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Low level Go around A320

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Low level Go around A320

Old 7th Feb 2018, 07:25
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Low level Go around A320

Hello guys,

simple question:

we make a go around in 1700 ft and the GA Altitude is 2000ft. So we put the thrust Levers short in TOGA and then again in the climb notch. The ATHR activates and where does the Speed bug jump to? it will protect us exceeding the placards right?

Thanks!
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Old 7th Feb 2018, 09:45
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Assuming above FMGC acceleration altitude target speed will be green dot.
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Old 7th Feb 2018, 12:06
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Assuming that you previously had at least Config 1 selected, SRS mode would engage when you selected TOGA. Your FMA would read “MAN TOGA / SRS / GA TRK (or NAV) / ATHR (in blue)

At CLB thrust selection your FMA would read “THR CLB / SRS / GA TRK (or NAV) / ATHR (in white)”

Approaching 2000’ your FMA would read “SPEED / ALT* / GA TRK (or NAV) / ATHR (in white)”

At ALT* your magenta target speed would jump from SRS commanded speed to Green Dot, regardless of the Acceleration Altitude programmed in the MCDU.

FCOM DSC-22-30-40 states that "If the managed speed/Mach target is set above VMAX (VFE, VMO, MMO), the FMGES automatically limits the speed to VMAX"

In theory, if the VFE was below G/D speed, the aircraft would accelerate only to VFE, but the magenta speed target would still show Green Dot. That being said in case of very quick acceleration, or environmental disturbance (turbulence, wind shift etc.), I would think it would be quite easy to exceed VFE.

Last edited by ESCAT; 7th Feb 2018 at 13:07.
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Old 7th Feb 2018, 12:36
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For what itís worth, this is my take on it (from experience)

In theory you are correct, the aircraft is supposed to protect you from an overspeed condition, however a go around with a low altitude level-off can turn into an overspeed very quickly, if you get behind the aircraft.

Itís because you are putting in a bootload of thrust (energy) in at low speed. It will initially go into srs, and pitch up significantly to maintain the srs speed target (hence a massive rate of climb) , followed very soon by alt* to level off.

Everything is essentially happening at once and youíre in alt* before you know it.

If you donít bring the thrust back to climb pretty quicky (which will engage the autothrust) you will accelerate rapidly and if old mate is a bit slow getting the flaps retracted you will overspeed.


Seen it happen in the sim (and done it myself during endorsement training)
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Old 7th Feb 2018, 17:04
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.... and if old mate is a bit slow getting the flaps retracted you will overspeed
True - but you could always take more power off so the acceleration is more manageable and only restore TLs to Climb gate when you are happy - like you used to do on previous aircraft types.
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Old 7th Feb 2018, 19:11
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Exactly! Nothing wrong with disengaging auto-thrust.
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Old 8th Feb 2018, 07:45
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To start with it is not a low level GA but high energy GA. LLGA is a different ball game altogether. In high energy GA when thrust levers are brought to CLB the FG overspeed protection is available. Next speed target will be GD. It is necessary to logically understand the sequence of these activities. First you get out of approach into GA phase. TOGA does that. Second, expect SRS to change to OP CLB or ALT* in a GA. No matter what SRS changes to it is always acceleration phase and you should be anticipating to retract flaps to next setting. The first retraction is important because the VFE for next flap setting is 30kts away. Like in any aircraft always remind yourself what next. If you have to do anything else like reducing thrust etc. means you didn't anticipate the next action. It is only salvaging a bad situation and not smart flying.
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Old 8th Feb 2018, 08:15
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don't forget to retract the gear whilst doing all that
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Old 8th Feb 2018, 08:54
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Hi vilas,
If you have to do anything else like reducing thrust etc. means you didn't anticipate the next action. It is only salvaging a bad situation and not smart flying.
Probably easy to say with your level of experience.

From FCTM the second of the Golden Rules for pilots says:
"2. Use the appropriate level of automation at all times. ....

Determine and select the appropriate level of automation that can include manual flight
Note:
The decision to use manual flight must be agreed between both pilots and must be based on an individual assessment of the pilot. This assessment should include aircraft status (malfunctions), pilot fatigue, weather conditions, traffic situation, and if the PF is familiar with the area."

Now the OP poses the question of how to handle a TOGA climb of only 300 feet. I would suggest that full TOGA power is inappropriate as ALT* will be triggered very quickly. On previous aircraft types the manufacturer fitted a reduced level of TOGA power and the easy ability to control the applied thrust - but it's not quite so easy on Airbus.

