US regional carrier SkyWest Airlines is preparing for the end of an era as it retires its last remaining EMB-120 Brasilias from service over the coming five months as it transitions to an all-jet fleet. The 30-seater turboprop is the smallest aircraft in its fleet and is flown for United Airlines and Delta Air Lines.

The airline revealed in November 2014 that it would end more than 20 years of operation with the type by the middle of this year. The retirement is, in part, in response to increased costs and additional challenges associated with new FAR117 flight and duty rules, implemented in January 2014.

The FAR117 rules require airlines to provide flight crews with increased rest time and SkyWest revealed during its second quarter earnings call last year that it had to hire additional pilots to meet the requirements. This is a major issue for small carriers due to the lack of skilled pilots and ongoing attrition as existing crews move to higher paid roles at larger carriers.

The changes to FAR 117 increases total operating costs for all airlines and particularly for smaller aircraft like SkyWest’s Embraer EMB-120 Brasilia, thus increasing revenue and demand requirements to continue operating.

Although the FAR 117 rules have been adopted in the name of safety, it has meant many smaller communities have lost air services since its introduction as the operation of niche routes with small capacity airliners has become unsustainable across many markets.

As SkyWest itself noted in a regulatory filing last year ahead of the retirement announcement, “small and medium-sized communities will likely see the greatest impact as we work to maintain the same level of service at higher costs”.