Q1. 其實如果approach用auto pilot(raw data) 同managed兩個有咩優勢？ 咁講la~ 我地用manage 之前，要明白隻機做緊咩。 其實selected同manage個profile都應該一樣，Follow同一個approach profile. 用Fully Managed就可以減少d pilot workload, situation awareness會好d(多d brainpower, 尤其是有failure) 但當個FMS profile有咩問題，開始deviate, 我地都要知點飛selected. 有d舊ge FM有bug. 所以只可以當To waypoint 係 final descent point先可以arm approach~ 所以before final descent point都係selected. 講得好d深！唔明要問~
Q.2不如講下cost index?
Cost index 係airline用嚟計 班機要飛快d 慳d 時間,俾小d 人工; 定飛慢d, 慳d 油.
咁佢地decide 左之後就會係FLT PLN 度.
而呢個number 對我地pilot 黎講唔代表d咩~
只係有個rough idea (CI 高就cruise 快d;CI 低就cruise 慢d)
好似上圖 CI10; pilot就要入CI10 落個FMS 度
(如下圖) 而FMS就會base on 個CI 去compute 個profile. (speed/ vertical profile/TOC/TOD...)
Q.3 如果OP descent + speed Manage(未有speed constrain嘅情況下) Airbus 會aim 咩speed pefer 用OP descent 定Manage定V/S幾時會用邊一個?
Manage speed 會follow FMGES (FMS) 個speed.(Depends on Cost Index)
Manage descent 會respect 埋d constrain.跟住個profile去!
但係OPEN DESCENT 係fixed thrust (IDLE) , 會maintain idle until ALT.
OP descent/manage descent/ VS 就睇情況. 如果check 哂所有constrain 都ok;就manage la~小d workload
但係有traffic ge 時侯會用VS去slow descent; 因為衝落去都無用又徙油~stay high~
Hi, I'd like to know more about how Vx, Vy change with altitudes.
For Vx IAS, by illustrating “thrust available Vs thrust required curve” I understand it increases with altitude because thrust available shifts downward whereas thrust required shift right, that means airspeed increases in order to achieve maximum excess thrust. But this is 'How" only, but why shift in that way? I still couldn't get it in terms of physics.
The same for Vy. Hope someone might help, cheers.