TOKYO, Dec. 13 (Kyodo) — Mitsubishi Heavy Industries Ltd. said Thursday its Mitsubishi Aircraft Corp. unit has signed a contract to provide SkyWest Inc. of the United States with 100 Mitsubishi Regional Jet aircraft for $4.2 billion from 2017.

SkyWest, which owns two regional airlines in the United States, also put an option on another 100 MRJ jets. If the option is implemented, Mitsubishi Aircraft will deliver the 100 MRJs from 2021.

Mitsubishi Aircraft was founded in 2008 to develop the MRJ with 70 to 90 seats. A test version of the MRJ is planned to make the first flight in the second half of 2013.

The SkyWest deal brings total MRJ orders and options to 325 planes. The other buyers are another U.S. firm and All Nippon Airways Co.

Mitsubishi Aircraft aims to get more than 1,000 MRJ orders over the next 20 years.