Pre-Frontal and Partial Lee: The makings of a bipolar variometer

The forecast ...

Winds:
0m: light and variable
1000m: 240 @ 8 kts becoming 260 @ 12+ kts post noon

Lapse Rate:
0m to 700m: -3.0 C/200m (unstable).
700m to 1200m: -1.5 C/200m (inverted)

Cloud Cover:
None expected over terrain under 1200m due to strong inversion.

Flying picture:
Approaching warm front expected to shutdown strong thermic activity with lowering cloud base but providing good to strong ridge lift. Use of Harvest Market bailout LZ a few kilometres behind launch expected.

The reality ...

We arrive on launch  @ 11AM to find the cycles blowing straight in from south west and increasing in strength and duration. Occasionally, the last remnants of the nightly catabatic outflow from Harrison Lake would make its presence known with a north cross at the bottom of launch, while smoke in the valley indicated that the increasing meteorologic wind was not yet a concern, likely held in check for the time being by the inversion.  No cloud development over launch rounded out the reassuring synoptic picture.

Knowing that winds were only going to increase as we passed noon, I quickly kit up in the wind shadow behind launch, rosette up the wing, and proceed a third of the way down the slope. The cycles were making laying out the wing unwise, requiring a progressive A and C riser inflation straight from the rosette.

Those last remnants of catabatic outflow? Not so last remnant as one might think. The wind sock at the base of launch was still showing cross cycles while the sock at the top was showing straight in.

Timing would be key to a successful launch. Launch during a cross cycle and I would end up kicking tree tops.

And so I start the waiting game, watching the upper and lower socks and anticipating the moment they would reach consensus.

A few minutes pass, the lower sock begins to show straight in while the upper is dead still. The cycle makes its presence felt while my fingers wrap tighter around the A riser mallions. The cycle grows and I bring the wing overhead, keeping it in check by softening tension on the Cs.

Turn.

One step.

A gust.

Pause.

Kite the wing, allow it to settle following the sudden change in airspeed.

Two more steps, airborne, into the pod ...

... and right into the claws of the sink monster.

I immediately begin extracting feet from the pod, thinking I might have snagged the speed bar (more like speed rope). No dice, but the wing planes out and I no longer need to pick between tree LZs A, B or C.

And proceed directly into the arms of the lift monster followed quickly by another visit from the sink monster.

Two more times, I rapidly yo-yo between +-4.0 m/s, my variometer concurrently sounding lift while showing sink (and vice versa). A Hand and Hammer of God type of flying experience.

Some might call managing a wing under these conditions active piloting, me, personally, would call it spastic puppet chair dancing. In either case, the wing remained overhead with little oscillation and nary a collapse.

Fleeing what is obviously a partial lee situation coupled with sharp edged spring thermals, I make my way to the LZ and land.

A short flight but an educational one. +1 for the judgement bucket.

The picture below identifies the unusually strong catabatic outflow from Harrison Lake rotoring over the ridge to the north of launch (in blue) versus the thermic activity making its way up the southwest face of the mountain (in red).

This is a classic partial lee situation and can be very dangerous, a trap lying in wait for unsuspecting pilots. One enters it expecting to find a consistent thermal generator only to be caught in a washing machine of particularly violent rotor.

Learning More

Kelly Farina @ Austrian Arena examines dangers of partial lee flying in one episode of his video series 'Understanding the Alps'. It would benefit every pilot to watch this video and become familiar with both the risks of partial lee and the techniques required to identify it in advance.

For our friends in Europe this weekend

'The Wind of Rotor'

'I flew into a Foehn Wind of Rotor,
I went down, down, down as the winds went higher.
And it churns, churns, churns.
The Wind of Rotor, the Wind of Rotor.'

- Johnny Crash

Checklists

After watching folk begin to unpack kit on launch only to start off in a diatribe of muttered curses, one can certainly appreciate the use of a checklist prior to leaving for the hill (in addition to the preflight taught during student progression prior to launching).

