Hubbard Air Service 1919-1927.
In 1921 for no discernable reason, Hubbard lost the USPS contract to Alaska Airways. Ancel Eckmann who, in 1929, would be the first to fly Seattle-Juneau, flew American Airways’ Curtiss HS-21 flying boat on the service. The contract reverted back to Hubbard six months later.
Upon Hubbard’s retirement in 1927, Herold Walker took over from Hubbard. He flew Hubbard’s B1 flying boat for Northwest Air Services Inc. until 1929.
Below is a Youtube video showing "The BEST of Farnborough Airshow 2018".