B737-700
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 16; Flight Crew Total 588; Flight Crew Type 588
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew FLC Overrode Automation; Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
On climb out from 6;000 ft to 13;000 ft with autopilot lnav vnav engaged. Vnav stopped being engaged. As 15;000 ft selected and confirmed the auto pilot disengaged. 15;000 ft in MCP replaced with 50;000 ft readout and aural warning sounded till touch down. Reset of auto pilot auto throttle and flight director did not work. We requested priority handling from ATC. East heading and 15;000 requested for troubleshoot. Unannounciated checklist and others assessed as well as coordination with company attempted. No response from company so air return to ZZZ vfr requested. Flight attendants briefed; pax briefed; descent checklist accomplished as well as vfr approach and landing into ZZZ accomplished. Taxi to gate and parking accomplished as well.
Aircraft X returned to ZZZ shortly after taking off; I received an automated diversion message from the crew and noticed they had turned back toward ZZZ; I then ask if we are diverting and did not receive anything back from the crew; once on the ground they said they tried to ACARS and call dispatch and I never received any ACARS or calls from the crew besides the automated message that comes through in DV. they said they had to fly back VFR due to losing altitude and heading capabilities; I assumed the communication breakdown was related and never saw them higher than Fl110. once I realized I could not reach them and they were returning to ZZZ I called the MDO; Ops manager; and ZZZ Ops to see if they had heard anything and no one had. I then saw in the flight feed portion of DV ops reported the Mode Control Fault.
Air carrier flight crew reported autopilot system failure resulting in an expedited landing.