Date: 201502
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Snow; 1/2
Light: Night
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Final Approach
Airspace: Class B ZZZ
ATC / advisory: Tower ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Physiological - Other
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Deviation - Speed All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Executed Go Around / Missed Approach
Contributing factors: Human Factors; Weather
Primary problem: Human Factors

Narrative: I was the PF on the ILS CAT III [approach]. Weather was light snow; night; 1-2 NM visibility and the ceiling was 700 OVC. I disconnected the autopilot for the HUD CAT III at about 2;000 AGL. I started experiencing vertigo and started deviating from the course. The FO properly called out the deviation; and I elected to go-around. Still suffering from my disorientation; I performed a poorly executed go-around and I over sped with the flaps in the 15 and 10 degree positions. (Max overspeed of 11 kts. at flaps 15) After level off; I had the FO take the aircraft and fly the approach and landing. FO performed an outstanding job during the entire event.


Second narrative: The Captain was the flying pilot; on approach he configured the aircraft to land and disengaged the autopilot at about 1;500 feet on the radar altimeter; to do a CAT 3 approach to runway XXL. Everything was normal and as briefed at this point; and the before landing checklist was completed. Weather conditions were as I best remember; snow and freezing rain; visibility was 1/2 mile and ceiling was 700 ft overcast. I noticed small localizer deviations at first; then a half dot deviation on glide slope; all of which I called out to the Captain. He made a correction every time; and I attributed this to the winds at about 250/58 kts at 1;500 ft shifting to somewhere about 220/4 kts on the surface and also some turbulence we encountered. I had no indication that the Captain was ill or incapacitated at all. The Captain then said 'I messed up; going around' as he pressed TOGA. I raised the flaps to 15 degrees and called out that I was doing this as the Captain had not called for it. At that point we both called positive rate; he called for gear up; and I raised the gear while calling tower to inform them of the missed approach. I was at that time still under the impression that the Captain had somehow not been set up properly for the approach; and that was the cause of the deviations and go around.Tower assigned us runway heading and 3;000 ft; which was set in the altitude window for missed approach; and asked us the reason for the go around. I saw the aircraft was turning to the right in a shallow bank; so I pressed heading and told the Captain to stop turning; we were instructed to fly runway heading. I then saw our speed approaching 200 kts as the captain turned further right and entered a descent. I called out for him to stop the turn and descent as I raised the flap handle. During this time the tower stated they saw us in a right turn and assigned us a new heading; I think 250; and again asked us the reason for the go around since I had not answered that previously. Since my attention was diverted towards getting the aircraft in a climb and on the correct heading; and the Captain also failed to call for flaps to come up; we over sped with the flaps at 15 and 10 degrees. The Captain then told me he was experiencing vertigo and to take the aircraft. I then took control of the aircraft; got it leveled off at 3;000 ft and on the assigned heading; and engaged the autopilot. I asked the Captain if he was ok; and he said he was ok at that point; the vertigo had passed but we both agreed that I should continue to fly. I then set up for another approach; this time a CAT 1 ILS XXL; briefed it; and flew it to a safe; uneventful landing. The Captain took control at taxi speed and taxied to the gate.In retrospect; I believe the Captain actually said 'I'm messed up.' If I had heard this correctly it would have given me a clue a little earlier that something was wrong and I could have taken the aircraft earlier; my attention would not have been diverted; and the flaps would not have been over sped. This is not the first time I have experienced degraded cockpit communications due to the noise level of the aircraft. Throw in a heavy workload and increased ATC communications and it makes the problem worse. [My previous airline] has an intercom lock switch so the pilots can communicate through their headsets without pressing to talk each transmission; and also issues noise canceling headset to their pilots. The intercom lock would have been very helpful during my flight and every 737 flight; but instead we are reduced to shouting and miscommunications; since it is too difficult to fly and push to talk each time you have something to say. The Captain I was flying with was unable to communicate effectively to me about his temporary vertigo. Why are we at [my current airline] lacking such an important safety feature that can also prevent hearing loss in our 737 pilots?


Synopsis: B737-800 flight crew reported the Captain experienced vertigo during an instrument approach so a go-around was executed; and the FO flew the subsequent approach.