Sweet. Cheers for sharing. I'll go with 12.Ashley Frew.

Great post ive been wondering the same as all i fly in the NGX is the east coast ML-SY-BN as yourself. Have been using CI40 but will try 12 and see what the difference is.

Hello, sorry for late reply.On a couple of Qantas flight plans I have, it has been 10.Cheers,Rudy

Rudy, you're a legend! I knew the -400's were 10 with varying secondary CI's but had no inkling on the -800's. Thanks so much for sharing!

Since the cost index affects climb, cruise and descent performance/economy. Profile speeds may still need to be manually adjusted on descents to meet common ATC expected profiles. It isn't a case of just plug in a 'set and forget' CI figure, this especially for some of the low CI figures quoted above, for sure airlines do not fly these figures on descent.

Having flown up front in -400's a few times, I know they play around with speeds a bit, particularly for descent and less regularly for climb. During cruise though, the flight plan cost index is used, and if required to get to point in minimum time, the flight plan secondary CI would be used. On one flight I noticed the skipper throw 250/.75 at the CDU and we maintained 250 KIAS from cruise to transition level with the skipper regulating speed by speedbrake usage. On the same flight - I don't recall any amendments to climb speeds.

Great post ive been wondering the same as all i fly in the NGX is the east coast ML-SY-BN as yourself. Have been using CI40 but will try 12 and see what the difference is.

Pleasure. I humbly suggest the use of a CI of 10. Refer to VHOJT's post and my post on the -400. I am certain about the -400's CI, and VHOJT is certain on the -800's CI.Good night gents,Ashley Frew.