| Flagstaff to Orbetello | 5,973.39 mi (9,613.24 km) |
| Flagstaff to Oria | 6,293.54 mi (10,128.47 km) |
| Flagstaff to Oristano | 6,003.66 mi (9,661.96 km) |
| Flagstaff to Orta Nova | 6,185.14 mi (9,954.01 km) |
| Flagstaff to Orte | 6,013.22 mi (9,677.34 km) |
| Flagstaff to Ortona | 6,087.71 mi (9,797.22 km) |
| Flagstaff to Orvieto | 5,990.60 mi (9,640.95 km) |
| Flagstaff to Orzinuovi | 5,781.98 mi (9,305.19 km) |
| Flagstaff to Osimo | 5,998.39 mi (9,653.48 km) |
| Flagstaff to Ospitaletto | 5,779.07 mi (9,300.51 km) |
| Flagstaff to Ostuni | 6,279.40 mi (10,105.72 km) |
| Flagstaff to Ottaviano | 6,168.13 mi (9,926.65 km) |
| Flagstaff to Ovada | 5,774.88 mi (9,293.78 km) |
| Flagstaff to Ozieri | 5,985.75 mi (9,633.14 km) |
| Flagstaff to Paceco | 6,246.70 mi (10,053.09 km) |