The one I developed prior to attending Nationals last year went as follows (some sage advice suggested transcribing this to the inside cover of ones logbook):

Check List

Night Before:

Review forecast/terrain

Download Camera

Download Vario

Charge Vario*

Charge Radio*

Charge Camera*

Charge Phone*

Day Of:

Confirm forecast

Check SPOT

Check Vario

Check Radio

Check Camera

Check Phone

Fill Ballast

Fill Water

Food

Sunscreen

Tylenol

Lip Balm

Bug Repellant

Harness

Wing

Flight Suit

Gloves

Helmet

Boots

Thermal layers

* I recall an adage that went something like, "Be sure to feed your horse before feeding yourself." The importance of plugging everything in before taking off for dinner/celebratory beer during a comp cannot be overstated. 

Flying Fast Forward - Summer 2012

After receiving a taste of XC during the Feb 2012 XC Open/Camp in Manilla, Australia - I decided 2012 was the make or break year for my flying. Either become a competent Intermediate pilot with the ability to successfully execute consistent XC (Cross Country) flights, or hang it all up, sell the kit and find another sport.

I quickly came to realize that self directed improvement for a novice is slow due to the trial and error method of learning resulting from a limited experience base, rendering a steep learning curve. Coaching is one method to reduce the slope of this curve by capitalizing on the experience of another; having an overall goal helps to direct a coach's effort.

In my case, the coach was Martina Lang from Jet Set Paragliding and the goal was the 2012 Canadian Paragliding Nationals in Pemberton (a test of XC ability for a novice pilot if there ever was one).

This video captures some of that training: flying during peak conditions, scratching, and spot/out landings, all while executing a flight plan.

Intermixed are the results during Nationals and a subsequent heli-para trip into the Tantalus Mountains near Squamish.

Enjoy!

Paragliding - Easter Weekend, 2013

Flying Easter Weekend - 2013

A high pressure system parks itself over the Lower Mainland, bringing with it unseasonably warm (and increasingly stable) air. This provided a rare spring time opportunity to break out the Wildcat (a high end EN-B that I am somewhat under weight on) and repeatedly appear at the top of the stack, even out climbing Ozone's new Delta 2 (which I happen to have on order).

Some would say it's the wing. Me, personally, thinks it's the pilot.

Good Friday - inversion at 1200m.
Saturday - inversion at 650m, rising to 750m by sunset.
Easter Sunday - inversion below launch, did not fly.

Judgement, Skill, and a golf ball.

Someone asked last night about pilot opinions of flying with a good luck charm and examples of what we kept in our kit.

A golf ball.

The story: last July, late afternoon, a few of us arrived on launch with a cloud layer moving over the back of the ridge from the south. The cycles died off and the typical cross launch wind disappeared, leaving dead calm. Figuring I had surrendered a twenty for the ride up and expecting nothing more than a 4 minute sled ride down, I kitted up and set up for the mad horde charge off the 'cliff'. Launch was as expected for the conditions and a quick turn west to go put a km in before turning east to set to land.

Or so I thought.

I start my short run west and the vario starts chirping, point two, point five, back and forth. Odd, the sun has been hidden for near half an hour, there is no dynamic lift, and cloud base is nearly 5000 feet above me, clearing the mountain peaks. I wander further west by a few hundred meters to 'tag' a ridge, thinking this is great. Then it hits me, a comment from Godfrey during the 2012 Australian XC Open regarding it becoming lifty everywhere for no apparent reason. I beeline for the LZ (landing zone, situated next to a golf course) and snap off a succession of quick 360's.

One hundred meters off the deck and the lift is gone. I touch down to discover a golf ball sitting in the grass at my feet. Not five minutes after, the sky unleashed its wrath with one of the strongest storms of the season. 

Two weeks later. I am at the Canadian Paragliding Nationals, laid out on launch with the words from the task committee in my head - 'thunderstorms expected'. I think of the golf ball from that fateful day (that I had since put in my flight deck), decide I'd much rather have a beer than fly, and pack up. Half way down the hill some of nastiest clouds I had ever seen in this region cleared Mt. Currie and began to unload on Pemberton. The fatal result of this storm system made itself known within a few hours, costing one competitor his life as his wing was rotored into a fast moving river.

I like to think of skill being the result of trying something and getting it right, where as judgment is the result of trying something and getting it wrong. The golf ball is my reminder of those two days and the initial gain in judgment and subsequent gain in skill.

(an edited/PC version of this post can be found on iParaglide.com)