However if the OP selected TOGA initially until the FMA confirmed the change then he reduced the power below the climb gate to say around 75%, he would have more time to reconfigure the aircraft.
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Old 8th Feb 2018, 09:07
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Originally Posted by vilas View Post
If you have to do anything else like reducing thrust etc. means you didn't anticipate the next action. It is only salvaging a bad situation and not smart flying.
So reducing the thrust while accelerating in level flight instead of keeping CLB thrust to prevent an overspeed if the PM is a second or two too late in retracting the flaps one step, raising the gear, monitoring the PF's actions and retracting the remaining flaps, probably during a go-around at a speed higher than Vapp and closer to VFE, is not smart flying?

I agree that reducing thrust below CLB is normally not required, but in case it is, there's no harm in doing so. It's called common sense and flying the airplane. You might know what's going on, but the pilot next to you might be overloaded.
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Old 8th Feb 2018, 09:15
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New Arbii (A350, 380) have a “soft go-around mode”, which is doing pretty much the same thing. It is also an option on new A330’s, not sure if it’s available on the 320
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Old 8th Feb 2018, 10:32
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GOLDEN and BDM
I am not against bringing thrust levers back to CLB. That will provide FG overspeed protection.
I agree that reducing thrust below CLB is normally not required,
Why is it required now, What do you think the protection does? It will reduce thrust to maintain VFE. Just retract the flaps that's it. As I said if you are prepared for the sequence of actions and know when and what the protection does it is very simple. If you left the thrust in TOGA till ALT* then it requires prompt actions because ATHR is only armed and not active so you can overspeed. Incidently if your GA altitude is high say 5000ft and at ACC ALT of 1500ft you forget to bring thrust levers to CLB can you tell me what will happen?

Last edited by vilas; 8th Feb 2018 at 11:07.
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Old 8th Feb 2018, 19:45
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Originally Posted by Sidestick_n_Rudder View Post
New Arbii (A350, 380) have a “soft go-around mode”, which is doing pretty much the same thing. It is also an option on new A330’s, not sure if it’s available on the 320
I think it's available now on A320 as an option, but I'm talking about reducing the thrust below CLB thrust to prevent excessive acceleration or overspeed after levelling off, as the level off altitude is immediately reached in the case described by Speedwinner.

Originally Posted by vilas
Why is it required now, What do you think the protection does? It will reduce thrust to maintain VFE. Just retract the flaps that's it.
Ok. Fair enough. You're right, A/THR will protect you from overspeed. But not everybody will remember this when they're in this situation where everything is happening in just a few seconds.
If I see the speed rapidly increasing and the PM doesn't retract the flaps after asking for retraction, my instinctive reaction is probably to reduce the thrust to prevent an overspeed before I have the time to realise that the A/THR will do the same.
My point was that there's nothing wrong with taking preventive actions yourself, instead of waiting for the automatics to do the same and risking ending up in an undesired state if they don't.

Originally Posted by vilas
As I said if you are prepared for the sequence of actions and know when and what the protection does it is very simple.
As others and I said before, the person next to you might not be and might be slow in retracting the flaps. Ofcourse it's manageable, but both pilots have to be fully aware of what's going on.
As for the protections, you're right, but it's not wrong to do something yourself what the automatics will do as well. The result is the same.

There are many protections, but that doesn't mean that it's not allowed to intervene before reaching the parameters that will activate that protection.

Originally Posted by vilas
If you left the thrust in TOGA till ALT* then it requires prompt actions because ATHR is only armed and not active so you can overspeed.
Incidently if your GA altitude is high say 5000ft and at ACC ALT of 1500ft you forget to bring thrust levers to CLB can you tell me what will happen?
Nobody mentioned passing thru ACC ALT and leaving the levers in TOGA until ALT*. The original question was regarding a go-around initiated close to your go-around altitude and immediately bringing back the levers to CLB.
If you pass thru ACC ALT and you leave the levers in TOGA, then the LVL CLB message keeps flashing, and obviously A/THR will not become active, but I don't see what this has to do with the original question and what is being discussed here.
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Old 9th Feb 2018, 06:37
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BDM
OP asked two simple questions. GA target speed is GD and yes protection is there. But this is usual thread discussion. Off course control of the aircraft is primary whether with automatics or manually. But instead of knowing what the aircraft does if you design a new procedure like disconnecting ATHR or reducing below climb to control speed is not smart flying. Executing a GA with AP on requires knowledge of the procedure and not skill. In Airbus, manual flying is not very demanding but it is also necessary to know it's automatics well because that's the way it is designed. What I asked next is a separate question for you to answer.
Incidently if your GA altitude is high say 5000ft and at ACC ALT of 1500ft you forget to bring thrust levers to CLB can you tell me what will happen?
with THR LVRs in TOGA will the aircraft overspeed?
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Old 9th Feb 2018, 08:55
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with THR LVRs in TOGA will the aircraft overspeed?
No - because the elevators are controlling speed during the climb (by adjusting the pitch).

