The Science of a Wave Flight:
1/26/18 10am: Daniel Sazhin, Philip Chidekel and John Bird discuss the weather forecast:
Daniel: Tomorrow looks very interesting at Wurtsboro. I’m curious to hear what you guys think about the forecast.
John: Weird. I’m not sure what to make of it
Daniel: Scutter thinks 240 wind:
John: Look at the sounding for 1400. There’s something weird going on with his forecast
Phil: Quick look: pre-cold front so the winds will be from an ok direction and the profile will be favorable… but it will rain at some point so be careful.
Phil: I don’t have any idea—I’m literally between a test and a quiz.
Daniel: This is the final exam! More important!
John: Yeah, it will likely fill in. I don’t get the feeling that any of the models have a great grasp on the moisture for tomorrow. SREF is pushing for later in the day on almost every member, but the NAM thinks as early as 1. This is weirding me about Skysight: (the hour immediately before and after look wildly different from this:
Daniel: That’s really interesting, when it comes to cloud cover. GFS as a whole is not picking it up either. But disregarding moisture for now, how does the wave look? And yeah, Skysight just went totally wonky. Between 12 and 12:30pm, there is an anomaly. I think it’s between model runs or something.
John: I’m not really sure what to think of the day. The wind and stability would indicate wave, I think Skysight might be overstating maximum altitude a bit, but there’s some weird stuff going on so idk:
Daniel: What’s happening at 4000 meters?
John: There’s a bump in the temperature gradient and wind profile.
Daniel: What sounding are you using?
Daniel: Can I see it?
John: Let me see if I can make it visible:
Daniel: Okay, so it doesn’t like that bend back after the inversion layer. How does the score parameter change over time?
John: I’m not really sure. This profile is just weird.
Daniel: Is it weird, or are the models are confused? Or both?
Daniel: Sounds like toward [this evening], it should clear up a bit?
John: idk we’re pretty close to the front which is going to be having impacts, I don’t usually look in-depth at prefrontal days so it may just be something I’m not used to looking at.
John: but prefrontal complexity also means lower confidence in model outputs.
Daniel: Sure, but that said, for a prefrontal day, it’s pretty dry early on. If there’s a day to give it a go, this has some reasonable promise.
John: Yeah, you probably would want to go earlier than later…at some point in the afternoon that moisture is going to arrive.
Daniel: And the moisture is coming in high, not low. At least from what I’m looking at. I mean eventually it will come in low too, but not before 4pm right now. Right now, the system looks like it will collapse between 4pm and 8pm.
John: Short range ensembles suggest low moisture is possible as early as 1, though not likely.
Daniel: I can see that NAM is not as happy
John: Here is what I have enough confidence to say:
* there will probably be wave
* I’m not sure how high
* watch out for the moisture
* check tomorrow morning when maybe there’s a bit more certainty
* a pirep would be interesting, forecasting these days will require experience
Daniel: It sounds to me that there’s a lot of uncertainty in the forecast. Perhaps tonight the models will have a bit more agreement? Basically here’s my position. Pre-frontally, it looks quite dry. As the front starts moving in, the moisture moves in very rapidly. Exactly what time is yet to be seen. The manner in which the system is predicted to collapse will influence decision making. A significant risk factor is that none of us have experience with forecasting these kinds of days. It sounds to me a good way to handle this set up is to launch early and build in a buffer in time relative to the collapse of the system. A number that popped into my head is say 2 hours (at least). So for instance, if the system begins decaying at 4pm, I would plan on being on the ground by 2pm. If it’s 1pm, this compresses the flying window in an unfavorable way.
Phil: I agree with John’s analysis–moisture is the wildcard, and models are bad at forecasting this. There should be wave. I don’t think it will be quite as good as Skysight thinks… but it will be there. Be careful.
Daniel: Careful is the most important factor here. I take that very seriously. Okay, so nominally this day is worth exploring. Tonight, let’s look at the models closely and look at the wave
and look at the moisture.
Phil: I’m not sure you’re going to get much more clarity this evening other than: launch early and be vigilant.
Daniel: That’s fair, but I want to see the volatility in the models over the day. Do they trend toward agreement? Does Skysight do something even more wonky? Sure, the models only go so far. And in the air, it will require approaching it in the context of judgment quite differently because the models can only do so much. But nonetheless, I would like to see what changes throughout the day. The things I am most interested in is the window of wave conditions and the timing of the collapse.
(Several hours later)
Daniel: When do you think it will be possible to launch? I see a very steep inversion in the morning. Is there a threat of fog?
