Flap retraction

[roulette]

:ugh: Gee you guys are getting yourselves tied up in knots (the nautical kind) :rolleyes:


tommoutrie (http://www.pprune.org/members/44543-tommoutrie) :
400feet, v2+x, then the engine fails.
whats your plan?
where's your data?


There is obviously no single answer to your question Tom.

Everything obviously depends on the particular aircraft/model & config/MTOW etc ...and normal company SOPs for TO (including compliance with local regs and environmental op constraints, etc) ... and the actual airport, and surrounding obstacle and terrain environment (eg, say up to MSA) ... not to mention the airspace and procedures in place there. So, even if you only have single and homogenous fleet and only fly in one region, it's obviously the latter two that will bethe distinguishing factor.

For example,the question about 2nd stage is almost irrelevant if the TO is over water (where no tall ships are allowed and there are no wind turbines) or you’re in rural flatlands somewhere (Denmark? Some parts of Netherlands?) – except for noise constraints, obviously. Equally obviously, the answer’s quite different if the departure airport is in Switzerland, or Guilin, or Taiwan, or mountainous Latin America for example.

Many operators create specific company-specific EO/EFATO SOPs/Charts/Instructionsfor such events. And of course, getting the appropriate performance data from the manufacturer (if you don't have what you need already) is critical input, before making the relevant analysis of the specific airspace, terrain and obstacle environment and determination about safe tracking - to where (location, MSA, whatever) and how (turns, bank, etc) about whether you even need flaps beyond the normal 400ft minimum.

I've seen lots of different types of such EO/EFATO charts/procs. Some of them have nothing much more than tracks (including turns/brgs) and alts depending on when the EO occurred.Others include a lot of tabular data that allows the PIC to determine criticalop/config factors when continuing - including prevailing factors (eg, weight, OAT, winds, etc) as well as minimum required config (eg, rating, flap settings, 1 eng inop, gear position, thrust, etc) to enable achievement of Eng Inop gradient. Some are presented on very pretty charts with full coloured graphics. Others are pretty simple charts plus tables. Others are tabular or text only.

They all aim to give the pilot a reasonably simple proc to follow (in cockpit and for aviate/navigate) to assure obstacle+terrain clearance at that location and get one to a position from where the crew can determine what's best to do next.



aeroncaman (http://www.pprune.org/members/48616-aeroncaman): I do not think the CAA accept ' remain VMC, see and avoid' as an adequate contingency procedure. I recall this being discussed at length in an audit several moons ago.


Agree, absolutely NOT an adequate contingency measure. I guess it doesn’t need saying that you might start the SID process in IMC anyway, so “remaining” VMC may not be an option. That’s why the MSA is there… and that’s also why you may/should have EOI procedures.



mutt (http://www.pprune.org/members/8504-mutt): … even Gulfstream have stated that ENGINE
FAILURE OCCURS EARLY IN THE DEPARTURE CLIMB, CONTINUATION OF THE SID CLIMB ON
ONE ENGINE SHOULD NOT BE ATTEMPTED.






:ok: …except where you’ve already determined that it may be safe with regard to obstacle/terrain clearance and more expeditious for handling subsequent actions (eg, return to dep AD or ALT).


As alluded to above, airline EO/EFATO contingency procs will sometimes have one or break-outs (location usually by distance from XXX &/or WPT &/or alt) from normal SIDs, depending on stated conditions. This not only helps the guys in the hotseats get themselves organised, but also minimises potential conflicts with normal ATM in the areas lower down and closer to the aerodrome.


So, those are the answers about flap retraction in Eng Inop situation.

For all engines, I believe you've now all accepted the appropriate answers!

[tommoutrie]

Can Mutt, Doug N, Clrdrvr, and the various other chaps who are thinking the answer is obvious give specific answers to these questions.

On an all engine operating take off do you retract flaps at 400 feet (presumably with V2+x)?

If the answer is yes, what data are you using for the climb from that point?

Please can you post a reference for any manual that you've used to show where the data is so I can have a look.

ta

[Doug Neidermeyer]

Did you pass Perf A?

[tommoutrie]

yes Doug

Whats the answer?

[tommoutrie]

Doug old fruit

There's a bet of a thousand pounds on this if you are keen to take it on. You seem to think I'm up for a Darwin award and that somehow I haven't got a clue what I'm talking about.

So take the bet on.

Its in public, its two way, I can't back out and neither can you.

Are you on?

[B200Drvr]

Tom, I posted the answer to both questions a few pages back, straight out of the Gulfstream 550 manual, but you chose to ignore it.

[Sillypeoples]

Take a look at the third segment flight profile...imagine something poking up through that.....

[Doug Neidermeyer]

Shall we have vote on that Tom?
I wonder how many people think you do not have a clue about what you are talking about...
Can we set that up on here?

[tommoutrie]

Are you taking the bet then?

Sillypeoples, lots of suggestion that I don't know what I am talking about. However, if the flaps are up at V2+20, there is no third segment. So if I imagine something poking up through where the third segment would have been I will be much higher above it.

More proof of just how badly this subject is taught!

Doug, are you taking my bet or not? You clearly think I don't know what I'm talking about. So for my part, if I win your thousand pounds, I'll give it to the dogs trust at Harefield.

Hows that?

just say yes in front of everyone whos reading this

[Empty Cruise]

Tom,

if the flaps are up... that is the operational word. If an engine fails before you reach Vfto (or whatever it's called on your type), you are scuppered. You are at a speed and config for which no data exists.

Tom, I will take your bet and pay up if you can show me any AFM data on any type for climb in clean config below the nominated Vfto, Venr or whatever the OEM calls it.

Until then - you a grand down in my book.

That being said, I agree that not pitching for V2+10-20-ish when departing is daft. That will give you noise abatement (which EASA commercial operators need to follow anyways) as well as sorting the problem about when you can retract the flaps.

