Individual oxygens masks are not mandatory ( or were not at the time the Tu154 was certified ) The SE210 ( Caravelle to the youngsters) also did not have individual O2 masks. The procedure in case decompression was to dive like a madman to 14.000 Ft. A couple of bottles with ONE mask each were avail to the FAs to give to the weak pax.... .I guess the same goes for the Tu 154 and probably a lot of other oldies...