Yonaza Airstrip

The airstrip, officially known as Sagae Glider Field (寒河江滑空場), was located on riverbed land (kasenshiki) of the Mogami River. Its closure was due to an administrative decision by the land's managing authority, the Ministry of Land, Infrastructure, Transport and Tourism (MLIT). The MLIT decided not to renew the land use permit for aviation activities as part of a revised river management and land utilization plan. This was not due to an accident or direct economic failure of the operators, but rather a government-led repurposing of the land.

The site has been repurposed since its closure. The paved runway remains physically visible on satellite imagery, but it is no longer used for aviation. A significant portion of the former airfield grounds has been converted into the 'Sagae City Mogami River Southern Kasenshiki Solar Power Plant,' a large solar farm. Additionally, parts of the runway surface have been painted with markings and are now used as a training course for a local driving school. The surrounding area remains part of the Mogami River Sagae Green Space public park.

The facility was not a public airport but a designated 'off-airport landing site' (場外離着陸場 - jōgai rikichakurijō) primarily used for recreational aviation. Its historical significance lies in its role as a major hub for glider and ultralight aircraft activities in Japan's Tohoku region for several decades. It served as the home base for numerous university aviation clubs, most notably the Tohoku University Glider Club and the Yamagata University Glider Club, which used the site for training flights and competitions. The name 'Yonaza Airstrip' appears to be an erroneous or alternative name used in some non-official aviation databases; it was locally and officially known as the Sagae Glider Field. The ICAO code 'JP-1371' is a non-standard, national-level identifier.

There are no known plans or prospects for reopening the site as an airstrip. The land has been officially and physically repurposed for renewable energy generation (solar farm) and commercial use (driving school). Given this significant redevelopment and the termination of the original land use agreement for aviation, a return to flight operations is considered highly improbable.