Water is one of the most powerful energy sources on earth. Because they lie in a fairly temperate zone, the Rocky Mountains produce a lot of gravity driven water, from snow melt, that cuts deep river valleys right up to almost pool table flat high passes.

This abundant vertical space, in the valley, makes approaching these high passes with limited excess engine thrust for climb somewhat safe. We lean our small engines (Stromberg carburetors were not the best) to get them to run properly at high density altitude. Limit the air (DA) and you have to limit the fuel, which reduces power. We need later in the day heat to produce needed wind energy, so we will often be operating at ceiling or less. This means that we will have a Vy pitch attitude in level cruise, other things being equal (which they are not.)

Prevailing westerly winds make west to east crossings a snap. We just have to closely ride the updraft producing ridge that is on the downwind side of the valley that goes up to our pass. Long engine climbs to get up going east waist this free wind energy. We just ride the ridge up and then stay up to benefit from the stronger tailwinds. The tailwinds are less down low and the tremendous reduction in ground speed climbing in open air will hurt more than will just following the terrain up. Of course we fly slow in updrafts and fast in downdrafts enroute to the valley ridge system.

Going east to west is the problem. If the wind is straight down a straight valley, we may be out of luck. We have to find a pass that has an approaching valley that is at some angle to the wind. We must use the ridge downwind of the valley that is going up to the pass. The lighter the wind, the closer we must fly to the ridge to get good updrafts. We also want some horizontal space between us and the ridge across the valley. The crux, as mountaineers call it, comes when we have ridden the downwind ridge to near the pass, the valley is closing in, less vertical space and less horizontal space is available, and we are now getting downdraft air from the high peak upwind of the pass. If our ridge will not get us safely to the pass or at least into the updraft air on the high peak downwind of the pass, we must use the energy management turn allowing the nose to fall naturally into the valley. There is no pull up here as the nose is already up and we are already slow. We just turn at whatever bank will miss the upwind ridge and let the nose fall through (don't pull back on the stick.) We are done. We either try another pass or just follow the valley until we can maneuver to lower ground going west.

If we make the pass, we need to stay low and get back down to lesser headwinds as soon as possible. Altitude is great, unless we can't make the next watering hole at this very slow ground speed.

I had no social network experience in 2013, put my foot in my mouth, and stepped on some toes. Anyway, this method of mountain pass crossing was common when I soloed at Jeffco in a 90 hp SuperCub in 1963. I have surmised from limited discussion of both thermalling and orographic lift that it is less common today.

I never saw or flew a small, light trainer airplane with larger than original engine in those days. With small 65 to 90 horsepower Continentals, mountain pilots mostly used the pass crossing technique I describe in the above post. Is anyone old enough, or low powered enough, or trained by old pilot enough to use this technique today? The most powerful common trainer in that day was the Cessna 150. Should I ask, "where have all the 150s gone?"

Jim,

I’ve been in pass crossings where the most powerful piston engine wasn’t going to outclimb the “down”. So, you look for the “not so down”. And sometimes, available fuel suggests that another day might be a better choice.

That said, I teach a level “canyon turn”. If you’re dumb enough to let yourself get that slow, in that tight a canyon, you most likely don’t have enough air under you to let that nose come down. The key in this is to NEVER allow yourself to get so slow that you can’t do a safe level turn.

In my experience, if you’ve got so slow, in such a tight canyon you can’t do a level, high performance turn, you’ve already screwed the pooch. Many experienced Alaskan aviators have demonstrated that phenomenon.

NEVER let yourself get so deep and so slow into a canyon.

Your mileage may vary.

MTV

Thanks for the info. Having moved to Wyoming, this topic is pertinent. Have Jim’s book. A reference there, some sketches or mentions of specific passes would be appreciated.

Best,

Tommy

When slow enough, Vy just to stay level, no zoom reserve remains for any pitch up to slow down for the turn. Already slow enough to get minimum diameter turn. However, too slow to make a safe level turn requiring pitch up to prevent altitude loss. Yes the safe turn, allowing the nose to go down, requires some vertical space. That would be at least 100' or so, as in crop dusting with a significant load. That vertical space increases rapidly as we go back down drainage.

