B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 60; Flight Crew Total 13500; Flight Crew Type 4071
Situational Awareness
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Weather; Human Factors
The First Officer accomplished the walk around and declared the aircraft 'good'. During cockpit checks the ground crew asked if we needed de-icing. I queried the FO (First Officer) and he said no. During taxi the lead flight attendant called to inform us that a pass riding crew member saw ice on the wing. I elected to pull over and have my FO accomplish a wing check. The FO checked the wings and had a short discussion with the passenger; a Flight Attendant. He still did not detect ice on the wing. We accomplished an uneventful takeoff and flight. On arrival a deadheading pilot approached us to say he saw frost on our wing. We agreed that company guidance precludes takeoff with any frost or ice on the top of the wing surfaces and that we simply didn't see any. We pledged to much more vigilant in the future.
Walk around on cold; clear morning; sun already up. Saw frost on outside of engine; but none inside engine cowling; on bottom of wing; or leading edge. Looked at top of wing from jet bridge and concluded no need to deice. I informed Captain of this. On taxi out; a Flight Attendant traveling in a window seat reported frost. Captain and I concurred to stop aircraft so I could do a wing check. I again didn't think I saw anything and asked Flight Attendant if he was okay with my assessment. He said he was. Takeoff and landing uneventful. At block in; a pilot came to the cockpit and told us he saw frost on top of wing before takeoff. Captain and I discussed importance of clean wing and discussed better techniques of looking through multiple windows - I'm aware of company policy towards going with ice or frost on top of wing or critical surfaces and will up my vigilance in the future. I was under no time constraints or pressures and I fully understand the adverse effects of a contaminated wing.
B737 flight crew reported departing without realizing frost was present on the top of the wings.