Narrative:

I'm going to first describe events that occurred on the evening of feb xa when I was attempting to depart ZZZ. Although not the subject of this particular report; it has direct bearing on decisions I made 11 days later. We were in the process of boarding passenger in ZZZ. The ATIS changed to indicate that light freezing rain was beginning to fall. I recalled a warning in the dornier 328 flight manual regarding operations in freezing rain. It reads as follows: 'warning: severe icing may result from environmental conditions outside of those for which the airplane is certificated. Flight in freezing rain; freezing drizzle; or mixed icing conditions (super-cooled liquid water and ice crystals) may result in ice build-up on protected surfaces exceeding the capability of the ice protection system; or may result in ice forming aft of the protected surfaces. This ice may not be shed using the ice protection system; and may seriously degrade the performance and ctlability of the airplane.' based on this warning; I decided that it was unsafe to depart and I informed dispatch of my decision. Dispatch disagreed; stating that I was 'absolutely incorrect' (even after I read him the warning). I was convinced that I was right; so dispatch called the director of operations who also tried to convince me that it was safe to depart. I read the warning to him but he remained convinced that the flight could safely depart. I was not convinced by the arguments presented by dispatch and the director of operations; so I canceled the flight. The following morning I was called in to the chief pilot's office. He tried to convince me that the warning in the afm did not constitute a prohibition against taking off into light freezing rain. His reasoning (and the reasoning of director of operations; director of safety and security; and manager of flight standards and training) was that the flight could be safely conducted for the following reasons: 1) the warning doesn't specify 'light' freezing rain; only 'freezing rain.' 2) there was a holdover time for type 4 anti-icing fluid for the conditions present at the time of departure. 3) the warning didn't specifically state that anything bad would happen; only that they may happen. 4) the NASA icing video which presented the danger of flight into sld was based on flts of a dehavilland twin otter and were; therefore; not applicable to a dornier 328 because the wings of the 2 aircraft were different. In order to obtain clarification I contacted dornier 328 support services. They sent me the following response: 'take off into freezing rain including light freezing rain is not permitted. Icing fluids protect the aircraft only on ground until brake release against ice accretion. By design most of the fluid is shed away from the airframe before liftoff. Freezing rain consists of large water droplets hitting the airframe aft of the boots with the result of lowering the stall angle of attack dramatically. A safe escape from those conditions; when entered unintentionally during flight; is defined in the manual requiring high minimum speeds to avoid stalling the aircraft. Takeoff is only permitted into normal icing conditions. The manual contains all information -- takeoff speeds; climb gradients; etc; for those conditions.' I shared this information with those present. They essentially ignored it; stating that they weren't convinced that dornier support services had the authority/authorized to interpretation the warning. They said they were going to try to get them to retract this statement. I will now describe the events of today. When I departed; freezing rain was in the current metar. Before I left; I contacted dispatch and told them that there was a chance that I would encounter freezing rain on the approach. I gave them copies of the e-mail from dornier support services so they would know what I was basing my decision on. Sure enough; when we were about 30 mins out; the ATIS was reporting light freezing rain. The ATIS was about to change so I decided to wait and see what the new ATIS had to say. When it came out; the new ATIS also reported light freezing rain. I contacted dispatch and told them that there was light freezing rain and; based on the explanation I received by dornier support services; I considered an approach unsafe. We decided that the flight should return to origination. When I landed; I was called in to see the director of operations. He told me that I made an extremely poor decision by choosing not to fly into light freezing rain; that I had no right to contact dornier support services to obtain clarification on the pertinent warning; and that I had no right to share this information with dispatch. Callback conversation with reporter revealed the following information: the reporter stated that dornier was quite clear that this aircraft should not be operated in any kind of freezing rain. This aircraft is equipped with deicing boots which may be the reason for this prohibition.

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Original NASA ASRS Text

Title: DO328 CAPT REPORTS REFUSAL TO OPERATE HIS ACFT IN LIGHT FREEZING RAIN.