People ask how you can do that out of eg FAB with a 2.4k level-off. Two options here, given that obstacles are not a consideration:

1) Gear UP - Speedmode - VS 1000 fpm (to stop yourself triggering RAs left, right and centre) - through V2+whatever and accelerating , Flaps 0

2) Gear UP - Speedmode - VS 1000 fpm, thrust back (to keep speed in cehck and thus not bust your gradient), maintaining V2+whatever-you-got-to. Cleared further climb select climb thrust continue climb and accelerate, clean up on schedule.

Ie either lower your flap retraction altitude (option 1) or draw thrust back to keep noise, fuelflow and gradient inside acceptable limits - whch ever fits most closely with your SOP and NADP.

Meanwhile, we are waiting for that below-Vfto-clean data, Tom. Either post that or say "OK, maybe I didn't know what I was talking about in this case".

[Empty Cruise]

Oh - and just to open the next can of worms...

...you don't belong to the "Imagination Failure Checklist"-group that use APG or FlugP for their perf and then continue on the SID after an engine failure, now do you? ;)

Now, to get the Darwin-award, you need to have actually killed yourself - so that's a bit pre-emptive... :} I don't believe that you are in any statistically significant danger of killing yourself, given the limited number of airports where the issues raised here are an issue, combined with the excellent MTBF on modern turbofan engines :ok: Again, from a statistical POV only. If you actually were to have an engine fail at INN 26 and operated according to what you have suggested above, I have no doubt that you would meet an untimely end, sorry. Again, this is only my belief, and I cannot prove that some act of God mightn't save you...

[bluesafrica]

What a list of arguments. I guess that everyone is correct...at least on his own mind. I have retracted flaps at 1500 AGL last 40 some years and its been working pretty well....:ok:

[aerobat77]

in the general thought that most aircraft will climb out clean with the best rate tommourie is basicly right, but thats all.

a jet driven corporate or airliner will ususally climb through 400 feet that quick you will hardly have time to think about raising flaps below since you just verified gear is up while your colleague calls first time radar frequency.

when between this and acc altitude an engine fails it should have nevertheless enough juice to climb and meet obstacle clearance . and you have in this case other things to do than change configuration.

and finally... the guy who truly tries to feed his family sitting infront really has other thoughts than debating day after day when to raise flaps exactly and why. this discussion dear gents is like most discussions on this forum a pure theoretical chair view.

@ empty cruise : innsbruck 26 is initially visual departure only. check your pdf charts.

when you are in IMC unable to make a back turn you are toast regardless what idea you have with your flaps. thats the reason in most cases innsbruck departs 08 even with tailwind .

[tommoutrie]

Cool! I have a taker!

Ok, once I am at V2+20 and am in the enroute configuration (flaps up gear up) I can use figure 41 on page 81 of the Performance section of the AFM. Thats the final segment net take off climb chart. Typically at max all up weight and for airfields up to 2000 feet the lowest climb gradient I can get is about 5 degrees and for every value I have checked is better than the flapped gradient (as expected). The really big advantage here is that as you can see from the conditions I am operating at max continuous and therefore I can continue the climb to MSA which you can't do if you are in the flapped condition. This is a huge advantage in terms of workload - the aircraft is easier to fly and you just stick in the autopilot and climb till you're safe. This is how the aircraft was designed to be operated. Incidentally, all the time the flaps are travelling the aircraft is trending towards a better climb gradient (this is the point which took about 40 mins on the phone to Montreal to get clear and I'm waiting for it in writing) but what that means is that if you select flaps up at V2+20 and the engine fails as the flaps start to travel you will ALWAYS be in a better situation but cant prove by how much. In addition, I have a few mins (the remaining of the 5 minutes) left at max thrust before I actually have to reduce thrust to max continuous so am outperforming the data. And I took off earlier along the runway. And I climbed better to the point where I retracted the flap and the engine failed. All of this is to my benefit - unaccounted for and I can't use it in my calculations - but its all gravy...

Once the aircraft reaches 1500 feet OR MSA I accelerated to my enroute climb speed of 190 kts and climb if desired.

Now... one bloke had the guts to take the bet.. you all need to club together to help him pay.

I will try to post the images but need to get them on the t'interweb to do that.

Either that or just send me your email address privately and I'll send them over.

Still all absolutely sure you know whats going on? Ever actually looked at the performance section of your challenger manual CLDRVR? ...thought not...

Just to reiterate. What I have been saying, what the manual tells you to do, is supported in the performance section of the manual (I strongly suspect it is for all the aircraft discussed here) and the fact is that very very few of us know how to use it. Most people don't even know what the different segments are! its all a bit of a joke.

[tommoutrie]

https://skydrive.live.com/redir?resid=564144EC8608DFAE!10427&authkey=!ADDrvgBL9-DXH4k

[mutt]

Once again you are looking at things in isolation, do your example again at the maximum airfield elevation and temperature, also please link the single engine speed/power chart referenced in this chart.

Finally and I hate to mention it again...... OBSTACLES!

Remember that the letter from Bombardier has to state that they "GUARANTEE" that you will clear ALL takeoff obstacles :)

Mutt

[Sillypeoples]

Tom -

How about this....you are in a box canyon.....at 300 feet you lost an engine....as the granite walls loom, do you retract your flaps and push the nose over for V2+20 or hold V2 like your life depended on it?

Thread ended.

[noneya]

http://awesomegifs.com/wp-content/uploads/dead-horse.gif

[tommoutrie]

sillypeoples - I don't understand your post. No. If the failure occurs before V2+20, I climb with the take off flap to acceleration alt. Participation in this thread is more useful if you read whats been posted previously.

