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Zomp
As I stated ".....more or less" -> GD, minimum drag, Vcl or Vm(manoevering) are not absolutely the same, however per aerodynamical law and definition they come up more or less the same. They are all +/- 1.3 of Vs with no limits on bank. Most manufacturers and operators only recommend flying below these speeds with T/O, CLB or MCT power settings. These V2 speeds are somewhat bank limited due to the very reason of beeing closer to Vmin, Vls or Vs whatever you want to call them. |
Am I right in saying that after take off, you must wait for a positive trend in speed before selecting the next higher flap setting?
You don't deliberately fly below the flap speed for any length of time. |
china are you from down under?
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Quite right, I believe there should be no confusion between flying below GD speed near the ground with engines at idle thrust during approach and flying at
V2+10 or greater with engine(s) on MCT or TOGA thrust at Take Off. As break dancer said:"You don't deliberately fly below the flap speed for any length of time." Next time, at or close Max TOW, when you retract your CONF 1+F, see what the V/S does, because of reduced "stall" margin: very scary close to ground. Back to the original post, I see quite a lot of guys on the left seat pushing you to do things they are unable to demonstrate or accomplish. Back with my current airline the first sector is "always the captain's sector", which initially irritated me, but now I really kind of like it, 'cause I see what's the jockey on the left seat worth from the outset and if I might learn something from him:ok: Happy landings. |
Zomp ...... ehh ..... no.
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Chin,
Not true mate. In an Airbus, Vls clean is 1.23xVs and at 10k and 200 tons that would be 192kts. Green dot under those same conditions would be.......227kts. Yep, Green Dot is just the Clean maneuvring speed and is set at 1.45Vs. So when you were flying around in the 'Ludmobile' at 1.3Vs you were actually .15 below Green Dot, so Green Dot is providing us with a 23kt buffer over your suggested limits, at the said conditions. Vls is a different matter, it ensures 1.23Vs when clean but that drops to only 1.13Vs when you have flap out and are taking off. Your comments about power settings close to Vls are certainly appropriate on take off. There is very little reason to fly too close to min speed, you trade margin and pax comfort (att) for just a little show off of knowledge of AOM's but lack of airmenship. I have absolutely no problem with a guy flying below Green Dot as long as he doesn't need to maneuvre the aircraft significantly and stays well clear of Vls. Out of interest, on the approach with full flap selected we routinely decay the speed to Vls+5 with idle power selected and the protection afforded there is still more than 15% below the clean situation decried above. Schnowzer |
You are absolutely, certainly, positively right mate. Give me at least credit having said "more or less"....... or +/-.
The general idea is to fly with a appropriate margin and that it's poor airmenship to fly too close to min speeds. I was referring to manoevering speeds versus minimum (selectable) speeds. If you state "I have absolutely no problem with a guy flying below Green Dot as long as he doesn't need to maneuvre the aircraft significantly" then you have to allow the question just WHAT are you doing if NOT manoevering when you fly such speeds................ If its for Vls+5 at Flaps 50, then you are on the final approach path and again bank and v/s limited (stall limited), allowing you to fly closer to min speeds. The slamming was for the rather silly answer to ones post stating "give me a good reason to fly below GD" which said ".. give me a good reason not to". Sounds like "give me a good reason not to use full lenght". |
china,was just wondering because you talk s**t
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China,
Good enough! Schnowzer |
I am guessing you are from Austria are you Zomp?
Don |
Don,
I guess you must be from oz then! |
Well who wudda guessed!!!! No wonder there are no Kangaroos in Austria:E
Don |
Just as a matter of interest Grumpy, where in the manuals did you find we can fly below gd? Do you often try to turn off the fuel pumps of an engine in flight? Ab doesn't mention it in the books neither. This is just common sense, which I obviously doubt you have any!
Thanks for your comments anyway, just wondering how you ever got into the LHS. |
Gents, all quite simple... Must agree for most part wirh schnowzer.
