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Starlionblue
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Re: A320, autopilot soon after takeoff

Fri Dec 01, 2017 3:08 am

That 320 report is very interesting. It pretty much proves that even the safest plane can be put into a hazardous situation by a determined crew.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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glen
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Re: A320, autopilot soon after takeoff

Fri Dec 01, 2017 8:56 am

longhauler wrote:
Chaostheory wrote:
As fantastic as the airbus setup is in the context of windshear recovery, it's important to remember that windshear avoidance is still key. Sometimes the weather is too dynamic for the protections to keep up and prevent stall. There has been at least one documented a319/320 stall during a windshear episode in China. Fortunately for the crew, alpha protection kicked in and the aircraft recovered with about 1000ft to spare. If I recall from the moment of ap disconnect, both pilots held their side sticks fully aft through the entire process.

That recovery ... sidestick full aft, TOGA thrust ... is current Airbus windshear recovery technique. It puts the aircraft in the best possible condition. FADEC giving all the engines have to give and fly-by-wire keeping the aircraft at maximum angle of attack.


No, that's Airbus GPWS recovery technique (and it's first TOGA and then sidestick full aft).
Windshear recovery is TOGA and then follow the SRS mode. (Speed Reference System) which gives you a speed guidance. The strategy of the SRS during windshear is to control speed as long as a positive vertical speed is possible. If a positive vertica speed is not possible, it controls altitude and lets speed decrease. Only at the ultimate limit the AOA protection will engage. Until the engagement of AOA protection the procedure can even be flown with autopilot.
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longhauler
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Re: A320, autopilot soon after takeoff

Fri Dec 01, 2017 2:02 pm

glen wrote:
No, that's Airbus GPWS recovery technique (and it's first TOGA and then sidestick full aft).

That is correct. I didn't want to get too involved with the explanation, so I went right to the point of ground contact being a factor.

It is interesting to note that the SRS concept goes right back to the A300 designed in the 1970s, when windshear accidents were very much a concern. We take it for granted on modern Airbuses today and the explanation is barely a paragraph in the FCOM. But I recall my A300 ground school and the very long explanation (hours) of how the idea works.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
T1a
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Re: A320, autopilot soon after takeoff

Fri Dec 01, 2017 8:47 pm

In the 320, once you pull the thrust levers from the TOGA or FLEX detent to the CLB detent at acceleration altitude in the takeoff climb, you don’t normally touch or move the thrust levers until 20/30 feet in the flare just before landing. Auto thrust controls the thrust the whole time.


I know this is how Airbus designed the aircraft and how most operators are using it. But this is not always the case. I work for a big European operator and our philosophy is quite different. Even though I work on a different fleet I know the guys and gals over on the bus very well and also most of their procedures. At our operator it is up to the individual pilot whether he/she switches off the Autothrust during approach. Most pilots switch it off pretty much all the time on final in order to keep their skills up. Of course this is not the case during an autoland approach, but I guess that's obvious.
At our parent company the rule is even more restrictive. There it clearly states: manual flight (as in autopilot off) means manual thrust. So you can never have the autothrust on when the autopilot is off. That rule is in place on all of their fleets. They have had that for decades now (really since the invention of autothrottles) and their safety department believes it very much reduces the risk of SFO or DXB like events.

As in when to engange the autopilot: on my fleet - Bombardier Dash-8 Q400 - the minimum engange hight is 1000' AGL. I've very rarly seen people use that though. Passing through 1000' we always set climb power and retract flaps to zero as per comapany procedure (no matter of NADP 1 or 2); after flaps have been selected zero is where I earliest engang the AP. As others have stated, enganging this early is good technique when it's busy, I regularly use it on the rather complex departures out of ZRH where you can often expact low level offs, which are a pain in the Q400. Otherwise I usually hand fly her until flaps are fully retracted, cruise power is set and airspeed is stable, this is usually around 3000'-4000' AGL.
 
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Starlionblue
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Re: A320, autopilot soon after takeoff

Sat Dec 02, 2017 2:01 am

T1a wrote:
In the 320, once you pull the thrust levers from the TOGA or FLEX detent to the CLB detent at acceleration altitude in the takeoff climb, you don’t normally touch or move the thrust levers until 20/30 feet in the flare just before landing. Auto thrust controls the thrust the whole time.


