B-737 air carrier crew reported an initial rejected takeoff due to faulty auto throttle system then a subsequent departure with loss of lateral and vertical guidance information on the aircraft PFD and MCP flight instruments after takeoff. The crew returned to the departure airport and landed safely overweight.
Synopsis
B-737 air carrier crew reported an initial rejected takeoff due to faulty auto throttle system then a subsequent departure with loss of lateral and vertical guidance information on the aircraft PFD and MCP flight instruments after takeoff. The crew returned to the departure airport and landed safely overweight.
Narrative
While on Runway XXC at ZZZ; air traffic control cleared us for takeoff. I was the flying pilot. I spooled the throttles to approximately 40% N1 per procedure; verified N1s were matched; then announced and engaged TO/GA when a split in the throttles was immediately felt; followed by a red auto throttles (A/T) fail light. We rejected the takeoff and advised ATC. This all happened prior to reaching 10 knots. We pulled off the runway after informing Tower of the rejected takeoff; sat for several minutes and ran through the appropriate checklist; channels; etc; and elected to attempt a second takeoff. The same issue happened on the second takeoff attempt (under 10 knots); we rejected; advised ATC; and returned to gate and were met by maintenance. The mechanics found faults with the Air Data Inertial Reference Unit (ADIRU) and ASM which warranted an MEL deferral of the autothrottle system. After a delay we headed back out for takeoff with no autothrottles and were cleared for takeoff once again. Immediately after lift off; we lost all lateral and vertical navigation symbology on the Primary Flight Display (PFD) and the Mode Control Panel (MCP). A [request for priority handling] was declared on initial check in with the Departure Controller where we requested and received runway heading and a level off-altitude right away from ATC. I hand flew the airplane using raw data for a few minutes with some navigation sources eventually coming back online; but were unsure if the sources were reliable. The autopilot was eventually reengaged successfully and I monitored the progress while guarding the flight controls and manually manipulating thrust as needed. We then ran through appropriate checklists; protocols; and procedures and had to make an overweight [priority handling] landing and requested for Airport Rescue and Firefighting (ARFF) to be present. We set up for a long final to XXC at ZZZ with the help of ATC. I performed the landing and rollout which was uneventful. We pulled off the runway to a complete stop and had ARFF inspect the exterior of the aircraft including the gear and brakes before continuing taxiing to the gate. Maintenance met us at the gate once again advised they would be removing the aircraft from service.
Second reporter narrative
After losing both lateral and vertical guidance we [requested priority handling] and returned to ZZZ. Overweight landing was performed. Cause: Guidance System malfunction.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.