When both were full this enabled a ferry range of over 1,200 miles ( 1,900 km ) .
Both made the aircraft unstable in flight and only straight flight and gentle manoeuvres at low altitudes were recommended by the pilot 's manual .
When both were full this enabled a ferry range of over 1,200 miles ( 1,900 km ) , although they made the aircraft unstable in flight and only straight flight and gentle manoeuvres at low altitudes were recommended by the pilot 's manual .