Ravinder gave Air India the lead in the 22nd minute from the penalty spot after Opara was brought down in the box by defender K. Poukillung.
Five minutes later, Air India doubled the lead after Opara tapped in from Habeel's precise cross.
The erratic Poukillung cost his team another goal after he fouled Mendon in the box and Ravinder completed his brace in the 34th minute with a penalty kick.
In fact, Army XI got their first clear chance three minutes after the breather, but S.K. Tuboi, set up by Raleng, shot wide.
Three minutes later, Army XI frittered away another opportunity when Mahesh Rai shot out despite having an open net.
Air India coach Bimal Ghosh was happy with his team's performance and said the result would put some pressure on two-time I-League champions Dempo Sports Club, who are the third team in the group.
'The three goals we scored today will add to our advantage and put some pressure on Dempo. We can qualify for the semi-final even if we draw the next match,' he said.