A320 question
 

On a recent A320 flight, the speed brakes were partially extended from top of descent all the way down to what I guess was about 5000ft, perhaps a bit higher.

Is this SOP's? The noise level is higher and the ride not as smooth in this configuration.

And is this the cause of the change in aerodynamic sound as observed from the ground in the Melbourne eastern suburbs which is under the inbound route from Tassie?

Appreciate informed replies. No A320 jokes thanks.

Cheers

CG

Chief

Certainly not SOPs.

Plenty of senarios available but i'd have to guess that, to have the speedbrakes out for so long, they may have been given a late descent clearance coupled with a speed reduction for separation.

With a late descent clearance we'll be above the normal descent profile (thrust idle, 280-300kts).

The preferred way to regain profile is to increase our descent speed (to say 320kts) which means more drag and therefore a steeper descent angle allowing us to intercept the original profile. This is why you'll sometimes hear us requesting cancellation of the 250kts below 10000' speed restriction if we've been held high. (other times we just want to get there quicker;))

But to be given a speed reduction to say 250kts from ToD means we'll be gliding further as we're then slowing towards our best glide speed (~200kts clean) which will cause the descent angle to shallow and the acft to diverge even higher from profile.

The only option left (short of radar vectors for more track miles-last option) is to deploy the speedbrakes- more drag, steeper descent profile. But, because we're descending at a slower speed the speedbrakes are less effective (remember parasite drag curve from your PPL) so they must stay out longer. The rumbling and rougher ride you felt is why we prefer not to use them if possible- passenger comfort.

The change of sound you mentioned is probably when we're configuring the acft for landing- slats/flaps/gear and the engines spooling up from the idle descent to approach power setting. This starts ~5000' when we have to shallow our descent so as to slow to initial flap extension speeds.

Which leads me into something you might reference for your ATC'ing- most jet acft can't "go down AND slow down". If you want us to descend quicker- allow us to speed up, if you want us to slow down- expect our rate of descent to decrease.

I'm sure i've explained alot that you already know- but i hope this helps anyway. Thanks for the question.

HJ

I'm guessing that Oz ATC kept them hi and they deployed the SpdBke to get down. If the A/P is engaged it will only deploy 1/2 anyway.
Or maybe they got their descent mucked up, or possibly got re-routed and given more direct which stuffed the prior planning up.
Any number of reasons.

Orrr..mayby they were just so distraught at having lost the Ashes...they completely lost the plot, and couldnt remember their 3 X's Table for the descent planning?

Nah cervix,

I think he had a plane load of poms and was trying to get the bad smell up the back of the plane.

;)

You are correct: the swooshing change of a noise is caused by the extension and retraction of the speed brakes. Coool sound A?

Thanks chaps, and HJ for your comprehensive explanation

The flight was to Maroochydore, so apart from being held up perhaps with some crossing traffic, I can't see how sequencing would be a problem. Maybe the traffic into Brisbane causes some profile problems.

Sincerest congratulations to the English Cricket Team (choke, gasp)

CG

At Maroochydoor? then its not an Airbus thing, i have flown into maroochy quite a few times, mostly in QF 737's and on most occasions the speed brakes have been deployed for the later part of the decent onto final, i think it has something to do with airspace limitations and flying over airfields such as caboulture and redcliff, every time the approach has been to the north, a few miles off the coast, then turning west, then north again onto finals.

Sounds like the typical Sydney approach scenario:

Pilot: "Plastic 320 leaving FL 350 on descent."

ATC: "Plastic 320 make speed 2 5 0 knots."

Pilot: "Thanks for that."

Into Maroochydore, I'd say the pilots were so excited at being able to do whatever they want instead of being nagged the entire approach, they wanted to get low on profile so they could enjoy the view.

But with a dinky little gay speedbrake lever such as an deathstar has, it's just as likely they didn't notice it was in the extended position.

Yet again, it may have been (as someone pointed out) that they were trying to rid themselves of the stench of 150 ripe, unwashed pommy back-packers. Takes a while for the pong to float up the back though, even with that body angle.

Chief galah,

The landing lights also cause a little noise in the cabin if extended over 250 kts.

