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-   -   Airbus A318 Use of the V/S to Climb (https://www.pprune.org/tech-log/479879-airbus-a318-use-v-s-climb.html)

italia458 15th March 2012 00:55


Another example would be glideslope from above, I can't stand guys who select 100 feet.
Select 100 feet?

HPbleed 15th March 2012 01:20

Some pilots just twist the altitude all the way down to 100 instead of up and using V/S.

A320 CURSED 15th March 2012 01:22

A318 P&W
 
Biz pilot Brazil.
Hello, just leave the airplane in managed modes throughout the climb.
If you are flying for AV Brazil or Ocenan A. I can tell you that I have flown those 318s when they were at LAN, and as a matter of fact we still operate a handfull of them. That Airframe/Engine setup is not very optimal, engines are derated big time, and it may take you up to 38 minutes to reach FL350 when you are heavy.
If you go on V/S mode you loose airspeed and once you reach your cruising altitude those engines will continue to deliver CL THR untill you reach you managed Mach speed.
The airplane is underpowered and just as heavy as an A320, believe it or not.

Regards.

bubbers44 15th March 2012 03:14

The first time I was descended from above the glide slope and it captured altitude because we weren't on the glide slope you will select a low altitude too to let it capture below the intercept altitude.

HPbleed 15th March 2012 04:22

So you'd rather it captured at 100? Why not twist is up to 1000 above what you're currently at? Then it won't capture, and the other Brucey Bonus is that if you go around it'll stop the climb at something sensible (there's the catch - remember to set g/a altitude at G/S capture) rather than climbing up to 10k +

Right Way Up 15th March 2012 06:40


There's nothing forbidden about it but airmanship and common sense should preside here - if you are climbing at m0.8 in managed climb and get a negative v/s then go to open climb with selected speed and notch off a couple of decimals of mach. If need be take it back to green dot.
Hpbleed you don't ever want to get back towards green dot when climbing at altitude. Going open climb and then reducing Mach just exacerbates the problem, it gives you a quick zoom climb followed by speed getting low with low or negative v/s. You also have the danger of getting into ALT* with a high RoC, something which too many people are unaware or blasé.
To be fair the Easy 319/320s are not bad at climbing at altitude so you probably haven't seen this performance issue.

Pizza Express 15th March 2012 07:12

Never had a problem myself! It sorts it self out in managed climb and so what if it takes a while or it goes negative for a short while?? If ATC ask for a higher rate say unable, never once needed to use VS at high FLs. It gets there in the end safely by its self.

If you really want to give yourself a heart attack press EXPD at FL 350 in the climb. See what hapens then...

HPbleed 15th March 2012 15:12

RWU,

I wouldn't recommend coming back to green dot no, however the method is still safer than using a v/s mode which overrides speed which could result in a stall. IMO. I've not had an issue with selecting Mach in open climb and coming back one or two decimals. I have however seen speed decay when others are concentrating so hard on climbing to an altitude using V/S and I won't ever use it at high altitudes to climb.

Right Way Up 15th March 2012 15:21

Hpbleed,

I know of instances of reducing mach to increase RoC that have ended in low speed excursions due to ALT*. Don't be too confident that OP CLB and CLB will completely save you. If setting V/S 500-1000ft/min results in a slow speed excursion then maybe the crew are not really cut out for their job.

As I said before your/our aircraft are fairly good climbers (both power and FMGS accuracy) and I have not had to use this technique at our company and I have no desire to. But there are older Airbus (old FMGS standard/underpowered) where this is a very useful technique. If you don't believe me ask any of your Captains who have flown older charter heavyweight A320/1s.

Don't even get me started with old heavy A340s where you sometimes had to descend to get the speed back to complete the climb. ;)


It sorts it self out in managed climb and so what if it takes a while or it goes negative for a short while??
Pizza Express
Don't forget to tell ATC that you are not maintaining 500fpm as per the UK AIP. ;)

HPbleed 15th March 2012 20:58

Fair enough - many ways to skin a cat and all that. I'll stick with my way for now though :)


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