B737-700
Flight Crew Air Transport Pilot (ATP)
Troubleshooting
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Unstabilized Approach
Air Traffic Control Issued New Clearance; Flight Crew Overcame Equipment Problem; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Executed Go Around / Missed Approach; Flight Crew Diverted
Aircraft; Weather
While executing an ILS approach we were on course and glidepath. The aircraft was accumulating a fair amount of ice (moderate icing in clouds). While trying to achieve final configuration at 170 knots indicated; I called for flaps 25. At that time; we both noticed the top of the amber speed bar at 170 knots. Both of us thought that our static ports or pitot tubes were icing up. A go-around was initiated. With the addition of go-around power and the nose of the aircraft pitching up; we received an 'Airspeed Low' alert followed be a brief stick shaker. I initiated a normal recovery and we were cleared by ATC to 11;000 ft. With the aircraft cleaned up; we decided the best course of action would be to go to our alternate. We then did a normal climb to FL250 and when we were trying to trouble shoot our problem that is when we noticed that the flap indicators were at 0 but there was a small split in the needles so; we realized we had a flap asymmetry and then we performed the QRH checklist for flap asymmetry. All indications were that the flaps were up but as a precaution we slowed to 250 KIAS and descended to FL200.Near the alternate; we slowed and positioned flap lever to 1. The flaps did not move so we realized we would have to do a zero flap landing. The QRH and OPC were complied with and we performed a successful 0 flap landing.  We also requested to have CFR standing by when we landed; and to follow us to the gate and to inspect our brakes before parking at the gate.  Passengers were kept informed during the entire time.
Flight crew reported that while cleaning up the aircraft on a missed approach they experienced a flap malfunction presumably caused by moderate icing. The crew elected to divert and landed flaps up.