Date: 201505
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: Marginal
Weather elements / visibility: Rain; Thunderstorm
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Mission: Passenger
Flight phase: Climb
Airspace: Class A 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: Communication Breakdown
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Airspace Violation All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Approximately 95 miles from ZZZ1; I queried ZZZ1 Radio for a current weather observation for our approach into the airport. Initially; which is very common; the weather report was hardly readable due to convective weather activity in the area and its effect on VHF frequencies. As we approached closer the ZZZ1 weather observer notified us of moderate rain moving onto the airfield reducing visibility. I asked about visibility and she reported visibility west of the airfield at 3 miles and east of the airfield at 2 miles. I reminded her that we were planning on shooting the approach from the west. As we were approaching [waypoint]; which is 11.8 miles out I queried again about the visibility and was told by the weather observer that visibility is now 1.5 miles. This reported visibility was below minimums (2.75 miles) and we were nearing our bingo fuel so I made the decision to go around and divert to ZZZ2. While climbing out; I reported on ZZZ1 Radio that we were executing a missed approach and proceeding to our alternate; ZZZ2. At that time the weather observer asked us why and I told her the weather was below minimums and she immediately said visibility was now 5 miles. I couldn't see the airport and we were within 3 miles. Since I was committed and rapidly approaching bingo fuel; plus we couldn't see the airfield due to the moderate to heavy rain showers although we were at about 3-5 miles north of the airfield; I told her it was too late and we were proceeding to ZZZ2. From our perspective during the Go Around; the rain shower still had about 2/3rds of it south of the airfield moving north. During the Go Around and divert while trying to communicate to SFO radio on HF; we climbed up and into the Class A airspace to conserve fuel and allow us to make our alternate safely. Because it took what seemed an inordinate amount of time to get our clearance via Commercial Radio; (Commercial Radio did not understand we were proceeding to our alternate while we climbed out during go around) we were finally able to convey our intentions and it was finally understood as we were climbing through FL270. Commercial Radio reported this to Center and we were told to call Center for a pilot deviation report. Upon arrival in ZZZ2; I made the call was admonished for being in controlled airspace without a clearance. I insisted had I not flown immediately to altitude or otherwise held at or below FL 055 I would have not had the fuel to make ZZZ2. He seemed to understand and assured me no report would be filed; but asked that I coordinate before flying above FL055 so I don't fly into another's altitude or airspace. I asked the Oakland center representative if it would be better if I declared an emergency and he hemmed and hawed and said he couldn't comment on that. Next time I have to divert from below Class A airspace into Class A airspace to safely and prudently proceed to my alternate/divert airport; I will declare an emergency.


Second narrative: ThreatsInaccurate weather observer reports at ZZZ1 on CTAF. Visibility reports appeared to be accurate until we reported a missed approach. The report that followed appeared to be a value that would allow the approach as opposed to an actual; factual report.Reduced fuel loads: Reduced fuel loads do not allow holding at island destinations when a passing rain shower is present. Extra fuel would have allowed us to loiter while the rain shower passed. The existing fuel load forced an immediate divert.Reduced fuel loads: The reduced fuel load force a fuel-efficient divert profile - an immediate climb to flight level on a direct route to the divert airfield. The reduced fuel load does not allow level flight at FL055 (beginning altitude of Class A airspace). This is where Oakland wanted us to remain while waiting for our clearance for climb. This took about 10 minutes to coordinate and 10 minutes at 5;500 feet would have required extra fuel that we did not have.


Synopsis: Air carrier flight crew diverted to an alternate upon reaching bingo fuel because the destination airport visibility was reported below minimums. The crew experienced communication difficulties and eventually climbed into Class A airspace without ATC clearance for fuel conservation purposes.