The pass at the top tends to be flat and obstruction free, so altitude there is not the problem. Flying west of Grande Prairie made me understand that some mountains have steep sided ditch maize systems that don't provide increasing grade stream between tightening ridge systems. Our volcano and fault created Rockies generally do. A map recon should be used to determine that.

Wind, the more the better up to the no longer comfortable point, increases the orograraphic lift of a ridge at any downwind angle.

Like anything in recreational avaition, avoiding the high passes in summer midday would be safer in low powered aircraft. Depending on altitude maintenance 2,000' AGL above the pass is not, especially if the pilot is unfamiliar with which drainage system she/he is in and which way is down hill.

Tommy,

A good close starter drill, with SW wind would be to takeoff from Alpine 46U and head up the stream/drainage that empties into Palisides Res at the 5 in the 5620 lake elevation mark on the Salt Lake sectional. Use the first ridge, if needed, East of Palisades road but come back around south side of the second ridge west of Palisades road. Take this ridge toward hill 9476, breaking off as necessary to go south of the next ridge. And so on towards hill 7386.

Should get good lift close to finger ridges but return to orient basically up the valley. On return from each finger stay close to downwind ridge for ridge lift.

Jim

My best friend and I rented a Piper Arrow from our local flying club, and took our wives from Marina, CA (near Monterey) down to LA for a day at Disneyland, then on to Las Vegas for another day, then back home to Marina the final day.

That flight from KLAS to KOAR was memorable, to say the least... We learned a lot about flying reasonably underpowered airplanes in High DA situations with fairly heavy (though well within W&B and CG range). We figured the 144 miles from KLAS to O26 (Lone Pine / Death Valley) would be plenty for us to be able to climb from roughly 2200' field elevation up to 14,500' to sneak through the pass just north of Lone Pine... Ha! We were doing pretty good, until just abeam Lone Pine, when we started feeling the effects of the wind coming over the mountains and dropping down over Death Valley... What had been a modest rate of climb turned into "parked" at around 12,000 ft. The very smooth downdrafts (virtually zero turbulence) just matched our best rate of climb and we were never going to get any higher than we already were...

After struggling to eke out enough altitude to go over the pass for a while, I decided I'd had enough. We landed at Lone Pine, refueled, then re-planned the final leg to fly back through the Tehachapi Pass. It meant that we landed back at KOAR after dark, but we were both night current and knew the area extremely well so we were not worried. In fact, it turned into one of the most beautiful evenings ever, with the lights in the central valley looking like jewels below us. Both wives were captivated by the beauty – almost enough to make up for the angst they felt when we were unable to climb above the terrain near Lone Pine...

All's well that ends well, I suppose. Best decision was to abandon the effort to outclimb the downslope winds. Better decision would have been to make that same decision BEFORE we took off from Las Vegas, and just planned to fly the Tehachapi Pass to begin with...

Thanks Jim, I will try this. About 6 months ago, I flew N out of 46U in my 182 toward the dam; there was a motor glider circling in the area and it was moderately bumpy. Went down the Snake into Swan Valley and came back upstream. Just before I reached the dam, I encountered the biggest bump ever. Although I was well belted, my headset hit the roof and anything not netted down went everywhere. Really severe but very momentary. I believe above the dam was snow over ice and I was above the flowing water. Still trying to figure this out. Lucky my wife was not along... She hates bumps even on the road.
Best,
Tommy

Unfortunately bumps and good wind to work with go hand and hand. A significant downdraft was more likely orograraphic wave or just a strong shaft. We are generally away from the higher ridge and mountains when this happens. Close in riding up and avoiding the declination line downwind of a ridge generally keeps effect positive or at least not negative. Wave has a long, multipeak, multiple up and down reach and thus can be a shocker on the down side. The motor glider was probably looking for the next significant up side of the wave.

When the dust comes off the floor into our face, we are just trying to stay somewhat level. On course thermalling needs milder shafts of air in the 1,000 to 3,000 fpm range. Wave can be in the 10,000 fpm range. Usually short duration.

A Huey at Ft Carson went from 7500' to 17,500' in a minute at flat pitch. So we got cool big boy oxygen masks at the Army's mountain flying course.

