I reckon the crew on that flight do not want
to compromise on fuel.For 777 going from SIN to Europe must have had almost max=min fuel.
Thus given cost index between 20~50,M.80 sounds ECON CRZ from FMC,My guess is that they want to mantain this speed in order to
conserve fuel.If they're poker player(like me),they could have accepted M.84 atFL280,
then ask for climb once under Chennai radar
(3.5 hours later)or Muscat radar(6.5hours later).
Management is mean,thus fuel available is lean.
