täiendav hapnik reisijate jaoks, kes ei toibu küllaldaselt peale kõrguse muutumisest tulenevat õhurõhu muutumist salongis, mille ajal neile anti lisahapnikku, the additional oxygen provided for the use of passengers, who do not satisfactorily recover following subjection to excessive cabin altitudes, during which they had been provided with supplemental oxy