First officer of a B747-200 allowed the aircraft to descend from assigned arrival altitude due to being distracted in slowing the aircraft and disconnecting the altitude hold mode on the autopilot.

Narrative

Rewritten in plain English from NASA’s original all-caps telegraphic report — facts, figures, and terminology preserved.

We descended to 11000 feet on the GOLDEN 4 approach. I was giving IOE to the co-pilot. The aircraft was on autopilot connected to the PMS.

I told the co-lag to slow the aircraft and explained the various ways to accomplish this. He proceeded to disconnect the aircraft from the PMS and engage the flaps for airspeed control, but he forgot to engage altitude hold to the autopilot.

He got involved with slowing the aircraft and when I looked at the altimeter the aircraft had descended to 10500 feet, at which time BAY APCH called with the news we were 500 feet below our assigned altitude. I had the co-pilot disconnect the autopilot and return to 11000 feet.

There was no traffic, but pride was hurt. I take responsibility as it was my aircraft and I should have watched the co-pilot closer than I did.