No problem flying below GD, as long as you stay out of trouble, which is avoiding the VLS. When would you do it? For example on an extended downwind where control asks you to reduce to below your green dot. Instead of getting the drag already out (an make it uncomfy for the pax with only slats out.. lol), you could just reduce to green dot. The moment you get your base turn, you get your flaps out and start turning... In my opinion that's great airmanship. About the comment that nothing is written in the book and the fuel pumps etc etc... When you switch off a fuel pump you'll get a light that says OFF, while airbus has a dark cockpit concept.. on the other hand, nothing prevents you from vlying below GD, even the AP will do it in selected mode. It gets dangerous near VLS, so that's where they built the protection, hence the name VLS. MR8 |
.............even the AP will do it in selected mode. |
GD is optimum clean speed, not lowest...
The whole purpose of managed mode is that it manages the profiles and the speeds to be optimum. For example, if you change the cost index, all the speeds will change.
Now, if you fly an approach completely managed (which is almost impossible because of ATC restrictions), the aircraft will fly a continuous descent up to the 'D'-point, where it will automatically activate the approach fase and start decelerating towards final approach speed if you select flaps, which you better do or you will end up hot and high. If we don't follow the profile because of radar vectors, and we activate the approach fase early, the managed mode will come back to an OPTIMUM speed, which happens to be minimum drag speed (same happens in the holding pattern) and thus GD. There is absolutely no reason for a managed speed to go below the green dot. We as pilots on the other hand might have reasons to go below green dot, like ATC requests on extended downwinds. And although it is below the OPTIMUM (GD), it is still better then the alternative, which is extending the slats. MR8 |
It is good to read the comments of others who are practical and apply good airmanship to a given situation. It is equally bad but not surprising to read the comments of others who merely resort to insults and personal attacks if their views are not the same as other contributors. It's easy to be rude and insulting on an anonymous forum; very brave. Take what you will out of the original post; perhaps there may be one item that provides food for thought. (p.s. "phase")
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My 2 cents:
GD is not a safe speed but a minimum drag speed. But in my opinion there is no valid reason to go below GD. Slats are mainly produceing lift with a minimum amount of drag. If you can get a grip on AB drag graph you'll see that flying 10kt below GD produces about the same amount of drag as flying the same speed with slats out. But there is another component to that. Although GD is not a safe speed, flying at or above protects you COMFORTABLY in any case. Try to fly at GD with the speed breakes out and do a 30 deg bank turn and you'll see that VLS is is about 1 or 2 kts below GD. So no major action needed by the engines. That is what really scares the pax and not the pitch build up by extending slats. Conclusion: It is perfectly safe to fly below GD but there is no need to and is therefor not recommended by the manufacturer. Do not compare an AB with what you have learned on a conventional aircraft. GD is not minimum clean speed. But there is still reason not to fly below, although it's not a safety issue. You safe more fuel with a decent desent planning than with flying below GD and THIS is a real issue within EK crews. |
WGU,
The speedbrake issue has nothing to do with Green Dot. If you leave the speedbrake out in many configurations it is possible to force the aircraft into Vls without turning at all. You have just removed lift from the wing so the min speed has increased. I think that argument is a red herring, we often have to modulate the amount of speedbrake selected to keep above Vls. Icare, being trite the logical conclusion is that we must descend on the arrow. If the FMS says decelerate, we must decelerate. If we are above the FMS calculated vertical profile we must use speedbrake to achieve it even though we know it is incorrectly calculated. It does not say in the manuals that we should put out the wheels before the flaps but sometimes going to Moscow you have to do it. Flying below Green Dot is an alternative just like selecting Flap 2, Gear down and flying at 180kts to get down to platform rather than decelerating and descending, which never seems to work as well. Surely (Don't call me Shirley) as pilots, it is our job to apply airmanship to come up with an appropriate solution in any given circumstances from a range of options. The actual definition of Green Dot may surprise you, it is the 'Engine Out Operating Speed in the Clean Configuration' which also corresponds to the best lift to drag. It would therefore seem to be pretty stupid to fly below it with full power on but in a descent at idle it may well not be the worst thing to do. Interestingly though during clean up on take off we do fly below it with full bore on the jet every day. Worth thinking about? |
Wow this is a really exciting topic.:ugh:
Come on!!!! There must be something more important to discuss. If you can hack it do it if not don’t. If your captain doesn’t want you to do it because of some odd reason then don’t. Who cares. If you people had had just a little excitement in your previous flying career before joining this circus you would not give a rat’s @ss. |
Doesn't Vls stand for Velocity Lowest Selectable? I think so. That means airbus has determined the lowest safe speed which we as pilots should select. The are plenty of safe guards built into the system which keeps us from stalling the bird. Some might have little buzz words like "if my family were on board, good airmanship, safety, v1.23, blah blah blah. It all boils down to one indisputable fact, Vls is Vls. If you want to use it then use it. If not then don't.
