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-   -   Interesting scenario A320 (https://www.pprune.org/tech-log/600138-interesting-scenario-a320.html)

Bkdoss 30th Sep 2017 02:10

Interesting scenario A320
 
Let us assume that you are on ILS and you are at 2500' with the Go Around altitude set to 7000'. Now ATC gives you a speed constraint of 160kts. As per the FCTM you can go below the maneuvering speeds, which is S speed for Flaps 1,as long as you're above Vls. So you choose to reduce speed to 160kts with flaps 1, with the help of speed brakes. You've got your speed down to 160, when ATC says Go Around.

The call in this case would be Go Around flaps and PF advances the thrust lever to TOGA. If TOGA is hit first before flaps are retracted, SRS would engage. Now the SRS speed target in a go around would be Vapp or current speed at October Around whichever is higher, restricted to Vls+25. So if your Vls with Config 1 was somewhere close to 150, then SRS will maintain current speed (as it is the higher of Vapp and current speed and is less than Vls+ 25 which is 175). Now you're flying the Go Around profile at Config 0, with speed locked at 160, which is a long way below safe flap Retraction speed. What would be the protection that would kick in at this point to keep us in the safe envelope?

RUMBEAR 30th Sep 2017 02:22

Why are you not in a "safe" envelope? You are above VLS and below VLS + 25?. Take-off Flap 1+F has a normal climb speed (V2 +10) well below S Speed.How is this situation different?

I think the key would be to ensure TOGA is selected before the flap lever is moved (if thats what you choose to do). As TOGA with GS and LOC still engaged would become interesting very quickly!

Bkdoss 30th Sep 2017 03:12

Take off flaps 1+f has flaps at 1+f. But in this scenario you've retracted the flaps at go around to flaps 0, well below S speed and speed locked at 160.

charlies angel 30th Sep 2017 03:53

Have you heard of the airmanship phrase " Aviate,Navigate,Communicate" ?

It was what pilots used to rely on to keep themselves safe before How To Handle The Big Computer Game became popular:O

In your scenario read the FMA.
Youve gone round from <2500' to 3000' and in flap one.
So FMA reads toga/srs/ga trk then alt* then spd/alt/ga trk. Push nav to engage nav mode for go around routing.
Your protection is autothrust speed mode at 160 knots selected.
A pilot would then suggest to his co pilot something like " Tell ATC to cancel 160kts cos its too slow if we need to manouvre" and wind the speed up to a speed that you are both happy with.
And Voila! youve Aviated Navigated and Communicated :D

vilas 30th Sep 2017 05:21

Bkdoss
Many pilots do not know that retraction of one step flaps in a go around is not a ritual nor is it mandatory. The purpose is to reduce excess drag of full flap to get better manoeuvreability and better gradient. Since 1,2 and 3 are takeoff configurations it is not mandatory to retract one step. Just hit TOGA and keep the flap. There is no problem at all.

Check Airman 30th Sep 2017 05:37

@bkdoss, is your company really suggesting that you retract the flaps in that scenario? How about you look at the other guy and say "go around, keep flaps 1"?

Meditate, Aviate, Navigate, Communicate

student88 30th Sep 2017 11:06

You only retract the flaps 1 stage if the config is greater than 1+F, otherwise leave the flaps where they are.

vilas 30th Sep 2017 12:47

The mandatory requirement to retract one step is for flap full. Airlines for standardization may keep the procedure to retract one step also for flap 3 since it can be landing flap. But it is not necessary. Why would you follow a procedure meant for landing flap when you are not yet configured?

Bkdoss 30th Sep 2017 13:08


Originally Posted by charlies angel (Post 9908452)
Have you heard of the airmanship phrase " Aviate,Navigate,Communicate" ?

It was what pilots used to rely on to keep themselves safe before How To Handle The Big Computer Game became popular:O

In your scenario read the FMA.
Youve gone round from <2500' to 3000' and in flap one.
So FMA reads toga/srs/ga trk then alt* then spd/alt/ga trk. Push nav to engage nav mode for go around routing.
Your protection is autothrust speed mode at 160 knots selected.
A pilot would then suggest to his co pilot something like " Tell ATC to cancel 160kts cos its too slow if we need to manouvre" and wind the speed up to a speed that you are both happy with.
And Voila! youve Aviated Navigated and Communicated :D

Hi Charlies Angel. Thanks for your reply. I'm sorry I didn't paraphrase my question correctly. Say you're at 2500 feet when your G/S intercept altitude is 3000. You're on glide and suppose the Go Around altitude is 7000'. Then you're in a mess having retracted flaps to zero.

Bkdoss 30th Sep 2017 13:10


Originally Posted by vilas (Post 9908785)
The mandatory requirement to retract one step is for flap full. Airlines for standardization may keep the procedure to retract one step also for flap 3 since it can be landing flap. But it is not necessary. Why would you follow a procedure meant for landing flap when you are not yet configured?


I'm afraid Airbus point blank says Retract one step of flaps for any Go Around. That is where my confusion stems from.

Bkdoss 30th Sep 2017 13:15


Originally Posted by vilas (Post 9908785)
The mandatory requirement to retract one step is for flap full. Airlines for standardization may keep the procedure to retract one step also for flap 3 since it can be landing flap. But it is not necessary. Why would you follow a procedure meant for landing flap when you are not yet configured?

