Nice Shades achievement.

[swenor]

Nice Shades
Open all umbrellas simultaneously on the Stunt airfield

The description is a bit misleading. It suggests you should be opening them all at the same exact moment, which is pretty hard (and not true at the same time).
All you need to do it to have them opened all for a brief moment at the same time. This way you can open one group, then another group and then another (an umbrella stays opened for a short period), and as long as all ubrellas are opened you will get the achievo.

[keedor]

The best way to gain this achievement, I found, was to use several of the yellow stunt planes (one for each set of umbrellas) and have them circle over them in a tight flightpath. This opens all the umbrellas simultaneously and gains the reward.

[swenor]

Nice find. We have 2 solutions then :D