[injb]

Bernoullis principle isn't necessary though because there are planes with symmetric wing sections that fly just fine, not to mention the fact that planes with conventional wing sections can fly upside down.

The article should probably be called "Half of people can explain why planes stay in the air, but the other half doesn't know they're wrong".

[rawgabbit]

Can you tell me the name of a commercial plane with a symmetric wing cross section?

[p_l]

Extra 300 would be one example. Generally you use symmetric profiles for acrobatic planes - as all profiles have their own pros and cons, and symmetric ones increase capabilities in inverse flight (and acrobatics) while sacrificing low speed and straight flight performance.

[p_l]

Symmetrical wings still use Bernoulli's principle.