with or without Slide Fastener Closing.
The copyright date on the envelope is 1938, the pattern could be a year or two later.
You get to the bush, of course, by flying your plane, perhaps a Stinson SR-10, which was first manufactured in 1938. The film Test Pilot, starring Clark Gable, Myrna Loy, and Spencer Tracy, was released in 1938 and was nominated for an Academy Award (losing to You Can't Take It With You)
Suggested fabrics include novelty cottons, suede cloth, velveteen (!), corduroy, woolens, flannel, linen.
Written in pencil on the front of the envelope, "Mrs White Pd" I have a fair number of patterns with names penciled on the front.
Wouldn't it be wonderful to have a snapshot of Mr. White wearing his snappy bush jacket?