If one follows the theme that Qantas only grounded the older B737s which were on the market as a publicity stunt, can someone offer a rational explanation why, on my count by comparing timetables, there have been on a per week basis 5 SYDADLSYD, 5 BNEMELBNE, 16 SYDBNESYD, 21 SYDMELSYD, 1 SYDPERSYD flights cancelled because they were selling the older aircraft anyway. On the other hand if an airline was having trouble getting enough manhours out of its engineers for whatever reason, wouldn't it make sense to take the older aircraft which by definition require more servicing out of service first? Just my thoughts.