flyers movements

I'm pretty confused in the rule book it says if a zooming flyer moves at 18in for combat speed and up to 36in for cruising speed and on the next page it says if a zooming flyer goes flat out for 12 to 24in.

I thought flat out was when you are moving your fastest, can someone help me out here?

A flat out move is done in the shooting phase in lue off shooting. Yes they are redicilously fast.

So they move their 36 in and then moves another 24 for flat out?

That's the way I read it. Or at least for a super sonic flyer.