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Slowing Down Suddenly In Airbus/Boeing's - How?  
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Posted (8 years 9 months 5 days 6 hours ago) and read 2746 times:

What is the best way technical way to slow down as soon as possible in a large aircraft? If you suddenly are asked by Air Traffic, or you are gaining too fast on the aircraft in front of you and need to cool it quickly, what is the best method? I assume that just selecting a lower speed on the autopilot would take to long for it to settle - would speed brakes be the best way or will they cause too much of a pitch difference?

J

22 replies: All unread, jump to last
 
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 1, posted (8 years 9 months 5 days 6 hours ago) and read 2731 times:

Quoting Julesmusician (Thread starter):
If you suddenly are asked by Air Traffic,

ATC is used to the speed characteristics of various aircraft. If they ask for a speed reduction, all I do is set the new speed in the speed window, if the aircraft is on autoflight, or if I'm hand flying, just bring the throttles to idle. (My own personal philosophy is speed brakes are for my mistakes not ATC's. They really make the ride uncomfortable and I try to avoid using them at all.)

If I have to slow down to a maneuvering configuration lowering flaps will help to slow down. Fully configured with landing flaps or gear, speed reduction is pretty fast. However on final, you really can't slow down any more, so perhaps a go-around would be more prudent?


User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 2, posted (8 years 9 months 5 days 6 hours ago) and read 2720 times:

Is this the same for a sudden change of heading - heard recently "Speedbird 238 turn now immediate left 180 degrees" - it was off his path to avoid unidentified traffic - is that a grabbing the controls movement or still an autopilot command?

User currently offlineBuckFifty From Canada, joined Oct 2001, 1316 posts, RR: 19
Reply 3, posted (8 years 9 months 5 days 6 hours ago) and read 2709 times:

If the ATC says 'immediate left heading 180 degrees due traffic' then the a/p will probably go off. Otherwise, if he does not qualify the statement like so, it just means you turn left heading 180 now, but using a knob, not the control column/sidestick/your own particular extremity.

Quoting PhilSquares (Reply 1):
(My own personal philosophy is speed brakes are for my mistakes not ATC's. They really make the ride uncomfortable and I try to avoid using them at all.)

We do use the boards quite often on the Airbii, very slippery aircraft. In fact, you'll see them out on our flights at least once per descent, minus the rollout, which is ops normal.

And I suppose it depends on what speed we slow down from to accomodate ATC. Not so good getting vectored somewhere out there (and have them forget us) just so they can fit a few planes in. Putting everything out there usually will do the trick, but sometimes it just doesn't happen fast enough.

This happens at JFK a lot, it seems. If you don't work with them, they'll make you pay. And no amount of on-air chivalry would change that fact.


User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 4, posted (8 years 9 months 5 days 5 hours ago) and read 2697 times:

Quoting BuckFifty (Reply 3):
This happens at JFK a lot, it seems. If you don't work with them, they'll make you pay. And no amount of on-air chivalry would change that fact

I've flown into JFK numerous times. Next time you arrive from the north ask for the "crowbar". That will open your eyes!


User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 5, posted (8 years 9 months 5 days 5 hours ago) and read 2691 times:

I have heard that CDG is much like that as well.

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17039 posts, RR: 66
Reply 6, posted (8 years 9 months 5 days 5 hours ago) and read 2665 times:

Quoting BuckFifty (Reply 3):
Quoting PhilSquares (Reply 1):
(My own personal philosophy is speed brakes are for my mistakes not ATC's. They really make the ride uncomfortable and I try to avoid using them at all.)

We do use the boards quite often on the Airbii, very slippery aircraft. In fact, you'll see them out on our flights at least once per descent, minus the rollout, which is ops normal.

As a pax, it's always my impression that the Airbus speed brakes are "gentler" on the ride than the Boeing ones.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 7, posted (8 years 9 months 5 days 5 hours ago) and read 2659 times:

Quoting Starlionblue (Reply 6):
it's always my impression that the Airbus speed brakes are "gentler" on the ride than the Boeing ones

After flying the 320 and the other Boeings, I'd be inclined to agree. Where I find the greatest difference is at high indicated speed. On the Boeing, you get a very large amount of vibration and not much increase in drag. However, in the 320 you don't get much vibration and you get a noticable increase in the descent rate. At speeds below 250 indicated, the vibration is markedly reduced and comparable to the 320.

