A320 - should Airbus be more accountable for ATHR system
Thread Starter
Join Date: Aug 2015
Location: Asia
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
A320 - should Airbus be more accountable for ATHR system
Whilst new to the A320 series, I have seen 2 important incidents which Airbus deny happen, but both should be addressed accordingly by Airbus.
First, G/S* and commenced descent FLAP 2 SPD selected 180kts, then SPD set managed, Gear Down and N1 increased from 34% to 83% immediately. A quick disconnect of autopilot and ATHR, immediate pull up to save the rapid speed increase to be told later, Airbus say leave the ATHR system alone it will not increase above FLAP Limit speed.
Second, FLAP 2 speed 165kts, gear down and n1 38%, due to very late ATC descent leaving the aircraft 1000ft high at 13 nms, the nose was pushed down to 2600 FPM, speed naturally increased towards VFE max-10 (190kts) then N1 responded to 82% pushing the speed to 207kts (VFE+7).
Has anyone else suffered at the hands of Airbus and Thales ? and what was your outcome?
In addition, the speed often reduces to VLS before the autothrust, but again Airbus deny this is a problem, but just cite "This is how it is designed to work!"
Certainly this is not acceptable behaviour by the auto system, lets get a thread going if this is the norm and maybe Airbus will provide pilots with a good tool for the job.
First, G/S* and commenced descent FLAP 2 SPD selected 180kts, then SPD set managed, Gear Down and N1 increased from 34% to 83% immediately. A quick disconnect of autopilot and ATHR, immediate pull up to save the rapid speed increase to be told later, Airbus say leave the ATHR system alone it will not increase above FLAP Limit speed.
Second, FLAP 2 speed 165kts, gear down and n1 38%, due to very late ATC descent leaving the aircraft 1000ft high at 13 nms, the nose was pushed down to 2600 FPM, speed naturally increased towards VFE max-10 (190kts) then N1 responded to 82% pushing the speed to 207kts (VFE+7).
Has anyone else suffered at the hands of Airbus and Thales ? and what was your outcome?
In addition, the speed often reduces to VLS before the autothrust, but again Airbus deny this is a problem, but just cite "This is how it is designed to work!"
Certainly this is not acceptable behaviour by the auto system, lets get a thread going if this is the norm and maybe Airbus will provide pilots with a good tool for the job.
Join Date: Sep 2011
Location: FL390
Posts: 238
Likes: 0
Received 0 Likes
on
0 Posts
Airbus say leave the ATHR system alone it will not increase above FLAP Limit speed.
Have never seen the situation you described - did it happen on different aircraft or the same one? My experience is that A/T is lazy to react sometimes on the A320 but never have I seen it add inappropriate power*.
Autothrust will allow speed decay below VAPP but not into VLS (in theory).
* Yes, yes, A319 speedbrake-with-flap exception...
Join Date: Feb 2004
Location: Sandpit
Posts: 177
Likes: 0
Received 0 Likes
on
0 Posts
Are you sure the Approach Phase was activated ?
Sounds like this could be the case as the A/thr should not command an increase in thrust if the target speed is below present speed and it also would explain your "diving" towards the target speed (250) .
Other than this "finger " trouble , never seen what you describe .
Sounds like this could be the case as the A/thr should not command an increase in thrust if the target speed is below present speed and it also would explain your "diving" towards the target speed (250) .
Other than this "finger " trouble , never seen what you describe .
Join Date: Apr 2005
Location: in the magical land of beer and chocolates
Age: 52
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by DescendNow
due to very late ATC descent leaving the aircraft 1000ft high at 13 nms, the nose was pushed down to 2600 FPM
Join Date: Mar 2005
Location: Uh... Where was I?
Posts: 1,338
Likes: 0
Received 0 Likes
on
0 Posts
I assume it is 1,000 high with respect to the profile.
That would be about 5,000 AGL. I understand the mode used was V/S? Like in an above glideslope capture?
In every mode there is a form of protection from overspeeding. That shouldn't happen. In V/S mode, the target will be reduced to remain below VFE. In OP DES the A/THR will revert to SPEED and keep speed below VFE. If you are hand flying and ignoring the FD the A/THR will also revert to SPEED.
If speed was exceeded something was really wrong.
It happens, sometimes, that a pilot first tries to steepen the gradient by means of descending in OP DES at high speed (that is, close to VFE) then once he gets LOC*, he arms/checks G/S is blue and sets the FCU ALT above actual altitude, thus inducing a reversion to V/S (and therefore SPEED). The problem is that selected speed target remains high and in case your actual speed is less than target, because you were still accelerating to it in OP DES at the time, as soon as SPEED engages the engines will spool up. It is fixed by reducing the speed then checking/activating approach phase and managing speed. But if you don't, there should be no overspeed, though. V/S mode has a protection.
That would be about 5,000 AGL. I understand the mode used was V/S? Like in an above glideslope capture?
In every mode there is a form of protection from overspeeding. That shouldn't happen. In V/S mode, the target will be reduced to remain below VFE. In OP DES the A/THR will revert to SPEED and keep speed below VFE. If you are hand flying and ignoring the FD the A/THR will also revert to SPEED.
If speed was exceeded something was really wrong.
It happens, sometimes, that a pilot first tries to steepen the gradient by means of descending in OP DES at high speed (that is, close to VFE) then once he gets LOC*, he arms/checks G/S is blue and sets the FCU ALT above actual altitude, thus inducing a reversion to V/S (and therefore SPEED). The problem is that selected speed target remains high and in case your actual speed is less than target, because you were still accelerating to it in OP DES at the time, as soon as SPEED engages the engines will spool up. It is fixed by reducing the speed then checking/activating approach phase and managing speed. But if you don't, there should be no overspeed, though. V/S mode has a protection.
