B737 Next Generation Undifferentiated
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Flight Crew Overcame Equipment Problem
Human Factors; Aircraft
A3 autoland failure. First Officer's leg. Weather was below Cat I minimums so we switched to an HGS HUD hybrid autoland; Captain flown.Engaged second auto pilot on a 10 mile final; had to re-engage both auto pilots and reset both master flight directors twice on the arrival. Prior to entering IMC; as briefed we switched to a heads up display arrival with increased minimums when the autoland autopilot system failed again. Shortly after that I received an approach warning in the heads up display; and with the approach lights [and] runway in sight; we completed the landing.The landing was on center line; but very firm. The taxi and shut down after that the normal. We wrote up the A3 automated system; and put it in the book. We debriefed the landing for the passengers and the crew.Maintenance is going to investigate the HUD; A3; and autopilot.
B737-NG Captain reported that an autopilot failure during approach resulted in a firm landing.