Date: 201504
Local time of day: 1201-1800
Location: ZZZ.Airport, us
Flight conditions: IMC
Weather elements / visibility: 0.25
Light: Daylight
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach; Final Approach
Airspace: Class B ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Situational Awareness; Confusion; Communication Breakdown
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue; Inflight Event / Encounter Weather / Turbulence
Detector: Person Dispatch; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Executed Go Around / Missed Approach; Flight Crew Took Evasive Action; Flight Crew Became Reoriented
Contributing factors: Company Policy; Procedure; Weather
Primary problem: Ambiguous

Narrative: During descent to Airport ZZZ; weather was reported as 200 OVC 1/4 mile visibility. NOTAMS indicated TDZ RVR OTS. Crew discussed CAT I minimums and the fact that there was no mid RVR but rollout RVR was reporting between 1800-2200 RVR at various checks. Captain was Pilot Monitoring (PM)/ First Officer was Pilot Flying (PF).  Late in descent; Dispatch sent a message that other aircraft had not gotten in; but were trying again. They also changed our alternate from ZZZ1 to ZZZ2 and we did not receive fuel plan of 3;700 pounds burn until below 5000 feet. We had sufficient fuel to fly the approach; missed approach and divert and arrive at ZZZ2 with 5;000 pounds. Approach was stable; the missed was well flown and ATC coordinated divert. Low altitude easterly profile awaiting climb clearance; strong headwinds enroute; along with cruise altitude hold down due to moderate turbulence all contributed to higher than planned fuel burn. Plus ZZZ2 was in single runway operations to Runway XY. Enroute we requested ATC shortcuts; and advised Center that we would be minimum fuel by the time we got to Approach. Our projected on deck fuel was now 4;300 pounds. When [Approach] asked us to descend to 3000 feet; vector off course and slow to 170 knots while we were still 22 miles from the field; I [notified ATC of our low] fuel to expedite handling. They cleared us to land and we were on deck with 4;300 pounds.Forecast visibility would have been suitable for the approach but with TDZ RVR OTS; Crews were left few options.  The late change in alternate compounded late arrival flight deck tasks. Dispatch comments regarding other Company aircraft attempting the approach gave Crew mixed signals. A review of airport configuration when no mid RVR is available.


Second narrative: Weather was forecast to be IFR but not near minimums. Alternate on release was Airport ZZZ1. At cruise we received word that weather was down to CAT I minimums. RVR 2800 V 4000. We elected to continue and to monitor the weather as it was above minimums and forecast to be better upon our arrival. Prior to descent the weather was now '' mile and RVR 2000; still above minimums of 1800. The ILS to Runway XY was planned and briefed based on similar weather. During descent we were informed by Dispatch that a Company aircraft had gone around at ZZZ and was going to try the approach again. This gave us the indication that they must have felt it was borderline to try another approach. We never heard back from Dispatch as to whether that aircraft diverted or not (they did). Dispatch did ask us to change our divert destination to ZZZ2. They gave us a fuel burn to ZZZ2 of 3;700 (vs 2;500 for ZZZ1). Our fuel state had us projected to be at the FAF with approximately 9;000 pounds of fuel. We accepted the new divert based on the 3;700. Also during the approach we were informed that the TDZ RVR at ZZZ was not working and that the Rollout RVR was the only available RVR for reporting. It was reporting 2000 RVR. Since ZZZ does not have a mid RVR we assumed that this would be adequate to shoot the approach; however; the FOM does not address this issue. Only that the mid can be substituted for TDZ for CAT I Approaches. It is not clear what to do if the airport does not have a mid to substitute. The resulting approach was uneventful and stable and we went missed approach at the DH as we never broke out. The go-around and re-filing with ATC were fairly uneventful; however; the standard routing to the southwest was used which has you climb due east and cruise at 8000 feet to 10;000 feet MSL for approximately 20 miles before turning towards the destination. As we climbed up we were capped at FL300 due to traffic. Our fuel projection showed 4;700 at ZZZ2. Despite our best efforts to shorten the distance flown and stress our lower than normal fuel state we were continuing to drive our fuel state at ZZZ2 down to the low 4;000 range (from 4;100 to 4;300). There was a 50-60 knot headwind on the arrival even down as low as 10;000 feet MSL and were not sure if Dispatch's 3;700 fuel estimate took that into account. During approach maneuvering with Approach we explained our fuel state and were told we were number one for the runway at approximately 30 miles out and sent direct to the field. When asked how much fuel we had in minutes we answered 'one hour' as at the time we had approximately 5;000 pounds of fuel on board. Soon thereafter (at approximately 20 miles out) we were then vectored off the direct course and told to descend and slow. At this point our fuel projection dropped below 4;000 at which time we [notified ATC of our low] fuel and were given priority handling and sent directly to the runway. We landed with 4;300 pounds of fuel and were asked to call Approach after we blocked in. The Captain called and talked to a Supervisor. I was not privy to the conversation other than that the 'one hour' estimate was confusing to them. Apparently they were satisfied with our explanation as to what happened.Better coordination with Dispatch on divert information and planning; we might have been able to make a quicker divert decision; had the projection for fuel burn been more accurate. We were never sent a divert plan ACARS from Dispatch. Just two messages one saying 'want to change divert to ZZZ1'; and; another a few minutes later saying 'fuel to ZZZ1 3;700.' Divert plan information should also include routing used and attitude we should plan for (conservative estimates of course). Also; if FOM prohibits shooting approach without the TDZ RVR at ZZZ; then this should be clearly stated somewhere so that both Dispatch and the Crew are aware and can plan accordingly.


Synopsis: A B737 crew executed a missed approach because of lowering visibility. Dispatch revised the alternate airport to further away but with sufficient fuel the crew headed toward it. Enroute higher than forecasted winds made alternate arrival fuel lower than forecasted.