Observation & Communication aircraft locator
- A-10 Thunderbolt II (Fairchild-Republic)
- A-37 Cessna (Cessna)
- AOP (Auster)
- B-24 Liberator (Consolidated)
- D.H. 4 (De Havilland)
- EO (Elias)
- F-24 Argus (Fairchild)
- HO (Huff-Daland)
- L-19 Bird Dog (Cessna)
- LS (Loening)
- M-80 (Loening)
- M-81 (Loening)
- M2O (Martin)
- MO (Martin)
- NE-1 Cub (Piper)
- NO (Naval Aircraft Factory)
- O-1 Bird Dog (Cessna)
- O-2 Skymaster (Cessna)
- O-38 (Douglas)
- O-46 (Douglas)
- O-47 (North American)
- O-52 Owl (Curtiss)
- O2B (Boeing)
- O2C (Curtiss)
- O2U (Vought)
- O3U (Curtiss)
- O3U (Vought)
- O4U (Vought)
- OA-1 (Loening)
- OA-10 Catalina (Consolidated)
- OA-12 Duck (Grumman)
- OC (Curtiss)
- OD (Douglas)
- OE Bird Dog (Cessna)
- OJ (Berliner Joyce)
- OK (Keystone)
- OL (Loening)
- OP (Pitcairn)
- OV-1 Mohawk (Grumman)
- OV-10 Bronco (Rockwell International)
- OY Sentinel (Convair)
- P5M Marlin (Martin)
- P6M Seamaster (Martin)
- SF (Grumman)
- VE (Vought)
- XVI (SPAD)