Skippers flying in the tropapause

[mr anderson]

Why is it that we here all these skippers aircraft flying at FL300!!
Has a new fuel management policy been put in place?

[Speedlever]

Mr Anderson, are you up there with the fairys, or just trying to wind people up. Even half a fool with any knowledge knows that drop down oxy masks are required for ops above FL250, that applies to the BRAS, DASH and METRO. If you had an IF rating, that might not come as a surprise. So, now we know you are telling porkies.

And as for fuel savings at that altitude, when you get some spare time have read about propeller efficiency as altitude increases in a turbo prop, then come back and show us what a clever little boy you are with all that newly aquired information.

[MinimaNoContact]

Whats the ceiling of their Conquests?

[I'm gone!]

Gday all,

Speedlever, I'm a bit confused by your post. The EMB120 has drop down oxygen masks.
Also, I recall seeing Max speed cruise data for the Bras being 312ktas @ F300 at ISA.

Climbing to F300 in a Brasilia would be no big deal at this time of year unless you are really heavy. Only thing that stopped me going up there when on the type, was not being RVSM compliant.

Cheers,
I'm gone!

[latetonite]

No, the only reason you would not be there is ATC would stop your climb a bit earlier before you would mess up all the airways and levels at your slow speed. ..

[gaunty]

Dunno about the others but the legendary std Conquest will go direct to FL 330 and better from a GW TO.

No probs 290KTAS and a cuplla litres an hour.

With Dash 10 and black macks it's even better.

It was designed to do just that, and get there in around 70-80 nm, the best fun is asking ATC to move those B200 outa the way so you can come through whilst they are struggling in the low to mid 20s trying to get the handbrake off :)

But I'm not biased. :E

As far as I know I still hold the unofficial PER - Coolangatta nonstop record 6+10 FL330 to FL350 with only average +35kts and enough fuel overhead to go to Sydney with holding.

It's one amazing dude of an aircraft.

[Wizofoz]

...And to answer Mr Andersons question, if it is the most efficient altitude for the Aircraft, why the hell wouldn't you go to FL300?

[mr anderson]

Speedlever!
You do sound like the typical GA know everthing!! Or FIGJAM
Firstly Metro's dont have drop down masks! Hence the ceiling limit of FL250 and I think you will find the same rule applies for the Dash! Can anyone please clarify this!!!!
"propeller efficiency as altitude increases in a turbo prop" That statement is just arse about as props lose there efficiency as altitude is gained! Hence the traditional crz lvls being high teens low twenties! Also you might like to know that props lose there efficiency greatly towards the high two hundreds hence why they are unable to design a prop jet that consistenly crz's above 300kts, the only airplane capable of that would be the c441-10 series or the "MACK" as someone else said!!
You have obviously missed the question being asked!!
It is a common known fact the Skippers operate the higest time c441's in the world, would structial intergrity be an issue especially after all the cycles these aircraft have done? Increased Diff pressures caused by higher crz levels being obtained. Metro's are the most efficient at FL160-180 NOT FL230-250!
SO as you can see there has to be more behind the reason why these aircraft are operating at the Tropapause!
"Speedlever" it seems you are the one with whom has to do some serious reading and as your name suggests stop DRAGGING your feet and get with the programme!!!
Luv MR Anderson:ok:

[Sheep Guts]

Mr. Ando,

Pretty sure the B350 King Air is certified to FL300 aswell. I fly ex US ARMY 90s to FL240, on Oxy :). As these beasts are unpressurised. Why we go so high? Best burn, best endurance and best range can all be achieved up there. Ofcourse wind has alot to do, with the range :).


Sheep:p

[mr anderson]

Thanks SHEEP GUTS for that info!! I'm not sure what the King 350 Does? May be someone out there can enlight'n us.
Airliners.net is a great site for specs check it out!!!:ok:

[Night Watch]

Have had a Metro 3 up to FL300 (ceiling 310) with not too many problems. Was on a freight run (with portable backup Oxy) AD-SY and had a ground speed of 392kts in the cruise, so any penalty or drop off in TAS was more than compensated from the big arse tail wind.

[Icarus2001]

From the good book... The height of the tropopause varies from about 15 kilometres above the Earth at the equator to about 8 kilometres above the poles. It marks the limit of most clouds and storms, and plays an important role in the development of large weather systems. Its height is sensitive to changes in atmospheric temperature caused by pollution and global warming.

8km = 26,248 feet 15km = 49,215 feet

[apache]

SO as you can see there has to be more behind the reason why these aircraft are operating at the Tropapause!

and

The height of the tropopause varies from about 15 kilometres above the Earth at the equator to about 8 kilometres above the poles. It marks the limit of most clouds and storms, and plays an important role in the development of large weather systems. Its height is sensitive to changes in atmospheric
temperature caused by pollution and global warming.