DeBurcs

Know of no jet that can fix a 70 kt speed reduction at altitude without speedbrake, early configuration, or additional track miles too keep profile.

The little speed brake seems to have no trouble increasing the ROD to over 10000 fpm, unlike a boeing, it doesnt stay extended if you go TOGA.

As far as being "plastic", that award goes to the 787.

:ok:

:ok: That is a good one SWH :ok:

I bet all pro boeings must be scratching their heads now :}

Atyourcervix73:

How do you know when a 747 full of poms has arrived at YSSY?

The engines stop but the whining continues.

(But congrats has to be offered - well done those poms - but please can we aussies have lessons on how to be losers? - it's a foreign concept)

Well there's always the old roll over and pull through technique. :E

Are you saying the 320 is a drag monster? That's the only option left if Newton is to be believed.

I'd like to see you try that in a 330. Oh I get it, you throw out the gear at 25 grand! :ok:

On closer inspection, you may note I was referring to the speedbrake lever. Small, dinky, French and gay just like the LG lever. Even cabin crew (who see them all) have commented on its lack of manliness compared to other makes.

As for being plastic, that award will forever be on the EADS mantlepiece. You see, the word "Plastic" refers to so much more than merely the compounds it is made of.

"10 000 ft/min" - Excuse me while I belly-laugh. :rolleyes:

Wash your mouth out Swh, its not plastic, its "composite":}

Airway...very dignified:ok:

DeBurcs..if you wanna smell bad, visit a place called the "redback" in Acton West London...now there is a hotbead of the great unwashed (mostly Aussies that could do with a shower and a shave..and the theres the Aussie guys:} )cheap beer tho.

Why is it that the little Joystick looks so like a joystick on an electric wheel chair???:p

hehe

Just to get back to the post...

It seemed a long way to have the brake deployed. I assume the AP was in control at this phase, so does that mean the machine decides the brake should be out?

I can't imagine the traffic management to the Sunshine Coast would begin that far out, and the clean profile would have been assessed well before then.

CG

Chief galah,

Yep, depending on what you do, you will get a speed limit exceeded message on the FMGC, and/or more drag on the top of the PFD, and/or nothing at all depends of the type of descent you have done.

DeBurcs,

Seems your just another ignorant Boeing pilot not knowing a thing about what they are talking about. TOD for a 320 kt profile and TOD for a 250 profile are miles apart. No real jet can wash off that energy, we are talking about aeroplanes not women with the inability of going down and slowing down.

And for your benefit :


Plastic : Any of various organic compounds produced by polymerization, capable of being molded, extruded, cast into various shapes and films, or drawn into filaments used as textile fibers.

Composite : A complex material, such as wood or fiberglass, in which two or more distinct, structurally complementary substances, especially metals, ceramics, glasses, and polymers, combine to produce structural or functional properties not present in any individual component.

As I said, the plastic award goes to the 787, and for your information, the 777 contains more "plastics" than most airbus types.

As for 10000ft/min, I have done it in the aeroplane, have you ?...didn’t think so.

:ok:

P.S. I didn’t need to know what the cabin crew thought of your small, dinky and gay speed brake lever, you have just scarred me for life. I have heard them called many names, I think you’re the first to call it a speed brake lever. Do you play cockpit games with your cabin crew at home ?

P.P.S. Airways was taking the pi$$ out of you with his post, not mine…happen to know him personally.

P.P.P.S. Come up with something original, all the A V B jokes and differances have been done to death on this site.

I really don't know why you are all responding to the this Galah Donkey who obviously knows nothing about A320 ops!

I mean, I'm not bothering and I know about 320 ops! :rolleyes:

One must really feel sorry for some people.

CG

Amos2,

I’d like to bring to your attention the “Profile” button. When pressed, it accesses a user's “Profile”. The definition of “Profile” must be easily found in many common dictionaries.

Profiles on this forum fit into three categories (or a mix thereof): truth, humour, & bullsh!t.

The original poster’s profile seems to be of the first part, yours is most certainly in the third realm.

Please don’t bother anymore, we're enjoying your retirement.

HJ