ptahturan88
Topic Author
Posts: 17
Joined: Fri Nov 01, 2013 11:51 am

Hi,

I have quarterly CASK and stage length data of Turkish Airlines. I am plotting CASK vs stage length on a scatter graph and I see a positive correlation between tho. How come is it possible? Doesn't CASK decrease with stage length?

ptahturan88
Topic Author
Posts: 17
Joined: Fri Nov 01, 2013 11:51 am

### RE: Cask Vs Stage Length

There is also a positive correlation between ex-fuel CASK (const dollar) and stage length. I am quite confused now

Rdh3e
Posts: 3150
Joined: Wed Mar 30, 2011 2:09 pm

### RE: Cask Vs Stage Length

 Quoting ptahturan88 (Reply 1):There is also a positive correlation between ex-fuel CASK (const dollar) and stage length. I am quite confused now

Doesn't make sense. It should be a curve where it declines then eventually increases due to tankering of fuel. That unless you're looking at it from 30k ft then you could have a break point where the length of the mission goes from requiring 1 aircraft for the rotation to needing 2 aircraft.

LAXintl
Posts: 21694
Joined: Wed May 24, 2000 12:12 pm

### RE: Cask Vs Stage Length

I'm not quite sure what you are trying for, or what raw data you are looking at but here is TK's data directly.

As far as stagelength remember TK is not a stable airline.
It continues to add to its fleet mix with more narrowbodies having arrived then widebodies as its network grows. Narrowbodies by their nature have higher CASK.
From the desert to the sea, to all of Southern California

skyhawkmatthew
Posts: 462
Joined: Wed Oct 26, 2005 4:42 pm

### RE: Cask Vs Stage Length

The CASK will decrease initially as the lower cruise fuel burn offsets the significant takeoff/climb burn, lowering the average burn for the flight. After a distance (I don't know what), however, the average cruise fuel burn will become greater due to carrying the weight of the additional fuel for the longer flight, causing the CASK to rise again with further increases in stage length.
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mandala499
Posts: 6461
Joined: Wed Aug 29, 2001 8:47 pm

### RE: Cask Vs Stage Length

Plus, widebody + narrowbody combo does make a difference too.
Widebodies have higher CASK than narrowbodies, but you use the widebodies for longer sectors, so that already skews it... (higher CASK is for pax... doesn't count cargo, which is an essential piece of widebody operations... now if you have CATK (cost per available ton kilometer), then the trend would be negative correlation as expected again).
Add what the others have said, and it'll be a puddle of jumble...

Pegasus on the other hand, is narrowbody only? So the CASK will continue to lower the longer the stage length, up to a point where it will rise again albeit slowly.
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ptahturan88
Topic Author
Posts: 17
Joined: Fri Nov 01, 2013 11:51 am

### RE: Cask Vs Stage Length

Thank you all for nice info.

Yea, Pegasus is narrowbody only. I think it's about THY's extraordinary growth story as you guys said. It's not a matured company yet.

ptahturan88
Topic Author
Posts: 17
Joined: Fri Nov 01, 2013 11:51 am

### RE: Cask Vs Stage Length

I re-read the posts and I think two posts are contradicting. Narrowbodies have higher CASKs or vice widebodies?
Thanks

mandala499
Posts: 6461
Joined: Wed Aug 29, 2001 8:47 pm

### RE: Cask Vs Stage Length

It depends on the labor supply behaviour of the country/company being looked at.
Here, the crew cost component between narrowbody and widebody aircraft per seat is generally equal.

Then we go to the configuration of the aircraft.
At max capacity CASK will be slightly cheaper on the narrowbody.
On single class non-sardine can, CASK will be cheaper on narrowbody.
On multi-class, it depends if they use the same seat pitches or not, if yes, it's equal if not cheaper on widebodies... if not, then it can make the narrowbodies cheaper.

Maintenance also depends. Basic consumable line maintenance effect on the CASK is cheaper on widebodies... BUT, once you go "full maintenance costing" for, say, 10 yrs (past and budgeted), then it can quickly make the narrowbody much cheaper on a CASK basis.

So, it all depends on what you're looking at, what cost behaviours you want to exploit in the analysis, etc...

My Post #5 is based on LCC configs based from what I know/seen... but where the widebodies are used for the range, not for the cram as many people in on a single trip...
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