@Background Pony #E5F4  
Which is where they SHOULD have the ‘Wingboner’ reflex; I always ‘headcannoned’ that as a reaction to shock, with a few crossed wires as it’s not unusual for sapient minds to confuse arousal with fear (and visa versa)  
And it’s supported by the occasional uses in the show, as they use the ‘popped wings’ kinda like I’d expect them to use the ‘fur standing on end’ if they were cats (especially for the tail; Animators like having bushy cat-tails as a visual indicator of shock) - whether showing shock or severe unease.  
It makes sense too; If you live on clouds, and have wings, it’s useful to immediately go into a glide when something shocking happens; That thing might be ‘fall through the clouds’ and this way you fall a minimal distance AND have more control.

Rd forgot that she’s a Pegasus

Wow that is amazing

@Inkan1969  
It’s always been my understanding that when they get surprised or hit by anything,pegasus dont immediately think to fly because they’re too dazed and flying require to be fully concentrated

@Background Pony #E5F4
 

 
The one moment Rainbow Dash forgets she can fly.

Pictured:Rainbow Dash and Applejack surrounded by faggots