[![enter image description here][1]][1] From the Chart Supplement it seems both airports are unattended for most or all of this requirement: Mon-Fri 10 AM to 4 PM. And for 1O5, it's likely the service in on-demand by calling up ahead. 1O5: Unattended SIY: Attended Sun–Fri 1600–0100Z‡ I got the chart supplement for both airports from [skyvector.com][2]. [1]: https://i.sstatic.net/t0663.png [2]: https://skyvector.com/airport/1O5/Montague-Yreka-Rohrer-Field-Airport