[tommoutrie]

Mutt, can you try picking it up from here?

http://myaccount.dropsend.com/file/039a3b42e3365bdd

[tommoutrie]

aeroncaman - not sure what your point is. I'm not suggesting that we change the planning. We still plan for the worst case - a failure at V1. However, in the event that both engines keep running until we get to V2+20 we can then retract the flaps and get a better rate of climb. We also have an aircraft thats easier to fly. And we have scheduled one engine inoperative data for that portion of the climb (I just posted a link to it). There is no downside - the problem has been that we are not doing what the manufacturer says, we've all been doing what we have been taught incorrectly to do.

[mutt]

I guess that I like flogging dead horses :):)

Even that chart doesn't show the required speed to achieve the gradient.

As for Sillypeoples, forget him as he is the 15th reincarnation of the infamous SSG......

Mutt

[tommoutrie]

haha.. yes thats true. Its on a speed to fly chart which gives you V2+20. I'm trying to get that one out of the CIC too.

Standby caller, your call is important to us, please hold..

Its surprising how hard it is to let go of an idea that is deeply held, no matter how much evidence there is to the contrary..

retracting flaps at 400 feet is a myth. Flaps do not - never have - cared how high they are. Flaps retract with speed and to maintain the manufacturers published gradients we should do them when the manufacturer says. For aircraft I have flown that is V2+10, V2+11, and V2+20. Flaps reduce the take off speed and therefore the tyre speed, they mean we get airborne in a shorter ground roll, they mean we have less energy to lose in the event of a critical engine failure before V1. But the great myth of perf A and of the way we are taught during type ratings is that they somehow make the aircraft fly better once airborne. We very quickly (all engines operating) pass the speed where they are useful and the lift to drag curve of the clean wing surpasses the performance of the wing when its flapped. Nobody explains this because it isnt the critical case but it leads to a lot of misunderstanding (as can be seen from the number of people telling me I'm up for a darwin award and don't know what I'm talking about). Truth is this misunderstanding leads to an awful lot of confusion - there are people flying medium and heavy business jets who have posted on here who simply haven't got a clue what to do if an engine fails after flap retraction in the climb. Some hold whatever speed they have, some pitch up to slow down to a speed where they can take flap again and climb with that - some have honestly never thought about it. Pilots think that the 400 feet one engine inoperative certification criteria where the powerplant fails at V1 is a limit which should be imposed on all take offs. Some think you need to climb to 1500 feet with the flaps. This amazing mixture of duff knowledge has come from compressed teaching and from tribal knowledge passed from pilot to pilot. Its utter, utter rubbish.

The manufacturer (all manufacturers) publish the way their aircraft should be flown and the way they will perform if you do what they say. Very few pilots read or understand this information. As a result, the benefits of flying as per the AFM are lost. The pilot of the G4 who doesn't know the difference between predicating a departure on two engine climb data and using one engine inoperative climb data has shown just how serious this issue is. We lose the extra safety margins of operating as the manufacturer intended, we create more noise, we burn more fuel, and when the day comes where the powerplant fails at a time other than the one we planned for, confusion will reign. Ask your colleagues what they think they should do when they they lose a powerplant at 500 feet in the climb, see if all the pilots you fly with know exactly what to do. I almost guarantee you will get a worrying array of answers..

[de facto]

As for Sillypeoples, forget him as he is the 15th reincarnation of the infamous SSG......

Mutt

Now ,that makes sense:E

[tommoutrie]

Doug Neidajob, you're never 32!! You look older!

Did you look at the final segment climb data? Maybe I do know something after all...

[Doug Neidermeyer]

Neidajob? 32? Look older?

[tommoutrie]

sorry, obviously got the wrong bloke. You're quite clearly Doug NeidaLessonInAircraftPerformance.

[mutt]

[1]You still haven't published a speed chart.
[2]You haven't come back with examples at the higher elevations or higher temperatures.
[3]You have clearly forgotten that some aircraft need to accelerate before they climb, look at the figures you were given by His Dudeness and someone else posted figures for the B737.
[4]You are fixated that there are only two heights involved in this process, 400 and 1500 feet.
[5]Your haven't mentioned obstacle clearance anywhere in your comments.
[6]You haven't received any response from the aircraft manufacturer justifying your stance.
[7]You haven't received any response from FSI, who you have accused of teaching people incorrectly.

And, now your comments are just getting downright rude, in fact your behaviour reflects that of many previous reincarnations of SSG.

So I think that we have flogged this horse to death........

Mutt

[tommoutrie]

Last point first, I've had people put me up for a Darwin award, say I haven't got a clue what I'm doing, say I am guilty of making up procedures which are not in the AFM, accuse me of being a bar room pilot, and send me messages in private which are not pleasant. Paul (Doug) is someone I have known for a long time - I worked with him at a previous company and he knows that when he pokes at stick at me I'll poke back because its fun.

[1]You still haven't published a speed chart.
I will as soon as possible.
[2]You haven't come back with examples at the higher elevations or higher temperatures. I'll work through any example you like. Send me a scenario.
[3]You have clearly forgotten that some aircraft need to accelerate before they climb, look at the figures you were given by His Dudeness and someone else posted figures for the B737.
[4] No I haven't. You take the flaps at V2+x wherever that may be. For many bigger aircraft (A340 for instance) that may well take quite a while but once at the speed, you raise the flap.

You are fixated that there are only two heights involved in this process, 400 and 1500 feet.
There are no heights in relation to raising the flap. There are only speeds. If you need a level platform to attain the speed in the event of an engine failure for instance then you can use any platform for which you can calculate the resultant climbs.

[5]Your haven't mentioned obstacle clearance anywhere in your comments.
[6] Because its a total red herring. If you have a particularly close in obstacle which affected your climb predicated on an engine failure at V1 you will be above it very quickly. Any obstacle which you will clear with an engine failure at V1 and take off flap you will clear if you are all engines operating to V2+20 then climb clean. Thats exactly what the chart I posted shows you.

