B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 95; Flight Crew Total 11500; Flight Crew Type 5420
Distraction; Situational Awareness; Workload; Fatigue
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Aircraft; Procedure; Human Factors
Cleared to descend via...RNAV arrival. Selected 8;000 FT and descended in VNAV. ATC then gave us a runway change and requested we slow to 230 KTS. I selected Level Change and selected 230 KTS. I then selected the runway on the Electronic Flight Bag to determine how it affected the approach. ATC then queried our altitude and I realized I had descended below the profile in Level Change. I regained the profile and continued the descent.I believe there were multiple causes for this lapse: #1: I should have handed control to the First Officer while I studied the new approach. #2: Despite being an augmented crew of three pilots; neither of the other pilots spotted the discrepancy due; I believe; to fatigue. Because of the nature of this flight; the movies were being played over the PA system so that; even though we had a Class 3 seat for rest; none of us could get any sleep. #3: This was the third day of early starts and long days. #4: Distraction of a runway change.In the future I will make sure that I positively hand over control whenever I am not directly monitoring the aircraft; i.e. selecting and briefing approaches from the EFB etc. Also I will not assume my crew is rested just because we are legal and have three pilots.
B737 Captain descended below profile when an airspeed restriction from ATC prompted him to switch from VNAV to Level Change.