This is brilliant, a simple idea executed very well. Super fun!
I wasn't big on the timer mechanic, it might be fun to explore the planes having limited explosions instead - with each explosion blowing off a chunk of the plane to communicate the state to the player - and have the plane plummet to the ground if the player takes too long without hitting another plane. I think it'd be a bit easier to parse because as it stands it's kinda hard to predict the time cost of each explosion and set up cool combos.
Great game though, a highlight for me I think! I hope you explore it further post-jam.