Anywhere: an altitude allowing a safe emergency landing without undue hazard to person or property on the ground; Over Congested Areas: an altitude of 1,000 feet above the highest obstacle within a horizontal distance of less than 2,000 feet; Over Unpopulated Areas: an altitude of 500 feet AGL; Over Open Water or Sparsely Populated Areas: an altitude allowing for a linear distance greater than 500 feet from any person, vessel, vehicle, or structure; Helicopters: If without hazard to persons or property on the surface, an altitude lower than in definitions 2, 3, and 4 above, provided in compliance with any routes or altitudes specifically prescribed for helicopters by the FAA.