If you were flying Speedwinner's profile (post #1) in your B747, would you use TOGA, full climb thrust or something less?

Last edited by Goldenrivett; 9th Feb 2018 at 09:15. Reason: punctuation
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Old 9th Feb 2018, 11:44
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GR
The answer is already given by ESCAT in post 4 and yet not many will answer this. You are out of SRS and accelerating in OP CLB the same FMGS protection will keep speed below VFE by increasing ROC till ALT* then if thrust levers are not in climb it will overspeed.
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Old 9th Feb 2018, 12:16
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Hi vilas,

We agree on your post above and ESCAT's excellent post.

"In theory, if the VFE was below G/D speed, the aircraft would accelerate only to VFE, but the magenta speed target would still show Green Dot. That being said in case of very quick acceleration, or environmental disturbance (turbulence, wind shift etc.), I would think it would be quite easy to exceed VFE."

In order to prevent an accidental VFE speed exceedence especially when the aircraft acceleration is faster than the flaps / slats retract. VFE limit moves with the flap handle position but the overspeed warning reflects the actual flaps/slats position.
There are two options.
1) Pull speed and control the rate of acceleration.
2) Reduce thrust manually to a sensible setting.

I have used both and prefer the manual thrust method.

The problem with insisting everything must be done using the automatics doesn't help crews when the automatics fail.

Last edited by Goldenrivett; 9th Feb 2018 at 15:51. Reason: typo
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Old 9th Feb 2018, 12:32
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I found that,

High energy GA.jpg
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Old 9th Feb 2018, 14:33
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Vilas,

I see your point in explaining the overspeed protections (ALT* or ALT with A/THR or TOGA in OP CLB), although leaving the levers in TOGA during a normal go-around (where there is plenty of time to notice the LVL CLB message flashing in case you forget) seems an unlikely situation compared to the high energy go-round where you end up in ALT* almost immediately.

Goldenrivett's and my point is that disconnecting the A/THR is not something that isn't allowed. You may call it salvaging a bad situation, but it's basically doing what the A/THR will do as well, but before getting close to the VFE limit.
I agree that you shouldn't end up in this situation in the first place, in fact no situation where the protections have to kick in, but people will always make mistakes and the ability to recover from them without depending on the automation is a necessary skill that I saw was disappearing in the previous company I worked for. (GS interceptions from above messed up, GPWS warnings on a visual part of an approach or at 8NM from the runway, attempted G/A without setting the thrust, etc.)
You probably know which company I'm talking about, but a simple disconnection of the automatics and flying the plane could have prevented those situations. The pilots are the first line of defence, not the protections or automatics.
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Old 9th Feb 2018, 15:52
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Once the pilot is in his seat if something is not happening as it should he must control the aircraft with the knowledge he has at that point of time. No argument about it. But it should be as an exception not to be converted into a procedure. If there was a need the manufacturer would have suggested that. Developing own procedures is fraught with danger in airbus FBW. Besides disconnection of automatics is not a panacea and can bring its own problems as in the case of air proximity incident between A330, A340 across the Atlantic, fatal one at Sochi. As an airbus pilot one needs to spend some time understanding the flight controls and auto flight systems. Airbus cannot be flown like a Boeing. In a flight path stable aircraft manual flying is not a great skill but one also needs to know its automatics well because that is the design philosophy. All that we are discussing high energy GA, rejected landing, interception of GS from above are routine exercises taught in a type rating syllabus and many 200hrs pilots do it satisfactorily. These are practiced procedures and not acts of acquired skill. All procedures a pilot is expected to know. Yes once in a while a human can make mistake no problem with that.
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