Mckaj...if you don't like this boring thread then don't read it. 7 |
Interesting subject..too many misconceptions
Vls(lowest selectable)...equal to: 1.13 VS at take off 1.18 VS when Flaps are retracted 1.23 VS when clean(stays there until lndg) Vls is corrected for M effect to maintain 0.3g buffet margin Vmc is taken into account V2/1.05 1.05 Vmca max certified (take off)...in all other cases eq.or greater Vmcl Green dot:ENG.OUT ops.speed in clean confi Conclusion 1:no problem to go below u r still protected as per above. Conclusion 2: Grumpy(and some other EK giants of knowledge) u have no clue about the AB prots in normal law ......but I like your att.and crm practices ;maybe I should leave EY and join EK u all seem to be a great buhch of people cheers:D |
Originally Posted by Schnowzer
WGU,
The speedbrake issue has nothing to do with Green Dot. If you leave the speedbrake out in many configurations it is possible to force the aircraft into Vls without turning at all. You have just removed lift from the wing so the min speed has increased. I think that argument is a red herring, we often have to modulate the amount of speedbrake selected to keep above Vls. My main point was you increase drag when extending flaps as well as when going below Greed Dot. So there is no NEED to go below GD. Just some thoughts of an FO that does not ask if he may use the speed breakes:ok: |
etihada
No, just stay where you are, there are enough doctors at EK already. Good to have the absolutely correct values rubbed into our noses again, especially the remark about the superb AB system that "..corrects for M effect to maintain 0.3g buffet margin." It's so much fun to wait for that little inversion, wake turbulence, wind shear or microburst as these phenomenons set in so gently, with timely preanouncement. Personally I prefer flying around with a sound margin. Might be because I am a less brave pilot than many around here, but hey ... Let's just try to stay live. |
:ugh:
tell me this, do you not fly below gd every other day, selecting flap UP at S speed when gd is 20..30 knots above... the fact of the matter is, those in EK do NOT understand GD, it has nothing to do with being BRAVE just to do with understanding. Indicated gd on the pfd in norm conditions is NOT best single eng speed... vls while being the lowest selectable velocity/speed still is 1.23vs1g X94% so yet again more protections built in. I am not saying that I myself condone flying at VLS or below, but reducing to below gd on an app to maintain a cda is acceptable, as long as it is controlled and the pf and pnf are in agreement and understand what and where they are. Those who have flown other olde Airbuses have seen gd and VLS are nearly co located, whereas on the A33F the lift to drag profile is such that a big split is always evident. p.s. How can you do an over weight landing if VFE next is below GD as is the case...well the QRH tells you select vfe next -5......:zzz: |
Mckaj,
Excrement, are you authorising me to start WIWOLing? Did I tell you about the time the Redtop......:zzz: . Sorry chaps put myself to sleep too! |
chinawladi,
thanx 4 the advice ....wilco...no offence ment whatsoever just trying to put some light into the subject...afterall is not the speed that kills u its the sudden stop:sad: |
The truth is that many FOs just do not have any basic knowledge, and quite a few captains as well... and most of them like to write on pprune...
