Cost Indexing... Aircraft Cost / Fuel Cost...
Anyways, happens often when SQ
used to operate the 310s between CGK
... over the delivery in SIN
, a little exchange of words about Mach Numbers... when the 310 filed for the same FL
only 5 - 10 mins ahead of a 777 going the same way, someone has to be given a different altitude, or the slower one to go behind the faster one.
I'm sure Phil and his employer doesn't wanna be held up on SIN
-Europe on the same flight level and behind an A310 to India/ME... Either the 310 gets a different altitude to let faster traffic through at their levels, or the faster one gets a shortcut around a dogleg (gotta love hearing SQ744/777s requesting direct PARDI out of CGK
to skip MES
and BTH or fellow SIN
bound traffic on the same flight level but at a much slower speed)... or someone gets a deviation to let traffic through or overtake slower traffic...
Slow everyone down and eventually traffic could clog up to the next FIR! And yes, theoretically it can happen!... (eg: the first time the Taliban affected my life when they took over Afghanistan... our poor 767 can't file the higher altitude it wanted going BKK
due to the Afghan airspace being closed and 744s filling up the air routes all the way to the Persian Gulf... imagine if we were to go in front of 30 744s on the same flight level... by the time we reached the Arabian Peninsula, the backlog could be all the way to the Indian FIRs! J/K
(Joke the crew made during cruise)