airspace

type Circle struct {
	Radius float64
	Centre orb.Point
}

type Feature struct {
	ID       string
	Name     string
	Type     string
	Class    string
	Geometry []Volume
}

type Volume struct {
	ID                string
	Name              string
	Type              string
	Class             string
	Sequence          int
	Lower             float64
	Upper             float64
	ClearanceRequired bool
	Danger            bool
	// The (horizontal) shape will be either a circle or a polygon.
	// One of:
	Circle  Circle
	Polygon orb.Ring
}