B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 385
Workload; Troubleshooting
Aircraft Equipment Problem Critical
Flight Crew Overcame Equipment Problem
Aircraft
We were number two for takeoff; we received a Single FMC FAIL in the scratch pad of the FMC. After a couple seconds it went away. We were cleared for takeoff; with no issues. Flight directors were working and airspeed indicators; everything appeared normal. I had the HUD down and the HUD was also working normally. After takeoff; and at 1000' I did the usual 'set speed; flaps 5; climb thrust.' We took off flaps 10. After that we got a climb to 19;000'. After a while my aircraft (although heavy for an -800) was not that heavy; being used to flying ETOPS with reduced thrust takeoffs; we accelerate no problem. But my aircraft was not accelerating and I had both the HUD and PFD I was looking at; and each time I put my nose on the horizon my pitch was not down enough to get to my airspeed of the flaps 5 bug to bring flaps to 1. I told the First Officer (F/O) there was something wrong. I glanced at his airspeed and it looked like mine. I asked him what the Standby was doing. He said the same as ours. I told the F/O to give me max thrust. He did and we got the flaps to one. Then we both lost the horizontal flight director bar. Then the vertical. All this time we are IMC. ATC gave us a turn to the right to go direct SYRAH. I told the F/O; NO. That our FD failed and I wanted to continue straight and level off at 10;000'. F/O did not hear me. He was in the Yellow and his head was down dealing with the FMC. The FMC had a note in the scratch pad that said something about being unable to select. So he was trying to figure that out. And I just wanted to climb out of the clouds and figure out what was wrong with the aircraft. I told him two more times I wanted to continue straight. He told ATC that we had flight director problems and needed to fly this heading and maintain 10;000'. Around 9500' we broke out and I was able to get the MCP to accept LNAV/VNAV and Autopilot A on. Autopilot B was not working with the LNAV/VNAV and would not connect. I did not want to try and figure out why it would not stay engaged on Autopilot B; so I tried Autopilot A again and LNAV/VNAV worked. At this time we asked for on-course and a climb. We then got into the QRH. I contacted Dispatch and told her the problem.
B737 Captain reported experiencing an auto flight system malfunction during climb out in IMC conditions.