Based on
http://www.dhv.de/typo/Betrachtungen_zum_Sa.1194.0.html
which hosts this video clip of a PG wing going parachutal.
Orignial writeup is in German on what can cause PG going parachutal.
This video clip shows a PG flying through rain, doing big ears,
pilot applies too much brake to open it,
wing goes parachutal and then ends up in a spin.
Caused by water accumulated in the trailing edge giving the wing a higher angle of attack.
Cold , high density air can also cause a PG to go parachutal.
More dense air has a higher drag, which can cause the wing to hang
bit a back more.
And during launch one has not got a wing in the normal angle of attack
position.
Another scenario, which got reported, was due to vacuum compress packed
new wings.
which developed problems on their first flight.
The wrinkles caused a non smooth airflow which caused parachutal behavior.
On the second launch the behavior was gone, with the cloth wrinkles
having disappeared.
Flying with short brake settings, tucking your ears,
and applying brakes to release them can cause your wing to go
parachutal
Do Regular checks, at least every 6 months,
and check your wing for line length changes.
In general a wing over time will have the tendency to go for a higher
angle of attack.
Which will result in a better chance to go parachutal.
How does one recognize a parachutal and how to get of it....
No more airflow noise, and the wing going down vertical.
Fully inflated canopy, with wrinkles on the lower canopy cloth.
Release your brakes. If nothing happens after a few seconds, apply speed
bar.
If you have no speed bar, push on the A risers.
DO NOT initiate a spiral dive, which will get you into a spin.
DO NOT apply full brakes, which will result in a full stall.
Be aware that applying any brake can result in a complete loss of airflow.
Which can make things worse.
If you are close to the ground, do nothing.
Any activity to get out of a parachutal can result in a pendulum.
Which can smack you into the ground.
Rather get upright in your harness, legs together and bent,
muscles tightened, and do a PLF.
Some pilots reported that they relied on their back protector.
And walked away.
The DHV backprotector test only simulates a 1.5 meter high fall.
Do not rely on your back protector when coming down parachutal.
Rather prepare for a PLF.
When landing parachutal do not apply any brakes,
or your wing will collapse behind you in the air.
Going parachutal is not a major problem.
DHV had 5 incidents reported in 2003.
The DHV testing got changed in 2003 to test also big ear behavior of
wings.
Safety advice
A wet wing can result in a changed flying behavior.
Avoid on a wet wing big ears, B-Line stall, full brake.
In low temperature ( 0 degree or less ?) avoid big ears or B-Line stall
Most parachutals occur at winch launches when the canopy is not above
the pilot and the pilot goes to tow.
Wings which have been stored for a long time, or packed very tight,
should be ground handled for a while until all the wrinkles are gone.
New canopies have tight tolerances.
The old approach that one can adjust the brakes to the pilot is
not applicable any more.
New wings manuals nowadays state that the factory brake length setting
can not be modified.
Always ensure that your wing has no tension on the brake lines with
no brakes applied.