(Clyde & Ralph O'Bannon, 510 S Kenilworth Ave, Oak Park, IL)
(Robert O'Hara, San Fernando, CA)
edit(Thomas H O'Malley, N E Warren, OH)
edit(O'Neil Airplane Co, Carlyle, IL)
(Terrence O'Neill, Ft Wayne, IN)
edit(Oakland Airmotive Co, Oakland, CA)
(Ostdeutsche Albatroswerke G.m.b.H.)
(Oaxaca Aerospace / Raul and Rodrigo Fernandez)
edit(V L Ochoa, Arlington, NJ)
(Josef Oberlerchner Holzindustrie / Ing. Fritz Birkner)
edit edit(Antoine Odier - see: ESTA)
edit( Österreichische Flugzeugfabrik AG)
(Michael Offierski)
edit(Dursley, Gloucestershire, United Kingdom)
edit(Österreichische Flugzeugwerke GmbH / Ing. Otto Kauba)
edit(Max Oertz)
(Saburo Ogawa)
edit((Henry H & Perry V) Ogden Aeronautical Corp, 1119 S Market St, Inglewood, CA)
(Õhu- ja Gaasikaitse Liit - Air & Aircraft Workshop) Tallinn, Estonia
(Tsunetaro Oguri)
edit(Ohio Aero Mfg Co (Pres: Judd Yoho), Youngstown, OH)
edit(Ohio Aviation Research & Development Foundation)
edit(Richard Ohm and Gordon Stoppelbein, McLean, VA)
edit(Owj Industrial Complex, Iran)
edit(Okamura Seiskujo Kabushiki Kaisha - Okamura Manufacturing Company Limited)
edit(Okay Airplane Co, Okay, OK (Pres: C N Martin))
edit edit(Rémy Olagnier)
edit(Barney Oldfield Aircraft Co, Cleveland, OH)
edit edit(Clifton P "Ole" Oleson, IA)
edit((Tage C and Uffe K) Oleson Aircraft Inc, Wayne, MI)
edit(Charles Ollivier)
edit(Olsen Standard Aeroplane Co (OSACO), Tomahawk, WI)
edit(Gordon L Olsen, Rosamond, CA)
edit(Olsen-Jonasson)
edit((Albert & Lars) Olsen-(Ward) Thomas, Middletown, NJ)
edit(Olson Aircraft Corp, Wilmington, NC)
edit(Port Angeles, WA)
edit(OMA SUD SpA, Capua (CE), Italy)
edit(Old Man's Aircraft Company - OMAC Inc, Reno, NV)
edit(Officina de Manutenção e Recuperção de Avioes, Ltda.)
edit(Omega Aircraft Corp)
(Ostmecklenburgische Flugzeugbau)
edit(Omni-Weld Company)
edit edit(Radu Onciul)
edit(Celje, Slovenia)
edit(Albuquerque, NM)
edit(Office National d'Études et de Recherches Aérospatiales)
edit((William) Ong Aircraft Corp, 838 Richards Rd, Kansas City, MO)
(Roman Orliński)
edit(St.Hubert Aircraft Engineering Works - Mr. Pierre Baudoux and Mr. Jose Orta)
edit(Otdel Opytnogo Samolyetostroeniya - section for experimental aircraft construction)
edit(Fritz von Opel)
(Palo Alto, California, United States)
edit()
edit(Optery X Engineering Ltd.)
edit(Option Air Reno (Pres: Carl O. Barlow), Reno, NV)
edit(Béla Oravecz)
edit edit(Orel Aircraft)
edit(Ordnance Engineering Co, Long Island, NY)
(Orlando Helicopter Airways, Inc, DeLand, FL)
edit(Orlican Národní Podnik)
(Orlogsværftet / Flyvetroppernes Værksteder - Naval dockyard / Flying Corps’ workshops)
(Harry A Orme, Washington, DC)
edit(Daniel J Ort, Dearborn/Detroit, MI)
edit(Selles-Saint-Denis, France)
edit(José Orta / Ecole d'Aviation de St. Hubert
edit(Leo Ortego, Alexandria, LA)
edit edit(Officine Sommese Aeronautica)
edit(Moscow Aviation institute)
edit(George Pereira / Osprey Aircraft)
edit(Ostergaard Airplane Works, Chicago, IL)
edit(Delmar Ott, Napa, CA)
edit(Gustav Otto Flugmaschinenfabrik (from 1911) / Aeroplanbau Otto-Alberti (1910))
(Otto Aviation Group LLC)
edit(Albert Oulette, Sanford, ME)
edit((Francis) Overcashier Airplane Co, 3515 Woodward, Detroit, MI)
edit(Overland Airways Inc, Omaha, NE)
edit(Oscar Wittenstein Aerodrom Milbertshofen - Dr. Otto Wittenstein)
edit(John Sidney Owens, Glenside, PA)
edit edit(George Owl, Gardena, CA)
(Yukiteru Ozaki)
edit(Le Bar-sur-Loup, France)