Narrative: I'M GOING TO FIRST DESCRIBE EVENTS THAT OCCURRED ON THE EVENING OF FEB XA WHEN I WAS ATTEMPTING TO DEPART ZZZ. ALTHOUGH NOT THE SUBJECT OF THIS PARTICULAR RPT; IT HAS DIRECT BEARING ON DECISIONS I MADE 11 DAYS LATER. WE WERE IN THE PROCESS OF BOARDING PAX IN ZZZ. THE ATIS CHANGED TO INDICATE THAT LIGHT FREEZING RAIN WAS BEGINNING TO FALL. I RECALLED A WARNING IN THE DORNIER 328 FLT MANUAL REGARDING OPS IN FREEZING RAIN. IT READS AS FOLLOWS: 'WARNING: SEVERE ICING MAY RESULT FROM ENVIRONMENTAL CONDITIONS OUTSIDE OF THOSE FOR WHICH THE AIRPLANE IS CERTIFICATED. FLT IN FREEZING RAIN; FREEZING DRIZZLE; OR MIXED ICING CONDITIONS (SUPER-COOLED LIQUID WATER AND ICE CRYSTALS) MAY RESULT IN ICE BUILD-UP ON PROTECTED SURFACES EXCEEDING THE CAPABILITY OF THE ICE PROTECTION SYS; OR MAY RESULT IN ICE FORMING AFT OF THE PROTECTED SURFACES. THIS ICE MAY NOT BE SHED USING THE ICE PROTECTION SYS; AND MAY SERIOUSLY DEGRADE THE PERFORMANCE AND CTLABILITY OF THE AIRPLANE.' BASED ON THIS WARNING; I DECIDED THAT IT WAS UNSAFE TO DEPART AND I INFORMED DISPATCH OF MY DECISION. DISPATCH DISAGREED; STATING THAT I WAS 'ABSOLUTELY INCORRECT' (EVEN AFTER I READ HIM THE WARNING). I WAS CONVINCED THAT I WAS RIGHT; SO DISPATCH CALLED THE DIRECTOR OF OPS WHO ALSO TRIED TO CONVINCE ME THAT IT WAS SAFE TO DEPART. I READ THE WARNING TO HIM BUT HE REMAINED CONVINCED THAT THE FLT COULD SAFELY DEPART. I WAS NOT CONVINCED BY THE ARGUMENTS PRESENTED BY DISPATCH AND THE DIRECTOR OF OPS; SO I CANCELED THE FLT. THE FOLLOWING MORNING I WAS CALLED IN TO THE CHIEF PLT'S OFFICE. HE TRIED TO CONVINCE ME THAT THE WARNING IN THE AFM DID NOT CONSTITUTE A PROHIBITION AGAINST TAKING OFF INTO LIGHT FREEZING RAIN. HIS REASONING (AND THE REASONING OF DIRECTOR OF OPS; DIRECTOR OF SAFETY AND SECURITY; AND MGR OF FLT STANDARDS AND TRAINING) WAS THAT THE FLT COULD BE SAFELY CONDUCTED FOR THE FOLLOWING REASONS: 1) THE WARNING DOESN'T SPECIFY 'LIGHT' FREEZING RAIN; ONLY 'FREEZING RAIN.' 2) THERE WAS A HOLDOVER TIME FOR TYPE 4 ANTI-ICING FLUID FOR THE CONDITIONS PRESENT AT THE TIME OF DEP. 3) THE WARNING DIDN'T SPECIFICALLY STATE THAT ANYTHING BAD WOULD HAPPEN; ONLY THAT THEY MAY HAPPEN. 