A319/A320 Auto Thrust
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A319/A320 Auto Thrust
Let me preface this by saying that I am new to the forum and an aspiring pilot. This is more of a sim question but it will help me prepare for the future. My question is, it is my understanding that Airbus says that the AT should always be on during flight and that it should be in CLB detent until landing/retarding before touchdown. Boeing on the other hand has the pilots control the glideslope by adding or reducing power. From an airbus perspective, when lying with AP off and AT on (CLB), how do you maintain proper glideslope if you are not controlling power? Is it simply the sidestick or is it more complicated? This is assuming I am stable by 1000ft. In my sim, I find myself above or below the GS and I am more or less chasing being on profile. Typically I switch AP off around 1000-500ft in normal weather. On the flip side, I know that some airlines have a SOP on whether or not you are to flying manually with AT on or off. Do any US airlines allow you to fly the 319/320 without AT during landing?
Only half a speed-brake
Hello.
The Airbus is normally flown the way you understand. On final approach following the GS, the sidestick is used to command changes in pitch and the resulting change of vertical trajectory. FBW system will trim the horizontal stabilizer automatically, and A/THR will adjust the engine thrust setting to match the target speed.
Thank you for the introduction. Knowing a bit about your situation makes answering easy and enjoyable at the same time. My generation and younger, almost all flew computer simulations before anything else.
Welcome to PPRuNe.
The Airbus is normally flown the way you understand. On final approach following the GS, the sidestick is used to command changes in pitch and the resulting change of vertical trajectory. FBW system will trim the horizontal stabilizer automatically, and A/THR will adjust the engine thrust setting to match the target speed.
Thank you for the introduction. Knowing a bit about your situation makes answering easy and enjoyable at the same time. My generation and younger, almost all flew computer simulations before anything else.
Welcome to PPRuNe.
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Thank you very much! I guess it will just take time and more practice. I think part of my issue might be that I am making too big of movements with the stick. thanks!
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Boeing on the other hand has the pilots control the glideslope by adding or reducing power.
The Airbus autothrust is an excellent piece of equipment, and due to the FBW control system there's barely any (noticeable) pitch/power couple as seen in conventional (non-FBW) aircraft with underslung engines. This enables you to happily leave the authothrust engaged all the way down to the deck even when flying with the autopilot switched off. The autothrust will manage thrust to achieve the commanded speed, whether that be pilot selected or FMGC derived. Without going into too much detail, essentially the autothrust will manage the speed in the range from idle thrust to climb thrust; hence the logic of the thrust levers remaining in the Climb detent.
On the flip side, I know that some airlines have a SOP on whether or not you are to flying manually with AT on or off. Do any US airlines allow you to fly the 319/320 without AT during landing?
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While the autothrust in the A320 family does an adequate job, i would never describe it as outstanding, nor the FBW with its noticeable few millisecond delay between external influence and correction. As someone who has flown the first 2000 hours or so on airbus (after 15 years of boeing) with autothrust off during approach, i certainly prefer it that way. Now that i work at an airline that likes us to use autothrust, i do that. But it is actually easier flying manually with manual thrust.
That said, fly-by-wire boeings have the same advise: keep autothrust active at all times, even during manual flight.
That said, fly-by-wire boeings have the same advise: keep autothrust active at all times, even during manual flight.
Bradzim21 I think you are misunderstanding how the ATHR works on the A320. The CLB detent is simply an electrical switch position that tells the autothrust system to control the actual thrust BETWEEN a minimum of idle and a maximum of climb thrust. Thus the thrust will be changing, as required, to control the speed on final.
Boeing 737 Classic (and 75/76?), has no FBW, so there is no compensation for the pitch/power couple caused by the underslung engines. Therefore when flying manually, Boeing recommend using manual thrust - so you know to compensate with elevator input and trim when adding or reducing thrust.
Airbus FBW however, does compensate for pitch/power couple, so it is entirely practical to retain A/THR when flying manually - it accelerates and decelerates neutrally. Airbus FBW also has a feature on approach called Groundspeed Mini(mum), which for example might suddenly increase the thrust a lot with a headwind gust, (to maintain a groundspeed rather than an airspeed). This is sometimes not very intuitive to follow in gusty conditions, so it can be easier to let the A/THR take care of it.