15km = 49,215 feet

a Conquest operating at 49000 ft ???? dream on. 30-33000... no probs... 49000 only Concrde and Bizjets get that high!


Yes a METRO is limited to FL250 in PAX ops... as is ANY a/c without dropdown oxy masks.

[Toodogs]

Mr Anderson and Speedlever,

Beech SKA 200's and B200's are certified to 31,000' and 35,000' respectively (although the cabin will be above 10,000' for the last 1,000 or 2,000'). Both have drop down masks for the pax. The additional requirement for the crew for flight above FL250 is that they have quick donning oxy masks.

As far as structural integrity goes and the idea of higher cabin diffs increasing with altitude: if the pressurization is set to 1,000' above cruise altitude (to acheive a low cabin altitude with a buffer under max cabin diff), then cabin altitude will only increase whilst going higher whilst cabin diff remains just below max diff. So from about 20,000' up you will be just below max diff. I am only refering to the operation of the BE20 here.

If you want to set a high cabin altitude and fly lower, then you can keep the diff down (but you may need to use those quick donning masks to wake yourself up prior to your arrival).

The KingAir has best speed/fuel flow at around FL240-FL270.

[Col. Walter E. Kurtz]

Piaggio Avanti: 395ktas @ FL280 Ceiling: FL410

They obviously worked something out!

[SmallGlassofPort]

Interesting, I thought that the Fl 250 limit on the M23/B190 etc types came about because at the time they were certified it was under SFAR23. The upper limit on the SFAR happens to be Fl250.
Earlier Metro's etc like the 3 got the higher alt as they came under for the want of a better word, a different set of rules.

As to efficiency, it would depend upon company policy. Are they looking for the better flight times or economy. As they seem to do their maintenance in house I would assume that they have told their crews that an extra few mins each flight will not hurt compared to the fuel saving.

My two bobs worth.

Oh, forgot the B190 has drop down masks.

Thought the O Connors C441 would be older than theirs?

[duke of duchess]

If anyone wants to know what the tropopause is sitting at, just look at the sigwx chart. Those little sqaures with numbers in it are the tropopause, it can change a lot. i have seen it as low as 220 and up to 600+!!!

We dont live in a perfect world so that met stuff we had to learn for our ATPL is not realistic.

talking about prop efficiency is one thing but look at the performance for the aircraft, it isn't just prop efficiency that dictates performance.

something that has intregued me for a while is why so many people look at saving fuel as if it is everything, if you save 50L but take 30mins longer is that really a saving to the company. 10mins of MR time may be worth more than 200L depending on your aircraft, it might just be worth sitting down at lower levels to get that increased TAS, but this is very specific to the aircraft.


every presurised aircraft i have flown sits close to max diff at normal cruise levels. Cycles are just counted as every time you have pressurised and depressurised, to what diff never enters into the equation.

I probably have a heap of spelllllling mistakes and punctuation errors as i am half asleep, and just got home from a big night, so for this i apologize :ok:

Have fun, and dont hit anyone in thise great NAS

DoD

[VH-ABC]

Duke...

Every pressurized aircraft you have flown sits close to max diff.?

Must be a hell of a fleet you are enjoying... every pressurized aircraft I have flown has too many leaks to get anywhere near max diff.

[Gudija]

I could not find it in the CAO's, but I thought the drop down mask above FL250 rule was changed a few years ago- I have no doubt some will let me know if I am wrong.

As a matter as interest the PC-12 does not have drop down masks and regularly flies above FL250.

[duke of duchess]

abc

you should buy the engineers some gum, its amazing what those crafty engineers can do with that stuff.

have fun

[Icarus2001]

Gudija

As a matter as interest the PC-12 does not have drop down masks and regularly flies above FL250.

In what type of operations?

CAO 20.4 Section 8 has the requirements for above FL250.

[Gudija]

Icarus2001

The only PC-12's I have noticed around have been with the RFDS, which operate as Airwork.

CAO 20.4 Section 8 only refers to oxygen supply, and only mentions quick donning masks for pilots.

[The Voice]

Gudija

there is at least one that I know of that flies the local constabulary and assorted baddies around up here in this northern bit of Oz...

[4dogs]

Folks,

From memory, you need to read CAO 108.26 for the oxygen equipment requirements.

Stay Alive,

[Cloud Cutter]

mr anderson, perhaps if you are going to argue with someone, you should pick a different point of view. That statement is just arse about as props lose there efficiency as altitude is gained!, I think you'll find that's exactly what he was eluding to.