Vilas again the performance for Approach Climb limiting weight for Config3 approach is computed with Config 2. Tables in FCOM for approach climb limiting weights are for Config 2&3 for Config 3&Full respectively. So I assume even if Landing is performed with Config 3, Go around has to be with flaps retracted one step up.

charlies angel 30th Sep 2017 13:20

Keep it simple.
You have flap 1 when you set TOGA so the aircraft will go into Go Around mode.
You now have even more time to aviate.
Toga/ srs / ga trk becomes alt* then spd/alt/ ga trk.
Once again push for Nav and you now have green dot speed and managed nav.
What's not to like?:ok:
Don't forget the aircraft will go into go around mode on selection of Toga depending on the flap handle position when you start the manouvre.
Activate the approach and have another go.
Always monitor and believe the FMA.

vilas 30th Sep 2017 14:45

BK
Approach climb is with OEI. If you see the graph it is not limiting. Unless it is limiting you can always leave it in three. Also if landing conf was full and you had not configured to full or if landing conf was 3 and you had not configured to three, then when you go around just keep the flap at whatever it is. As I said the one step retraction procedure is from landing flap configuration and not intermediate position. Why would you retract from two to one or from one to zero? Procedures have a logic. There is no point blank.

akindofmagic 30th Sep 2017 14:50


I'm afraid Airbus point blank says Retract one step of flaps for any Go Around. That is where my confusion stems from.
Airmanship. Have you heard of it?

Bkdoss 30th Sep 2017 15:16


Originally Posted by vilas (Post 9908879)
BK
Approach climb is with OEI. If you see the graph it is not limiting. Unless it is limiting you can always leave it in three. Also if landing conf was full and you had not configured to full or if landing conf was 3 and you had not configured to three, then when you go around just keep the flap at whatever it is. As I said the one step retraction procedure is from landing flap configuration and not intermediate position. Why would you retract from two to one or from one to zero? Procedures have a logic. There is no point blank.

Thanks for your explanation Vilas. Yeah I do agree procedures have a reason and logic. The problem is a guy new on the BUS is always taught go around is with flaps retracted one step up. I agree with your point that a certain airmanship is essential. But Airbus being a company which has such elaborate technical notes wouldn't it have been more prudent for them to have specified clearly when to carry out the Go Around flap retraction and when not to.

vilas 30th Sep 2017 16:01

BK
There are additional procedures like Landing with slat/flap jam or overweight landing. On ground in spare time if you question the why and how of these procedures it becomes very easy to apply them when the need arises and helps keep track of what one is doing. Otherwise mere button pushing with ECAM can leave one unsure of what he has done.

STFMD80 30th Sep 2017 16:35

If you use flap 2 to slow down instead of that ill though way of using the speed brakes to go below S speed at 2500ft (why would you do that?), you will not put yourself in the mess you describe...

pineteam 30th Sep 2017 16:43

Airbus can't write a specific procedure for all the possible scenarios. Airbus offers guidelines but sometimes you have to think out of the box. Most of the time at 2500 feet if you are on the glideslope you should be already on config 2. Especially on the A 319, unless you like to do Flaps 1, then gears down before Flaps 2. Anyway like all the guys said before, just apply good airmanship. if you have to go around, at 2500 feet with flaps 1. You still have lots of time to act and think. No need to rush. Quickly set to Toga then back to climb Detent and announce " go around, standby for flaps" or you can just discontinuity the approach by pulling open climb or pressing the approach push button and take appropriate actions or Vertical speed zero... Plenty of options there. Remember if you don't set TOGA, at least once, you won't have the go around phase. Not a big deal if you expect radar vector but better set TOGA at some point before the runway threshold or you might lose the flight plan if I'm not mistaken. Just keep the speed safe, make sure you undestand your FMA and don't forget to retract the gears before 220kt IAS. Happens more than we think. Enjoy =)

Goldenrivett 30th Sep 2017 16:57

Hi Bkdoss

What would be the protection that would kick in at this point to keep us in the safe envelope?
FCOM, DSC-27-30-10: Alpha/Speed Lock,

If, in the scenario you describe, AOA was above 8.5 degs then the slats would not retract.
If AOA was less than 8.5, then the slats would retract and SRS would attempt to follow 160 kts (or max VLS+25). Depending on Alpha you may get TOGA LOCK with Alpha PROT / up to Alpha Max.

If you insist on blindly following "Go Around flaps" call /procedure then use managed speeds.

vilas 30th Sep 2017 17:12

pineteam

Remember if you don't set TOGA, at least once, you won't have the go around phase. Not a big deal if you expect radar vector but better set TOGA at some point before the runway threshold
It is a big deal. I think you are mixing up GA mode and NAV mode. You must hit TOGA otherwise the FDs will take you down as they will remain in approach mode. There were at least three incidents of this nature. In the worst case the aircraft in poor visibility was 14 feet on the runway before they ignored the FDs and pulled up. When below the FCU altitude TOGA and back to climb as you suggested is a better option. Discontinued approach is not a smart option it will sequence the airport creating extra work plus too much thinking. TOGA is better option even if you were above FCU altitude TOGA will still engage SRS only it will not have target altitude. You can push VS to change SRS set a target altitude and pull climb and cleanup.


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