Flight Crew Air Transport Pilot (ATP)
Flight Crew Type 909
Aircraft Equipment Problem Critical; Inflight Event / Encounter Fuel Issue
Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Maintenance Action
Aircraft
Approximately 1.5 hours into the flight; crew was alerted by CDU message 'FUEL DISAGREE - PROG 2' and observed 3;600 lb difference between Total and Calculated fuel quantity. Fuel leak was suspected and QRH checklist referenced. Center tank fuel had just been exhausted. Slowly increasing fuel imbalance between left and right main tank and visual inspection of left engine confirmed fuel leak. Decision was made to divert to [a nearby alternate]. ATC [was advised] and diversion requirements communicated. Diversion coordinated with Dispatch and cabin crew; passengers advised. Landing performance data obtained for overweight landing and appropriate checklists referenced. Uneventful landing.
[Report narrative contained no additional information.]
B757 flight crew reported diverting to a nearby alternate after confirming a fuel leak from the left engine.