crash and burn and skies of fury

[Charistoph]

.....A Flyer can end it's move over enemy models?

Can someone point to the rule which says a flyer is wrecked if it can't move the full 18"?

Really struggling to see why this is an issue

It's in the Flyer rules, Charon quoted them.

FLYERS AND OTHER MODELS
Models that physically fit under a Flyer model can move beneath it. Likewise, a Flyer can end its move over such models. However, when moving this way, enemy models must still remain 1" away from the base of the Flyer, and the Flyer cannot end its move with its base within 1" of other enemy models.

ZOOM
Flyers can usually only make a special kind of move called Zoom. Some can also Hover – see opposite. Zooming allows the Flyer to move at fantastic speeds, making it very difficult to shoot down, but limits its manoeuvrability. If a Flyer Zooms, it has a Combat Speed of 18" and a Cruising Speed of up to 36". However, as a certain amount of forward thrust is required for the vehicle to stay in the air, a Zooming Flyer can never voluntarily move less than 18" in its own Movement phase. If a Zooming Flyer is forced to move less than 18" in its own Movement phase, it is automatically Wrecked.