Interesting... while the flight shows wide open, the fares filed (for sale outside of India) only have Y and B available.
Code:
AD03NOVMAAHKG/ACX -MD-
** AMADEUS AVAILABILITY - AD ** HKG HONG KONG.HK 10 TH 03NOV 0000
1 CX 632 J9 C9 D9 I9 Y9 B9 H9 /MAA I HKG 1 0315 1100 E0/330 5:15
K9 M9 L9 V9 S9 N9 Q9 O9
>fqdmaahkg/acx/d03nov
FQDMAAHKG/ACX/D03NOV
03NOV11**03NOV11/CX MAAHKG/NSP;EH/TPM 2307/MPM 2768
LN FARE BASIS OW INR RT B PEN DATES/DAYS AP MIN MAX R
01 FOW1 90975 F - - - - - 12M+M
02 JOW1 81120 J - - - - - 12M+M
03 FRT1 151625 F - - - - - 12M+M
04 JRT1 135200 J - - - - - 12M+M
05 YOW1 52545 Y - - - - - 12M+M
06 YRT1 87560 Y - - - - - 12M+M
07 YSC25 39410 Y - - - - - - M
08 YSD25 39410 Y - - - - - 12M+M
09 YSD25 65670 Y - - - - - 12M+M
10 BEE3M1 56715 B + - - - - 3M+M
Methinks you should contact a TA in MAA or India to check on the local fares. Checking an outside online travel portal may not result in the best fare suggestions.