121.353条的内容如下：

除经局方批准外，合格证持有人在无人烟地区上空或者在局方规定的需要配备紧急情况下进行搜寻和救援的设备的任何其他地域上空（局方在该合格证持有人的运行规范中规定）实施运行时，该飞机应当装备有下列设备。。。。。。

有人问我这个无人烟地区到底指中国的什么地方？

我只能说我也不知道。似乎国内没有人给过定义。

正好找到一份FAA的NOTICE：《Operations Over Uninhabited Terrain Areas》

The requirements of § 121.353 were implemented to increase the chance of survival and rescue for airplane occupants in the event of an accident or emergency in areas of uninhabited terrain. The Preamble to the Final Rule that amended § 121.353 in 1995 (60 FR 65832) did not attempt to change requirements for flying over uninhabited terrain, nor did it attempt to clarify or amend the definition of “uninhabited terrain.” The Preamble stated that defining uninhabited terrain is “not necessary …[s]ince implementation is on a case-by-case basis.” Currently, no legal interpretation that speaks to the definition of “uninhabited terrain” exists and none are expected.

妈的原来FAA也说没定义。顺手找到文中提到的1995（60 FR 65832）：

In addition, this rulemaking does not define ‘‘uninhabited terrain.’’ When the predecessor regulation to § 121.353 was proposed in CAB draft release 58–24 in 1960, ‘‘uninhabited terrain’’ was defined as ‘‘flights for long distances over frigid or tropical land areas for which the Director finds such equipment to be necessary for search and rescue operations because of the character of the terrain to be flown over.’’ When the rule was adopted, the wording was changed to provide the Administrator more flexibility in identifying uninhabited areas.
Since implementation is on a case-by-case basis through operations specifications, it was determined that the proposed wording was not necessary. This provision has been in effect for over 30 years without any problem about the meaning of ‘‘uninhabited areas.’’

其实我看不太懂1995（60 FR 65832）到底说的是什么，看样子是在修订规章时的流水账。

所以，FAA的解释说在1960年的时候有过解释，但是为了更便于管理者灵活地使用这一条，解决办法是在运规中case-by-case的批准。

但是我好像也没看到过有国内公司批准这条运规的。有谁见过请告诉我。