[7]
You haven't received any response from FSI, who you have accused of teaching people incorrectly.
Verbally they have told me that it is a Flight Safety SOP, nothing more. They are very unlikely to say anything more than that to me as I am a CAE customer.

I've had someone accept the bet which is great, and posted the climb charts.
I will put the speed chart up as soon as I can - probably when my kid is asleep.

[Cough]

There are no heights in relation to raising the flap. There are only speeds.

There are heights when the manufacturer specifies them in the AFM. You don't mess with this stuff. Both types of commercial jet I have flown specify it for the reasons given in my first two replies. Not for reasons of pure numbers on a chart.

[5]Your haven't mentioned obstacle clearance anywhere in your comments.
Because its a total red herring

Scares me.

[tommoutrie]

http://myaccount.dropsend.com/file/3e0e7c7fcf8cbc20

Final segment climb speed.

Thats all the data posted which proves your net climb gradients clean when you take flaps up at V2+20.

Would you like any more data?

Send me any scenarios you wish run that you think change the manufacturers AFM.

Fact is, what most people do is not in the AFM and what I have suggested to you is exactly what the people that make the planes want us to do. There is a clear divide here - somewhere along the line the message has become confused and we no longer deal with any engine failure case other than the one that is most critical. It is correct that we plan for that but it is not correct to then degrade the flight path performance of the aircraft by not doing what the manufacturers say.

Almost all of us - me included until recently - have been doing it wrong because we have been taught badly.

[tommoutrie]

Cough..

Its great that its in the commercial type you previously flew - which type was it?

An all engines flap retraction height is not in the Challenger manual, its not in the XLS manual, its not in the Lineage manual, its not in the Phenom manual, its not in the Citationjet manual, its not in the Hawker 125 series manual, and I don't understand what scares you. I've never seen an all engines flap retraction height in any flight manual ever. I've never seen a flap retraction height at all - only acceleration altitudes. If you don't need the level platform then no platform exists.

The obstacle clearance is irrelevent to the arguement because the take off performance calculation is exactly the same - the obstacle clearance and net take off flight path calculation is based on OEI at V1 so nothing has changed. What I think is misunderstood is the effect of retracting the flaps as per the manufacturers AFM and performance data. In fact, I'll go further. If you don't do it the way the manufacturer says, you are on unknown ground. What type do you fly and what departure profile do you use for a noise abatement and non noise departure? Lets see how compliant it is.

Explain exactly what scares you. I do the same perf calcs as anyone else - almost certainly a lot more as I cross check the FGP data. I then fly the aircraft as the flight manual states. Does it scare you that I don't simply copy what I learned on an airliner and apply it to a business jet? Does it scare you that I'm doing exactly what it says in the manual?

I've kind of had enough of tribal knowledge ruling this thread. Post the legislation that imposes a flap retraction height in the case of an all engines operating take off. Post the data which shows a flap retraction height as opposed to an acceleration altitude exists at all. Post any AFM procedure which states that exceeding V2 by 30, 40, 50 knots is acceptable practice and has no effect on aircraft performance. You need 1.25 V2 to have the flaps retracted on a challenger - thats what the speed to fly table gives you. Thats not even V2+20 so at V2+20 you have plenty of handling margin and thats probably why the speed was chosen. What you definitely dont have is any idea how much you have degraded the flight path by if you dont raise the flap.

bizarre that you all think this is sensible but don't have any data or any statements in the AFM that show it!

[tommoutrie]

Cough.

Post the section of your AFM that discusses an all engines operating flap retraction height. I've had a bet accepted for a thousand pounds that data did not exist for a clean climb below 400 feet and I've posted it. From the AFM. I'll directly issue a double or quits to you if you like that what you do on a normal departure does not come from your AFM. I'm going to suggest it comes from Flight Safety.

Are you up for the double or quits? Are you sure what you are doing is what the people who built the plane think you're doing and that I'm nuts?

If so, bets on.

[tommoutrie]

by the way, saying I'm up for a Darwin award and I make stuff up when it comes straight out of the manual is offensive.

The bets still open to anyone else who wants to take it.

[Denti]

On the 737 and with the way our performance is set up any obstacle and engine failure between V1 and passing MSA is considered. To be safe during that time we have to stick to the calculated flap schedule which is based on heights. V2 + 20 can be up to 50kts below minimum clean speed, so pitching down to accelerate those 50kts upon reaching V2 +20 will immediately invalidate any obstacle clearance (not to mention any required NADP). The furthest obstacle considered I've seen was around 30NM from the departure end of he runway, our EFB tells us something like that just for information. Acceleration heights are usually different for all engines operating and one engine out, both have to be filled into the Take Off Ref page 2 during preflight, same as the thrust reduction height.

[BizJetJock]

Tom, you're getting increasingly strident on here and all you're doing is proving the old adage that a little knowledge is a dangerous thing.

You keep banging on about one graph in the AFM as if that were the only factor, when I and others have pointed out to you that several other things, not least EU-OPS, are the driving factors.

To give a couple of similar examples:
1. According to the AFM I can join the visual circuit at Oxford at 300 knots; you know perfectly well, though, that the Rules of the Air limit us to 250 below 10k and that for practical reasons of preparing for the final approach and fitting in with other traffic we want to be back nearer 150knots and configured appropriately. By your logic I should go for the higher speed clean and damn the rules and other airspace users.
2. Where in the AFM does it say that I can't land in 100m RVR? By your logic because it doesn't say it in the AFM I can go ahead and do that if I want.

