Mountain Waves / Downdrafts

[Seth]

Mountain wavese happen not just out west.  They happne on the east coast too.  Traveling back from Western Virginia, not West Virignia but the west portions of Virginia yesterday, there was a warning of turbulance below 15,000 along with two PIREPs during my briefing: 

 

1)  A Pilatus warning of Severe Turbulance near Charlottesville, VA at 7,000 feet (if a PC-12 says it's severe, that's a much bigger plane than my Mooney)

 

2)  A C-172 near Baltimore warning of moderate Turbulance at 2,5000 feet.

 

Upon departing and finidng relativly clean air at 9,500, I figured I'd stay high as long as I could to give my passenger a cleaner ride (she is used to the bumps near Dulles east of the Appalachians). 

 

This was a VFR flight plan as there was not a cloud in the sky (scattered layer around 7 - 8,000 feet, and I didn't want to be forced down early near DC and get banged up in that air at 7,000 feet (PIREP)

 

I stayed high until I hit the north side of the SFRA, and then decended down near FDK to 3500 before turning South and heading to KGAI - it actually worked out quite well.

 

MOUNTAIN WAVE.  While travleing in the NE direction just east of Winchester (KOKV) maybe south of Charles Town (if looking at the sectional), my autopilot started commanding a vast nost up attitude and I started bleeding off airspeed due to the higher angle of attack.  I increased power as I fell to 115 knots (after crusing in the 150/160 range - indicated), and then turned off the autopilot thinking something was wrong to take manual control.  I lowered the nose and though 10 degrees easy over the horizon (big up angle - people don't realize how high 10 degrees is) I start losing altitude, I double check my pitot heat is on and then realize I'm in the down side of a mountain wave as the mountains are just to my left.  So I add full power, crank the RPMs back to climb, and hold 9,500 feet.  after a few minutes I started climbing as opposed to holding level with the nose up attitdue, so I level the nose, and was "out" of the wave.

 

At night, I'm not sure I would have noticed the pitch up as quickly (sight picture).  The wave was calm enough that a full power climb easily took care of keeping me level, and I had my out as to turn around or head directly east and get to lower terrain, but if I was in the rockies, didn't have a ton of clearance, and didn't have a turbo engine (I don't hava turbo now) I can see first hand how that can kill you.  The wave had no turbulance associated with it - just all of a sudden my AP is at high nose angle in order to keep the altitude - again - at night I hope to have noticed that prior to getting to stall speed.

 

Very odd feeling, but I knew about the PIREPS of the bumps, and figured to be on the look out for odd conditions - I just hadn't experienced mountain waves until yesterday for the first time.

 

-Seth

[timpercarpio]

I've experienced this several times over the Blue Ridge mountains in a J model. I was able to maintain altitude, but lost some airspeed. Once, in a Grumman Toger, I was unable to hold 7500 feet, told the controller, and finally stabilized at 5000.

[PMcClure]

Been there in my F model north of ATL. There was a strong wind from the NW. ATC routed me north to stay away from ATL. The turbulence was not that bad, but the Airspeed dropped to 90 knots. ATC would not give me any lower or route me south. I canceled and flew under the ATL bravo deck well south of the mountains. The unusual thing for me (also a first time experience) was the only sign was the drop in airspeed and pitch change to keep altitude. 

[Cruiser]

I have experienced this many times crossing the mountains going east or west between Johnston, Pa. and Morgantown, WV. mostly smooth sailing without much turbulence but a definite need for pitch control and power changes to hold altitude.

[AndyFromCB]

It's amazing what even a hill can do if it's windy enough. Iowa is mostly flat like a pancake but around here in the Omaha area we have these weird formations called loess hills that stand about 200ft tall out of nowhere. The are exactly on the approach patch of Eppley Airfield when landing to the north on ILS. It can really catch you off guard.

 

Once on a landing in Cheyene I essentially maintained almost full power to about 500ft to stay on the glideslope before things settled down a bit. It was gusting to 40 on the ground. I'm too old for these things anymore, anything over 25knots on the field, I'm staying on the ground.

[Hank]

I fly in WV, SW VA and W NC frequently, and have only experienced mountain wave activity once. I was coming home from GA, probably flying between 000 - 010 at 10,000 msl somewhere south of AVL. There was very little sensation, I just went up ~300-350 feet nice and slow (once I quit fighting it), then casually down to ~9700, and cycled several times before settling back out on 10,000. This was not near Mt. Mitchell. In-cloud updrafts are much stronger and very noticeable. Only been West once, went to BIL then south to KCOD to avoid the big rocks.

