User Panel
Posted: 4/7/2017 8:28:57 PM EDT
On pretty much every airliner flight I've ever been on, in fact I'll say every one, 100%, I witnessed varying degrees of spoiler deployment during descent. Presumably, these were all automated deployments.
It makes me wonder: in terms of spoiler use during descent, why is it not possible to effectively achieve the same thing with less throttle and more nose-down attitude? Wouldn't that be less wasteful? |
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Airliners are surprisingly slippery. They have glide ratios on a par with sporting gliders. Sometime you have to lose a lot of altitude. You may be above safe flap deployment speed, and if you just push the nose over, you may go a little too fast. Most spoilers can be deployed at a higher speed than flaps, and can be "feathered" more than flaps. There is also less associated change in pitch with spoilers.
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Speed brakes. It's a way to dirty up the aerodynamics & slow down.
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Speed restrictions likely play a part in that.
Even with zero throttle, they may not be able to descend fast enough without exceeding ATC/FAR/STAR imposed speed restrictions. |
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May need to keep the turbines spun up enough to maintain pressurization in the cabin.
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What if it's less than 10c with visible moisture and you need keep the engines spooled up to more than 55% for effective engine anti-icing and you need to make an altitude restriction or comply with an ATC restriction because of crossing traffic or you encounter turbulence and need to slow to give pax a better ride or you started down late because you were in the last two hours of a 14 hour duty day or you just plain fucked up?
Shit happens in the big leagues |
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What if it's less than 10c with visible moisture and you need keep the engines spooled up to more than 55% for effective engine anti-icing and you need to make an altitude restriction or comply with an ATC restriction because of crossing traffic or you encounter turbulence and need to slow to give pax a better ride or you started down late because you were in the last two hours of a 14 hour duty day or you just plain fucked up? Shit happens in the big leagues View Quote On really large aircraft there's so much available bleed air at all rpm's that it's nolonger an issue. On the 75 and 76 it used to be a lot easier to make descents and speed restrictions without flight spoilers until they started installing winglets. Now the damn things are kites and don't want to come down. On virtually every descent I need to deploy spoilers because they glide so well. But spoiler use is never automated. That always requires manual use by the pilot. On most aircraft spoilers can be deployed at all speed ranges. Lear Jets are an interesting exception. They have a hard limit of no spoilers while flaps are out of zero. This is because the spoilers are positioned directly over the flaps. If flaps and spoilers are deployed simultaneously it can create such a low pressure void between them that it could damage the skin of the wing. Every other aircraft I've flown has the spoilers positioned out of line with the flaps so this isn't an issue. But without spoilers we'd never make our descent crossing restrictions and speeds. We'd either blow over the altitude or blow through the speed restrictions. |
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On pretty much every airliner flight I've ever been on, in fact I'll say every one, 100%, I witnessed varying degrees of spoiler deployment during descent. Presumably, these were all automated deployments. It makes me wonder: in terms of spoiler use during descent, why is it not possible to effectively achieve the same thing with less throttle and more nose-down attitude? Wouldn't that be less wasteful? View Quote If your at idle and already going as fast as the speed of heat going any faster will cause things to start shaking like a sight impaired priest at a Cub Scout Jamboree so you gotta have drag........not the kind like in the cabin in the form of a boy stewardess dressing like a girl!, |
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On pretty much every airliner flight I've ever been on, in fact I'll say every one, 100%, I witnessed varying degrees of spoiler deployment during descent. Presumably, these were all automated deployments. It makes me wonder: in terms of spoiler use during descent, why is it not possible to effectively achieve the same thing with less throttle and more nose-down attitude? Wouldn't that be less wasteful? View Quote Throttle is usually already at idle and nose-down too much just increases your speed. Some jets are just too hard to slow. If you are too steep than you simply keep speeding up, thus risking overspeed and not making restrictions set forth by ATC. ATC is there to manage traffic flow, so if the bird in front of you can't go 320 knots