11 minutes would be pretty standard. I know a paramedic in the park (she no longer works there) and procedure would be a call to the ride to assess. The severity of the accident may not have been apparent to ride staff, especially with the position and height of the ride. Remember, those taking photos are at a different vantage point to staff.
AT is in a reasonably remote village some distance from the main hospital. Calling emergency services immediately before assessment isn't usually done because more often than not you've got a kid with a nosebleed or someone who's just been sick and fetching an ambulance miles off the beaten track for that would be overkill.
The Ride Operators are not much older than kids and would follow protocol - call the Park First Responders. Their base is by the entrance so they would need to get across the park, into the belly of the ride to the casualties and make an initial assessment, which would have been to immediately call for emergency assistance. 11 minutes isn't bad at all.