Simviation Forum - Gaining altitude for a mountain flight

Feb 5^th, 2010 at 1:04pm

Titan_Bow Offline
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Caveat... I am not a real-world pilot, and my knowledge is fairly limited.
I live outside of Boulder, CO, and in FSX, I like to fly my Carenado Cherokee 180 up to spots in the high country. I usually fly out of Jeffco (KBJC). The airport is at 5673ft. In order to get to Granby, I have to gain enough altitude to get over the mountains. I fly Rollins Pass, wich is 11680ft. then on to Granby.
My question is, what would be the most realistic way to gain the altitude before heading up and over the mountains?

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Reply #1 - Feb 5^th, 2010 at 1:08pm

Titan_Bow Offline
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I should rephrase that....What would be the proper, or correct way, to gain the altitude?

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Reply #2 - Feb 5^th, 2010 at 1:47pm

Brett_Henderson Offline
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I wouldn't take a 180HP, normally-aspirated airplane 12,000' up into the mountains under even ideal circumstances.

Throw in any density altitude.. and any type of weather (even just gusty winds), and you're on the ragged edge. Plus.. the last part of the slow climb getting to nearly 13,000msl, and the time you'd spend at that altitude; requires that you be on oxygen.

This type of flight calls for at least a twin, or turbo-normalized single. . ..

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Reply #3 - Feb 5^th, 2010 at 2:27pm

Titan_Bow Offline
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I realized that the plane was doing all it could to get over the pass Wink

About the oxygen, is it an FAA requisite? I routinely hike, camp, hunt, and fish at elevations at or above treeline (11-13,000ft.) without it.
Are there regional adjustments, etc. that people make to small aircraft operating in the high country? I've seen cessnas and other small single engine planes at Granby, Vail, etc. They'd have to be operating at the altitudes or higher?

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Reply #4 - Feb 5^th, 2010 at 2:49pm

beaky Offline
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Titan_Bow wrote on Feb 5^th, 2010 at 2:27pm:

I realized that the plane was doing all it could to get over the pass Wink

About the oxygen, is it an FAA requisite? I routinely hike, camp, hunt, and fish at elevations at or above treeline (11-13,000ft.) without it.

Flying above 12,000 and driving up into the mountains to hunt, fish, etc. are two very different things... the body doesn't have much time to adapt during a normal climb to that altitude, esp. from a mountain airport tat's already up there a bit.
The FAA's requirements are certainly conservative, but they seem to work. I once heard a recording of comms from a 747 crew that had become seriously hypoxic, and they didn't sound normal until ATC got them below 12,000.

The requirements is (for all flights, VFR, |IFR, commercial, non-commercial) that all pilots flying their aircraft above 12,500 feet for 30 minutes or longer or at 14,000 feet or above during the entire flight must use supplemental oxygen.

Quote:

Are there regional adjustments, etc. that people make to small aircraft operating in the high country? I've seen cessnas and other small single engine planes at Granby, Vail, etc. They'd have to be operating at the altitudes or higher?

A bigger issue than oxygen for these pilots is adequate performance for operating in high density altitude conditions. On a hot day, taking off from a 5000-foot elevation runway can be like taking off at the very limit of your engine's ability to produce power. And many mountain airports have short runways surrounded by high obstacles.
So mods to improve lift at lower airspeeds, bigger or turbocharged engines, climb props... stuff like that is fairly common for planes based in such areas.
They also load with such performance issues in mind: taking off with only enough fuel for the trip plus a reserve, minimizing baggage, etc.

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Reply #5 - Feb 5^th, 2010 at 6:58pm

Brett_Henderson Offline
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Titan_Bow wrote on Feb 5^th, 2010 at 2:27pm:

I realized that the plane was doing all it could to get over the pass Wink

About the oxygen, is it an FAA requisite? I routinely hike, camp, hunt, and fish at elevations at or above treeline (11-13,000ft.) without it.
Are there regional adjustments, etc. that people make to small aircraft operating in the high country? I've seen cessnas and other small single engine planes at Granby, Vail, etc. They'd have to be operating at the altitudes or higher?

There are quite a few turbo-normalized singles out there.. Cessna, Piper ,etal.. Turbo-normalizing constitutes using a turbo-charger to keep manifold-pressure at something near sea-level, even thoug you're well above sea-level. It's not turbo-charging for horse-power (ala a Mooney Bravo, where manifold pressure can be as high as 40 inches), so it doesn't require a highly-modified engine. It usually uses some sort of waste gate that keeps manifold pressure under 30 inches. This "fools" the engine into thinking it's at a lower altitude.

Cessna 182s are a common airplane for this.. and I believe a Turbo Arrow is only turbo-normalized. I can't think of an airplane using a fixed-prop that would also employ turb-normalizing. I'm sure though it's been done (especially by pilots flying mountains). Even though you can realistically modify your Carenado Warrior for turbo-normalization, we get back to the question of realism. Without a constant-speed prop, you'd likely end up spinning the bearings out of that $18,000 engine employing sea-level manifold pressure at high altitude.

For me ? In the real world ? I won't fly where oxygen is required, unless I'm in a pressurized airplane. Tubes in my nose, or a pesky mask will be for when pressurization fails Cheesy

.. Since simming allows me to be adventurous.. I'd take a twin, or my modified Carenado M20 up over the Rockies Cool

Since you've already gotten a taste of Carenado quality.. most of the default models just won't do (the default Mooney is a good airplane for this duty).. The Carenado Turbo Arrow would be fun, too...

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Reply #6 - Feb 5^th, 2010 at 7:16pm

peter-reebok Offline
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I went on a motorcycle trek over the Himalayas last year.

Up to 18,600 feet.
Oxygen was at a premium, and it forces you to make some decisions at a time when your judgement is impaired.

We spent 2 weeks above 13,000 ft in total.
people suffered to differing degrees.

Dont underestimate the effect of low oxygen, and dont let someone else talk you into accepting their judgement that it will be 'ok'.
Having said that - the experience was amazing.

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Reply #7 - Feb 5^th, 2010 at 7:20pm

Brett_Henderson Offline
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How did the altitude effect the motorcyle (just curious) ?

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Reply #8 - Feb 5^th, 2010 at 8:24pm

aeroart Offline
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If you're flying in FltSim, be a simulator test pilot. Just see how high your airplane will go. I tried that with the default P-51D in Combat Flight Simulator 1, and it got to about 42,000 ft before it ran out of steam. I just Googled "P-51D service ceiling," and it said 41,900 ft.

Service ceiling was a military spec. It's the altitude that the rate of climb is down to 100 ft/min. Absolute ceiling (0 climb) would be somewhat higher.

When you're climbing, do as much of it as possible straight ahead. Your rate of climb is better that way than while turning because you have to lower the nose in a turn to maintain climb airspeed.

Art

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Reply #9 - Feb 5^th, 2010 at 8:47pm

beaky Offline
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Here's that audio clip, BTW... apparently the crew (Kalitta 747) somehow disabled their O2 system in cruise, and got all goofy before they realized it.

It's eerie to listen to the captain- he knows he is losing the airplane, knows what he needs to say, but can barely get the words out... sounds just like he's really, really drunk and sleepy. And of course he is feeling quite euphoric, and probably not actually doing what he thinks he's doing with the airplane.

Eventually they get down below 12,000 or so and he's pretty much back to normal (as is the FO). You'll never catch me up there without oxygen, and if I ever do go up with onboard O2, I'll be very, very careful with it.

http://www.natca.org/assets/multimedia/cfs09/5th-archieaward-ngl-zob.wmv

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Reply #10 - Feb 6^th, 2010 at 10:41pm