[Jeev]

Yea they are to be respected.  I fly back and forth Vegas to Denver about 4 times a year and refuse to go through some of the passes in the middle of the Rockies and also will not go unless its VFR and winds through the passes are less then 25kts.  Even with those rules I have been caught in many waves + and - 500 fpm ( not a big deal) and one time coming through the La Veta pass I got an updraft of over 3000fpm and rode it up to 17500 (with o2) ) then I had to drop the gear to stay below 18000.  This was over the south end of the Rockies and decided to stay on the upwind side of the wave and continue south over low terrain since there is no way I could counteract the same downdraft in my N/A J.

 

I done a lot of flying around the mountain SW and have a high level of caution and respect for ICE and Mt Waves.  As you did, always have an out.....

[midlifeflyer]

East or west, 4,000 or 14,000, smooth or craggy, mountains are mountains and the wind goes over and through them pretty much the same way. And they deserve the same respect. The difference in density altitude is a difference in your airplane's capability, not on the effects of mountain weather.

[John Pleisse]

First of all, let's qualify this. Winds aloft yesterday were 45+ at 6,000 in this area. Surface winds were 27022G31 at MRB. I was up for a about an hour around Westminster and my teeth were clanking. It was rough. I would have held the altitude direct EMI, then hang a right and descend when clear. I hit all kinds of rotors yesterday, just west of FDK. Very typical.....airspeed holds and the VSI says plus 800fpm...then, wait for it....ROLL!!! I know you were cutting the corner and wanted to get home.

[Joe Zuffoletto]

Out here in Colorado I've experienced mountain waves with 3 or even 4 oscillations. One was on the east side of the Sangre de Cristo mountains at 16,500', starting about 30 miles east of the peaks. Winds aloft were 40KTS out of the west. Autopilot engaged. Hit the downdraft first, so the nose went up slightly, lost about 10 knots of airspeed. Then the updraft: nose back down, gained about 15 knots of airspeed. Then up and down again twice more, with the airspeed fluctuations getting bigger each time. The last oscillation, closest to the peaks, I dropped about 30 knots of airspeed, then gained back 40. Amazingly, no turbulence that day.

[TTaylor]

If you are VFR why worry about holding altitude? Use the wave don't fight it. Slow down in the lift and climb, speed up in the sink and minimize the time spent in it. Also learn to angle parallel to the ridges to climb when approaching the ridge on the lee side and turn perpendicular to the ridge and dive through the sink bands.

[aviatoreb]

... and minimize the time spent in it. 

 

And opposite goal of a glider pilot.

[Rwsavory]

I was also in the same area Sunday morning going North from MOL to MRB on my way to Harrisburg. I've experienced wave before in those mountains, but this was the strongest by far. I lost about 2,000 feet twice despite full power (could have used a couple more cylinders), dodged a rotor cloud, and got bounced around quite nicely. Great wave day if you're flying a glider!

[Seth]

If you are VFR why worry about holding altitude? Use the wave don't fight it. Slow down in the lift and climb, speed up in the sink and minimize the time spent in it. Also learn to angle parallel to the ridges to climb when approaching the ridge on the lee side and turn perpendicular to the ridge and dive through the sink bands.

 

That makes perfect sense!

[Seth]

First of all, let's qualify this. Winds aloft yesterday were 45+ at 6,000 in this area. Surface winds were 27022G31 at MRB. I was up for a about an hour around Westminster and my teeth were clanking. It was rough. I would have held the altitude direct EMI, then hang a right and descend when clear. I hit all kinds of rotors yesterday, just west of FDK. Very typical.....airspeed holds and the VSI says plus 800fpm...then, wait for it....ROLL!!! I know you were cutting the corner and wanted to get home.

 

Hey John -  It was actually smooth enoguh until I got down low.  I stayed up high and stayed VFR so that I would not have an issue with Potomac bringing me down low earlier as I didn't want to get slammed around near the mountains.  By the time I got over FDK I was still around 5500 and decending.  As soon as I hit 3600 I made the right turn, and by the time I hit the Bravo shelf I was closer to 3200/3000.  Just kept decending from there until I was at GAI. 

 

My crosswind landing in VA (Hot Springs - HSP) on Friday used many of my skills.  The landing at GAI had the winds and gusts nearly down the runway and actually was pretty good.

 

Glad you were up flying and using your beautiful 201 again!

 

-Seth

[piperpainter]

That's a normal and expected occurance as you pass the cascades in WA via V2. It's even more wierd to watch when you're in IFR conditions. I've had it bleed down to around 90kts or less before finally getting over the hump and then I had the nose pointed almost 10degrees or so down. It's an odd feeling but once you see it a couple times you can expect it. Flying around the mountains you learn a lot about when and were to expect bumps or odd things to happen. Just like shaddows give you drops and sunny side gives you lift!

