Assessing the Cloud Structures of a 1980 Icing Accident Using in situ Data from a Research Aircraft and a High Resolution Model

On March 2, 1980 the Desert Research Institute’s B-26 research aircraft crashed on a supercooled cloud physics research mission over the Sierra Nevada Mountains. The pilot, co pilot, and both of the onboard scientists were killed. The official cause of the accident was determined to be aircraft icing.

The research aircraft atmospheric sensors and cloud physics probes collected data throughout the flight, including the icing encounter and the final descent. During the crash the magnetic tapes that were recording the flight and atmospheric measurements were smashed and shredded into pieces ranging in size from a fraction of an inch to several feet in length. They were scattered across the mountainside at the impact site. Colleagues of the B-26 flight team visited the accident site numerous times, collecting muddy tape fragments and locating the flight notebook of one of the onboard scientists. These recovered tape fragments were pieced together and the flight notes were used to recreate a snapshot of the cloud structures and aircraft behavior during the icing encounter. Some of the recovered data suggested that large cloud drops and liquid water contents as high as 1.4 g m^-3 were encountered.

In this talk, we review the large scale observed weather conditions, aircraft flight track including the final decent, aircraft and cloud physics observations from the recovered flight tapes and the flight notes. We then simulate the mesoscale weather conditions and resulting microscale cloud structures using a 1-km WRF model run specifically for the case. The results of the model are used to further analyze the weather associated with the icing accident.