That's why I really don't like using speedbrakes on the 400. There are more comfortable ways to slow the aircraft down.


User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 8, posted (8 years 9 months 5 days 4 hours ago) and read 2650 times:

It will be interesting to see how they intend to slow the A380 down...

User currently offlineStarlionblue From Greenland, joined Feb 2004, 17039 posts, RR: 66
Reply 9, posted (8 years 9 months 5 days 4 hours ago) and read 2646 times:

Quoting PhilSquares (Reply 7):
Quoting Starlionblue (Reply 6):
it's always my impression that the Airbus speed brakes are "gentler" on the ride than the Boeing ones

After flying the 320 and the other Boeings, I'd be inclined to agree. Where I find the greatest difference is at high indicated speed. On the Boeing, you get a very large amount of vibration and not much increase in drag. However, in the 320 you don't get much vibration and you get a noticable increase in the descent rate. At speeds below 250 indicated, the vibration is markedly reduced and comparable to the 320.

There's also a big difference when the speedbrakes are retracted. On the 737 it's basically "clonk!" Directly from fully extended to retracted. This makes the whole plane change attitude for a second. You really feel it. On the 32x, the speedbrakes are gently retracted and the effect dissapears almost imperceptibly.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 10, posted (8 years 9 months 5 days 4 hours ago) and read 2627 times:

The only time in my career I ever uttered that deadly phrase: "watch this" came in response to Coast Approach asking me how fast I could be slowed to 180. I was flying a BAe-146 with that terriffic tail-mounted speed brake (and the aerodynamics of a pumpkin) I went from 250 to 180 in, as he told me, one sweep of his radar.

Most jetliners don't do it that quick and "suddenly" is a relative term.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently onlinePihero From France, joined Jan 2005, 4445 posts, RR: 76
Reply 11, posted (8 years 9 months 5 days 3 hours ago) and read 2608 times:
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Quoting PhilSquares (Reply 1):
ATC is used to the speed characteristics of various aircraft

Agree though they - as a general rule - don't take into account the vastly differing approach speeds of a 321 and , say a319 .
Good airmanship : announce your approach speed to tower when flying a heavily loaded 321 behind another medium hauler.



Contrail designer
User currently offlineBri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 12, posted (8 years 9 months 4 days 17 hours ago) and read 2454 times:

No one mentioned that you can deny a particular clearance from ATC if you must. It's so nice that airline pilots want to give passengers the best ride possible. But, if they get asked to slow down, and the only safe way to achieve the requested rate of deceleeration is flight spoilers / speedbrakes, they're probably going to use them versus declining the newly cleared speed (to avoid one of those vectors to nowhere and beyond). Unless, of course, they absolutely cannot. I was on a flight recently (listening to ATC on UA channel 9) when the ground controller requested a fairly abrupt and rather tight ground manuever, and when the pilots finished laughing, they informed the controller that was not going to be possible in this lifetime or the next. Evidently, the flight plan had somehow become filed as as 737 instead of a 777, and they were not yet in the line of sight of the controller.


Position and hold
User currently offlineMastropiero From Spain, joined Dec 2005, 125 posts, RR: 0
Reply 13, posted (8 years 9 months 4 days 10 hours ago) and read 2328 times:

What would be the do not exceed speed for speed brakes extension?

User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 14, posted (8 years 9 months 4 days 9 hours ago) and read 2311 times:

Quoting Mastropiero (Reply 13):
What would be the do not exceed speed for speed brakes extension?

I've never seen any that weren't usable all the way up to VMO /MMO and presumably beyond in emergencies.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineJush From Germany, joined Apr 2005, 1636 posts, RR: 3
Reply 15, posted (8 years 9 months 4 days 9 hours ago) and read 2300 times:

Quoting PhilSquares (Reply 4):
I've flown into JFK numerous times. Next time you arrive from the north ask for the "crowbar".

Could you describe it more. I'm not a pilot but i would really like an explanation for the "crowbar"

Regds
jush



There is one problem with airbus. Though their products are engineering marvels they lack passion, completely.
User currently offlineMastropiero From Spain, joined Dec 2005, 125 posts, RR: 0
Reply 16, posted (8 years 9 months 4 days 9 hours ago) and read 2292 times:

Quoting SlamClick (Reply 14):
I've never seen any that weren't usable all the way up to VMO /MMO and presumably beyond in emergencies.