JP256,

I've been busy and just now have looked at the sectional concerning your planned flight over the pass west of Lone Pine. While the valley ridge systems up to most of the passes in that area are quite straight, normally a good thing, they also are mostly oriented the same direction. All slightly NE drainage means a slightly SW wind is generally not going to be any help. We need the wind to come at an angle to the downwiind ridge of a ridge valley system to provide ridge lift. Any N-S range, as most in the lower 48 are, will have downdrafts on the east side in prevailing westerly winds. The only up air in the area, with wind going straight down the drainage from the pass is in the pass itself, with the venturi effect.

Thermalling up to 14,000 is sometimes an option on hot afternoons. The airspeed of the Arrow is a bit fast, but strong ups can be caught in time with pitch up and strong downs can be dived through quickly.

And then there is mountain wave, which can be caught well downwind when lucky...or unlucky. Going from 7500 to 17,500 in a minute at flat pitch is not fun without oxygen.

Finding a lower pass with better valley/ridge orientation was certainly a wise move.

contactflying wrote:Finding a lower pass with better valley/ridge orientation was certainly a wise move.

And my "I learned about flying from that" moment. Shoulda known better than even try it at that time of day with that load in the plane. That day, I definitely took some out of my "luck" bucket and put it in the "experience" bucket...

I did the same thing on a XC and mountain checkout from Las Cruces to Gallup across the Mimbres Mountains in the student's 182. I had him try two of the first valley ridge systems running just slightly SW-NE on a very hot afternoon with strong slightly SW winds. Finally I had him fly north along the east edge of the Black Range until we found a valley ridge system running NW-SE where we used ridge lift to go on over. In the first one I was able to demonstrate the energy management turn from the north ridge toward the drainage south of it. On the second, he turned back just fine.

TommyN,

With any wind from slightly SW all the way around to S, a ridge ride to Mountain King private airport would work well. Go over the bridge and ride the long E-W ridge north of Greys River to where the stream from Hoback Peak joins the Greys. Turn SSE with the Greys and ride the ridge east of the Greys to near ranch and break off the Greys over the east ridge toward hill 10361. Ride the higher terrain toward hill 10345 and ranches. When higher than the ridge east of hill 10742, turn to Mountain King.

Thanks Jim; finally got a chance to look at this.

Interesting—have been looking at routes to get over the nearby mountains to go NE, say to KRAP. My 182 is 260HP, fuel injected but normally aspirated. Have considered following the Snake up to Hoback and then following the valleys SE to KPNA, then turning NE at SPAWOS. Other one route I looked at was going S past Afton and crossing somewhere down that way.

The route you describe is more direct. The winds here are usually from the S- SW or N- NW. Other directions are rare. Curious as to the altitude you might suggest I fly? Or how to determine best altitude? How high above the ridge can I fly and still take advantage of the ridge lift? I have done ridge soaring in a glider and we were only 100 ft or so above the ridge.

Thanks again for your insight and willingness to help others.

Best,

Tommy

Tommy,

Drainage systems and wind direction are the big decision makers in route planning, map recon. Sectional is fine for cross country but 1:25,000 quadrangle is better and safer for intense high pass crossings. Your main concern throughout the planning and throughout the flight is which way is down drainage and am I in position to turn there allowing my nose to go down naturally.

100' above the ridge directly below you is fine if you are in position to turn back down drainage (away from the ridge and toward the upwind valley) should the lift not work out and terrain up parallel to the ridge is climbing too fast. The same as you learned in the glider. Gnarly edged ridges must be taken into consideration both for turbulence and cutting off a turn to lower terrain allowing the nose to go down naturally. Concave cuts into your ridge are fine is they can be followed easily. They are often venturi and thus increase lift.

Higher above the ridge straight below can work with stronger winds. Don't get pulled into complacency by higher. We still must orient on the valley ridge system rising up to the pass. Breaking out on top of everything seems good until the downs that accompany the up come into play. Then 2,000' above the highest terrain means little.

