B737-800
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 265
Situational Awareness
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
General None Reported / Taken
Environment - Non Weather Related; Weather; Human Factors
I proceeded to the gate to get an early start on my preflight. Although there was no snow or precipitation; it was colder out than I'd experienced previously so before I walked around I walked straight back and looked out the windows at the wings. It was still fairly dark but I thought I could see the wings well enough with my flashlight to see any ice and I didn't note any. I did my initial preflight and then proceeded to do my walk-around. I'm a new First Officer; have been on the line for 3 months; and during the walk-around I was specifically looking for ice. I was surprised not to see any on the walk-around and remembered thinking it must be due to the dry air. I finished my walk-around and continued my duties in the cockpit. The Captain specifically asked when we taxied if we needed deicing and I told him no. I was completely surprised to hear we had a call indicating we had taken off with icing. Looking back now; I know the best course of action would have been to check the wings when the sun was completely up and after my walk-around and initial preflight. I think I was reluctant to re-check the top surface of the wing as I wanted to look before the aircraft was filled with passengers. Subsequently; the walk-around with zero indications of any ice led me to mistakenly believe my initial look at the top of the wings provided an accurate assessment. I was incorrect and learned a valuable lesson. I will always look in full daylight or with adequate lighting.
On the ground; my First Officer and I got to the aircraft. He walked back to the overwing exits and inspected the wings for frost/ice and then proceeded to do his walk-around. I asked him if there was any frost/ice and he said 'No frost or ice; we have a clean aircraft.'
B737-800 flight crew reported inadvertently departing with ice on the wings because the new First Officer missed it on the walk-around.