| McDonough to Orbetello | 4,952.70 mi (7,970.60 km) |
| McDonough to Oria | 5,306.57 mi (8,540.10 km) |
| McDonough to Oristano | 4,916.81 mi (7,912.84 km) |
| McDonough to Orta Nova | 5,191.09 mi (8,354.25 km) |
| McDonough to Orte | 5,004.19 mi (8,053.47 km) |
| McDonough to Ortona | 5,096.85 mi (8,202.59 km) |
| McDonough to Orvieto | 4,983.21 mi (8,019.70 km) |
| McDonough to Orzinuovi | 4,800.15 mi (7,725.09 km) |
| McDonough to Osimo | 5,017.27 mi (8,074.52 km) |
| McDonough to Ospitaletto | 4,801.26 mi (7,726.87 km) |
| McDonough to Ostuni | 5,295.61 mi (8,522.46 km) |
| McDonough to Ottaviano | 5,153.59 mi (8,293.90 km) |
| McDonough to Ovada | 4,768.05 mi (7,673.44 km) |
| McDonough to Ozieri | 4,913.70 mi (7,907.83 km) |
| McDonough to Paceco | 5,167.33 mi (8,316.01 km) |
