Safe Altitude in the pass

Tom-D

Tom-D

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Tom-D
As most here know I live in Puget Sound, any way out of here is thru a pass or south around the mountains.

what is a safe altitude to transit the passes like Stevens? or Snoqualime ?


This is a vfr question I know what the MEAs are.

How close to the trucks can you go?
 
The winds in the Cascades are always west to east and seldom over 20k on a clear day that's VFR thru the mountains.
 
Tom-D said:
As most here know I live in Puget Sound, any way out of here is thru a pass or south around the mountains.

what is a safe altitude to transit the passes like Stevens? or Snoqualime ?


This is a vfr question I know what the MEAs are.

How close to the trucks can you go?
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I went through Snoqualmie pass at 3022' MSL last Sunday, and got as close as 10 feet to the trucks (on my left and right). But I was driving.
 
The Colorado Pilots Association Mountain flying course recommended at least 1,000' clearance for crossing passes.

As others have noted, wind plays a major factor since we're concerned with any possible downdraft that we can't dive out of.
 
I'd do 500' as long as the winds are light. Otherwise its 1k+. At 3500 MSL you still have pretty decent climb performance.

Here in Colorado I use Clark's 1k as a minimum (but then I'm generally looking at passes that are above 10k MSL)
 
Also what are the dimensions of the 'pass', is it a keyhole with steep and tall vertical walls or a broad flat valley? And, what lays below, a busy highway with trees or pastureland?
 
Let'sgoflying! said:
Also what are the dimensions of the 'pass', is it a keyhole with steep and tall vertical walls or a broad flat valley? And, what lays below, a busy highway with trees or pastureland?
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You can see all that on Google maps Highway 2 is Stevens Pass, and Highway 90 is Snoqualmie Pass.

Mostly this time of year it will be a rare day you can do the Passes VFR. but when you can, it will be lots of snow tall trees and a couple high lines, and 1 ski area at each pass.

The Picture is of the Skagit Valley but typical of all the passes in the Cascades.
 

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As has been said previously, how you fly through canyons should be dictated by winds, DA and visibility. With winds, it really depends on their direction and the topography of the area. It's best to remember that winds in canyons are not always the same as winds experienced in the general area, an example of this is the Columbia Gorge, it can be regularly howling down the gorge when there are only light winds a few miles outside of it and to the north and south of the river.

The winds in the Cascades are always west to east and seldom over 20k on a clear day that's VFR thru the mountains.
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I fly regularly in the Cascades and I don't recognise your description of them by what you say above. I've frequently encountered winds that are not west to east and have frequently experienced winds > 30kts flying over the top on a clear day.
 
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I'd say at least 1000 above the max elevation of the pass, and more if the wind is blowing -- at least 2000 if the wind is up in the 35-50 knot range.
 
Ron Levy said:
I'd say at least 1000 above the max elevation of the pass, and more if the wind is blowing -- at least 2000 if the wind is up in the 35-50 knot range.
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Isn't that the recommendation for crossing mountain ridges to avoid wave and downdrafts?
 
Ron Levy said:
I'd say at least 1000 above the max elevation of the pass, and more if the wind is blowing -- at least 2000 if the wind is up in the 35-50 knot range.
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IMHO if you had to go 2000' higher than the pass, why go in ? And if the weather is so bad that you must get down into the pass its self don't go .

Snoqualime pass you never follow the road anyway, you follow the highline, which is about 1000' higher than the road. because the highway turns a switch back that you can't do with any aircraft.
 
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IMHO if you had to go 2000' higher than the pass,
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That's like the guy flying 10K over the tops of all the peaks, calling it "Mountain Flying"; nuh-uh.
 
Let'sgoflying! said:
That's like the guy flying 10K over the tops of all the peaks, calling it "Mountain Flying"; nuh-uh.
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There are only two rocks higher than 8k' in the whole range. If it is good enough VFR to go, go high, go long.
 

