A320
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 68; Flight Crew Total 276; Flight Crew Type 276
Time Pressure
Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
General None Reported / Taken
Procedure; Weather
Initial takeoff out of ZZZ. Reviewed weather and noted that ZZZ1 was designated as takeoff alternate. Briefed both FO and Lead of the takeoff alternate. ATIS stated that RVR was 500 but continuously being updated. Tower was calling RVR of 1200 due to ground fog. FO and I briefed both his minimums for takeoff as well as reviewed the back of the Airport Diagram page. Airport Diagram page stated with adequate visual reference we needed 1600 or 1/4 mile. Taxiing out watched other aircraft depart as the ground fog was quickly burning off. As we approached number one Tower stated 'RVR is 1400 v 3500'. They did not provide a base RVR and I did not ask. We informed Tower we were ready when they were. Tower cleared us for takeoff and I stated to the FO that visibility was good and that I could see the departure end of the 9000 ft. [Runway]. My estimate was visibility was greater than 2 miles. We took off uneventfully and shortly thereafter atis stated visibility was 3 miles. On climb out; FO and I discussed weather and reports. Upon inquiry into the FOM; it seems that we should have either queried Tower for specific RVR or delayed takeoff until all numbers were above 1600. Also; I was lulled into a VFR mindset because in hindsight what I was physically seeing did not match the min RVR Tower stated.
During preparation for takeoff; morning fog was burning off at a rapid pace. Airport Diagram page showed take off minimums for runways in ZZZ to be 1600 RVR. ATIS was updating to RVR 500 however we clearly could see the runway all the way to the end which is over 9;000 ft. long. Airport conditions were over 2 mile visibility without restrictions. Tower confirmed [a] new report of 1400 RVR variable to 3500 RVR. We told Tower that we were ready for takeoff whenever they could clear us. We were cleared for take off shortly after. The doubt we had was lack of clarity on [the] actual RVR report even though we were VMC at this point and had no problem seeing all of the runway environment. Shortly after rotation ATIS updated again to 3 SM visibility. 3 flights prior to us departed which added to the confusion of required RVR. Conditions did not match RVR reports.
Flight Crew reported departing with RVR under minimums.