Possible Clues:

• During singing, like that of a lark
• "Send in the Clowns" site
• Battle of Britain arena
• Region in which there could be intersecting planes
• Where trapeze artists connect
• Bad place to meet
• Bad place to be hanging
• Kind of collision
• Halfway up in region well above the ground?
• Note, over half of dairymen appear to be in flight