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TangoWhiskey said:
I went through Snoqualmie pass at 3022' MSL last Sunday, and got as close as 10 feet to the trucks (on my left and right). But I was driving.
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My standard way to go through that pass, too.

Tom-D said:
There are only two rocks higher than 8k' in the whole range. If it is good enough VFR to go, go high, go long.
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Yup, and if you can see them they are easy to miss. On a clear day, 9500 MSL eastbound and 10,500 MSL west bound. On a not so clear day, take the sea level pass through the mountains (Columbia River gorge). On a really bad day, drive.
 
Ron Levy said:
Sharp eyes! Yes, it is. It's good guidance for snaking through passes, too.
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If one were to follow that advice you'd never go VFR thru any of the passes in North Cascades.

Which is pretty good advice by the way.

My minimums are 1500' of vis between me and the rocks. That is 1500' above the pass elevation 2900 for Sno, and 3000' for stevens.

My advice to new pilots that want to fly east, be at 8000' at Derington, cross the ridge just north of Glacier Peak, and fly down and out the Lake Chelan Valley.
 
ChrisS said:
Isn't that the recommendation for crossing mountain ridges to avoid wave and downdrafts?
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No.

I will guarantee that you can encounter wave and downdraft at 1,000' AGL over passes in the Rockies.

The rule of thumb is to be greater than 1/2 the elevation change from valley floor to peak to avoid the worst of the wave and downdraft problems. I've been way up high, +15,000 over the New Mexico Rockies, and encountered downdraft greater than my climb ability. The turboDakota will climb okay at max power at 15,000' so this was a bad day in terms of conditions.

Don't take anything for granted over the mountains...
 
Clark1961 said:
No.

I will guarantee that you can encounter wave and downdraft at 1,000' AGL over passes in the Rockies.

The rule of thumb is to be greater than 1/2 the elevation change from valley floor to peak to avoid the worst of the wave and downdraft problems. I've been way up high, +15,000 over the New Mexico Rockies, and encountered downdraft greater than my climb ability. The turboDakota will climb okay at max power at 15,000' so this was a bad day in terms of conditions.
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The recommendation is a widely quoted one. I'm not saying it is what is required in all circumstances due to the topography of the area, I know this for a fact, and sometimes given the option I would go higher if I can. I don't have my copy of Sparky Imeson's book at hand but I seem to remember that it may well be mentioned in there as well, maybe someone out there will confirm/correct me on this.

Clark1961 said:
Don't take anything for granted over the mountains...
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I know, everytime I go flying I will be over or within 30 miles of sizeable mountains ranges.
 
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ChrisS said:
Isn't that the recommendation for crossing mountain ridges to avoid wave and downdrafts?
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I believe that the idea of the recomendation is not that you will avoid a mtn wave or downdraft, but that you will have more time (altitude) to fly out of the downdraft. When mountain flying and encountering a downdraft you must avoid the natural reaction of pulling back and trying to maintain altitude, and instead push over and fly out of the downdraft as quickly as possible. If you get into a serious downdraft you will most likely not be able to out climb it in the aircraft we all fly (and sometimes even the aircraft that Mari flys :hairraise: ). This is also the reason for approaching ridges at a 45* angle, so that you can turn towards lowering terrain quickly and fly out of a downdraft should you encounter one.

My rule of thumb for the Rockies is if winds aloft are 25kts or greater, then I wont fly over the divide. The planes that I fly are limited in altitude, and the chance of encountering nasty turbulence/rotor are too great.
 
Tony's got it right, the idea is to have enough altitude to turn towards lower terrain and dive out of a bad sink. It's a nice idea and I hope I recognize the situation when I encounter it some day.

A week ago Saturday I flew from south-central Wyoming back to Denver and encountered some serious sink over the Front Range northwest of Fort Collins. I was downwind of a ridge but about 2,000 ft above it and 10 miles past it (sort flew into the downwind position from north of the ridge). It was interesting to say the least. I hate to be at a higher altitude because I've got to get under the Denver Bravo so my choice is either stay to the north or fight the sink. On really windy days I stay to the north - up by the Wyoming-Colorado border. It's still plenty bumpy...
 
