Choosing most optimum altitude/FL

[matthewgamm]

For the Citation Excel, is there any technique to calculating the most optimum altitude/FL, given the trip distance? I understand that we've got to factor the winds at altitude; however, I was wondering if there is a certain bracket of cruise altitudes/FLs for a given trip distance.

Also, what is the best way to calculate the total trip fuel required?

Thanks

[hollingworthp]

Generally go for the same level number as you trip distance (eg 267nm = FL300, 800nm = FL430 (or as high as you feel comfortable)

Fuel burn approximate 1800lbs in first hour, then 1600 for 2nd hour and 1200 thereafter.

[oz_faf81]

I don't know if Cessna did it for the Excel, but, for the CJs, they made some booklets called "Flight Planning Guide" that include relevant information for trip planning.

[Sepp]

bral There isn't such an entry in either the OM or AFM. Climb, cruise and descent tables, yes (OM). Mission planner, no.

matthewgamm Cessna's "Mission Planning Guide" (read: sales literature) for the XLS includes the following snippet:

Distance (nm) .............. Typical Cruise Altitude (ft)
0 - 99 .......................... 6,000 - 18,000
100 - 199 .................... 17,000 - 31,000
200 - 299 .................... 29,000 - 39,000
300 - 499 .................... 35,000 - 41,000
500 - 999 .................... 39,000 - 43,000
1000 + ........................ 41,000 - 45,000

Along with more comprehensive figs and a pretty (useless) graph. Fwiw, Flight Safety includes the following similar table (for the XL) in their recurrent notes:

Distance (nm) .............. Typical Cruise Altitude (ft)
0 - 100 ....................... 10,000 - 18,000
101 - 200 .................... 17,000 - 33,000
201 - 300 .................... 31,000 - 39,000
301 - 500 .................... 37,000 - 41,000
501 - 900 .................... 39,000 - 43,000
901+ .......................... 39,000 - 45,000

Cessna do publish Flight Planning Guides for the XL and XLS. You need to order pub. code 56XPP (ser -5001 to -550) or 56XPPA (-5501 and on) or 56XPPB (-6001 and on) - each are quoted at USD 43.00 in the publications catalogue. HOWEVER, if these are just a reprint of OM sec. IV (as is the case with the FPG for the C550), there won't be a mission planner in there, either.

edit/ For working out your fuel burn, don't rely on shonky mission planning guides - work out your route to find the total trip distance then use the proper climb/cruise/descent tables. Even better, get your Ops to use some form of computer-based planning tool. Just about all of the operators (all EU AOC) that I have driven for have used PPS - and I find it works just fine. Others may disagree. /edit

Cheers.

[dirk85]

https://support.cessna.com/docs/custsupt/contacts/docs/servicesoverview/content/XLS/Fpg-CXLS.pdf

[Sepp]

Yep, that was the XLS FPG I was talking about.

Don't forget to add your required reserve to the fuel burns quoted!

[Sepp]

bral Yes, I agree that "proper" flight planning (climb, cruise, descent, hold) data exists, but in the OM rather than the AFM.

I was talking about the rather more blunt-pencil trip fuel/time tables. Now, when someone is sure of their facts, it causes me to go check mine and - I'm happy to stand corrected - having done so, the OM does indeed include trip fuel/time tables. I maintain, though, that the AFM (which is sitting on the table in front of me) only includes t/o and ldg data plus the enroute climb grads.

Hopefully, though, the distinction is not really an issue over which to fall out.

[His dudeness]

I think he already did:

bral Yes, I agree that "proper" flight planning (climb, cruise, descent, hold) data exists, but in the OM rather than the AFM.

What about the Electronic Operationg Manual, that is not a bad thing to use either. Did a 2350nm trip last week, the EOM would suggest a fuel burn of 9200lbs with a 30 kts HW and 43000 ft cruise.

We used 9200 lbs and were 9 minutes faster than predicted. Not bad IMO.

That was in a C680, but I trust there is the same thing available for the XL/XLS/XLS+

[Sepp]

"Yes, bral, I do." Happy?