The Airline Cost Index (CI) Thread

Jack1985

Thought it would be interesting to start a thread on the real economics of the CI entry on aircraft - I'm still a bit confused with how it exactly works, my understanding is the lower the CI, the lower the in-flight speed and thus the lower the fuel-burn - great for airline economics for sure.

The CIs that I know of are;

Aer Lingus (319/320/321) - 5
Ryanair (B738) - 6

Of particular interest to me is in a delay situation do OPs allow the CI to increase? From talking to a few lads at Ryanair it seems 6 is fairly water-tight although there is some wiggle room?

Would appreciate input :-)

smurfjed

The concept of cost index compares costs for fuel versus variable hourly related flight costs, and then provides a speed tot fly fast if the fuel is cheap, or slowly if the fuel costs are high. Considering that Ryanair have crews at different bases on different salaries and the fuel costs vary, its strange that they are using a constant value.
On our B777 fleet we use values between 60 and 600 depending on the route.

Jack1985

smurfjed wrote: »

Considering that Ryanair have crews at different bases on different salaries and the fuel costs vary, its strange that they are using a constant value.

Funnily enough I asked that exact question, and was told its the way management purchase fuel that the cost of it is fairly constant, although I never got an answer about the crew cost variation.

EI costs are fairly consistent so its easy to see how it works for them.

Regards yourself, if you operated a delayed sector would OPs allow an increased CI to make up track?

IngazZagni

Ryanair recently changed flight planning systems. The new system will allow them to introduce variable CI's in the future if they so wish.
As for sticking to the CI. You normally would, whether on time or late. However in some circumstances, especially for instance in London airspace ATC may ask you to maintain a set speed for sequencing which could be higher or lower than the speed for the CI on the flight plan.

For short haul flights, different CI's might only make a few mins difference to the flight time.

bkehoe

The biggest noticeable difference in cost indexes is the descent speed. Climb speed is also affected and finally the smallest difference seems to be cruise speed. The difference between CI6 and CI30 in descent speed is about 30kts. Whereas in cruise its probably only around 0.01 Mach.
CI6 could still result in a 'fast' cruise depending on winds (the FMC magician does his magic) - I've had CI6 giving me just over 0.79 once with a 160kt headwind whereas 0.77/0.78 is more normal.

smurfjed

management purchase fuel that the cost of it is fairly constant

Probably thanks to a small route structure, but we can see differences of around $3:00 per gallon or more, so an average CI value just won't work.

Jack1985

Thanks for the replies lads! Very interesting subject.