Date: 201811
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Climb
ATC / advisory: Center ZZZ
Aircraft component: Flap/Slat Control System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Communication Breakdown
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Returned To Departure Airport
Contributing factors: Company Policy; Human Factors
Primary problem: Ambiguous

Narrative: During initial climb out LE SLAT EICAS message with Master Caution switch and aural occurred right after retracting flaps. These messages persisted intermittently along with both flap indicator needles being stuck at half until we were at 15;000 feet and had been in a hold for a while talking to maintenance and operations on the radio. Crew actions and considerations: The FO (First Officer) continued to fly the airplane - it handled relatively normally other than the indications and caution notifications. Captain called Radio for a phone patch to company; and FO took ATC Comms. Coordinated to ask for holding so that we could maintain within radio coverage for the phone patch. ATC directed at hold at 15;000 feet at ZZZZZ intersection. LE SLAT ASSYM/DISAGREE EICAS messages continued to display intermittently while we ran QRH procedures; communicated situation with dispatch; and calculated fuel. Roughly 20 minutes into holding; the LE SLAT issues cleared.  Company concluded that the fuel at [our destination] would not be sufficient; so we planned to return to ZZZ after holding to burn off enough fuel to land under the Max Gross Landing Weight. ATC asked how much time in the hold would be necessary and the FO informed them that we would be returning to the field and requesting the longest runway available. The Captain ended the phone patch; returned to speaking with ATC; and they gave us a new hold until our estimate for the arrival. We began the Arrival shortly after the planned EFC [expect further clearance] time; and were assigned the RNAV Approach. While setting up for the arrival; the AUTOBRAKES would not engage. The arrival and approach occurred with no further abnormalities. Upon landing; ATC advised the emergency vehicles were standing by. They escorted us to our gate. We wrote the slat issue and autobrakes up in the logbook and gave maintenance all available information. It would be helpful is dispatch was able to quickly calculate required fuel numbers at any point in the flight given actual weights.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B767 flight crew reported a delay in receiving fuel requirements from Dispatch following a post-takeoff LE SLAT ASSYM/DISAGREE alert.