4) THE NASA ICING VIDEO WHICH PRESENTED THE DANGER OF FLT INTO SLD WAS BASED ON FLTS OF A DEHAVILLAND TWIN OTTER AND WERE; THEREFORE; NOT APPLICABLE TO A DORNIER 328 BECAUSE THE WINGS OF THE 2 ACFT WERE DIFFERENT. IN ORDER TO OBTAIN CLARIFICATION I CONTACTED DORNIER 328 SUPPORT SVCS. THEY SENT ME THE FOLLOWING RESPONSE: 'TAKE OFF INTO FREEZING RAIN INCLUDING LIGHT FREEZING RAIN IS NOT PERMITTED. ICING FLUIDS PROTECT THE ACFT ONLY ON GND UNTIL BRAKE RELEASE AGAINST ICE ACCRETION. BY DESIGN MOST OF THE FLUID IS SHED AWAY FROM THE AIRFRAME BEFORE LIFTOFF. FREEZING RAIN CONSISTS OF LARGE WATER DROPLETS HITTING THE AIRFRAME AFT OF THE BOOTS WITH THE RESULT OF LOWERING THE STALL ANGLE OF ATTACK DRAMATICALLY. A SAFE ESCAPE FROM THOSE CONDITIONS; WHEN ENTERED UNINTENTIONALLY DURING FLT; IS DEFINED IN THE MANUAL REQUIRING HIGH MINIMUM SPDS TO AVOID STALLING THE ACFT. TKOF IS ONLY PERMITTED INTO NORMAL ICING CONDITIONS. THE MANUAL CONTAINS ALL INFO -- TKOF SPDS; CLB GRADIENTS; ETC; FOR THOSE CONDITIONS.' I SHARED THIS INFO WITH THOSE PRESENT. THEY ESSENTIALLY IGNORED IT; STATING THAT THEY WEREN'T CONVINCED THAT DORNIER SUPPORT SVCS HAD THE AUTH TO INTERP THE WARNING. THEY SAID THEY WERE GOING TO TRY TO GET THEM TO RETRACT THIS STATEMENT. I WILL NOW DESCRIBE THE EVENTS OF TODAY. WHEN I DEPARTED; FREEZING RAIN WAS IN THE CURRENT METAR. BEFORE I LEFT; I CONTACTED DISPATCH AND TOLD THEM THAT THERE WAS A CHANCE THAT I WOULD ENCOUNTER FREEZING RAIN ON THE APCH. I GAVE THEM COPIES OF THE E-MAIL FROM DORNIER SUPPORT SVCS SO THEY WOULD KNOW WHAT I WAS BASING MY DECISION ON. SURE ENOUGH; WHEN WE WERE ABOUT 30 MINS OUT; THE ATIS WAS RPTING LIGHT FREEZING RAIN. THE ATIS WAS ABOUT TO CHANGE SO I DECIDED TO WAIT AND SEE WHAT THE NEW ATIS HAD TO SAY. WHEN IT CAME OUT; THE NEW ATIS ALSO RPTED LIGHT FREEZING RAIN. I CONTACTED DISPATCH AND TOLD THEM THAT THERE WAS LIGHT FREEZING RAIN AND; BASED ON THE EXPLANATION I RECEIVED BY DORNIER SUPPORT SVCS; I CONSIDERED AN APCH UNSAFE. WE DECIDED THAT THE FLT SHOULD RETURN TO ORIGINATION. WHEN I LANDED; I WAS CALLED IN TO SEE THE DIRECTOR OF OPS. HE TOLD ME THAT I MADE AN EXTREMELY POOR DECISION BY CHOOSING NOT TO FLY INTO LIGHT FREEZING RAIN; THAT I HAD NO RIGHT TO CONTACT DORNIER SUPPORT SVCS TO OBTAIN CLARIFICATION ON THE PERTINENT WARNING; AND THAT I HAD NO RIGHT TO SHARE THIS INFO WITH DISPATCH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE REPORTER STATED THAT DORNIER WAS QUITE CLEAR THAT THIS ACFT SHOULD NOT BE OPERATED IN ANY KIND OF FREEZING RAIN. THIS ACFT IS EQUIPPED WITH DEICING BOOTS WHICH MAY BE THE REASON FOR THIS PROHIBITION.

Data retrieved from NASA's ASRS site as of May 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.