Date: 201403
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Night
Aircraft: B737-700
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Taxi
Reporter organization: Air Carrier
Reporter function: First Officer
Human factors: Other / Unknown
Second reporter function: Other / Unknown
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Passenger
When detected: Aircraft In Service At Gate; Taxi
Result: Flight Crew Became Reoriented
Contributing factors: Weather; Human Factors
Primary problem: Human Factors

Narrative: While reading back our takeoff clearance to Tower and preparing to taxi into position; the flight attendants called the cockpit. The message was that a deadheading crew member noticed some frost on the upper surface of the wing. We advised Tower that we would need to exit the runway and return to the ramp. We coordinated with Ground; Ramp; Iceman and Dispatch/Ops. After completing the deice process; we departed. When we flew in it was a nice VMC night temp-6/dew-9 swapped aircraft and prepared to depart. I performed a thorough preflight looking very closely for ice and finding none. Neither I nor the Captain walked back to check over the wing. In the future I will make it a point to ask the Captain if he had a chance to check.


Second narrative: On this day; I was a nonrevenue passenger traveling home from a vacation. The flight was delayed because we were awaiting the entire crew off another inbound flight. The aircraft had been at the gate for about 2.5 hours awaiting the crew. It was late into the evening. The agent began boarding around after the crew arrived. When I boarded the aircraft; I introduced myself to the A Flight Attendant and asked to step into the flightdeck to say hello to the crew. The Captain was in the lavatory and the First Officer was completing his duties. I briefly said hello and mentioned I was a Company Pilot on a nonrevenue ticket commuting home. He said hello and I continued to the back to take a seat. I sat down at Seat XXF; a window seat.As I took my seat; I noticed the wings were covered in frost and ice. The flaps and the ailerons were covered with frost and ice. The frost went pretty far out toward the leading edge of the wing and toward the winglet. The passenger who sat next to me said hello and mentioned to me he was ready to get to XXX because of a drive he would have to make once we arrived. I mentioned to him we would be on our way once the aircraft was deiced. He looked out the window and said; 'Oh yea; there is a lot of ice on the wing.' As we pushed back; everything seemed normal. We started our taxi and I thought we were going to get in line to be deiced. As the customer next to me continued to speak with me; I noticed we were heading toward the runway without deicing. When I saw we were about to take the runway; I asked the customers to let me out and I quickly walked to the aft galley and spoke with the Flight Attendant. I showed her my ID and said I was a Company Pilot. I asked her to contact the Captain and let him know there was a lot of ice and frost on the wings. The Flight Attendant contacted the Captain and relayed to him exactly what I said. I then returned to my seat. The Captain came over the PA and told the passengers we would have to return to the gate because of ice on the wings and we needed to be deiced. The aircraft taxied to the deice pad; we got deiced; and the aircraft took off with a clean wing. When we arrived; the Captain met with me and said thank you for speaking up. We shook hands and called it a night (it was morning).It appeared this was the classic case of a flight that was late with a crew coming from another flight late into the evening. The crew did an aircraft swap and was doing everything to get the flight out as quickly as possible. This created the external threats we talk about all the time in CRM. I think the only preventative measure is to reinforce slowing down when the external threats really start to add up. I know that CRM worked because I was a commuting crew member who noticed an external threat and immediately passed it along to the Flight Attendant. She contacted the Captain and we got the issue resolved. The aircraft got deiced and we flew safely with a clean wing.


Synopsis: A B737 flight crew and a pass riding pilot report canceling a takeoff clearance and returning for deicing when the pass riding pilot informs a Flight Attendant of frost on the wings.