Yangon Airways, Myanmar, 1996-2019 renamed to Air Thanlwin. -  #1/#2(diff. color shade),  #5, #6:

     -   #8:

YEMENIA, Sanaa, Yemen, founded 1961.   #1/#3/#6(all same design, but diff paper and maker):

YETI Airlines, Nepal.  -   #2 front and rear shown:

-   #5 front and rear shown,             #6 only one line, Logo w/o waves, color dark green :

Yunnan Airlines, Kunming - Yunnan Province, China, 1992-2003 merged into China Eastern (q.v.).
   -               #3,                                                         #1: