United Airlines will shrink its Guam hub from November 2017, as it shifts Boeing 737s back to the US mainland.

The redeployment of three 737s to the mainland from Micronesia will allow the Chicago-based Star Alliance carrier to increase aircraft utilisation, says Howard Attarian, senior vice-president of flight operations at United, in a letter to pilots on 4 April.

United can fly the aircraft about eight hours per day on the mainland compared to about four hours per day out of Guam, he says.

"One of the most important initiatives underway at United is a renewed focus on growing our airline through improved fleet utilisation," says Attarian.

United is in the midst of a domestic expansion primarily enabled by increased aircraft utilisation. It expects a 3.5% to 4.5% increase in domestic capacity in 2017, which chief executive Oscar Munoz says is driven largely by higher utilisation and completion factors.

The airline bases four 737-700s and seven 737-800s at its Guam hub, the United Airlines fleet website shows.

United will end service on its Tokyo Narita-Seoul Incheon route, which is flown by Guam-based 737-800s and crews, later in 2017, says Attarian.

He does not comment on what other markets could lose service with the Guam reductions.

"Guam has long been an important part of our airline, and we're committed to keeping our Guam operation for the long-term, but the specific flying being removed (NRT-ICN service) is not core to our Guam network," says Attarian.

Guam is United's smallest hub, with just 2.02 million seats in 2016, FlightGlobal schedules show. Current schedules show seat capacity increasing nearly 2% year-over-year in 2017 after a 3.1% year-over-year reduction in 2016.

The US carrier has faced increased competition to Guam in recent years. HK Express added service to the island from Hong Kong in December 2016 and nearby Saipan in January, and Cebu Pacific to Guam earlier in 2016.

United and its Guam-based Continental Micronesia subsidiary officially merged on 1 April. While understood to be just a paper merger – the operations were already branded "United" – the integration allows for the combination of employee groups.

Source: Cirium Dashboard