I know this is how Airbus designed the aircraft and how most operators are using it. But this is not always the case. I work for a big European operator and our philosophy is quite different. Even though I work on a different fleet I know the guys and gals over on the bus very well and also most of their procedures. At our operator it is up to the individual pilot whether he/she switches off the Autothrust during approach. Most pilots switch it off pretty much all the time on final in order to keep their skills up. Of course this is not the case during an autoland approach, but I guess that's obvious.
At our parent company the rule is even more restrictive. There it clearly states: manual flight (as in autopilot off) means manual thrust. So you can never have the autothrust on when the autopilot is off. That rule is in place on all of their fleets. They have had that for decades now (really since the invention of autothrottles) and their safety department believes it very much reduces the risk of SFO or DXB like events.



An DXB type event in an Airbus is extremely unlikely because you set the thrust levers to TOGA yourself to go around, and then thrust levers don't move from there. You don't press a TOGA button and then have to positively check the thrust levers move in response.

An SFO type event is a bit more plausible, for example if the pilot uses incorrect technique for glideslope interception for above.

As you say this is company wide for you. Some companies have company wide procedures for all fleets that often don't align with type as well as they should.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
BoeingGuy
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Re: A320, autopilot soon after takeoff

Sat Dec 02, 2017 3:36 am

Starlionblue wrote:
T1a wrote:
In the 320, once you pull the thrust levers from the TOGA or FLEX detent to the CLB detent at acceleration altitude in the takeoff climb, you don’t normally touch or move the thrust levers until 20/30 feet in the flare just before landing. Auto thrust controls the thrust the whole time.


I know this is how Airbus designed the aircraft and how most operators are using it. But this is not always the case. I work for a big European operator and our philosophy is quite different. Even though I work on a different fleet I know the guys and gals over on the bus very well and also most of their procedures. At our operator it is up to the individual pilot whether he/she switches off the Autothrust during approach. Most pilots switch it off pretty much all the time on final in order to keep their skills up. Of course this is not the case during an autoland approach, but I guess that's obvious.
At our parent company the rule is even more restrictive. There it clearly states: manual flight (as in autopilot off) means manual thrust. So you can never have the autothrust on when the autopilot is off. That rule is in place on all of their fleets. They have had that for decades now (really since the invention of autothrottles) and their safety department believes it very much reduces the risk of SFO or DXB like events.



An DXB type event in an Airbus is extremely unlikely because you set the thrust levers to TOGA yourself to go around, and then thrust levers don't move from there. You don't press a TOGA button and then have to positively check the thrust levers move in response.


That's a poor excuse. Boeing procedures don't tell you to push the TO/GA Switch ("buttons" are on your shirt) and wait for the thrust levers to move by themselves. In the event of a Windshear or if terrain contact is imminent, you aggressively push the thrust levers forward and then push TO/GA.
 
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Starlionblue
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Re: A320, autopilot soon after takeoff

Sat Dec 02, 2017 6:37 am

BoeingGuy wrote:
Starlionblue wrote:
T1a wrote:

I know this is how Airbus designed the aircraft and how most operators are using it. But this is not always the case. I work for a big European operator and our philosophy is quite different. Even though I work on a different fleet I know the guys and gals over on the bus very well and also most of their procedures. At our operator it is up to the individual pilot whether he/she switches off the Autothrust during approach. Most pilots switch it off pretty much all the time on final in order to keep their skills up. Of course this is not the case during an autoland approach, but I guess that's obvious.
At our parent company the rule is even more restrictive. There it clearly states: manual flight (as in autopilot off) means manual thrust. So you can never have the autothrust on when the autopilot is off. That rule is in place on all of their fleets. They have had that for decades now (really since the invention of autothrottles) and their safety department believes it very much reduces the risk of SFO or DXB like events.



An DXB type event in an Airbus is extremely unlikely because you set the thrust levers to TOGA yourself to go around, and then thrust levers don't move from there. You don't press a TOGA button and then have to positively check the thrust levers move in response.


That's a poor excuse. Boeing procedures don't tell you to push the TO/GA Switch ("buttons" are on your shirt) and wait for the thrust levers to move by themselves. In the event of a Windshear or if terrain contact is imminent, you aggressively push the thrust levers forward and then push TO/GA.


I agree completely. My point was that due to the architecture of the thrust levers on Airbus compared to Boeing this particular scenario is less likely to happen. It was still an error and quirks of the system architecture are no excuse. That's what type ratings are for.

Bottom line: In all aircraft, if you follow proper procedure your chances of having a successful outcome increase dramatically.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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