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Guest bisinchi

best way to slow down?

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Guest bisinchi

Which is the best way to slow down the 767? Is this using AirBrakes (but this is uncomfortable for the passengers), or is it by decreasing the V/S?Using Airbrakes also results in high descent rates, so you can end up keeping the same airspeed, but descending faster, which is not necessarily the wanted result!!!Francois

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Francois,I have a video of a 767 flight from JFK to San Pedro, Brazil taken from the inside the cockpit. The captain did a great job of explaining what he was doing at each stage of the flight. When he was cleared to descend to lower altitudes and his speed was still too high, he engaged the airspeed brakes to slow him down. He kept the speedbrakes deployed until his speed came down from about 260 kts to 200 kts. So I think it's an accepted procedure during a descent to use speedbrakes. When I used them in PIC, I noticed the descent rate also increased, but that was only temporary until the autopilot adjusted for the use of the speedbrakes. Hope this helps.Jason

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Guest ilh

I've been a passenger on plenty of flights where airbrakes were used and I was in no way uncomfortable. Last one was a BA 777 and I was sitting right over the wing.Lee Hetherington (KBOS)

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I rarely ever use speed brakes - but I rarely use ATC. If you can plan your own descend there should be no problem in slowing down your 767 - only some little planning is required and knowledge what 767 can do.Michael J.

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There is no one way, it depends on your situationIf you are still high, you can use the speedbrakes. No problem there and it isn't uncomfortable either, as long as the pitch adjustments are made smoothly. Used very often on airliners.If you're on final approach and you have to drop down to intercept the glideslope, speedbrakes aren't recommended as you might forget to retract them and run into trouble. Instead use the landing gear.In an emergency you could use both the gear and the speedbrakes, your sink rate will exceed 5000 fpm, so handle with careGood luck,Mark

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I have been in a 767 where the airbrakes are left on for long periods of time. The comfort level does go down as the airbrakes cause light vibrations and a loud noise as well as the slowing down effect. For a person who loves flying this is not a problem, but to nervous passengers it can be terrible.

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Guest fwsov

For the "gun" pilots in the airlines you'll find they'll be 300kts downwind for a 4nm final and manage to slow that thing down without the use of speedbrakes. However, there is NO shame in using the speedbrakes, in fact it's very common and sometimes a necessity to use them as a 767 with very little flap or clean configuration can be quite difficult to slow down.You mentioned that speedbrakes resulted in high rates of descent and no airspeed decrease. This is exactly how they are effective. If you are at say 300kts and want to slow to 250kts and in clean configuration and use the speedbrakes, you will notice the V/S decreasing to a very high rate, so to convert this high descent rate into a loss in speed you increase your angle of attack, (pull up) till you reach the descent rate that you want and watch the airspeed decrease due to the greater drag. So what is effectively happening when you raise the speedbrakes is a loss in lift, which has to be counteracted by an increase of AOA, resulting in higher drag.With close monitoring on your airspeed and your descent rate you can use speedbrakes even on final approach (providing you are relatively high)Hope this helps a bit, I'd imagine using the speedbrakes on final is a bit dodgey but we'll see what the real 767 drivers say about it :-)Regards-Andrew

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Guest fwsov

Oh, and regarding passenger comfort, safe operation of the aircraft comes first (as you probably know) so using speedbrakes is one method on safe operation thus it shouldnt' be a problem. The best way to avoid getting high and fast is to plan your approach while you are in cruise or on descent in the FMC so you can use VNAV to give you accurate ETA's and an accurate and stable descent profile all the way to final approach. If however your plan is disrupted by delays etc. and you are using V/S then to slow down the only other things you can do is make sure the engines are at idle thrust and if you are really desperate, making sure you are below max airspeeds, you can start lowering gear and flaps etc.-Andrew

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Guest Iz

With regards to the speedbrakes, you "should" always plan for a descent without 'em and anticipate what will happen. Is there a lot of congestion, will I have to descend early, or descend fairly late, what about speed restrictions at altitudes or beyond speed limit points on the arrival?Taking all this into consideration should provide you with a descent profile that incorporates the necessary speed reductions without the use of speedbrakes.The scenarios where you would need to use the speedbrakes:- Due to congestion or otherwise, ATC vectors you so that your descent profile is shot to pieces and you end up high or fast, relative to the planned profile.- Due to a change in runway or arrival procedure, the track miles to go until touchdown have decreased significantly, so you are now too high above your profile.- Winds cause you to go above your descent profile (tailwinds)- You need to use anti-ice, causing a higher idle setting, causing you to go above your profile if you didn't expect this.- You made a miscalculation yourself.So in all cases, speedbrakes are used when above the necessary descent profile (path). At high altitude, another way to gain excess altitude is by increasing the speed (speed intervention), causing higher descent rate.In a 757/767, VNAV does a good job of figuring out the best (=most economical) descent path, even considering winds, anti-ice etc. So if circumstances don't change, you won't need the speedbrakes.In any case, a speed reduction is done by decreasing thrust, rate of descent and optionally increasing drag by use of speedbrakes, landing gear or flaps.It then becomes an issue of priority. What is more important, slowing down first or descending faster?Iz

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Jason,Do you have the Transbrasil In the Cockpit #13? If so, yes it is very nice indeed. I love the explanation the Capt. gives...the TCAS with the traffic to name but a few of the many items of interest.On minor correction, the flight terminates in S

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(Real World)One of the main-pains in speed-brake usage is it kills the efficeny of the flight. The "problem" is the new generation of Boeings are so efficient(read "less drag") they are used now to mesh in with other traffic. The old 727 would slow-up at 10,000' real nice just buy holding level about 5 miles to bleed off the 30 knots. The 757 to bleed off speed is more like 12 to 15 miles. When the 757 first came on line they were flown on the line using the old methods before the crews and controllers got used to the tendancy.You will here (in the US) the call "...slowing at ten, decending to seven..." when not on speed restrictions. If you look at STARs you will see the speeds at crossing restrictions.Controllers have a limited amount of airspace, altitude to work with, so speed is one of their cards they play, but they hate it as we do since it involves configuration changes and set-ups.Also, nobody says in flight sim you have to use full deployment of speedbrakes. Sometimes, a little over a slightly longer length of time is better than cramming full speed brake on all at once.Timothy

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