B757 Undifferentiated or Other Model
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 139; Flight Crew Type 1282
Distraction; Situational Awareness; Troubleshooting; Workload
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Diverted
Weather; Aircraft
Upon leaving; the WX (Weather) forecast for ZZZZ was -RA OVC 025 tempo OVC 012.  Upon arrival; the ATIS was showing -DZ BKN 003; TEMPO 2000 RA.  ZZZZ1 WX was similar but ZZZZ2 was VFR; dry runway.Arriving at ZZZZ; we initially planned an Autoland.  When lowering the flaps to 1; we noticed a split in the gauge but no EICAS.  One flap read 1 when the other read zero.  The handle was rechecked and the gauge was tapped.  We ran the TE (Trailing Edge) flap disagree checklist and planned a full LE (Leading Eddge) slat VREF 30 + 40 approach as directed and used the longest runway; best weather and driest runway.  That was ZZZZ2 which was our primary alternate.  Dispatch concurred with this decision and SATCOM patch with [Operations Control] offered no extra ideas.  ZZZZ was ruled out due to almost CAT III conditions with a wet and shorter runway.We landed with 8500 pounds of gas taxied to the gate.  One brake peaked at 4.  Of course the FA's; (Flight Attendants) PAX (Passengers) were notified.  [ATC was advised] as well.
[Report narrative contained no additional information.]
B757 flight crew reported a trailing edge flap anomaly upon extension; resulting in a diversion to an airport with a longer runway.