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Thread: Lesson Apr 19, 2014 - Wave and Ridge

  1. #1
    Join Date
    Jan 2011
    Schleicher ASW-24

    Lesson Apr 19, 2014 - Wave and Ridge

    Today's lesson is an analysis of another pilot's flight - namely Luke-SD. Some really good wave flying and ridge flying. A perfect example of how to fly wave and ridge. Well worth detailed analysis. I know several pilots are interested in this subject, so maybe we could do a piece by piece analysis of this particular flight.

    But first we need to hear from the pilot, which may not happen for a few days, since he has a job.

    See the recent flights out of Williams on this link...

    The subject flight was on Saturday, April 20, 2014. See the thread describing flights on that day on this link...

    Luke flew past Snow Mtn, heading for Sheet Iron Mtn and then decided to head west towards Gravelly Valley/Lake Pillsbury, Hull Mtn area.
    I flew to Snow Mtn, was over 12,500 and headed directly towards Gravelly/ Hull Mtn and tried to climb in that same area, but gave up in my attempt to fly the same track as SD.

    I had difficulty evaluating the wind properly. I was using a Cambridge L-Nav nav system, but I have been so spoiled by the more modern equipment. I suspect I have just become plain lazy at evaluating drift. I needed to be more analytical than I was, as I struggled in my climb from 8,500 up to 9,000.
    I could see the wind on Lake Pillsbury. I could see two columns of smoke on the west and NW sided of Lake Pillsbury - all good wind indicators. But the wind was on the surface was not the same as the wind at 8 to 10, 000 feet. It was veering (increasing in compass direction clockwise- as opposed to "backing") as It rose above the friction layer of the terrain. It was changing from a vector of from 260-ish degrees to about 310-ish degrees. Looking at See You Map display and the Meridians of Longitude showing North, it all becomes apparent to me - 24 hours after the fact. I sure wish we didn't have nearly 20 degrees (16 to 18) of variation between magnetic and true north. The wind readouts are in degrees true. Many of us think in degrees magnetic, or at the least, get a bit disoriented and refer to north or west improperly. (I still have difficulty referring the runway at Williams as 16-34 (instead of 18-36), when you can clearly see it is parallel and perpendicular to the section lines that are all oriented true north south east and west). but we all know why we use Mag heading for runways, just as we use magnetic vectors for surface wind reports.

    I asked Luke to read me the bearing and distance to the Gravelly runway TP (from his nav equipment), and he did so. That saved my bacon. I may of may not have eventually found that small pocket of lift on my own.

    Another issue for me is the various setting we use on our equipment for distance - but it isn't really a factor for most people, because I seem to be one of the few pilots who is totally vigilant about my position, and have a precise answer anytime someone wants to "really" know my location. I always know my distance and bearing to a given point in the data base at all times - period.
    Few other pilots seem to have a need for that habit of mine.
    And then if I am able to get a report from another pilot, I never know if the miles provided are in statute or nautical - but such precision rarely matters to most pilots. Just another factor that makes flying different for each pilot.
    Last edited by Peter Kelly; 04-20-2014 at 10:24 AM.
    Peter Kelly

  2. #2
    Join Date
    May 2011

    Re: Lesson Apr 19, 2014 - Wave and Ridge

    Thanks Peter,
    I think the tracks on the gps map to mark the lift in wave make all of the difference. In fact, it almost feels like cheating, because you do not need to evaluate drift. Another nice feature is the topography display - find the most prominent geographical features and then make an educated guess about where the wave is based on the wind direction. But I found myself yesterday spending a bit too much time looking at the wind and map and not outside enough.

    I took a quick video with my phone along the Cortina ridge. It would have been a lot better if there was more wind on it, but as Key brought to my attention later, the Cortina ridge is often a combination of ridge lift and wind triggered thermals. It sure was a fun day.


  3. #3
    Join Date
    Jan 2011
    Schleicher ASW-24

    Re: Lesson Apr 19, 2014 - Wave and Ridge

    Thanks Luke. Appreciate the video too.

    I am going to look at a few salient points on the flight, using See You software to display the GPS flight track. The release from tow, the glide towards Hull, the climb at Black Butte, and the flight along the ridge.

    Off tow at Tree Farm - legend is netto vertical speed.

    Click image for larger version. 

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    Note the initial search then the move westward solidly into the primary lift and then the extended ground track loops - one on top of the other - in parallel lines and finally the departure, heading to the north. Disciplined flying. No wandering about once the lift was mapped.

    From Goat, to past Snow Mtn it looks like a clear decision to head upwind to back side of Hull Mtn. In fact, Luke announced that turn, saying something like ... there should be good lift on the downwind side of Hull Mtn... so off he went.

    Click image for larger version. 

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    Departed the cruising altitude of 12,300, and headed straight into the wind. There is anexact wind match with the heading selected and the wind arrow displayed in See You when you play the flight back on your computer.

    The altitude loss. Possibly committed to Gravelly for the land out option, but not really. Luke said he did not commit to Gravelly, but almost. He felt he still had the optin to get home. Would you do it? You would if you had Luke's ability to predict lift, read conditions and his ability to predict if he still had the capability to make it back to the East side of the Snow Mountain.

    I was there myself 30 minutes later, and I too was down below 9,000 feet. Not totally UNcomfortable, since Gravelly was a good landing strip, but it is a long expensive retrieve - assuming Rex has the time to send his resources to get you. I finally departed that same area of lift where Luke made his climb - after climbing up from 8,500 back up to 9,000 ft and feeling comfortable with the expectation of finding lift on the way back to Sheet Iron. I continually monitored the need for a return glide to Gravelly. Here is Luke's trace. I climbed in the exact same location.

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    Sheet Iron to Gravelly is a distance of 12.1 miles Elevation change is 6500 at SIron down to 200 ft at Gravelly. If I had to go back, I would need to make the decision early since there is a 3500 ft (elev) ridge 3.5 miles east of gravelly. In that situation I had a minimum altitude in mind for the trip to Sheet Iton - no less than 7,000 ft. It could be as far as 7 miles to clear that ridge, over totally unlandable terrain, with a headwind that could be as strong as 20 knots, 3500 feet over 7 miles was a fat margin. It is the same logic I used when searching for lift before having to commit to an engine start in the motor glider, or the same logic I use when starting a final from an expected area of lift to an area where I could land.

    After going north all the way to Anthony Peak, Luke ran back to Black Butte - obviously expecting to find lift and - he did.

    Again, the important point here is that Luke was never without a place to land.

    Click image for larger version. 

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    next portion will address the ridge flying.
    Peter Kelly

  4. #4
    Join Date
    Jan 2011
    Schleicher ASW-24

    Re: Lesson Apr 19, 2014 - Wave and Ridge

    The next portion will address the ridge flying.

    16:00 left Bear Valley, and 17:10 left the ridge for the glide home.

    Click image for larger version. 

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    Some questions that may lead to discussion points:

    Would you drop down to the ridge ( from 5,000 to 3,000 ft)? how would you go about it?

    How would you get home? could you make it back from 3 Sisters from an altitude of 2,400 ft.

    Luke landed with a normal pattern at 17:18.
    Peter Kelly

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