Mammoth Yosemite Airport the most convenient airport, but flights are limited to a few West Coast cities.
Airports in Los Angeles and Las Vegas, both over 200 miles away from Lone Pine, make logical starting points for a south-to-north exploration of the Eastern Sierra. Otherwise, it makes sense to fly into Reno, NV, and travel south. Either way, if you want to avoid backtracking, try to fly into one airport and out of another.
Eastern Sierra Transit Authority buses make a round trip between Lone Pine and Reno ($59, six hours) on Monday, Tuesday, Thursday and Friday, stopping at all Hwy 395 towns in between. Fares depend on distance, and reservations are recommended. There’s also an express bus between Mammoth and Bishop ($7, one hour, around three times daily) that operates Monday to Friday.
In summer, connect to Yosemite via YARTS bus in Mammoth Lakes or Lee Vining. Mammoth to Lee Vining costs $6 one-way, while Mammoth to Yosemite Valley is $18 (including free park entry, plus one free under-12s ticket per adult ticket purchased), with one to two early morning departures per day.
The Eastern Sierra is easiest to explore under your own steam. Keep in mind that some mountain roads close in winter, as do most of the passes that take you over the Sierras from east to west, including Tioga Rd (Hwy 120) to Yosemite.