You may have more options and better pricing going on a TPAC routing instead of TATL; flying UA or NW to BKK, then hopping onto Thai from BKK to BOM or DEL. Or fly UA or NW to SIN, and take a lovely SQ flight to Chennai or wherever else they fly in the sub-continent. SQ is a *A partner as well.

There may still be a double miles promo going for flying UA TPAC as well. Good luck and safe travels.