Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue
Flight Crew Landed As Precaution; Flight Crew Diverted
Human Factors
We had an extensive delay departing due to a deferral that requires the aircraft to be overwing fueled. In addition; due to a fuel distribution issue; operations and the on-call chief pilot were contacted for further assistance. Also a takeoff alternate had to be added to the release due to the low visibility. Once resolved we departed an hour and a half late. After reaching 10;000 feet the flight attendant called the flight deck and informed me that there was a passenger who noticed a 'contrail' coming from the left wing. I checked the fuel and it was well balanced and we were showing the planned fuel amount for that point of the flight. I then called the FA back and asked her to take a look at the left wing and report to me what she saw. She called back and confirmed that there seemed to be fuel coming from the top of the left wing. Nearing cruise altitude I made arrangements with the FO and FA to exit the flight deck and inspect the left wing as I could not see from my seat anything unusual; partially because of the position of the sun. Upon reaching the exit row I observed out a passenger window an unsecure fuel cap with fuel 'venting' out of the over-wing filler port.Upon returning to the flight deck I conferred with the FO and subsequently made the decision to divert to [a nearby airport]. We had just overflown that airport and noticed it was in the clear and the long runways would be ideal for accommodating an overweight landing. We advised ATC due to the nature of the issue but there was no immediate threat. The FO was the pilot flying and he made the visual descent and subsequent visual approach to a smooth landing as I communicated the event to our Dispatcher and set up the diversion. Upon landing we were met by airport fire and rescue trucks who followed us to the gate. A gentleman boarded the aircraft to make sure the crew and passengers were ok and advised us of a strong fuel odor that trailed us on taxi but was dissipating. Due to the overweight landing maintenance control decided to inspect the aircraft before returning it to service so a spare was flown in to accommodate the passengers. I then communicated with our Dispatcher and two chief pilots.The most prominent threat was the refuel SOV deferral. The possible error that stands out is that it is conceivable that the fuel cap was not secured properly before departure. The fuel leaking from the left wing tank was certainly an undesired aircraft state and could only be corrected by landing at the nearest suitable airport. Which we did.As a new Captain and having dealt with this unusual situation I will certainly make it a priority to personally inspect or have another flight or ground crewmember double check that the fuel caps are properly secured any time we are over-wing fueled. From a company standpoint I would try to keep aircraft with this deferral closer to base. It may not have prevented the diversion but the large amount of fuel and subsequent balancing/structural limit issues may be mitigated.
CRJ-200 reported diverting to a nearby airport when a passenger noticed fuel streaming from an improperly secured over wing fuel cap.