[jnisley]

The first time I experienced mountain waves over the the Appalachians it scared me, if you're IFR, advise your controller and they'll work with you because it's easy to bust your assigned altitude.

[201er]

Wave is not limited only to mountains. I've hit wave over Long Island sound and lost as much as 20 knots while raising the nose to maintain altitude!

[Cruiser]

Wave is not limited only to mountains. I've hit wave over Long Island sound and lost as much as 20 knots while raising the nose to maintain altitude!

first I heard of this. Got a source I can learn more?

[aaronk25]

Last Thursday at 6:30pm I was trying to get from 8k to 10k west bound between Millville NJ heading to MN and I went up at 1700fpm then a min later was at best rate, 100ROP and indicating 105kts nose up about 5 degrees and in a 200fpm decent. Winds at 4k were 40kts. ATC called before I did and inquired as to my assigned altitude and asked why I stopped the climb and I said I'm at max rate of climb and we're decending. The lady said she moved traffic for us and asked us to advise when able to maintain altitude. I never realized little 4,800ft mountains could cause a mountain wave at 10,000ft!!!!! This happens 3 more times and stopped once west of the rocks.

[Seth]

I realize i probably have flown through lighter mountain waves in the past on the east coast.  I've always wondered why on flightaware.com after a flight I sometimes have an oscillation in speed +5-5+5-5+5-5 etcs on the graph over a short period of time - my guess now is that I have encountered these waves in the past and just figured it was a change in headwinds/tailwinds. 

 

I just hand not experienced the magnitude of the one experienced last Saturday.

 

-Seth

[BorealOne]

There's a story in circulation that I've not been able to verify from official sources about an Ovation pilot flying over the northern Rockies btw Alberta and Prince George BC who encountered the mother of all mountain waves. From what I'm told, it rolled the aircraft fully inverted - over the longitudinal axis - a number of times before spitting him out sunny side up, a little shaken if not stirred.

 

Both my mechanic and a guy I met on a tarmac in N. Saskatchewan recounted the same story.

 

Apparently the plane was subsequently inspected by factory reps and determined airworthy.

 

Anyone here have any additional detail on this?

[scottfromiowa]

My wife and I flew to CVK (Northern Arkansas) to visit my sister a couple weeks ago. Winds were pushing on the way down out of the North West. (Course was almost due south). I had either 04 or 22 available. Winds were at 290 so elected for 22.

I entered pattern at midfield left turn for downwind. Uneventful until on final. I had a sharp crosswind from left that was tough to crab and stay aligned. I made mistake(s) of putting in full flaps and chopping power when I had runway made...I got the stall horn! Lowered nose and added a little power and just dropped in....Nice bounce...power flare and down.

The winds were definitely gusting big time when we got to tie down. Winds were jumping around. Possible that I got some wind sheer? My review said I should have held more power on final and really just needed 1/2 flaps with the wind. Any other thoughts? I would say winds were 20-30 gusting...NOT FUN.

The area has low hills/valleys...wouldn't call them "mountains", but there is terrain.

[RJBrown]

This thread illuminates why I no longer own a J. Without the ability to climb to a reasonable (20,000'+) altitude a J is unsafe in many normal conditions. Coming into Cenntennial on the LARKS arrival and not being able to maintain MEAs is quite disconcerting. Out east a non turbo can get high enough to clear most wave activity or if lower still be able to maintain due to lower density altitudes. Out here where the dirt starts higher than the mountains discussed here and the Rocks top 14,000' turbos are much more important.

Once the house and hangar are completed on Pegasus (5AZ3) I will buy another Rocket. Untill then I am better off planeless than stuck flying a plane that disapointed each time it was flown.

[aviatoreb]

I found an impressive downdraft in the pattern at Newport, VT airport (KEFK) last March.  It was a windy day, like 25-27kt gusts, but not anything I hadn't done before....but that airport is on the lee side of the green mountains.  Those are not especially tall mountains but I guess if the wind hits them right...you get downdraft in the pattern.  I applied some really significant power to hold altitude with the increasing pitch on downwind.  That was not the prettiest landing I ever made either.  I had sufficient power to cope but it reminded me what could happen on an even windier day.

 

I also once found some significant winds in Rutland, VT, which is an airport in the notch between two small mountains and one of the approachs is along the notch between two of the mountains - these are "small" east coast mountains.  But that day with gusty winds again in the upper 20's knots but this time changing directions, lots of power changing to compensate for up and down drafts, I made two go arounds and a change of runway as the wind changed direction.  I was amazed to have made a squeeker, but that was dumb luck as I was touching down just between gusts I guess. I later learned that the local airline, Cape Air that flies Cessna 402s, ceases operations into that specific airport at some more-conservative-than-I would have thought wind of (I can't remember for sure) 30kts....no matter even if it is straight down the runway.