B737 Captain and Dispatcher reported a fuel imbalance during climb. Flight returned to departure airport.
Synopsis
B737 Captain and Dispatcher reported a fuel imbalance during climb. Flight returned to departure airport.
Narrative
Climbing to cruise out of ZZZ; we noticed the amber IMBAL by the tank 1 qty (left side). We both quickly realized that the quantity on that side was decreasing at a faster than normal rate. The imbalance accompanied by a high decreasing rate of the fuel quantity initially suggested a suspected fuel leak. At that point; we concurred on the need to return to our just departed ZZZ. We talked to ATC; requested priority handling and began our return. The FO (First Officer) did a great job flying the airplane; managing the icing conditions while returning back to ZZZ. As he continued flying the airplane and manned normal ATC communications; I pulled the Fuel Leak checklist. As I started reading and going thru the first items; I noticed the fuel qty on tank 1 was not decreasing anymore; but it actually reversed the trend with a slight increase. At that time I paused that checklist; we had good engines; lots of fuel remaining and ZZZ just ahead of us; and with the plane stabilized in a shallow descent; the FO (First Officer) and I started more discussions; and that led us to the IMBAL checklist. We decided to follow that to balance the tanks and while we were still discussing and monitoring the fuel; (once again the #1 fuel qty increased some) we were almost on final for Runway XX. The fuel was balanced. We requested a couple of vectors to complete our checklists; and with the fuel panel properly and normally configured for landing; we continued the approach. Underweight landing with a smooth touchdown; we exited the runway and stopped for fire rescue inspection; and we were told there was no sign of leaks and everything looked normal. Uneventful taxi as we continued to the gate.
Second reporter narrative
During my flight following I got notified of the flight diverting. There was a little bit of confusion but then I got a call from the Maintenance Dispatcher saying my flight was indeed showing as diverting. I had heard nothing from the crew at this time and sent up an ACARs as they headed back toward ZZZ. It took about 10 more minutes after my ACARs for the crew to respond that they were indeed diverting do to a fuel leak but the information was vague. Upon going through the non-normals with help around me it was determined only by assumption that they were air returning due to the 'Land nearest suitable' in the check list. Furthermore; going back into the flight progress tool from the latest fuel checks there was a three-thousand-pound fuel difference and increasing. None of which of this information was communicated from the crew. Next; I then followed my diversion checklist in the Dispatch Tool and sent the proper paperwork and forms and added the single engine MEL and sent the calculated landing data. I then called ZZZ Tower to see if they had indeed requested priority handling and to make sure we had emergency services available for them. The aircraft then landed on the ground with no issues.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.