm (pilot monitoring) set speed; flaps 5; climb thrust. When the pm went to select the airspeed in the MCP; the window remained closed. As we started to accelerate we begin to retract the flaps on schedule. Trying to reduce the workload in the flight deck; I tried engaging the autopilot. Shortly after engaging the autopilot; we received the autopilot disconnect warning. Unable to accelerate above v-mass I disconnected the autothrottle and let the aircraft accelerate to 210 knots.during that time we received erroneous airspeed and altitude indications. This continued until passing 18;000 feet when the MCP started to operate normally. During cruise; the airspeed remained constant. During our descent into ZZZ1 we felt the best way to control the airspeed was to request the RNAV xxr approach. We thought the approach would give us a way to control the airspeed. Everything seemed normal until the FAF; when we started to configure for landing. Shortly after configuring; our airspeed bug was increased to 304 knots with no inputs from the flight deck. When that happened; the nnav increased our descent rate to keep us on the path. Shortly after that happened we picked up the airport and landed visually. After landing we found that the problem had been written up one day prior. We made the appropriate entries in the maintenance log. Erroneous airspeed and altitude indications.

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Original NASA ASRS Text

Title: B737-800 flight crew reported erroneous airspeed indication and altitude overshoot on climbout.

Narrative: After departing Runway XX from ZZZ; we received an unexpected increase in airspeed with the nose set to approximately 12 degrees pitch up. At 1;000 feet; I had the PM (Pilot Monitoring) set speed; flaps 5; climb thrust. When the PM went to select the airspeed in the MCP; the window remained closed. As we started to accelerate we begin to retract the flaps on schedule. Trying to reduce the workload in the flight deck; I tried engaging the autopilot. Shortly after engaging the autopilot; we received the Autopilot Disconnect warning. Unable to accelerate above V-MASS I disconnected the autothrottle and let the aircraft accelerate to 210 knots.During that time we received erroneous airspeed and altitude indications. This continued until passing 18;000 feet when the MCP started to operate normally. During cruise; the airspeed remained constant. During our descent into ZZZ1 we felt the best way to control the airspeed was to request the RNAV XXR Approach. We thought the approach would give us a way to control the airspeed. Everything seemed normal until the FAF; when we started to configure for landing. Shortly after configuring; our Airspeed bug was increased to 304 knots with no inputs from the flight deck. When that happened; the Nnav increased our descent rate to keep us on the path. Shortly after that happened we picked up the airport and landed visually. After landing we found that the problem had been written up one day prior. We made the appropriate entries in the Maintenance log. Erroneous airspeed and altitude indications.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.