I'm 99% agree with grumpy, I'd be happy to hear noting me about using the speedbrake, 'cos 90% of the cases we do not need them... Here's another gum for you to chew: On an ILS if you follow 1 dot above the glide all the way down to runway, where you gonna touch the runway? |
Originally Posted by what_goes_up
My 2 cents:
GD is not a safe speed but a minimum drag speed. But in my opinion there is no valid reason to go below GD. Slats are mainly produceing lift with a minimum amount of drag. If you can get a grip on AB drag graph you'll see that flying 10kt below GD produces about the same amount of drag as flying the same speed with slats out. But there is another component to that. Although GD is not a safe speed, flying at or above protects you COMFORTABLY in any case. Try to fly below GD with the speed breakes out and do a 30 deg bank turn and you'll see that VLS is is about 1 or 2 kts below GD. So no major action needed by the engines. That is what really scares the pax and not the pitch build up by extending slats. Conclusion: It is perfectly safe to fly below GD but there is no need to and is therefor not recommended by the manufacturer. Do not compare an AB with what you have learned on a conventional aircraft. GD is not minimum clean speed. But there is still reason not to fly below, although it's not a safety issue. You safe more fuel with a decent desent planning than with flying below GD and THIS is a real issue within EK crews. Totally agree with that! Thanks |
Originally Posted by fiddlair
Here's another gum for you to chew: On an ILS if you follow 1 dot above the glide all the way down to runway, where you gonna touch the runway?
...But if you follow the one-dot-high beam exACTly down to touchdown, you would be touching down EXACTLY at the normal touchdown point (plus the distance the G/S needle is displaced on the ILS display on board) past the "normal" touchdown point. (Stick with me now, folks) In other words, like, 0.25 cm's. (You would have to keep adjusting that "one dot high" with some fast finesse all the way to touchdown in the same way you would "home" to a beacon vs "track with wind-correction". Kapish? No? Get a beer and re-read it then, hombre. :) HowEVER, if you kept yourself above the dot to a "cut-off" point somewhere along the approach-path, after which you would transition to the VASI's (etc), and kept yourself, say, 2 1/2 white for eg, then you will touch down long (as is a sadly over-practiced habit where the crew have only flown into vast tracts of endless runways all of their career). :sad: I've seen crew proudly boast they did a great landing... (yes, habibi, but it was 2,000 feet beyond the touch-down zone). := I'll guess, with a FIRM landing, say...6 to 800 feet. Cheers, R.D. |
Ray,
Nope, you'll hit the touchdown point off a slightly steeper approach and just need to flare a tad harder to get a nice touchdown unless you have a magic moving ILS antenna! Then you'll fall asleep in the bus back to CBC because of all the mental anguish caused from trying to workout what would happen. The car ride home would be horrific cos you would be reading the FOM to see whether or not you were able to do it with the A/Thrust engaged and without SVP authorisation. You'd get home, write your resignation letter, give back your free furniture and then have a good nights sleep for the first time in years without the alarm going off at 2am.:zzz: |
Ray the short answer is : at the same point. Of course only theoretically, as you have to keep a slightly higher rate of descent( about 900 ftpmin depending on the weather and weight naturally) and you want to flare nicely. The long answer is: If we talk about FCOMs, and data from there, then you have to specify the type you are talking about when mentioning 14 and so on feet...
