Narrative:

The aircraft had a deferral for the power control unit monitor system. The MEL has no operational limitations. I was the pilot flying. This was a busy; very short flight from ZZZ to sna. The aircraft was lds (large display system). I have flown lds aircraft infrequently and my previous 31 years of flying have been round dials. We briefed the entire flight in the blocks because we knew we would be so busy in flight. We were empty so we briefed a potential low altitude capture. We were cleared to 4;000 feet MSL on departure. The sun was right in our eyes. The first officer (first officer) had a sunshade up and I was wearing sunglasses and a cap to block the sun. The ap (autopilot) was engaged at approximately 2;500 feet MSL. The airplane was climbing normally. I had preset the sna localizer; but parked the frequency. Prior to top of climb I briefly looked down to dial in the localizer frequency (an obvious mistake). The pm (pilot monitoring) called 'altitude' as the aircraft continued through 4;000 feet. I disconnected the ap and pushed the airplane over to 4;000 feet. I think we went no higher than 4;250 feet. I was having a hard time seeing the display due to the sun. Neither of us saw a low altitude capture; and were surprised the airplane did not level at the selected altitude. The ap was reengaged.things were busy with radio; traffic; and setting up for the approach. I slowed the aircraft and we selected flaps one. Shortly thereafter we were cleared to 3;000 feet nearing the approach intercept. I selected flight level change and extended the speedbrakes. I selected speed 170 kts. And called for flaps 5. All this time ATC; traffic and following the pm's actions drew my attention. As we reached 3;000 feet the aircraft leveled; but the at (autothrottles) did not advance. The airspeed dropped below 170 kts. And was trending down. As I pushed the throttles up and called for flaps 15 the pm called out airspeed. Airspeed was not increasing so I disconnected the ap and ats and verified full throttle. It was then I realized the speed brake was still extended. I retracted the speedbrakes. At that time the airspeed increased and we ballooned to approximately 3;900 feet. No flap limits were exceeded. The ats and ap were reengaged. We advised ATC of our situation and requested vectors to get set up again and evaluate our status.since we were so near; we called ZZZ operations as we considered contacting maintenance to ask if the deferral should have any impact on the autoflight system. During the vectors we were placed in a long line of arrivals and had time to be fully prepared for our next approach. We were given altitude changes and heading changes. Throughout the vectors and ATC climbs and descents the aircraft seemed to be operating normally. When finally cleared for the approach we were confident things were normal and the remainder of the flight was normal. ATC never advised of any deviations or violations. On the ground the mechanic said the deferral would have no impact on the aircraft going through selected altitude or at operation. We never had any EICAS or messages. I don't know why the ats did not come up but I do know I missed the speedbrakes! If I have speedbrakes extended I normally keep my hand on the handle with my arm against the throttles. If the throttles come up it's a good reminder to retract the speedbrakes if I forget. This time I took my hand off of the speedbrake handle as I was busy manipulating the MCP. I've done this short busy flight before without any of these mistakes. I think my limited exposure to lds aircraft (the airspeed and altitude trends are not quite as intuitive as round dials for me yet) combined with a high workload flight was definitely a major contributing factor for my errors. I will work on this and not trust the aircraft to do what I think it should do.

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Original NASA ASRS Text

Title: Air carrier flight crew reported exceeding cleared-to altitude during approach to SNA airport; as well as slowing below flap minimum speed due to autopilot and autothrottle malfunctions.

Narrative: The aircraft had a deferral for the Power Control Unit Monitor System. The MEL has no operational limitations. I was the Pilot Flying. This was a busy; very short flight from ZZZ to SNA. The aircraft was LDS (Large Display System). I have flown LDS aircraft infrequently and my previous 31 years of flying have been round dials. We briefed the entire flight in the blocks because we knew we would be so busy in flight. We were empty so we briefed a potential low altitude capture. We were cleared to 4;000 feet MSL on departure. The sun was right in our eyes. The FO (first Officer) had a sunshade up and I was wearing sunglasses and a cap to block the sun. The AP (Autopilot) was engaged at approximately 2;500 feet MSL. The airplane was climbing normally. I had preset the SNA localizer; but parked the frequency. Prior to top of climb I briefly looked down to dial in the LOC frequency (an obvious mistake). The PM (Pilot Monitoring) called 'altitude' as the aircraft continued through 4;000 feet. I disconnected the AP and pushed the airplane over to 4;000 feet. I think we went no higher than 4;250 feet. I was having a hard time seeing the display due to the sun. Neither of us saw a low altitude capture; and were surprised the airplane did not level at the selected altitude. The AP was reengaged.Things were busy with radio; traffic; and setting up for the approach. I slowed the aircraft and we selected flaps one. Shortly thereafter we were cleared to 3;000 feet nearing the approach intercept. I selected flight level change and extended the speedbrakes. I selected speed 170 kts. and called for flaps 5. All this time ATC; traffic and following the PM's actions drew my attention. As we reached 3;000 feet the aircraft leveled; but the AT (autothrottles) did not advance. The airspeed dropped below 170 kts. and was trending down. As I pushed the throttles up and called for flaps 15 the PM called out airspeed. Airspeed was not increasing so I disconnected the AP and ATs and verified full throttle. It was then I realized the speed brake was still extended. I retracted the speedbrakes. At that time the airspeed increased and we ballooned to approximately 3;900 feet. No flap limits were exceeded. The ATs and AP were reengaged. We advised ATC of our situation and requested vectors to get set up again and evaluate our status.Since we were so near; we called ZZZ operations as we considered contacting Maintenance to ask if the deferral should have any impact on the autoflight system. During the vectors we were placed in a long line of arrivals and had time to be fully prepared for our next approach. We were given altitude changes and heading changes. Throughout the vectors and ATC climbs and descents the aircraft seemed to be operating normally. When finally cleared for the approach we were confident things were normal and the remainder of the flight was normal. ATC never advised of any deviations or violations. On the ground the Mechanic said the deferral would have no impact on the aircraft going through selected altitude or AT operation. We never had any EICAS or messages. I don't know why the ATs did not come up but I do know I missed the speedbrakes! If I have speedbrakes extended I normally keep my hand on the handle with my arm against the throttles. If the throttles come up it's a good reminder to retract the speedbrakes if I forget. This time I took my hand off of the speedbrake handle as I was busy manipulating the MCP. I've done this short busy flight before without any of these mistakes. I think my limited exposure to LDS aircraft (the airspeed and altitude trends are not quite as intuitive as round dials for me yet) combined with a high workload flight was definitely a major contributing factor for my errors. I will work on this and not trust the aircraft to do what I think it should do.

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.