AERO-ALPHABET - Os

OSA (Officine Sommese Aeronautica)
O.S.A. 135
O.S.A. 200

OSKBES (Moscow Aviation institute)
MAI-223
MAI-208
MAI-890
MAI-920

Oškinis {ErZ}

Osprey (George Pereira / Osprey Aircraft) {ErZ}
Osprey GP-4
Osprey GP-5

Oster {ErZ}

Ostergaard (Ostergaard Airplane Works - Chicago . IL . USA)
Ostergaard 1919 Aeroplane