Yeah, the Strikers will follow laws of physics - you can trade altitude for velocity but obviously a Witch is not going to rival any actual plane that outweighs her by an order of magnitude or more. The turning rate depends on her core muscles, as the Witch needs merely to move/twist her legs. The show is a little iffy when it comes to this, as sometimes they can switch from flying to hover in a second, but at other times they need to slow down first before turning. Basically, think of Strikers as a VTOL-capable craft and you're very close to the mark. Close enough for this thread, in any case
"Hanna, coming down on your right, break left on my mark!" You shout through the radio and dive in. Pumping as much magic into your Strikers as you can, your air speed quickly grows and the invader craft looms larger. You swing the massive AT-rifle around and take careful aim.
"Mark!"
Hanna surprises the sleds by making a gut-wrenching 90-degree turn to the left, dropping even closer to the foamy waves. Your target is slow to react - just as you hoped. You hardly even feel the recoil in your excitement as you pump a round after 20mm AP round into the damn thing. Then you're past the trio and start climbing, flipping around so that you can see the effect you had.
Your target is gone, though there is an oily ring in the water thats expanding. The other sled is turning in a large, wide circle - probably aiming for Estonia, since you're between it and the direct route to Leningrad. Hanna is also climbing and coming back to meet you.
"Kyllikki! So good to see you!" She exclaims. She has a Lahti-Saloranta M/26 light-machine gun on her back.
A) No time to chat as it's time to finish this. Take that thing down.
B) Check on Hanna and then head back, the last sled is not a threat.
C) Enlist Hanna to help taking out the sled.