Date: 201601
Local time of day: 1801-2400
Location: SCT.TRACON, CA
Flight conditions: Marginal
Weather elements / visibility: Cloudy; Rain; 2
Light: Dusk
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach; Initial Approach
Airspace: Class B SAN
ATC / advisory: TRACON SCT
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Workload
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; Flight Crew Executed Go Around / Missed Approach
Contributing factors: Aircraft; Weather; Human Factors; Airport
Primary problem: Weather

Narrative: We were scheduled with straight wing; with unavailable intercom feature; fully loaded; landing limited with only 12 minutes of contingency fuel due to heavy loading; TAF TEMPO weather conditions at arrival time just above approach minimums (actual weather upon arrival was even worse and ended up going missed and diverting); #1 fuel gauge MEL'd requiring dripsticking prior to departure. First leg flying together as Crew; flown by F/O (First Officer) due to SNA scheduled later in the day and trying to preserve normal alternating leg schedule. Upon check-in with SoCal approaching SAN; the first radio transmission heard was a Company aircraft diverting. ATC described heavy bands of precip in vicinity of the airport; with clear gaps between; with obvious recent missed approaches/diversions. We checked weather again at our alternate; LAX as well as ONT. LAX weather was better; due to early descent by ATC; limited contingency fuel; and additional uncertainty due to an MEL'd fuel gauge we knew that we had one shot at SAN; if unsuccessful we would divert. Without too much detail; radar picture; and reports from SAN ATC and SoCal indicated that we would have a window of opportunity. We commenced the approach. ATC kept us high and fast as long as they could. Workload was extremely high; flying a non-precision vertical speed approach near mins with the energy issues thrown in. Preceding aircraft went missed as we approached the marker. This aircraft is extremely loud to begin with. After the marker and in the FA (Final Approach) segment; we encountered heavy precipitation; and the noise on the windscreen; when combined with no intercom feature resulted in us practically yelling at each other for Pilot-to-Pilot communication. Of course ATC is still in the matrix. About 300 feet above DDA (Derived Decision Altitude); as the PM (Pilot Monitoring); I turned the wipers on high. Other than one other issue I have had in my career while there was a pressure leak producing a deafening high-pitched whine; this now became probably the loudest cockpit I have ever been in again; a very loud; old aircraft as a baseline; no feature for the intercom; heavy precip; and wipers screaming. My window was approaching Niagara Falls status with a constant near stream of water. We went missed. After diverting; we reviewed the sequence mentally; and on the missed approach. We could recall no procedural errors in either callouts or sequence of events. But aircraft control and Pilot-to-Pilot communication in what ensued in the subsequent 20 or so seconds was full yellow if not red. We had to literally yell at each other; and we simply misunderstood/miscommunicated with each other. In that short period there were several miscommunications that occurred. One example; upon telling Tower we were missed; they issued a heading and altitude. As the PM I read it back; set up the MCP; etc.; but almost immediately; the PF (Pilot Flying) started asking a question which I thought related to the missed approach instructions. I literally could not understand him; his question was due to confusion with the Flight Director. It took me probably 10 seconds to turn off the wipers; which helped; but in the ensuing confusion for example the PF's confusion resulted in shallowing out our climb. I directed 'climb' and started to put up the flaps uncommanded beyond the 15 detent which had properly been called for on the go-around in an attempt to prevent overspeed. Bottom line; we had a slight flap 15 overspeed; shortly thereafter; the FMC locked; and we were in the midst of a divert; with an inop fuel gauge and so on. I've never had so much difficulty simply communicating within the cockpit.Crew actions could simply be summed up by better basic aircraft control by PF and 'quicker' intervention by PM; but the communication difficulty literally slowed the pace of all activity as we tried to coordinate. Again; procedurally (callouts; aircraft ground track; etc.) all occurred as they should; but if any additional stressors had been there; this probably would not have been the case. The real issue is twofold: The specific aircraft should not have been dispatched; given weather; MEL; loading status; and not having an intercom feature. If we had been in a newer aircraft; communication would not have been difficult; and in the end; 9 times out of 10; a diversion would not have been necessary either. However; the greatest simple fix; the older model aircraft NEED to be modified to reduce the workload of simple intra-cockpit communication. This aircraft was so loud inherently; when added to heavy precip; wipers at high speed and no ability to use the intercom easily that it essentially became a one Pilot aircraft. This is a situation easily avoided at many levels; and in my opinion is borderline unsafe.




Synopsis: Aircraft on a non-precision approach executed a go around due to heavy rain at the missed approach point. The flight crew then decided to divert to a more suitable airport.