The reason why EU-OPS and every equivalent regulation round the world says you must follow your Part B procedures is precisely to stop people who've read one bit of information in isolation coming up with their own hare-brained procedures. And once again, you must follow your Part B; it's not a case of " maybe if I feel like agreeeing with it I'll do it". If you think your Part B isn't correct, then raise a fuss with your company until they either explain why it's written the way it is or change it if in fact your point is correct.

And finally, again this has been written before but you choose to ignore it because it doesn't fit your little theory, the heights mentioned in some AFM's and many SOP's are not retraction heights; they are acceleration heights, except that normally on two engines in high performance bizjets you are already above the minimum retraction speed when you get there. Just because many people refer to them incorrectly due to poor training does not invalidate the procedure.

[apruneuk]

Tom,
I think that BizJetJock has highlighted an important issue. We, as commercial pilots, are bound by several parameters: firstly, what the AFM says that the aircraft is capable of, secondly what the Regulating Authority says is legal, and thirdly what the AOC of your particular company has decided to do (potentially more restrictive than the other two).
Rightly or wrongly, we are bound by the AOC, which is an evolving document and should, with time, address any anomalies that might occur. On the Hawker in my operation, the Authority, the AFM and the AOC allow either flap 0 or flap15 take-offs. The AFM publishes second segment climb profiles for both and under certain circumstances we get a better rate and gradient using flap 0. However, the AFM doesn't publish a profile for a combination of flap 0 and flap 15 to 1500', therefore we have to use one or the other.
The practical advantage of flying flap 15 to 1500' with both engines operating is that the aircraft is already configured such that it will give a known climb gradient if one engine fails at any point between V1 and 1500' agl provided that climb power is set on the operating engine and the aircraft is pitched to climb at V2. Of course, with two engines operating we will follow the SID which, unless stated otherwise, has a Terps climb gradient requirement of 300' per nm or so to clear obstacles (or 900'pm at 180 kts).
Therefore, all you need to do with a fully functioning aircraft is to climb at a sensible speed and adjust rate of climb with power such that you at least achieve the required SID climb gradient. If an engine fails before 1500', apply climb power and pitch for V2. However, if your AOC says that you must leave climb power set until 1500' regardless of how many engines are operating just in case one fails and you forget to apply climb power to the live one then you have another set of problems to contend with, particularly on a cold day out of Farnborough with an initial level-off at 2200 agl !
Of course, without an AOC, operators are only bound by the law and the AFM. It is often the ambiguous wording of AOCs that causes pilots to fly illogical procedures and these anomalies should be highlighted to the Operator for possible amendment.

AP

[Cough]

Tom,

We have the same profile for both my types, the 737 and 320. In both types the profile is the same, around v2-v2+20 until minimum 400' (Though our thrust reduction alt is higher) then select climb thrust and accelerate. If we are using full thrust on departure, or given a positive windshear then I will pitch to maintain a stable climb speed within those values. Gin and tonic isn't served on take off.

The 400' reference is found the the QRH for the all engines running, normal takeoff profile for both airbus and Boeing.

As for the noise profiles, we comply with them as written.

[tommoutrie]

evening Cough

Thats exactly in accordance with what I've been trying to raise as you are flying to the speeds suggested in the AFM. What I'm trying to raise is the fact that the majority of business jet pilots will routinely exceed the flap up speed by 30, 40, 50 knots, sometimes even more, because they believe there is a mandated flap retraction height. If a particular manufacturer has imposed one (I've seen it in the Boeing training guide for the 737 and 757 and many 737 operators impose an MFRA of 1000 feet) then thats fine and you have to comply with it but nobody should make the mistake of believing that its in EU-OPS or EASA (my knowledge of EU-OPS is pretty good, my knowledge of EASA is not so good) until a reference is found. I cannot find one, I have asked many times if any pilots can quote one.

thanks for your input - haven't flown airliners and its interesting that this difference exists.

[tommoutrie]

400 feet is not mentioned in the AFM of any type flown by my company. I'm not at all sure that it is best practice - I think its tribal knowledge and promulgated by training organisations on types for which its not appropriate. Its a bad place for to use as a trigger for retracting the flaps precisely because its a common place for things to start happening - turning on a SID for instance, or getting told on the radio to contact another frequency. A height check is just not logical for moving flaps - the wing configuration is only dependent on speed so what is the logic? Its utter rubbish to say "you might move the wrong lever" otherwise it would be mandated that you leave the gear down and you can't go around under 400 feet. You degrade the climb performance of the aircraft in both the all engines operating and one engine inoperative conditions if you fail to retract the flaps once you are through the retraction speed (otherwise what is the logic in retracting them at all?).

The chap with the Hawker has the data - compare a typical take off with flap and without. Look at the OEI net take off climb chart for the same conditions. Which has the better gradient? If its clean, take off clean. If you cant take off clean because of runway limitations, why don't you raise the flap at V2+10 and benefit from the improved climb gradient at that point? What is the logic of climbing against drag? As soon as the flaps start to travel the aircraft is trending from the net gradient flapped to the net gradient clean so what stops you doing it? I'm getting a Hawker manual from a colleague today so I can see if its true that Hawker mandate that you can't do this in the AFM.

The argument about needing "maneuvering margin" when clean is also bogus. The minimum clean wing speed on a Challenger is 1.25Vs. At low weights this is V2+4, at high weights its V2+7. However, the manufacturer says flaps up at V2+20 - the margin is already there which is why they set that speed.

So far nobody has posted a regulation and nobody has posted an AFM reference which states this (I take Cough's comments on the Boeing and the Airbus because I have seen 400 feet and 1000 feet referred to in training notes but I very much doubt any operator of an airliner would exceed the minimum flap retraction speeds by 20 to 50 knots in the way that business jets routinely do).