Oh, thanks. I thought there was a speed limit, just as for flaps.


User currently offlineStarlionblue From Greenland, joined Feb 2004, 17039 posts, RR: 66
Reply 17, posted (8 years 9 months 4 days 8 hours ago) and read 2269 times:

Quoting Mastropiero (Reply 16):
Quoting SlamClick (Reply 14):
I've never seen any that weren't usable all the way up to VMO /MMO and presumably beyond in emergencies.

Oh, thanks. I thought there was a speed limit, just as for flaps.

The logic is that even if you are at max speed you still sometimes need to brake. One example I can think of is an emergency descent from cruising altitude. Just pushing the nose down might entail overspeed, so the speedbrakes come out and you can descend at full speed.

Also if you have done an idle descent to start your approach, you don't want to have to level out to bleed airspeed when you reach 10000ft (or whatever). But your current airspeed may be quite high.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 18, posted (8 years 9 months 4 days 8 hours ago) and read 2251 times:

Quoting Julesmusician (Reply 5):
I have heard that CDG is much like that as well.

I have never really had too many surprises going into CDG except for the often "late" clearance to land or go-around but FRA often let's us decend with no speed restriction and then turns us in close for the app....yeeehaa!


User currently offlineSPREE34 From United States of America, joined Jun 2004, 2248 posts, RR: 9
Reply 19, posted (8 years 9 months 4 days 7 hours ago) and read 2212 times:

Quoting Julesmusician (Reply 8):
It will be interesting to see how they intend to slow the A380 down...

The aerodynamic laws are the same.It will slow down just like eveything else.



I don't understand everything I don't know about this.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17039 posts, RR: 66
Reply 20, posted (8 years 9 months 4 days 7 hours ago) and read 2209 times:

Quoting SPREE34 (Reply 19):
Quoting Julesmusician (Reply 8):
It will be interesting to see how they intend to slow the A380 down...

The aerodynamic laws are the same.It will slow down just like eveything else.

Just turn all the 555 airvents forward and open at full blast Big grin



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineWing From Turkey, joined Oct 2000, 1571 posts, RR: 23
Reply 21, posted (8 years 9 months 4 days 5 hours ago) and read 2164 times:

Quoting Mastropiero (Reply 13):
What would be the do not exceed speed for speed brakes extension?

The 737-800 has a max 300 kts speed limit in a turn as I remember.

Quoting Julesmusician (Reply 2):
this the same for a sudden change of heading - heard recently "Speedbird 238 turn now immediate left 180 degrees" - it was off his path to avoid unidentified traffic - is that a grabbing the controls movement or still an autopilot command?

Unless it is a TCAS RA advisory there is really no need to disengage the AP to avoid the traffic in my opinion.

And finally if we come back to the original question ,there is no "sudden slowing down" on airline flying since we have to stay in the game(even infront of it) all the time.There is always options of changing the pitch (with different intervention technics) to play with the speed.

If on the approach course you are getting closer to the airplane infront you can consider to configure earlier with the flaps and the gear.

But sometimes ATC guys want you to slow down and descent at the sametime(they are trying to be funny I guess  Smile ) That leaves you no option but to use the speed brakes.

These are all situations come to my mind require a quick slow down.Sorry if I am missing any,I had a long day of flying.Cheers.WING



Widen your world
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 59
Reply 22, posted (8 years 9 months 4 days 5 hours ago) and read 2143 times:
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Quoting Julesmusician (Reply 2):
heard recently "Speedbird 238 turn now immediate left 180 degrees" - it was off his path to avoid unidentified traffic - is that a grabbing the controls movement or still an autopilot command?



I can't speak for airline ops, but from a general aviation perspective, I interpret "immediate" as RIGHT NOW. A few years ago, I was doing some pattern work at KYIP (Willow Run, outside of Detroit), which has three pairs of parallel runways.

I was on a midfield left downwind for 23L, I believe, when the controller instructed me to "make immediate right turn". I started my turn instantly, even before acknowledging the request, and I'm glad I did. About 5 seconds later, I saw a blur to my left. Apparently, another aircraft had strayed from it's assigned course and blundered into my path.

Also, the tone of the controller is a good indication of the urgency. If his/her voice increases by an octave, it's probably in your best interest to hurry things up.  




2H4




[Edited 2005-12-19 21:39:47]


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