FAR 91.119 Minimum Safe Altitudes: General.
最低安全高度: 義務付けられている最低飛行高度は?
離着陸時を除き、最低必要とされている高度は、
(1) どこでも、Anywhere! エンジンが故障した際、地上にいる人間や資産(不動産など)に危害を与えずに緊急着陸が出来る高度。
(2) 人口密集地 Congested Area、Desely Populated Areaでは、
半径2,000フィート内で一番高い所から1,000feet以上の高さを飛行する事。
(3) 人口密集地以外では
地上より500feet以上を飛行する。
(4)
海上(Open Water)やひと気の無い範囲(Sparesely Populated Area)では、
人、船、自動車、建物から500 feet以上離れて飛
行する事。
注意: 1000 feet有ればOKと勘違いしてしまいそうですが、現実はEngineが故障しても地上のものに危害を加えない高度ですよ。
Except when necessary for takeoff or landing, no person may operate an
aircraft below the following altitudes:
(a) Anywhere. An altitude allowing, if a power unit fails, an emergency
landing without undue hazard to persons or property on the surface.
(b) Over congested areas. Over any congested area of a city, town, or
settlement, or over any open air assembly of persons, an altitude of 1,000
feet above the highest obstacle within a horizontal radius of 2,000 feet of
the aircraft.
(c) Over other than congested areas. An altitude of 500 feet above the
surface, except over open water or sparsely populated areas. In those cases,
the aircraft may not be operated closer than 500 feet to any person, vessel,
vehicle, or structure.
(d) Helicopters. Helicopters may be operated at less than the minimums
prescribed in paragraph (b) or (c) of this section if the operation is
conducted without hazard to persons or property on the surface. In addition,
each person operating a helicopter shall comply with any routes or altitudes
specifically prescribed for helicopters by the Administrator.