The starter drill I suggested with SW winds is not the way most pilots would fly the route. They would use engine power to climb up over the lake or just go up the fairly straight drainage west. How would a glider pilot approach that route? The four fingers (ridges) coming down toward this drainage are each lift producers on their SW slopes. Stay close to the ridge going toward higher terrain in the Big Elk Mountain complex, turn back before vertical space runs out. Turn West away from the slope but return to the same slope going back toward the drainage we are orienting on. For practice go back toward the drainage of orientation each time. The lure of being higher than the next finger can be upsetting on the lee side of that next ridge. This unnamed drainage on the sectional is shown to end beyond V465 and the drainage beyond the pass goes into Greys Lake Outlet. Under V465 notice the wine glass where the drainage from Caribou Mountain joins.

I will look at the other routes you mentioned when I have tracked down the identifiers one at a time.

Jim

A clarification about on course, straight line, thermalling, Tommy; we thermal up using very slow climb airspeed in up air and very fast dive airspeed through down air. That is over level terrain. That would work on a hot afternoon up the valley to Afton. On a prevailing windy day, ridge riding up the Salt River Range would probably work better.

With ridge riding up to the pass, we are more concerned with maneuvering airspeed than with rate of climb. We don't want to slow down as in the updraft ride while thermalling. We always want sufficient zoom reserve to maneuver around or over irregularities in terrain. We have lots of vertical space available upwind toward the valley floor where the drainage lies. We want enough maneuvering airspeed, however, to be able to do that quickly when necessary and also to not have to do that with every momentary lapse in good lift.

We also, in the 182, may have enough power to get up out of the valley ridge system to the pass. Again, not always wise. Regardless of height above the ridge directly below, we orient on the ridge and the drainage upwind of the ridge. That drainage is our only safe out. I have never understood the admonition to cross ridges at a 45 degree angle. Why the hell are we crossing ridges to begin with. Stay with the ridge to get up to the pass.

Thanks for the clarification, Jim. Will noodle on all this. Agree that 2,000 ft. above these mountains may not be enough...

SPAWOS is an AWOS station at the southern end of the mountains between KPNA and KLND.

Best,

Tommy

Tommy,

Your Snake to Hogback, to South Pass to Rapid City route is fine. Lets assume SW winds again. The run up the Snake will have various irregular terrain to work with north of the Snake. The gap just east of "school" on the Hogback River is a little tight and the winds off the ridge running north of Hogback Peak may give some turbulence. Make your run to South Pass over the lakes north and east of PNA and as close to the higher terrain of the Wind River Range as comfortable. The tight irregular valleys going up to between the high peaks tend to be venturis and thus helpful, but sometimes turbulent. Find the best up air that is still somewhat smooth. You could get significant ups but don't go over the range without a definite pre-planned egress down drainage out of the range.

By South Pass you will be high and up against the higher Wind River range. Don't get cut off by the toe of the boot just north of hill 8820.

Jim

Tommy,

The nice thing about your route to Rapid City is that on the way back SW wind would also provide ridge lift from South Pass back to the Snake and then you are down drainage to Alpine.

You have power to choose your altitude from Rapid City to South Pass. If I were in any of the 65 hp trainers, I would stay 200' AGL into the headwind until bldgs on the Sweetwater River and take the river to the stream from Granite Peak that joins the Sweetwater just south of South Pass City and ride that up to the west slopes of the Wind River Range. Those river valleys are tighter, but at 60 mph max airspeed not a problem should an energy management turn back become necessary. Going NW along the Wind River range would be a crosswind and both Hogback and Snake rivers would be down drainage. So low again there. Slow airspeed and small fuel tanks dictate that kind of planning.

Jim

Concerning the October V35 Bonanza crash up drainage from Telluride, three problems present. Both up drainage east to Red Mountain Pass and up drainage south to Lizard Head Pass are a lot of climb in a fairly short distance. Second the light westerly wind gave little hydraulic lift either way, especially east with the wind aligned with the drainage. Third the airplane cruise airspeed is a bit fast and the weight a bit great for optimum lift with light winds.

Here is where the suggested down drainage egress really proves itself the safest choice, regardless of horsepower. Down drainage to Placerville and then ridge riding to Lone Cone would give plenty of distance to get plenty high even with light west wind before turning east.