Originally Posted by Emmerson Bigs

Gotta mind those FMAs.
My guess: Hand flying. Initial level off was 5000, they got cleared to 11,000 very close to level off. 5K was already captured and they were in VNAV ALT. Altitude window gets spun to 11,000 but knob is not pushed to command VNAV SPD and A/T to climb power. PF raises the nose to start the climb and gets slow.