John: Broadly consistent, maybe slightly favoring earlier but I don’t have enough confidence in the model to say that that is real. Fog / low cloud is definitely a risk early. I don’t know the area well enough to say when it’ll clear at Wurtsboro. Monticello will clear between 8 and 10 probably.
Daniel: [Wave] consistent up to ~4000 meters?
John: Yeah, within the confidence I have in the forecast.
Conversation with Phil:
Daniel: So, am I completely out of my mind trying tomorrow?
Phil: Look, there will be wave. This I am confident of. I don’t think it will be a 15000ft day. But there will be wave. However, it will also rain at some point. This I am also confident of
Daniel: How high?
Phil: I dunno… 9000ft is what I’m tempted to say, but without much evidence.
Daniel: And why?
Phil: I dunno.. John’s 1/l graph went above 14 km around 3000M. So, that would equate to a climb to around 10000 ft.
Daniel: When do you think the precip will come in?
Phil: I wish that were more predictable… I don’t think it’s going to be a problem till later in the afternoon, but this stuff is very difficult from a modeling perspective.
Daniel: I appreciate that it’s difficult. I can accept a high confidence interval, meaning say 4pm, plus or minus 2 hours, or whatever it may be. I accept that once in the air, I will need to fly the weather I see. I am just trying to get a sense of what I’m dealing with. If the boundaries get uncomfortable, I could bag the effort.
Phil: I don’t think it’s going to be a problem until the afternoon… but I can’t really give you an interval like that with any hope of being on target. You don’t understand–it’s not like there is model agreement at 4pm, and then a few stragglers at 1pm. That’s not how this works.
Daniel: Then how does it exactly work? This is quite important.
Phil: There is large spread as to what type of moisture occurs at what altitude and when across all the models. This is what John was saying before… I can say this much: you should be fine flying in the morning. I do not think it will be raining until late afternoon. However, there is potential for things to become IMC at the altitudes you will be flying earlier than that and when that occurs is something that is very difficult to model. Anything at the higher levels is more within my control. I can monitor that and adjust accordingly.
Daniel: The other thing, what do you think about fog in the morning?
Phil: I can’t see that being an issue, certainly not extensively. Unless: how much snow is still on the ground up there?
Daniel: There could still be snow. It may have melted this week completely, or not.
Phil: I don’t think it will be too big of a deal.
Daniel: That’s good to know, then I can push the start back harder.
Phil: Like I said, I don’t think you will run into trouble until at least 2pm… but this is really difficult stuff to be certain of.
Meanwhile, calls were made to Dan Yates in order to organize operations. As the glider of choice would be the Grob Twin Astir, I looked for a back-seater. Steve Beer was called first and he promptly answered. I told him to find an oxygen system and arrive at Wurtsboro by 8am.
Next, I made the calculations for decision altitudes necessary to make alternate landing sites. Plan was to tow 30 miles downwind of Wurtsboro airport to the wave area. With the wind predicted to be at 45mph and a 40-degree headwind component coming back, I would be committed to either the wave lift, or an immediate landout. The relevant options were Kingston, Ellenville and finally Wurtsboro. Piolis was omitted due to the crosswind and its unsuitability for a wide glider like the Grob.
Making the calculations showed that the minimum altitudes to make it to the airports were as follows:
The decision altitude to stay in the wave or head to Kingston was 5500ft MSL. I also reviewed relevant fields on the SW side of the Ashokan reservoir on The Ridge Map, in case anything went really wrong.
Plan was to tow to 6000ft to the wave area indicated by Skysight:
With the operations, weather and flight plan sorted out and after spending an hour and a half checking over all my equipment, I was ready to go.
1/27/18 Daniel, Steve Beer and Daniel Shrug Yates go soaring
The Art of a Wave Flight
The alarm went off at 5:45am and my eyes shot open. Damn, the quality of my rest wasn’t ideal. I will feel tired later on today.
30 minutes later I was out the door, driving on the dark Brooklyn streets. Something moved within me to go a different route today. With the highway free of cars, I chose to drive through Manhattan instead of going across the Verrazano Bridge.
The car humming along the BQE, I saw the first of the sun’s rays started to radiate throughout the sky. The Statue of Liberty was on my left and the whole New York skyline off my bow. The city that never sleeps felt a bit lethargic today.
As I snaked around the BQE, I looked at the skyscrapers. What was it like when the natives lived here, only 400 years ago? When it was an untouched natural expanse?
A right turn and I’m on the Brooklyn Bridge. My old university off my right, round the bend and I’m shooting up the FDR. As I’m navigating the potholes, I looked at all the high-rises, skyscrapers, smokestacks, bridges, cars…. I felt enveloped in the greatest human creation. Millions of people around me, a jungle of concrete and twisted metal.