Please, somebody, post the rule which prevents the flap retraction before 400 feet and, failing that, the section of the AFM which prevents the flap retraction during an all engines operating take off when passing V2+X. If that bit is hard to find, please explain why we bother to take the flaps up at 1500 feet if the climb is better with flap?

ta

[BizJetJock]

So far nobody has posted a regulation

Several people have posted references to regulations, but since you don't want to listen to anything that doesn't fit your idea, you just ignore them. Not so much confirmation bias as confirmation bigotry.:ugh:

[tommoutrie]

they quoted a section of FAR25 without quoting the conditions one of which is a failure of the critical powerplant at V1. How is this relevant if you have planned for that failure but actually achieved V2+X and are climbing with all engines operating to that point?

Let me stress again because some people seem to be concerned that the planning changes. The planning remains performance group A - nothing has changed. In the event of a failure of a powerplant at any stage the actual flight path exceeds that of the net take off path calculated (as shown by the two charts I posted).

What I've been suggesting is that we follow the AFM. What most pilots are doing is making up procedures which rely on falling back to the most degraded flight path possible and I have no idea why they are not following the manufacturers guidelines. I'm being accused of making up procedures - the opposite is true. I'm suggesting that we read the AFM properly and do exactly what it says rather than come up with utter rubbish like climbing against drag to control the speed, delaying flap retraction so that theres "handling margin" and all these other bogus arguments which would be in the flight manual if they were true.

If you are going to quote regulations you have to understand them. FAR25 is for certification and nothing I've said changes what you do if an engine fails at V1. But the lack of aerodynamic understanding and made up rules that people are applying simply because they have never even considered failures at other points in the climb is astonishing. Where have you got your procedures for an engine failure at 500 feet with V2+50 and take off flap set? It simply doesn't exist! Its nowhere and you made it up! More likely, someone else made it up and you and others follow it blindly without thinking about it. What is the problem with following the AFM? I simply don't understand what the argument is against doing this.

If its in the AFM then fine (cough and his 737 and 320, its very good that he's read it and knows its in there) but is isnt in the AFM for the types I have flown or written manuals for. Is it actually in the AFM for your aircraft or do you just think it is?

[dynamite dean]

ballyeck 297 posts including mine - on flap retraction, Im with poster number 10 of referring to handling the big jets from a bygone era but still very relevant . Im pragmatic anything less than 400ft its a bit early (which is all the fuss is about I think?) and unless your doing the NAPD 1 or 2 then if there not up by 1500ft tell me otherwise I may think you've forgotten them anyway I don't loose too much sleep I'll stick with the phrase 'height and speed good' before I my hand on the lever. 400,500, 1000, 1300 1500, 3000ft. Whatever I dont loose to much sleep ; I follow whatever SOP provided has its been said many many times so long as its in the AFM

1st prize if this makes 300 posts:E

[tommoutrie]

What do you fly? Is it in the AFM? Where? Can you post it?

If you cant move the correct lever below 400 feet you can't go around at any height below that so you have to modify your part B. You have to move flap at 200 feet and the gear shortly afterwards on positive rate. How can you do that below 400 feet?

just doesn't add up

[BizJetJock]

EU-OPS has also been quoted several times and you have completely ignored it.

The procedure for an engine failure at 500 feet is to continue the climb to acceleration altitude in the takeoff configuration, reducing the speed to V2 +10 if you are already above that speed. This is specified in the 604 and 605 manuals, but not in the 601.

I'll turn your question around. Where in the AFM does it say we should retract the flaps as soon as aerodynamically possible? You know perfectly well that it doesn't say that anywhere, so your bleating about following the AFM doesn't hold water.

I'm coming to the conclusion that the real problem is the African sun is getting to you...

[apruneuk]

Tom

Put simply, second segment climb finishes at 1500' agl with the required gradient being predicated on the worst case scenario, an engine failure at V1. If an engine fails after V1 but before VFTO then, if you pitch to V2, you will achieve a known gradient starting from a higher point, which is a bonus. If you have already accelerated to VFTO (around 160kts in the Hawker) and have retracted flaps before an engine fails then the Hawker AFM advises to continue climb at that speed until clear of obstacles. In other words, for the Hawker, second segment climb gradient is assured below 1500' as long as the flaps are retracted at or above VFTO and that speed is maintained until 1500'. However, there is no harm in leaving flaps at 15 with all engines running until 1500' if that is what your AOC demands. If the resultant deck angle bothers you (max pitch is 20 degrees from the Hawker AFM) then all you need to do is reduce power until you have a happy balance between deck angle and rate of climb. If you pitch for VFTO then you will have a limited drag penalty. If you pitch for anything less than 220 kts then you won't over speed the flaps. 160-180 kts and 90 per cent N1 works well for the Hawker, giving a good rate of climb and pleasant deck angle. I am slightly confused about all these pilots who are allegedly over-speeding the flaps; if both engines are running and you pitch for VFTO, controlling ROC with power, how can you over- speed the flaps?

Finally, the Flight Safety manual suggests 400' and VFTO as the flap retraction point, presumably as a belt and braces safety measure. There is no mention of 400' in the approved AFM, although the two are often achieved at about the same time. The AFM for your type will tell you how the aircraft should be flown to achieve a desired outcome. Your Authority and company AOC may require a different procedure, possibly for standardisation reasons. If there is a situation whereby the AOC requirements cause your type to be flown outside the limitations of the AFM or in an unnecessarily inefficient manner then you should make this known to your bosses such that the AOC can be amended.

AP

[tommoutrie]

Put simply, second segment climb finishes at 1500' agl
It absolutely does not. This is demonstration of how badly taught this is. Second segment ends at flap retraction. It has nothing whatsoever to do with height. In the event that you lack sufficient power to accelerate to flap retraction speed your aircraft is certified to use certain acceleration platforms and that varies. The most commonly used is 1500 feet but some aircraft use 400 feet. Because the gradient achieved is better clean than flapped, it is permissible and sometimes essential to reduce the platform from 1500 feet where obstacle clearance is not an issue. Just to confirm. Second segment has nothing at all to do with height and on an all engines operating departure you are final segment when you retract the flaps and enroute segment when you have accelerated to your enroute speed.


with the required gradient being predicated on the worst case scenario, an engine failure at V1.