in descent, then you have to follow the ATC speed assigned. Look at a lot of STARs and you will see restrictions assigned for better flow into the airspace. Here you see that into LAX on this STAR, crossing GLESN the speed is a hard restriction of 280 knots. You can be at or above 24,000 feet and at or below 30,000. At CRCUS, speed at 270, between 12,000 and 14,000 feet. ATC will usually give you vectors at some point with their own altitude and speeds, but it's important to understand that getting down is tough at times. Obviously avoiding the speedbrake is possible if ATC lets you do your own thing, but they are managing traffic around you, so you kinda need to let them help you out. Attached File ETA: The only "automated" spoiler deployment is on touchdown. The pilot will arm the speedbrake/spoiler and it will deploy to full when the mains touch down. |
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Throttle is usually already at idle and nose-down too much just increases your speed. Some jets are just too hard to slow. If you are too steep than you simply keep speeding up, thus risking overspeed and not making restrictions set forth by ATC. ATC is there to manage traffic flow, so if the bird in front of you can't go 320 knots in descent, then you have to follow the ATC speed assigned. Look at a lot of STARs and you will see restrictions assigned for better flow into the airspace. Here you see that into LAX on this STAR, crossing GLESN the speed is a hard restriction of 280 knots. You can be at or above 24,000 feet and at or below 30,000. At CRCUS, speed at 270, between 12,000 and 14,000 feet. ATC will usually give you vectors at some point with their own altitude and speeds, but it's important to understand that getting down is tough at times. Obviously avoiding the speedbrake is possible if ATC lets you do your own thing, but they are managing traffic around you, so you kinda need to let them help you out. https://www.AR15.Com/media/mediaFiles/49490/ANJLL-183004.JPG ETA: The only "automated" spoiler deployment is on touchdown. The pilot will arm the speedbrake/spoiler and it will deploy to full when the mains touch down. View Quote |
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The only time I've ever heard of those exact restrictions was on the CRJ. Back then we considered the use of spoilers to be a failure on the part of the pilot to properly plan his descent unless, as you say, it was necessary to keep N1 up to feed the anti-ice. The CRJ engine needed this limitation because they were pretty underpowered. On really large aircraft there's so much available bleed air at all rpm's that it's nolonger an issue. On the 75 and 76 it used to be a lot easier to make descents and speed restrictions without flight spoilers until they started installing winglets. Now the damn things are kites and don't want to come down. On virtually every descent I need to deploy spoilers because they glide so well. But spoiler use is never automated. That always requires manual use by the pilot. On most aircraft spoilers can be deployed at all speed ranges. Lear Jets are an interesting exception. They have a hard limit of no spoilers while flaps are out of zero. This is because the spoilers are positioned directly over the flaps. If flaps and spoilers are deployed simultaneously it can create such a low pressure void between them that it could damage the skin of the wing. Every other aircraft I've flown has the spoilers positioned out of line with the flaps so this isn't an issue. But without spoilers we'd never make our descent crossing restrictions and speeds. We'd either blow over the altitude or blow through the speed restrictions. View Quote On the A-321 with sharklets (winglets to any other airplane) using the speed brakes is just about an every flight occurrence. All of those LAX arrivals pretty much require it, it's a big glider as well. The VNAV logic on the bus gives itself +/- 20 knots from the constraint speed to make the altitude, so if we want to comply with both the speed and altitude we have to use them. We get "too steep path ahead" and "more drag" messages all the time. Even when everything looks great at TOD. |
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On the MD80 there was a limitation, that with the wing heat on, you had to carry enough power to keep the Anti-Ice low temp lights out. There wasn't a hard power setting, but it required quite a bit of power above idle. In the winter, with a strong tailwind if we were doing any of the D.C. arrivals from the west, it required the boards pretty much from top of decent if we wanted to get down. View Quote |
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We had a Chief Pilot named Nelson at Northwest, he called them "erasers" as in to erase any mistakes you made in planning your decent. Half speed breaks would be called a "half Nelson" and full boards were a "full Nelson". Funny that with 1/2 speedbreaks in the B727, you got double acting spoilers and would increase the roll rate by almost double, not good for the passengers, but you would look shit hot in the break!
The B727 would need to carry power on the one or more engines to produce enough bleed air to keep control of the cabin pressurization above about FL200. For years the airliners were 3:1 airplanes. For every 1000 feet of altitude loss, you needed three miles. So from FL310 to a 1000' airport, you would start your decent 70-90 miles or so from the point you were to be at 250 knots, 10000' and 30 miles to go. Now the newer airplanes with higher residual thrust and glider like aerodynamics are 4:1 airplanes. From 41000' you start your decent 150-160 miles out, and you need to be at 250 knots, at 10000' 40 miles from the airport. ATC will of course screw up your decent planning, but the speedbreaks are for our mistakes, not theirs. |
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Spoilers used in flight increase your rate of descent. In a commerical environment, pulling power and going nose down increases passenger frustration.
Also, depending on flap location, spoilers are used to increase the authority of your ailerons. Something to look for. Will |
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The bus plans an idle descent path based on winds that have been entered into the computer, and if the winds are different than what was entered, it throws things out of whack. Plus anytime ATC assigns a speed slower than what is programmed in for the descent, out come the speed brakes to slow down because we're probably already at idle.
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Throttle is usually already at idle and nose-down too much just increases your speed. Some jets are just too hard to slow. If you are too steep than you simply keep speeding up, thus risking overspeed and not making restrictions set forth by ATC. ATC is there to manage traffic flow, so if the bird in front of you can't go 320 knots in descent, then you have to follow the ATC speed assigned. Look at a lot of STARs and you will see restrictions assigned for better flow into the airspace. Here you see that into LAX on this STAR, crossing GLESN the speed is a hard restriction of 280 knots. You can be at or above 24,000 feet and at or below 30,000. At CRCUS, speed at 270, between 12,000 and 14,000 feet. ATC will usually give you vectors at some point with their own altitude and speeds, but it's important to understand that getting down is tough at times. Obviously avoiding the speedbrake is possible if ATC lets you do your own thing, but they are managing traffic around you, so you kinda need to let them help you out. https://www.AR15.Com/media/mediaFiles/49490/ANJLL-183004.JPG ETA: The only "automated" spoiler deployment is on touchdown. The pilot will arm the speedbrake/spoiler and it will deploy to full when the mains touch down. View Quote |
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Are the NOS charts that bad? I like them lol. Jeppesen offer what over these?
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Living The Dream Pt. III |
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The only time I've ever heard of those exact restrictions was on the CRJ. Back then we considered the use of spoilers to be a failure on the part of the pilot to properly plan his descent unless, as you say, it was necessary to keep N1 up to feed the anti-ice. The CRJ engine needed this limitation because they were pretty underpowered. On really large aircraft there's so much available bleed air at all rpm's that it's nolonger an issue. On the 75 and 76 it used to be a lot easier to make descents and speed restrictions without flight spoilers until they started installing winglets. Now the damn things are kites and don't want to come down. On virtually every descent I need to deploy spoilers because they glide so well. But spoiler use is never automated. That always requires manual use by the pilot. On most aircraft spoilers can be deployed at all speed ranges. Lear Jets are an interesting exception. They have a hard limit of no spoilers while flaps are out of zero. This is because the spoilers are positioned directly over the flaps. If flaps and spoilers are deployed simultaneously it can create such a low pressure void between them that it could damage the skin of the wing. Every other aircraft I've flown has the spoilers positioned out of line with the flaps so this isn't an issue. But without spoilers we'd never make our descent crossing restrictions and speeds. We'd either blow over the altitude or blow through the speed restrictions. View Quote View All Quotes View All Quotes Quoted:
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What if it's less than 10c with visible moisture and you need keep the engines spooled up to more than 55% for effective engine anti-icing and you need to make an altitude restriction or comply with an ATC restriction because of crossing traffic or you encounter turbulence and need to slow to give pax a better ride or you started down late because you were in the last two hours of a 14 hour duty day or you just plain fucked up? Shit happens in the big leagues On really large aircraft there's so much available bleed air at all rpm's that it's nolonger an issue. On the 75 and 76 it used to be a lot easier to make descents and speed restrictions without flight spoilers until they started installing winglets. Now the damn things are kites and don't want to come down. On virtually every descent I need to deploy spoilers because they glide so well. But spoiler use is never automated. That always requires manual use by the pilot. On most aircraft spoilers can be deployed at all speed ranges. Lear Jets are an interesting exception. They have a hard limit of no spoilers while flaps are out of zero. This is because the spoilers are positioned directly over the flaps. If flaps and spoilers are deployed simultaneously it can create such a low pressure void between them that it could damage the skin of the wing. Every other aircraft I've flown has the spoilers positioned out of line with the flaps so this isn't an issue. But without spoilers we'd never make our descent crossing restrictions and speeds. We'd either blow over the altitude or blow through the speed restrictions. |
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I never knew that in flight spoiler deployment was done manually. I always figured a computer handled it. Interesting.
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Actually, and this really doesn't apply to this discussion, the one example I can give that spoiler use is automated is the C-17. They're automated into the primary flight controls to provide roll control with the ailerons. View Quote View All Quotes View All Quotes Quoted:
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What if it's less than 10c with visible moisture and you need keep the engines spooled up to more than 55% for effective engine anti-icing and you need to make an altitude restriction or comply with an ATC restriction because of crossing traffic or you encounter turbulence and need to slow to give pax a better ride or you started down late because you were in the last two hours of a 14 hour duty day or you just plain fucked up? Shit happens in the big leagues On really large aircraft there's so much available bleed air at all rpm's that it's nolonger an issue. On the 75 and 76 it used to be a lot easier to make descents and speed restrictions without flight spoilers until they started installing winglets. Now the damn things are kites and don't want to come down. On virtually every descent I need to deploy spoilers because they glide so well. But spoiler use is never automated. That always requires manual use by the pilot. On most aircraft spoilers can be deployed at all speed ranges. Lear Jets are an interesting exception. They have a hard limit of no spoilers while flaps are out of zero. This is because the spoilers are positioned directly over the flaps. If flaps and spoilers are deployed simultaneously it can create such a low pressure void between them that it could damage the skin of the wing. Every other aircraft I've flown has the spoilers positioned out of line with the flaps so this isn't an issue. But without spoilers we'd never make our descent crossing restrictions and speeds. We'd either blow over the altitude or blow through the speed restrictions. |
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Actually, and this really doesn't apply to this discussion, the one example I can give that spoiler use is automated is the C-17. They're automated into the primary flight controls to provide roll control with the ailerons. View Quote |
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The C-135 has spoilers and flaps at the same wing stations. View Quote View All Quotes View All Quotes |
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On the 737, you're pretty much using spoilers on every arrival. Many times, during decent, it's because the crappy auto-throttles see you're 10 knots fast/5 knots from overspeed, and decides now is a good time to ADD power.
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On the 737, you're pretty much using spoilers on every arrival. Many times, during decent, it's because the crappy auto-throttles see you're 10 knots fast/5 knots from overspeed, and decides now is a good time to ADD power. View Quote |
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In a 727 below 10,000 feet with wing & engine anti ice on you might need some spoiler to stay under 250 kts
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View Quote I fly the 777 and it's a clean machine... if you are left high and fast in any capacity the brakes are coming out, at least a little. I try to minimize their usage, but then again.. they bought an airplane ride, give them an airplane ride |
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came here to post this.. 1:46 I fly the 777 and it's a clean machine... if you are left high and fast in any capacity the brakes are coming out, at least a little. I try to minimize their usage, but then again.. they bought an airplane ride, give them an airplane ride View Quote Now the old turbojet reversers on the 737's were a good way to scare other passengers.. OMG the engine is falling off! |
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You'd love how we use the spoilers. The VSI on my iPad said 11,350 fmp the other day. View Quote View All Quotes View All Quotes Quoted:
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To us cattle in the back, it's just a bit of rumble. Now the old turbojet reversers on the 737's were a good way to scare other passengers.. OMG the engine is falling off! "Challenge accepted " |
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To us cattle in the back, it's just a bit of rumble. Now the old turbojet reversers on the 737's were a good way to scare other passengers.. OMG the engine is falling off! View Quote |
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You'd love how we use the spoilers. The VSI on my iPad said 11,350 fmp the other day. View Quote View All Quotes View All Quotes Quoted:
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To us cattle in the back, it's just a bit of rumble. Now the old turbojet reversers on the 737's were a good way to scare other passengers.. OMG the engine is falling off! |
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You talking about the 737-200 bucket style reversers? I don't think airborne deployment was permitted. View Quote I also told my grandmother when I was like 10 that "can you believe this entire airplane is only sitting on 3 pipes" |
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If it weren't for those pesky air traffic controllers View Quote No, OP, they are never "Automatic" in fact, one has to make a conscious effort to remember to retract them. LoL to the guy that said it's to keep the engines spooled up for pressurization. Thank God, it ain't that complicated. |
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This, is the truth of it right here. We could keep it clean until 6 miles, if allowed to do our own thing. No, OP, they are never "Automatic" in fact, one has to make a conscious effort to remember to retract them. LoL to the guy that said it's to keep the engines spooled up for pressurization. Thank God, it ain't that complicated. View Quote |
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We never had that problem on the 200, but it did require pilots to fly it. View Quote |
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Well, on some aircraft, you do have to keep the engines up a little to avoid losing too much pressurization (you won't dump all pressure, but your ears will pop and the cabin altitude will rise), so in a descent you may have to use them. I assume not all aircraft do, but they do exist. View Quote |
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Some of the captains I fly with flew the classics and they say its AP/AT seemed to work better than the NG. To top it all off, the latest software update, causes screen blanking from time-to-time, usually at the most inopportune time. It always come back fairly quickly but it's an annoyance. The 737"NG" has a nice panel, but the AP/AT is something to be desired...especially if you've flown anything else. The OLDER 757/767 AP/AT we're much better IMO. View Quote View All Quotes View All Quotes Quoted:
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We never had that problem on the 200, but it did require pilots to fly it. In the 737-200 we had dual ILS & ADF with a simple flight director. The autopilot would track a VOR and manually couple to the ILS. Altitude hold had to be selected manually. Descent points had to be calculated manually after using the DME to determine ground speed and come up with a wind component. We had no ground speed readout. The throttles worked the old fashioned way, the flying pilot would use his hand and look at RPM/Fuel flow. All the instruments used needles and pointers, The only thing that was automatic was the cockpit door opening when the seatbelt sign was turned off. That's when a young voluptuous, pectorally superior heterosexual female air stewardess would pop in and say, "What can I do for you boys" in an authentic sincere suggestive kind of way. If that ain't classic I'll kiss your ass! On the old 200 the latest "soft wear" update was the black lace brassiere that the Senior Air Stewardess just got from Frederick's of Hollywood. |
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Too bad the old DC8-60/70 series aren't still in service. Top of decent with an airplane the size of a 727 with the wing area of a L-1011. Screw the spoilers, pop the number 2 and 3 T/R's.
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They would shake like a sight impaired homo at a wiener roast
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Some of the captains I fly with flew the classics and they say its AP/AT seemed to work better than the NG. To top it all off, the latest software update, causes screen blanking from time-to-time, usually at the most inopportune time. It always come back fairly quickly but it's an annoyance. The 737"NG" has a nice panel, but the AP/AT is something to be desired...especially if you've flown anything else. The OLDER 757/767 AP/AT we're much better IMO. View Quote |
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These days I fly a very updated albeit very antique Falcon 20. It will definitely pop your ears if you pull the throttles back too far. The air brakes are perforated like a citation and also only have open and close positions. Back in the citations I would haul as much ass as a citation could then use the spoilers to slow to configure. The owner liked that. My new owner hates rapid throttle movements and the brakes. That's sometimes a problem in the Falcon trying to meet crossing restrictions. It's a slick plane and going down while slowing down is what the brakes were put there for. He'll just bitch when we unload the bags.
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