Join Date: Aug 2013
Location: Middle Europe
Posts: 80
Likes: 0
Received 0 Likes
on
0 Posts
not a big fan of A/THR but ruling out finger troubles or so-called "wrong levels of automation" as mentioned before i've never experienced any of the first 2 situations described. but yes, A/THR is quite lazy at times and/or doesn't work 100% to plan and sometimes isn't helpful at all in my eyes (i.e. gusty situations). disconnect it then if you don't like it/if out of limits.
A/THR going below VAPP: yes, but i've never seen it going below VLS. since you have VLS+5kt for A/THR ON (or even more for whatever) and considering the PM callouts required for speed deviations (-5kt,+10kt) it's within limits i'd say. but again: if you don't like it, disconnect ATHR and to quote FCTM
A/THR going below VAPP: yes, but i've never seen it going below VLS. since you have VLS+5kt for A/THR ON (or even more for whatever) and considering the PM callouts required for speed deviations (-5kt,+10kt) it's within limits i'd say. but again: if you don't like it, disconnect ATHR and to quote FCTM
If the A/THR performance is unsatisfactory, the pilot should disconnect it and control the thrust manually.
Last edited by sierra_mike; 12th Aug 2015 at 03:55.
Join Date: Jun 2007
Location: Wanderlust
Posts: 3,404
Likes: 0
Received 0 Likes
on
0 Posts
DescendNow
I find your statements paradoxical. You say you are new to Airbus and you make a statement putting A320 on the mat. The examples you gave have a greater element of mishandling due to insufficient knowledge than any real systemic fault. I can understand you asking clarifications at this stage but the eureka like nature of statement and the title of your post appears a bit presumptuous. To put it simply what you experienced and the way you say it happened is not possible. There is definitely an omission or commission that is not noticed by you.
I find your statements paradoxical. You say you are new to Airbus and you make a statement putting A320 on the mat. The examples you gave have a greater element of mishandling due to insufficient knowledge than any real systemic fault. I can understand you asking clarifications at this stage but the eureka like nature of statement and the title of your post appears a bit presumptuous. To put it simply what you experienced and the way you say it happened is not possible. There is definitely an omission or commission that is not noticed by you.
MB, I don't disbelieve you but do you mean the actual speed - not the trend arrow - actually settled below VLS and the A/THR did nothing? Or was it only below VLS for a split second in a gust or just very slow to correct?
Join Date: Mar 2005
Location: Uh... Where was I?
Posts: 1,338
Likes: 0
Received 0 Likes
on
0 Posts
MB, I don't disbelieve you but do you mean the actual speed - not the trend arrow - actually settled below VLS and the A/THR did nothing? Or was it only below VLS for a split second in a gust or just very slow to correct?
Join Date: Feb 2010
Location: At home
Age: 42
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
Disconnecting A/THR before 1000ft is recommendation, not obligation (it says should, not must) and if you are visual with the RWY you are allowed to be stabilized at 500 ft. Also you are allowed to make small corrections anyway according to FCOM. I don't think there is a need to make a go around.
And I don't see why is such a problem to use manual thrust. If you are not satisfied with A/THR, don't use it. It's not mandatory. With just a little practice, with manual control of the THR, you can control it more precisly then A/THR. And with some specific crosswinds with heavy gusts, A/THR is almost unusable.
I was flying for years using only manual thrust because it was mandatory to switch off A/THR when you switch off A/P. We were using Lufthansa procedures and whole Lufthansa was also flying like this for years
FCOM:
If the aircraft is not stabilized on the approach path in landing configuration in the following
conditions:
‐ at 1 000 ft above airfield elevation in instrument conditions, or
‐ at 500 ft above airfield elevation in visual conditions, or
‐ as required by Operator policies/regulations.
Then a go around must be initiated unless the flight crew estimates that only small corrections are
necessary to rectify minor deviations from stabilized conditions due, amongst others, to external
perturbations.
And I don't see why is such a problem to use manual thrust. If you are not satisfied with A/THR, don't use it. It's not mandatory. With just a little practice, with manual control of the THR, you can control it more precisly then A/THR. And with some specific crosswinds with heavy gusts, A/THR is almost unusable.
I was flying for years using only manual thrust because it was mandatory to switch off A/THR when you switch off A/P. We were using Lufthansa procedures and whole Lufthansa was also flying like this for years
FCOM:
If the aircraft is not stabilized on the approach path in landing configuration in the following
conditions:
‐ at 1 000 ft above airfield elevation in instrument conditions, or
‐ at 500 ft above airfield elevation in visual conditions, or
‐ as required by Operator policies/regulations.
Then a go around must be initiated unless the flight crew estimates that only small corrections are
necessary to rectify minor deviations from stabilized conditions due, amongst others, to external
perturbations.
VLS on approach is actually Vref. The +5kts (Vapp) is for A/thrust lag, ground speed mini is for the wind. Trend arrow is where the speed will be in 10secs if nothing changes. Understand this and the Bus auto flight system works well. It may involve opening an FCOM though, so I see where the confusion may lie.
PS...To a poster above, 1000 feet high at 10nm would be 4000 AGL not 5000. You need to multiply the distance by three not the altitude. This use to be taught before P2F was invented.
PS...To a poster above, 1000 feet high at 10nm would be 4000 AGL not 5000. You need to multiply the distance by three not the altitude. This use to be taught before P2F was invented.