Clark1961 said:
Tony's got it right, the idea is to have enough altitude to turn towards lower terrain and dive out of a bad sink. It's a nice idea and I hope I recognize the situation when I encounter it some day.
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I can assure you that you will recognize the situation. I had an occassion once just to the east of Salt Lake City where I flew into a downdraft, 2,500ft above the ridgeline I was about to fly over. I was approaching at 45 degrees when suddenly my VSI maxed out downwards, I banked back to the east and descended straight through a rotor. It wasn't very enjoyable.
 
Tom-D said:
IMHO if you had to go 2000' higher than the pass, why go in ? And if the weather is so bad that you must get down into the pass its self don't go .

Snoqualime pass you never follow the road anyway, you follow the highline, which is about 1000' higher than the road. because the highway turns a switch back that you can't do with any aircraft.
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I frequently follow the road through Snoqualmie. The switchback requires more than standard rate, but nothing particularly extreme. Just don't fly up the box canyon near Alpental, the remains of more than one aircraft are still up there.

Following the powerlines (if they are the ones I am thinking of, 3 parallel rows of towers with a clearing a quarter mile wide) does not take you through Snoqualmie pass, it takes you through Stampede pass. You are correct though, the terrain is less challenging that route.
 
Tom-D said:
There are only two rocks higher than 8k' in the whole range. If it is good enough VFR to go, go high, go long.
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I would say that there are quite a few peaks higher than 8K in the Washington Cascades... Baker and Rainier are the big uns of course, but Glacier Pk, St Helens, Mt Adams, Mt Stuart, Shuksan, Jack Mt, Mt Lago, Bonanza, Copper, Cashmere, and a bunch of un-named peaks are above that.
 
slacktide said:
I frequently follow the road through Snoqualmie. The switchback requires more than standard rate, but nothing particularly extreme. Just don't fly up the box canyon near Alpental, the remains of more than one aircraft are still up there.

Following the powerlines (if they are the ones I am thinking of, 3 parallel rows of towers with a clearing a quarter mile wide) does not take you through Snoqualmie pass, it takes you through Stampede pass. You are correct though, the terrain is less challenging that route.
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you are about 11 miles south, I use the high line and don't need to follow the road, a bit higher and one ridge hop and your free to descend into Easton.
 
slacktide said:
I would say that there are quite a few peaks higher than 8K in the Washington Cascades... Baker and Rainier are the big uns of course, but Glacier Pk, St Helens, Mt Adams, Mt Stuart, Shuksan, Jack Mt, Mt Lago, Bonanza, Copper, Cashmere, and a bunch of un-named peaks are above that.
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If there is a rock in the way, go around. remember we are VFR. and just because there is a rock higher than you, doesn't mean you must go there.

Next time your around OKH stop by, say hi.
 
Tom-D said:
If there is a rock in the way, go around. remember we are VFR. and just because there is a rock higher than you, doesn't mean you must go there.

Next time your around OKH stop by, say hi.
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Will do, where are you on the field? I stop by OKH on the way home from FHR occasionally, taking advantage of the fuel prices.
 
Tom-D said:
you are about 11 miles south, I use the high line and don't need to follow the road, a bit higher and one ridge hop and your free to descend into Easton.
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Ah, I think I see your powerlines on Google Earth. The ones that scoot just south of the 1'st ski area, Hyak I think?
 
slacktide said:
Will do, where are you on the field? I stop by OKH on the way home from FHR occasionally, taking advantage of the fuel prices.
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I'm in Hangar 10, look for the silver Jeep. or give us a hollar on the cell (360) 202-0961
 
Flying westbound I entered at 6,500 from Cle Elum and cut the switchback descending through 6,200. I didn't follow the road at the switchback, I "cut" between that big peak and the valley just to the south. I hugged the peak and had two routes to lower if things started acting up. Other than when approaching that big peak at the switchback, I felt okay. Winds were light, about 12 kts.
 
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