This is real.
Billions of lives have been affected here. Trillions of dollars’ worth of commerce has flowed through this harbor or through the electrons zipping into the computers in those tall buildings. Millions of immigrants had their first start in the squalor of the Lower East Side. At the UN, nations have been founded, wars have been reconciled and the plight of far-off peoples debated.
I pondered the absurdity of what I set out to do. This crazy idea of taking a sailplane into the sky with the hope of there being a massive air-current that will lift me thousands of feet into the sky. I am the only one thinking about soaring, among all these millions of people.
Isn’t this the definition of insanity?
What is my business doing this anyway? Shouldn’t I be in this city, being like everyone else? Or at least sleeping at this ungodly hour…
A left turn and I’m on Rt.94. Several minutes later, the George Washington Bridge flashed into view. Looking off my left, at the Manhattan bank of the Hudson, I saw where Wolf Hirth had soared his sailplane in front of the eyes of thousands of people. He was also the pioneer of wave soaring.
Crossing the bridge into New Jersey, the landscape was changing. I saw hills and more and more trees. Back in New York state again. The hills are getting higher and the sun is shining. Onto Route 17 and the ridge slowly comes into view.
The way things are done here is different. It feels like you can wander into a corner and no one will find you.
Coming over the ridge now and I see the expanse of the Wurtsboro valley. The swamp, meadows, fields and trees. Granite rocks, formed billions of years ago. Rivers that had carved this land over millennia.
This is real.
And I decided that indulging in the greatest human fantasy of flight was the realest thing I could do.
I arrived at the airport at 8:15 am, to find the glider mostly prepped. My back-seater, Steve had arrived 45 minutes prior and got all the covers off and getting comfortable with the back-seat of the club Grob. We quickly got to work prepping all of our equipment. Securing the oxygen was a challenge, though we finally figured out that we could mount the bottles horizontally, secured to the belt-attachment points. An hour and a half later, we were ready to go. The wind was dead calm. Towrope hooked up and we’re off into the air.
500ft later, we turned to the northeast. I handed off the controls to Steve and settled in for the long aerotow ahead. As we rose, I saw the valley was enveloped in a thick haze. Looking NW on the plateau was also just a bit hazy. And the top of Slide Mountain, our 4100ft monolith was totally clear. There was not even the slightest ripple of turbulence and we were moving at the speed of heat.
The wind has to be spilling over the mountain and bouncing into the inversion. The wave has got to be there.
27 miles into the 30 mile tow and dead smooth. I was getting antsy.
The towplane dips down slightly. A minute later, it moves up just a whisker. I asked Dan on the radio, “Did you change the power setting?” He replied, “No change.”
“Must be wave,” I thought. I told Steve, “My controls” and pulled the release handle.
Two knots! We got it!
I radio back to Dan, “Two knot wave! Two knots!” He answered, “I love it when a plan comes together!” and started the long slog back to Wurtsboro into the 45 mph wind.
Smooth as can be, we gently rose in the silky air. The width of the wave was only several miles wide, but it was as honest as can be. Steve was absolutely thrilled, flying the glider, doing short beats, with the crab angle only 20 degrees from the wind.
The view was spectacular. The sun off my bow, the Ashokan reservoir off my right wing and the expanse of the Catskills underneath. The valley enveloped in a milky haze.
Climbing through 9000ft, I was a bit tensed. Can we make 13,000ft so we can comfortably make it back to Wurtsboro? Climb rate unfailing, we kept going up at a steady 2 knots.
11,000ft, we were climbing faster. Up to 3 knots and we shoot through 12,000ft. We have it made! And this wave is going and going!
13,000ft, 14,000ft. Steve remarks, “This is easy!” I laughed!
15,000ft, 16,000ft and the wave is unfailing. I remembered Steve is an instrument rated pilot. Maybe we can somehow convince Boston Center to open up the airspace and let us keep climbing?
I took the controls and he looked around for a frequency. We talked to New York Approach and then Boston Center. They were kind and terribly confused as to how a glider got to where we were. When we said negative transponder, they couldn’t oblige our request. Oh well, next time and hopefully when we have a wave window!
We leveled out at 17,900ft. I could make out the outline of the Hudson River as it made its way to the Atlantic. The city was covered in a milky haze, the skyscrapers just barely visible, stifled by the overwhelming ocean of air.
There are so many people that made this flight possible. Thanks Phil and John for the in-depth weather analysis. Thanks Dan Yates and the Wurtsboro team for this very special tow! Thanks Steve for your help and sharing this experience. And thanks to Aero Club Albatross for providing the high performance Grob, which made this flight possible.
Find the flight log here.