1.  Regulations require the remaining pilot to wear an oxygen mask when alone at the controls in case there is a sudden loss of air pressure, Witkowski said.

2.  In both cases, the airline locked out remaining pilots.

3.  Remaining pilots, not with the Pasity union, supported the strike with a sick-out.

4.  The remaining two pilots, who were also freed, decided to stay and work in Congo, Russian officials said.