This is a Chinook helicopter landing at the California Redwood Coast-Humboldt County Airport earlier this year.

From Pacific Gas and Electric:

Pacific Gas and Electric Company (PG&E) will be flying helicopters in Humboldt County starting today through the end of the month for routine maintenance of power poles and electrical towers and to check for drought-stricken trees near power lines.

PG&E will use helicopters, including a Chinook, a very large military helicopter, to upgrade electric facilities and transmission lines in order to improve reliability and enhance capacity near and around the communities of Dinsmore, Mad River, Bridgeville and Trinity Pines. The flights will aid in the maintenance of existing poles, set new poles and perform other improvements at various structures along Highway 36. The Chinook will transport both wood and steel poles as well as crews and construction equipment to and from work site locations, starting in Dinsmore. Some of the poles could be as long as 100 feet. This work will happen through September 21, 2016.

Also today, PG&E will use a contract helicopter service to fly foresters around other parts of the county to check for trees weakened by the drought. This patrol is in addition to the annual patrols PG&E does along power lines to identify trees and vegetation in need of pruning and removal. Weakened trees and branches can fall into power lines, leading to outages and even wildland fires. 

Those flights will only happen today from 8 a.m. to 5 p.m., weather permitting. Flights will occur along Highway 96 and Highway 169 over the towns of Hoopa and Orleans and near or around the communities of: Weitchpec, Martins Ferry, Mettah, Surgone, Johnsons, Wright Place, Somes Bar and Klamath River.

Residents are advised the helicopter will fly low – about 200 to 300 feet – along distribution power lines.