Distraction; Human-Machine Interface
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew Took Evasive Action; Flight Crew FLC complied w / Automation / Advisory
Human Factors; Procedure
We did not notice until airborne that we took off with a 2;000 LB main tank fuel imbalance. While hand flying the departure as the pilot flying; I made a comment about the aircraft requiring a lot of left trim. The pilot not flying looked down to see an amber FUEL IMBALANCE indication and the left fuel tank showing 2;000 LBS less than the right. TOT: 20.0 LEFT: 6.5 RIGHT: 8.5 CTR: 5.0. All fuel pumps verified on. Crossfeed verified closed. I engaged the autopilot and we ran the QRH fuel imbalance checklist. Imbalance corrected.When checking fuel quantity on the ground; double check each fuel tank; not just the total fuel on board which agreed with our required fuel. The amber light does NOT illuminate until airborne; so we can't rely on it to detect a main tank imbalance on the ground.
A B737-800 Left Fuel tank contained 2;000 LBS less than the Right Tank at takeoff. The FUEL IMBALANCE annunciator does not illuminate unless the aircraft is airborne; the crew missed the imbalance during preflight.