Date: 201508
Local time of day: 1201-1800
Location: DEN.Airport, CO
Flight conditions: VMC
Weather elements / visibility: Thunderstorm
Light: Daylight
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B DEN
ATC / advisory: TRACON D01
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Distraction; Workload; Situational Awareness; Communication Breakdown
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Fuel Issue; Inflight Event / Encounter Unstabilized Approach
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure; Airport; Weather
Primary problem: Weather

Narrative: Half way to DEN multiple changes to arrival STAR for possible weather in DEN. Extended enroute vectors to southeast arrival corridor for North flow runways. Initial clearance was for visual approach to Runway 34R. While on final for 34R; approaching CORDE radar fix we both noticed large outflow from storm cell just west of the airport which had blown a large dust cloud toward the final. The dust was well defined and had noticeable vortices and swirls. I decided to discontinue the approach; and Approach Control gave us a left turn off the final to a 270 heading. We accomplished the go-around and then we were turned South bound to reenter the downwind for what then was going to be final for 35L. I discussed fuel state with First Officer (FO) and stated that we had enough fuel for one more approach before divert. He concurred. While FO was setting FMC up for new runway; I asked Approach how long a downwind we could anticipate and he said about 'seven more miles'. Not long after that we were turned crosswind and a dog leg vector to intercept the visual final for 35L. Once we had intercepted the final; I began configuring flaps to five (we had been flaps one for assigned speed) and started descent from 8;000 feet to 7;000 feet for the DYMON fix. Configuration continued with landing gear and flaps 15. At this time we both noticed on the radar that a new cell was forming over the west part of the airport. The initial outflow dust that caused our initial go-around from 34R had now dissipated and rain was on the 35L final. We crossed DYMON fix and intercepted the glidepath and started the descent. Tower cleared us to land; as I recall; two or three times. FO missed the radio calls from Tower. I prompted him and he responded to the clearance. Winds were a quartering headwind which eventually moved to an almost direct crosswind. There were some initial gusts that I was concerned might cause an overspeed which led to my delay in the final configuration. After landing; FO and I discussed the delay which led to final flaps 30 below 1;000 feet. FO had stated something like 'we're good for flaps' in which he was implying that we weren't fully configured but what I understood was a comment on the wind gusts and potential overspeed. I then asked for flaps 25 (concerned about gusts) and then flaps 30. I believe the final configuration was complete approaching 800 feet AGL.


Second narrative: After discussing the event; it became clear that my prompts to configure ('flaps 25/30 speed is [high]') were actually being interpreted by the Captain as a warning not to over speed the flaps because he had the plus 30 gusts on his mind; when; in fact; I intended my prompt to get him to configure. Turns out we were not on the same page. This was a subtle communications error. To preclude this error I could have stated we 'need to configure by 1;000 feet AGL AND you are good for flaps 25/30.'The following conditions task loaded us and may have led us to leave the Green and forget that we were at flaps 15 until very late: All the reroutes had burned all our extra fuel and we were at a tight fuel load that would not allow for another attempt at landing and instead require us to go to the alternate. The heavy rain. Concerns about possible airspeed gains.Better articulation of when (and monitoring of when) we would configure in light of the conscious decision to hold off configuring until necessary.


Synopsis: An air carrier crew executed a go-around on approach to DEN Runway 34R because outflow from a thunderstorm was seen on final. The second approach was unstabilized when excess airspeed was held due to airspeed variation concerns. The flight landed safely.