With the loss of visibility, descent to an altitude below the freezing-level may not have been possible. The crew returned to NAS Whidbey, which meant that the

With the loss of visibility, descent to an altitude below the freezing-level may not have been possible. The crew returned to NAS Whidbey, which meant that they had to overfly Washington's Cascade Mountains. The freezing level that day was 7,000 feet or less [1], and some of the mountains are taller than that (many near 7k, a big one reaches 10.5k, and Rainier is 14.4k). It also appears to have been cloudy over the mountains from about noon onward. There is a pretty good chance that they were blind until they were sure they were back in the Puget Sound region. I'll bet they descended as soon as they could. [1] https://www.nwac.us/data-portal/location/stevens-pass/q?field_name=temperature&year=2018&custom_startdate=2018-01-29&custom_enddate=2018-01-29 https://www.nwac.us/data-portal/location/stevens-pass/q?fiel...