B737-700
Flight Crew Last 90 Days 202; Flight Crew Type 8500
Training / Qualification; Confusion
Ground Event / Encounter Other / Unknown
General None Reported / Taken
Weather
We were cleared to line up and wait on Runway 9L. The visibility was good and there was light precipitation falling; rain with a few snowflakes. The outside air temperature was above freezing. The First Officer and I were very diligent about whether any precipitation was adhering to the aircraft and it most definitely was not. As we were sitting in position; Tower stated 'Company XXX; new ATIS calling light snow pellets. Fly heading 081; cleared for takeoff.' I released brakes and we took off uneventfully. The question that arose is whether we should have declined takeoff clearance and de-iced or if we were okay to press on with the takeoff. It is not a question of safety; because there was minimal precipitation and we most definitely had a clean aircraft. Since we were in position on the runway; we did not bring up the new ATIS on ACARS because it would have been inappropriate at that time.... Our concern is not whether our actions were safe; because we definitely had a clean aircraft. Our question is whether at the time with the limited information we had; should we have taken off or de-iced? It was obvious looking out the windows that the precipitation was light and not adhering to the aircraft or any outside structures. It was a very light mist falling and the OAT was above freezing. I believe if it was stated by ATC as 'ice pellets' and I hadn't yet started pushing up the power; the correct action would have been to clear the runway and have Type 1 and Type 4 sprayed on the clean aircraft. While commencing the takeoff and getting the short; verbal ATIS from Tower about 'light snow pellets;' I believe we were correct in our actions.
When cleared for takeoff; B737-700 flight crew was informed by Tower of an ATIS change to 'light snow pellets.' After an uneventful takeoff; flight crew questioned the legality of taking off without applying Type 1 and Type 4 fluid to the aircraft.