This is true and your performance calculations are predicated on this case but you have tables in the Hawker AFM for flapless departures. Therefore, if you depart in a flapped condition but make it with both engines to flap retraction you can use the flapless gradient from that point which will outperform the flapped gradient. There is no third (level) segment for acceleration because the excess power of all engines operating has both climbed and accelerated you to the retraction speed.


If an engine fails after V1 but before VFTO then, if you pitch to V2, you will achieve a known gradient starting from a higher point, which is a bonus.

Correct. This is, however, unquantifiable without all engines operating tables which we commonly don't have.

If you have already accelerated to VFTO (around 160kts in the Hawker) and have retracted flaps before an engine fails then the Hawker AFM advises to continue climb at that speed until clear of obstacles. In other words, for the Hawker, second segment climb gradient is assured below 1500' as long as the flaps are retracted at or above VFTO and that speed is maintained until 1500'.

I dont have a Hawker AFM but am hopefully getting one later today. Could you post or email me the reference where I can find that in the AFM?

However, there is no harm in leaving flaps at 15 with all engines running until 1500' if that is what your AOC demands.

If you remain below the declared speed for noise abatement departures and thats what you are doing you are correct.

If you are departing without consideration to noise then you are climbing at an unknown gradient (especially if you have reduced power) and would have calculations to make in the event of an engine failure. For instance, if you are on a departure requiring a SID gradient of 5% and you chose to climb at 1000fpm at 200 kts because its comfortable you are under the required SID gradient. If you then fail an engine you will have an element of "zoom climb" while you reduce speed to V2 but it is unquantifiable. So you are under.


If the resultant deck angle bothers you (max pitch is 20 degrees from the Hawker AFM) then all you need to do is reduce power until you have a happy balance between deck angle and rate of climb. If you pitch for VFTO then you will have a limited drag penalty.

This is sort of true but you will have even less of a drag penalty if you are clean. You also have the advantage of an aircraft thats easier to fly in the event of an engine failure and you have no third segment to pitch for. You are already final segment (in fact, because of speed, enroute segment)


If you pitch for anything less than 220 kts then you won't over speed the flaps.

True, but as discussed before you are potentially degrading the climb gradient to a point where you are below the required.

160-180 kts and 90 per cent N1 works well for the Hawker, giving a good rate of climb and pleasant deck angle.

You are wasting fuel against extra drag and you are making more noise over the ground. There is no benefit to leaving the flaps down at that speed.

I am slightly confused about all these pilots who are allegedly over-speeding the flaps; if both engines are running and you pitch for VFTO, controlling ROC with power, how can you over- speed the flaps?


Nobody has mentioned flap overspeed.


Finally, the Flight Safety manual suggests 400' This is a Flight Safety SOP.

and VFTO as the flap retraction point, presumably as a belt and braces safety measure.

absolutely right - this is a presumption. It isn't, as you said, in the AFM

There is no mention of 400' in the approved AFM,

oh, there you go..


although the two are often achieved at about the same time.
This may or may not be true for your type (I would think it depends a lot on load, temperature, departure elevation etc.

The AFM for your type will tell you how the aircraft should be flown to achieve a desired outcome.

Absolutely right, I'm suggesting we follow it.

Your Authority and company AOC may require a different procedure, possibly for standardisation reasons.

This is also possible but quite how the Authority overides the AFM I really don't know. Right at the beginning of most company operating manuals it says something like:-

Each aeroplane is operated in compliance with the terms of the Operations Manual (OM), its Certificate of Airworthiness and within the approved limitations contained in its Aeroplane Flight Manual (AFM).

All operations personnel involved in the dispatch or conduct of a flight must be familiar with the laws, regulations and procedures pertinent to the performance of their duties, including those of the States in which operations are conducted.

The relevant personnel shall adhere to the rules, regulations, instructions and information contained in the OM at all times. However nothing shall keep the personnel from exercising their own best judgment during any irregularity for which the OM gives no provisions or in an emergency situation.

The rules and regulations laid down in the OM (Part A to D) do not overrule any State law or the instructions of the aeroplane’s manufacturer as laid down in their respective Aeroplane Flight Manual. If there is a discrepancy between this manual and any regulation, the Chief Pilot (CP) must be informed immediately.



If there is a situation whereby the AOC requirements cause your type to be flown outside the limitations of the AFM or in an unnecessarily inefficient manner then you should make this known to your bosses such that the AOC can be amended.


Further to that, if there is a situation where the AOC requires the aircraft to be flown in such a manner the AFM is the manual that your ops manual tells you to follow.

[FCS_TEST]

Wooah...relax Max !:}

[apruneuk]

Tom

From the Hawker manual re: second segment climb: "this extends from 35 feet to a height of 1500 feet or until the three and a half minute point is reached, whichever occurs first"

However, the manual also states "the charts in this sub-section (net take-off flight path) are provided to enable a complete net take-off flight path to be constructed........once it has been established beyond doubt that all obstacles will be cleared, there is no need to proceed further with the calculation."

That is what the manual for my aircraft says and 1500' is what my company and performance programme use for the end of the second segment regardless of clearing all known obstacles prior to that.

You really are getting your knickers in a twist over very little in my opinion. The time taken to 1500' with all engines operating is a matter of seconds in my type anyway so any potential unnecessary drag penalty by leaving 1st stage of flap set is there for such a short period of time as to be inconsequential. Maybe you should see if your type allows flap 0 take-offs; then you could rest easy.

