在 FMS 准备过程中， INIT 页面的 TROPO 数据是可以修改的。一般来说我们参考高空气象图来输入一个更精确的对流层顶，但有个问题是，如果航路上对流层顶变化较大，比如从北方的 37000 到南方的 53000，那在巡航过程中是否需要实时进行修改呢？
空客的回复是，不强求，但可以：
请注意，在飞行过程中并没有定期更新对流层顶高度值的要求。
当预计对流层顶高度会有所不同时，建议在驾驶舱准备阶段输入飞行第一段航程的对流层顶高度值。然后，在飞行过程中，若能获取到准确的相关信息，飞行机组可以决定更新在驾驶舱准备阶段所输入的对流层顶高度值。
原文
Q
As required in PR-NP-SOP-60 A FMS PREPARATION - INIT, "In order to have accurate FMS predictions, the flight crew should update the CRZ TEMP and the TROPO values in accordance with the predicted values at the top of climb, if the default values are different."
For flights that cover a relatively large range of latitudes, the change in the tropopause will also be relatively significant, such as from 37000 to 53000. Does the flight crew need to modify TROPO during cruising?
If needed, what is the recommended time interval of modification?
A
For A350 aircraft with FMS Standard S6, the flight crew can enter CRZ TEMP and TROPO values in FMS INIT page according to flight preparation.
The entry of the tropopause altitude is optional. It is used by the FMGS to compute vertical temperature profile and predictions. A precise tropopause value entered improves the precision of the predicted data.
The tropopause altitude entered by the flight crew may have an effect depending on the flight phase considered:
- During the climb phase, considering a tropopause different than the tropopause at TOC could lead to a fuel burn increment due to a modification of the climb speed profile.
- During the cruise, the FMS uses the tropopause value entered by the flight crew for the REC MAX FL, EFOB and ETA/RTA computations.
Please note that there is no requirement to update the tropopause value regularly in flight.
When a single tropopause value is available, it should be entered during cockpit preparation.
When different tropopause levels are expected, it is recommended to enter the value of the tropopause for the first segment of flight during cockpit preparation. Then, during the flight, the flight crew can decide to update the tropopause value entered during cockpit preparation, when this information is available and accurate.
