Originally Posted by
sourabh
Hello everyone . I am not able to understand the various thrust modes in A320. According to me in climb and descend the mode should be speed mode because we climb or descend with constant speed but AFM says the thrusts is in power or thrust mode.
Can anyone please help me in understanding various modes of Thrust and open climb mode also.
Hi sourish,
To help with your understanding of the modes, it would help if we knew a bit about your experience.
Is this your first Turbine/Jet Rating?
Is this your first rating on something with a decent AutoPilot/Flight Director system?
The reason I ask is, in the bigger transport Jets, (EJet, 737, A320,777, A330 etc) the Thrust Modes and the Vertical modes are connected, unlike the training aircraft or even smaller Jets and TurboProps.
Lots of good advice already, but to really understand the Thrust Mode, you need to understand the Pitch Mode. Re Read the first 3 answers and they will provide you with the clues you need to get your head around this.
To use some "familiar" terms.
OP CLB or OP DES = SPEED ON ELEVATOR - Fixed THRUST setting and PITCH to control the speed.
OP CLB = CLB THRUST - and the speed is set via FMGC or FCU(selected) and is maintained by the Elevator pitching the aircraft
OP DES = IDLE THRUST - and the speed is set via FMGC or FCU(selected) and is maintained by the Elevator pitching the aircraft
SRS, V/S, CLB, DES, FPA, ALT, ALT*, ALT CRZ, ALT CST *, ALT CST, G/S*, G/S, FINAL APP and FD's OFF = SPEED ON THRUST - Fixed PITCH and THRUST to control Speed
(I think I got them all?)
In all these modes the aircraft pitches as directed, eg: 1500fpm and the thrust is adjusted to maintain the Speed set by the FMGC or manually via the FCU.
-EXCEPT-
CLB is basically the same as OP CLB = Max Thrust and Pitch for Speed but it will conform to ALTITUDE constraints so can shallow out the climb and reduce the thrust to maintain a speed.
DES is a 2.5º path at slightly more than IDLE thrust and will also conform to ALTITUDE constraints. DES also has the ability to go 20kts faster or slower to maintain the path and/or increase/decrease thrust as required to stay on the Path.
It is difficult to visualise, but have a search around on Youtube and you should be able to find some videos of the aircraft in action. It will make a lot more sense once you see it in action.
Good luck and have fun.
As a side note, the fact that the thrust levers don't move is immaterial, you get ALL your Thrust information from the FMA, ASI and N1 gauges. (I have flown 3 types of jets with movable thrust levers, and 1 without, you never set thrust from the position of the thrust lever in the quadrant in flight. eg: Power (N1) + ATT = Performance)