Optimum Altitude for a PC12 Pilatus

[B737 lover]

Hi,
Can you please help me out on this, it seems like I can't find an optimum altitude for a PC12 anywhere...
Thanks in advance.

[Another_CFI]

How far are you flying? If you are flying the shortest scheduled route in the world from Westray to Papa Westray, a distance of around 2nm, then 1,000ft would possibly be the optimum altitude.

As a rule of thumb when I used to fly a Turbo-Commander we assumed that the optimum level was numerically the same as the flight distance. Therefore for a flight of 140nm the optimum level was FL140.

[barit1]

As with any airplane, optimum altitude is a function of GW.

[777300ER]

There is a difference between "Optimum" altitude and "Recommended" altitude. As previous posters mentioned, on short flights climbing to optimum could actually result in wasted fuel.

[B737 lover]

Most of our routes are around 275nms and the Service Ceiling is 30,000' and we are always climbing that high for that distance, but I heard it from a couple of ATRs and Dash 8's Captains saying that even though their Service Ceiling is 25,000' but their optimum altitude is about 18,000'. So I thought that maybe we are misusing the PC12 for climbing very high.
Thanks for the input so far..

[nitpicker330]

Ok so here's a tip, 2 actually!!

1/ look at your PC 12 perf charts
2/ next time try FL 180 and see what the time and fuel burn was for the sector, then compare to FL 250.

:ok:

[Wizofoz]

Exactly!

Surely you have charts that give you TAS and F/B at various altitudes and conditions?

But, maximum altitude is rarely optimum altitude if it's performance limited.

[B737 lover]

Thanks! Will try to do so but it seems like nobody has never tried to do this with this particular plane. Then I will be happy to be the first one to probably find out the solution of this issue.

[captjns]

Can't leave wind or ISA deviation out of the equation either.

[Wizofoz]

Will try to do so but it seems like nobody has never tried to do this with this particular plane.

I find that VERY hard to believe.

[Agaricus bisporus]

it seems like I can't find an optimum altitude for a PC12 anywhere...

It hardly seems credible that a pilot would make such a statement - and anyone in an organisation operating a PC12 or any other aeroplane would know where/how to find that info.

Edit; As the top item in my Google search for "PC12 performance" included cruise and long range cruise tables (admittedly for sim players, but the tables looked genuine) anyone can find this info at the touch of a button.

What's going on?

[El Comat]

The rough rule of thumb that I used on the PC-12 was was (distance/10) + 2000'. So a trip of 190nm I would go to FL210. This, of course, does not take winds/weight into account. The PC-12 is an excellent climber with a very good wing, so you may as well go high and get your fuel burn down, plus have a few more minutes of glide time in your back pocket!

It's been 5 years since I've flown the PC-12, I miss it!

[B737 lover]

Thanks El Comat, that's exactly the rule we are using in our Company, in fact + 2000 varies according to the Elevation of point of Departure or Destination or both. After going through Performance Charts and your comments, I have decided to stick on this particular rule of Climbing high and play around with Tail winds as much as possible.

[ant1]

Given the PC12 speed, winds aloft are a major factor when deciding at what FL to cruise.

[B737 lover]

I totally agree with you:ok:.
Thanks!

[rigpiggy]

our sectors average around that, flying the 1900 but a good rule of thumb was if less than 1.5 block a 40kt difference in wind we would stay lower ie 12-14k. But then again I don't worry about gliding range

[Natstrackalpha]

I got some mates who fly the PC 12 they reckon they cruise at around 20/22,000ft - thats for about 800 NM.

[inbalance]

First of all you have to tell us what kind of PC12 you are flying.
The old PC12 and the NG have a different max. ITT, so different Power and Speed at different altitudes.

The PT6 in the NG has a max ITT of 820°, but Pilatus recommends 780° max.
The older B engines have 760° max.

Useing 780 in icing condition, a heavy weight and flying minimum icing speed takes the aircraft very long to climb to cruising altitude.

The older PC12 have different max. Take Off weight.
There are 4700 kg for the -47
there are 4500 kg for the -45
and there are still a vew very old aircraft flying with 4200 kg max weight.

So tell us the Type and I will be able to help.

[B737 lover]

We have old and middle class PC12s 45 series, and we are always restricting our climbing ITT to 720 for longer engine life. I don't have any experience on NG and our Max takeoff weight is 4500 kgs.

[B737 lover]

Google? Ha ha. Well I'm a humble Man who always want to learn and never argues...
I had to ask this Question here because I tried to go through all the Performance Charts without any direct success, TAS for every altitude decreases with altitude but fuel flow also decreases during Climb for PC12. Long range Charts didn't work as well because for Optimum altitude you need good Speed not only low fuel flow.
Well I'm a little bit new on type about 400 hours but I'm not an inexperienced Pilot. I managed to get the Optimum Cruise Altitudes for B737s and Dash 8 series through compensations like this and experience on types.
Will appreciate your comment more than criticism:ok:

[inbalance]

This may help you to find the optimum altitude:

PILATUS PC12 -45
Maximum Cruise Power
Max Take Off Weight
No Wind
No Alternate

100 NM
Alt time fuel
22000 00:33 255
20000 00:33 258
18000 00:33 259
16000 00:33 263
14000 00:32 267
12000 00:32 273
10000 00:32 282
8000 00:32 286
6000 00:32 295

200 NM
Alt time fuel
28000 01:00 403
26000 00:59 409
24000 00:58 416
22000 00:57 424
20000 00:57 436
18000 00:57 447
16000 00:56 458
14000 00:56 472
12000 00:56 484