You can fly an Airbus completely manually though.
@FlightDetent, Surely when following a glideslope, (the OP’s question), pitch controls path, thrust controls speed?
Airbus FBW however, does compensate for pitch/power couple, so it is entirely practical to retain A/THR when flying manually - it accelerates and decelerates neutrally. Airbus FBW also has a feature on approach called Groundspeed Mini(mum), which for example might suddenly increase the thrust a lot with a headwind gust, (to maintain a groundspeed rather than an airspeed). This is sometimes not very intuitive to follow in gusty conditions, so it can be easier to let the A/THR take care of it.
You can fly an Airbus completely manually though.
@FlightDetent, Surely when following a glideslope, (the OP’s question), pitch controls path, thrust controls speed?
Only half a speed-brake
Uplinker: wish not to derail this, only protest seeing what I found not to be true. That the "on a jet pitch controls path, and thrust the speed" is the proper new trick opposite to the classic Pitch(+trim) control speed, thrust adjusts the sinkrate.
I'd call the p=p & t=s way the flight-director method, but since nobody told me to change over, I use the latter and it works perfectly - without the FD. My take on the merit of "On the jet" is that it might have applied to single engine, centre-line thrust jet fighers after the WWII prop era, and later for 727/Caravelle/TU104/TU134 tail mounted machines. Sure, adding thrust would just speed you up. But is is not any magic of the propulsion, but the old pitch-power couple not being there. ATRs work that way too. The teaching is valid but misworded. Pity 411A is not here to share what it was like.
I did only a little 737 time, but adding one fistlength of thrust to recover from a half-dot below GS, while keeping the A/C trimmed for the speed and steady with pich, was in my experience by far the easiest way to get back, providing for a more precise handling. I admit openly that on Airbus FBW it becomes a blurred argument due to the presence of the auto-trim. On the flip side, you know well that the autotrim only poorly masks the pitch-power couple. On a gusty day if A/THR kicks in an additional 10% N1, a pro-active push on the stick is needed to keep from balooning up.
For my next Direct law ILS coming in two days, i will keep the pitch at 2,7 degrees and use half-inch TL movemens up and down to manage the energy and chase the G/S. Works like magic in manual reversion too. But that is just a personal preference which gives me a more nicely polished result, since nobody untrained the old ways off me.
The p=path & t=speed works too, everybody to his liking.
I'd call the p=p & t=s way the flight-director method, but since nobody told me to change over, I use the latter and it works perfectly - without the FD. My take on the merit of "On the jet" is that it might have applied to single engine, centre-line thrust jet fighers after the WWII prop era, and later for 727/Caravelle/TU104/TU134 tail mounted machines. Sure, adding thrust would just speed you up. But is is not any magic of the propulsion, but the old pitch-power couple not being there. ATRs work that way too. The teaching is valid but misworded. Pity 411A is not here to share what it was like.
I did only a little 737 time, but adding one fistlength of thrust to recover from a half-dot below GS, while keeping the A/C trimmed for the speed and steady with pich, was in my experience by far the easiest way to get back, providing for a more precise handling. I admit openly that on Airbus FBW it becomes a blurred argument due to the presence of the auto-trim. On the flip side, you know well that the autotrim only poorly masks the pitch-power couple. On a gusty day if A/THR kicks in an additional 10% N1, a pro-active push on the stick is needed to keep from balooning up.
For my next Direct law ILS coming in two days, i will keep the pitch at 2,7 degrees and use half-inch TL movemens up and down to manage the energy and chase the G/S. Works like magic in manual reversion too. But that is just a personal preference which gives me a more nicely polished result, since nobody untrained the old ways off me.
The p=path & t=speed works too, everybody to his liking.
Thanks. Am changing type and off the 73 now but will try this method when I get back on line.
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Coming from the 737, i did that journey a few years ago, manual thrust on the bus seems somewhat iffy. It is quite sensitive as the available thrust lever range is so small, and the thrust levers, at least for me, are a bit farther away from my seat than i like, but then, i am kinda small. I was told during the type rating (in a company where manual flight meant manual thrust on the bus as well) to "walk the thrust levers", to achieve the small changes necessary. After getting used to it, it is actually quite easy to fly manually.