That is because on one aircraft 1 dot means 0.4 degree, on another 0.5 degree or maybe more and the ILS might be anything between 2.8 and 3.3 degrees I guess, so if the glideslope is 3.0 degrees, it's 5.2% which means you are probably 52 feet over the treshold (again theoretically) and the touchdown is 1000 ft from treshold. You can maintain 2 or more dots above, and still catch the ground the same place. |
Originally Posted by fiddlair
...If we talk about FCOMs, and data from there, then you have to specify the type you are talking about when mentioning 14 and so on feet...
Originally Posted by Ghostflyer
...and just need to flare a tad harder ...
Peace, y'all. ~R.D. |
1 dot is .15 degrees from memory, your figures look like Localiser figs....but,and I say again,but who the **** cares,,,fly glideslope......land..end of...:D
flying is an easy job people with "theories" try and make harder.:ugh: As for green dot ...dont try and out think the plane or the people who designed it,if you were that clever you would be doing their job , then you could get the system to do it the way you would like it to work.... Speed request below G/d, few knot, maybe 10 is a good number , discuss and select ,if you both feel comfortable......it won't fall out the sky by the way, if not put the bloody flaps out ,don't try and complicate it, 1.23Vs ,1.05., blah,blah, bull,blah..yawnnnnn . Feels nicer with flap/slat out, lower nose attitude, actually helps in TMA to see other planes, also feels better for crew and pax not to have 8-9 pitch attitude...also 1 less thing to screw up, 1 less thing to explain at subsequent board of enquiry....... My aim is to get as much money as possible from the buggers and to try and make the job as easy as it could or should be be. |
Hoo-bloody-rah:D
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QRH,
My aim is to get as much money as possible from the buggers and to try and make the job as easy as it could or should be be |
Originally Posted by grumpy_bugger
Although much has been said about the falling standards of new recruits at EK I think it fair to acknowledge that in the current environment of rapid expansion this was inevitable and is a function of pilots available and the experience levels of the same.
As a result of this and personal observations over the past few years I have come up with a set of policies (that might be added to) that can be printed off and once read, be signed before the commencement of a flight duty. 1. Thou shalt not taxi with the nose wheel on the taxiway lights 2. When changing radio frequencies listen before transmitting to ensure you aren’t transmitting over someone else 3. When using the radio English is the language we use 4. Aircraft radios are not the appropriate medium to chat with your mates; I recommend the pub for this, or else the telephone 5. We do not deviate around ground returns from the weather radar; use the tilt function and look out the window 6. We do not both have the radar on maximum range at night whilst engrossed in the Sudoku; you will not see the top of the next CB 7. Don’t concentrate solely on the radar picture. Look out the window; its amazing what you will see 8. Don’t ask for block clearances in RVSM airspace. If you cant climb 2000’ stay where you are until you can 9. Check your FMS descent profile against altitude and distance to run. Inserting altitude and speed constraints into the flight plan changes the computed profile and its not always accurate 10. Don’t touch the speed brake without asking; its probably not necessary. If you end up in level flight with flap out you have probably cocked it up 11. It is permissible to fly clean below green dot speed 12. If ATC impose speed constraints requiring flap and there are many miles to run request extra track miles and maintain a higher (clean) speed 13. Do not accept speed constraints that are unreasonable or inconsistent with the characteristics of your aircraft or company SOPs 14. When acting as PNF and a configuration change command is given; check the speed and do it. There is no rule against selecting gear and flaps at the same time 15. If landing on a 4000m runway the touchdown zone is the same as a 2200m runway. Performing a “greaser” 1000m from the threshold might impress the punters but it doesn’t impress me 16. Thou shalt not taxi with the nose wheel on the taxiway lights 17. It is your job to give the Cabin Crew their hours not mine 18. In the CBC after a flight the prime objective is to get out of there as quickly as possible. If you want to chat with your mates get a taxi because I’m gone. I have read and understood the above requirements and agree to abide by them. First Officer _________________________ Date: Signed: _____________________________ Are you sure that this relates to EK? Cause it surrrrrrrrrre sounds like many of the F/O's I have to work with. Same sh*t, different comrads! |
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