300NM
Alt time fuel
28000 01:25 547
26000 01:23 561
24000 01:22 577
22000 01:21 593
20000 01:20 614
18000 01:20 634
16000 01:20 654
14000 01:20 676
12000 01:20 696

400NM
Alt time fuel
28000 01:50 692
26000 01:48 713
24000 01:46 737
22000 01:45 763
20000 01:44 792
18000 01:44 821
16000 01:44 850
14000 01:44 881
12000 01:45 908

500NM
Alt time fuel
28000 02:15 836
26000 02:12 866
24000 02:10 897
22000 02:09 932
20000 02:08 970
18000 02:08 1008
16000 02:07 1046
14000 02:08 1085
12000 02:09 1120

600 NM
Alt time fuel
28000 02:40 981
26000 02:37 1018
24000 02:34 1058
22000 02:33 1101
20000 02:32 1148
18000 02:32 1196
16000 02:31 1242
14000 02:32 1290
12000 02:33 1332

700 NM
Alt time fuel
28000 03:05 1125
26000 03:01 1170
24000 02:59 1218
22000 02:57 1270
20000 02:55 1325
18000 02:55 1383
16000 02:55 1437
14000 02:56 1494
12000 02:57 1544

800 NM
Alt time fuel
28000 03:29 1270
26000 03:26 1322
24000 03:23 1379
22000 03:21 1439
20000 03:19 1503
18000 03:19 1570
16000 03:18 1633
14000 03:20 1966
12000 03:21 1756

900 NM
Alt time fuel
28000 03:54 1415
26000 03:50 1447
24000 03:47 1539
22000 03:45 1609
20000 03:43 1681
18000 03:43 1757
16000 03:42 1829
14000 03:43 1903
12000 03:45 1968

1000 NM
Alt time fuel
28000 04:19 1559
26000 04:14 1626
24000 04:11 1699
22000 04:09 1778
20000 04:07 1859
18000 04:07 1944
16000 04:06 2025
14000 04:07 2108
12000 04:09 2179

1100 NM
Alt time fuel
28000 04:44 1704
26000 04:39 1779
24000 04:35 1860
22000 04:33 1947
20000 04:30 2037
18000 04:30 2132
16000 04:29 2221
14000 04:31 2312
12000 04:34 2391

1200 NM
Alt time fuel
28000 05:09 1848
26000 05:03 1931
24000 04:59 2020
22000 04:57 2116
20000 04:54 2215
18000 04:54 2319
16000 04:53 2417
14000 04:55 2517
12000 04:58 2603

1300 NM
Alt time fuel
28000 05:33 1993
26000 05:28 2083
24000 05:23 2180
22000 05:21 2285
20000 05:18 2393
18000 05:18 2506
16000 05:17 2612

1400 NM
Alt time fuel
28000 05:58 2137
26000 05:52 2235
24000 05:48 2341
22000 05:45 2455
20000 05:42 2571
18000 05:42 2693

1500 NM
Alt time fuel
28000 06:23 2282
26000 06:17 2387
24000 06:12 2501
22000 06:09 2624

There is no performance data for 720° available.
Our -45 aircraft is not RVSM aproved, so my performance calculator doesnt show any data above FL280.

[flyboyike]

This sounds like a fairly strange question coming from someone who supposedly flies the actual airplane for an actual company. Then his handle is 737lover. Anyone else suspect we're dealing with a simmer?

[inbalance]

Anyone else suspect we're dealing with a simmer?

No, because the 720° ITT Pilatus recommends for the B engine you don´t find in the POH and also not on the internet.

This sounds like a fairly strange question coming from someone who supposedly flies the actual airplane for an actual company.

The data is in the POH, but one has to calculate every distance and altitude.
The data above takes a week to be calculated by hand.

[B737 lover]

You are a Star that I don't know but maybe one day I will. This information is exactly what I was looking for and now I have it and as far as I'm concerned! This chapter is closed. Will ask you more Qs if necessary through PM. You have just added 100 years more for me to Fly probably by help of God. Let me know when you come to Tanzania one day.
Cheers!

[rigpiggy]

now adjust these numbers for a 30kt at 14k or 85kt at fl220

300NM
Alt time fuel
28000 01:25 547
26000 01:23 561
24000 01:22 577
22000 01:21 593
20000 01:20 614
18000 01:20 634
16000 01:20 654
14000 01:20 676
12000 01:20 696

[inbalance]

now adjust these numbers for a 30kt at 14k or 85kt at fl220


Head or Tailwind?

[rigpiggy]

CYXE0300 270/049 +10 -046270/048 +10 -045269/047 +11 -043268/045 +11 -042 CYXE0250 268/050 +09 -046268/048 +10 -044268/047 +10 -043268/045 +10 -042 CYXE0200 263/045 +08 -040264/044 +09 -039266/043 +10 -040267/042 +11 -039 CYXE0150 264/040 +08 -037265/039 +09 -036266/039 +10 -036268/038 +11 -035 CYXE0100 261/038 +08 -034263/037 +09 -034265/037 +10 -034267/036 +11 -033 CYXE0050 256/033 +08 -029259/033 +09 -029261/033 +09 -029263/032 +10 -029 Avg. Trip Winds=> - 38 Headwind - 37 Headwind - 37 Headwind - 36 Headwind FLT TIME==> 1:57(+01) 246TAS 1:56(+00) 250TAS 1:55(-01) 251TAS 1:54(-02) 253TAS Fuel Burn==> 840 Lbs 852 Lbs 873 Lbs 891 Lbs

[rigpiggy]

last from fltplan.com, ywg-yxe. as you can see you would gain no real benefit from going higher except better gliding range. within 50# burn but faster block speed, engines running cooler, and less time in the climb

[B737 lover]

Thanks a lot rigpiggy. All copied:ok: