Narrative:

I observed freezing rain during the walkaround. Upon returning to the cockpit and discussion with the captain determined a holdover time to be 1:05-2:00. Prior to departure; I observed light ice pellets. Reduced holdover times to :50 mins per 2007/2008 deicing guide. Deiced aircraft; received report from deicer and pushed for taxi. On taxi out observed light freezing rain. This was based on visibility; open window check and aircraft feel. We departed without incident. After review and discussion with the captain it is believed the flight may not have been conducted within legal limits for various conflicting reasons. It was noted the holdover chart states 'no holdover time for snow pellets; ice pellets etc' while the 2007/2008 deice guide states :50 or :25 mins based on conditions. Also missed that according to part 1 the absence of a minus sign determines the fzr as moderate (my mistake). Also ice pellets are one thing; freezing rain is another and ice pellets with freezing are a third; throw in pilot assessment and the ATIS and you have a whole new ball game. While conditions observed by the flight crew on taxi were confirmed by the WX observations just prior to departure too many sources of information and conflicts during this time of very dynamic WX changes make it very hard to determine safe and legal operations. Supplemental information from acn 764496: we feel the dispatcher really let us down. Dispatcher apparently had WX information that indicated that we should not be operating this flight because the intensity of the falling precipitation was both moderate and was mixed. Flight manual requires the dispatcher to cancel the flight if; in his opinion; the flight cannot operate or continue to operate safely; as planned or released. The dispatcher kept that information from us until after we were airborne.

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Original NASA ASRS Text

Title: AN ACR CREW FEELS THEY DEPARTED IN FZR AND ICING CONDITIONS OUT OF SAFE LIMITS. THE CREW ASSUMED AN INCORRECT HOLDOVER TIME FOR PRESENT CONDITIONS. REPORTER STATES DISPATCH WITHHELD INFO FROM THEM.

Narrative: I OBSERVED FREEZING RAIN DURING THE WALKAROUND. UPON RETURNING TO THE COCKPIT AND DISCUSSION WITH THE CAPT DETERMINED A HOLDOVER TIME TO BE 1:05-2:00. PRIOR TO DEP; I OBSERVED LIGHT ICE PELLETS. REDUCED HOLDOVER TIMES TO :50 MINS PER 2007/2008 DEICING GUIDE. DEICED ACFT; RECEIVED RPT FROM DEICER AND PUSHED FOR TAXI. ON TAXI OUT OBSERVED LIGHT FREEZING RAIN. THIS WAS BASED ON VISIBILITY; OPEN WINDOW CHK AND ACFT FEEL. WE DEPARTED WITHOUT INCIDENT. AFTER REVIEW AND DISCUSSION WITH THE CAPT IT IS BELIEVED THE FLT MAY NOT HAVE BEEN CONDUCTED WITHIN LEGAL LIMITS FOR VARIOUS CONFLICTING REASONS. IT WAS NOTED THE HOLDOVER CHART STATES 'NO HOLDOVER TIME FOR SNOW PELLETS; ICE PELLETS ETC' WHILE THE 2007/2008 DEICE GUIDE STATES :50 OR :25 MINS BASED ON CONDITIONS. ALSO MISSED THAT ACCORDING TO PART 1 THE ABSENCE OF A MINUS SIGN DETERMINES THE FZR AS MODERATE (MY MISTAKE). ALSO ICE PELLETS ARE ONE THING; FREEZING RAIN IS ANOTHER AND ICE PELLETS WITH FREEZING ARE A THIRD; THROW IN PLT ASSESSMENT AND THE ATIS AND YOU HAVE A WHOLE NEW BALL GAME. WHILE CONDITIONS OBSERVED BY THE FLT CREW ON TAXI WERE CONFIRMED BY THE WX OBSERVATIONS JUST PRIOR TO DEP TOO MANY SOURCES OF INFO AND CONFLICTS DURING THIS TIME OF VERY DYNAMIC WX CHANGES MAKE IT VERY HARD TO DETERMINE SAFE AND LEGAL OPS. SUPPLEMENTAL INFO FROM ACN 764496: WE FEEL THE DISPATCHER REALLY LET US DOWN. DISPATCHER APPARENTLY HAD WX INFO THAT INDICATED THAT WE SHOULD NOT BE OPERATING THIS FLT BECAUSE THE INTENSITY OF THE FALLING PRECIP WAS BOTH MODERATE AND WAS MIXED. FLT MANUAL REQUIRES THE DISPATCHER TO CANCEL THE FLT IF; IN HIS OPINION; THE FLT CANNOT OPERATE OR CONTINUE TO OPERATE SAFELY; AS PLANNED OR RELEASED. THE DISPATCHER KEPT THAT INFO FROM US UNTIL AFTER WE WERE AIRBORNE.

Data retrieved from NASA's ASRS site as of January 2009 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.