B737 flight crew reported that after landing a passenger commented that the flight departed with sno...

Narrative:

We got to the aircraft with snow falling during preflight duties. The captain and I talked about the weather and both agreed we needed a two-step deice/anti-ice application. With ATIS reporting -sn; br (mist); temp of +2 C. We determined we could not use the 'snowfall intensities as a function of prevailing visibility' chart to determine snowfall intensities because of *1 note at bottom of chart. The note states 'use this table when snow is the only reported precipitation and visibility is not being reduced by other forms of obscuration (e.g.; fog [fg]; mist [br].' using established company policies and procedures the holdover time was calculated using the clariant safewing type iv chart for the current weather conditions.type iv clariant safewing at -3 and above @ 100% was started at time. Approximately 8 to 10 minutes later the deicing crew informed us we had a clean aircraft and the 2 step was complete. The captain and I used the holdover times tables from the cockpit to determine a very conservative (moderate versus light) holdover time of 0:49-1:20. Just prior to taking the runway for takeoff we performed a flight deck check and we could see no contamination on the aircraft. The takeoff was conducted without incident and landed also without incident. During deplaning a passenger informed us that we had taken off with snow on our wings.

Original NASA ASRS Text

Title: B737 Flight Crew reported that after landing a passenger commented that the flight departed with snow on the wings.

Narrative: We got to the aircraft with snow falling during preflight duties. The Captain and I talked about the weather and both agreed we needed a two-step deice/anti-ice application. With ATIS reporting -SN; BR (mist); temp of +2 C. We determined we could not use the 'snowfall intensities as a function of prevailing visibility' chart to determine snowfall intensities because of *1 note at bottom of chart. The note states 'Use this table when snow is the ONLY reported precipitation and visibility is not being reduced by other forms of obscuration (e.g.; fog [FG]; mist [BR].' Using established company policies and procedures the holdover time was calculated using the Clariant Safewing Type IV chart for the current weather conditions.Type IV Clariant Safewing at -3 and above @ 100% was started at time. Approximately 8 to 10 minutes later the deicing crew informed us we had a clean aircraft and the 2 step was complete. The captain and I used the holdover times tables from the cockpit to determine a very conservative (moderate versus light) holdover time of 0:49-1:20. Just prior to taking the runway for takeoff we performed a flight deck check and we could see no contamination on the aircraft. The takeoff was conducted without incident and landed also without incident. During deplaning a passenger informed us that we had taken off with snow on our wings.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1531262
Time
Date	201804
Local Time Of Day	0001-0600
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Dawn
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 389
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Events
Anomaly	Deviation - Procedural FAR Deviation - Procedural Published Material / Policy Inflight Event / Encounter Weather / Turbulence

B737 flight crew reported that after landing a passenger commented that the flight departed with snow on the wings.