Personally, I fly the profiles required by the AOC where specified and according to the flight manual and airmanship where not. What else can we do?

AP

[apruneuk]

Sorry, Tom, indeed you did not say that pilots are routinely over speeding flaps but that they are routinely over speeding minimum retract speed. In the same post you suggest raising the flaps at v2plus 10 with all engines operating. I don't know about your type but in the Hawker, VFTO is when the flaps come up in the climb with all engines operating, which is usually about V2plus 30, depending on conditions. We bug V2 as a reference speed in case an engine fails at V1. In that scenario flaps are raised at V2plus 10 in level flight at 1500' while accelerating to VFTO.

AP

[tommoutrie]

hello againn apruneuk

the issue is that it links to putting together cohesive arguments about NAP to the authorities. At the moment most people don't really understand performance and the way its taught confuses people.

For instance. The reason the Hawker manual says 2nd segment goes to 1500 feet or to 3.5 mins is thats the point at which you need to accelerate and take the flaps up. Its actually the flap going up that changes the segment - you go to third segment (level acceleration) if you need it to accelerate and because your engines are limited to 5 mins max thrust you level at 3.5 mins to accelerate enough to take the flap up and do a final segment climb to 1500 feet where you would level accelerate again and climb at Venr or Vfto whatever you choose to call it.

So if you raise the flap at V2+10 at any height you have entered final segment climb, if you keep accelerating to Vfto you are in the enroute climb. There are advantages to climbing at Vfto - there's no level segment needed at 1500 for the final segment climb because you're already at the required speed and its easier to fly with a failure. But this is also true if you are at V2+10 clean.

The argument regarding needing a further margin over V2+10 is also not valid - you actually need less lift in the climb than in the level segment and everyone seems happy to raise the flap at V2+10 in the level segment. The margins are already built in as explained in a previous post.

I don't understand the logic of flying a less efficient departure, climbing against unnecessary drag. It simply not true that its mandated - thats urban myth. I don't really care how people choose to fly the planes but we shouldnt make up rules that simply don't exist. This myth of a 400 foot flap retraction height and even the 1500 foot one just causes confusion in pilots and they don't really understand the problem. I've been accused of making up my own rules and all sorts on this forum simply for saying "why don't we do what the manual says" and its revealed all sorts of holes in peoples knowledge which is also why I object to how its taught. In many companies, a call of 400 feet is the trigger for flap retraction and its totally without logic.

anyway, as you say, got my knickers in a twist..

but they are very valid points eh..

[deefer dog]

Surely the question to answer is:

Will the aircraft, with OEI and flown at V2 or V2+10, make a better angle of climb, considering the conditions, with flaps in the take off position?

If a clean climb will produce a better climb angle (not rate), then tommie is surely correct, but can he prove that it will work in all conditions?

[Kak Klaxon]

Tom,

You are wrong, wrong wrong wrong wrong wrong.

[apruneuk]

Tom

From the Hawker manual, V2: take-off safety speed. V2 is equal to VR plus the increment in speed attained prior to reaching 35 feet with an engine failure.

VFTO: The final take-off climb speed. "When a positive rate of climb has been established, retract the landing gear. Raise the flaps at approximately 160 kts but not below final take-off climb speed. With both engines operating at take-off thrust, the airplane should be allowed to accelerate to an airspeed of 160 KIAS, this airspeed being maintained until obstacle clearance height is reached."

VERC: en route climb speed.

So for a two engine noise abatement departure we aim for 160kts whilst adjusting power so as not to exceed the maximum mandated pitch of 20 degrees. Flaps are then raised, the aircraft accelerated to VERC and climb power is set.

So for the Hawker, V2 plus 10, whilst unlikely to make the aircraft fall out of the sky, is not the most efficient speed to raise flaps whilst maintaining the close-in obstacle clearance profile (second segment). Or, put another way, retracting flaps at V2 plus 10 in the climb will degrade climb angle as opposed to waiting until VFTO. From the manual.

AP

[deefer dog]

why don't we sort the wheat from the chaff and forget about noise abatement! it was not brought up in the original argument....tommie's argument is based on his belief that the airplane will climb at a better angle with flaps up, and thus he believes that one will clear obstacles by a better margin with OEI if the airplane is cleaned early while both engines are operating, and before one of them quits.

there are a lot of self proclaimed experts here who seem to differ, but as far as I can see nobody has yet disproved the central premise that he is putting forward.....will it make a better angle with flaps in the take off position with OEI?

my gut feeling is that it will not....irrespective of the conditions, but i'll check my AFM tomorrow.

[Sillypeoples]

Tom is trying to convince you his cruise climb speed (V2+20)is an obstacle clearance speed..

In a nutshell he's trying to argue that Vy instead of Vx is what you use to get over obstacles..

Brilliant.

I vote to stick him back in a C172 and have him fly at hills all day long using Vx and Vy to get over them until he figures out the difference.

[tommoutrie]

deefer, that bit is interesting for my aircraft.

Comparisons of a departure at MAUW from sea level at 20 degrees give 5.8% for the final segment and 5.7% for 2nd segment.

40 degrees, 41,000lbs, sea level, second segment is 5.0 % and exactly the same for final segment.

I'll do more tomorrow (I'm visiting inlaws..)

Although you can't account for the credit, the conditions for 2nd segment are with the APR (power reserve) triggered which is an extra 2% N1. The engines are producing significantly more thrust in this condition and you are limited to 5 mins. For the final segment tables the engine conditions are max continuous so significantly less thrust. Achieving the same percentage climbs with less power would indicate a more efficient climb but that is a hard one to argue so I can only claim the same gradients. I promise to post it if I find conditions where final is worse than 2nd segment.

Dont forget that the APR would be triggered in the event of a failure anyway so you would absolutely definitely out perform the quoted final segment numbers (engines delivering more power), there would only be a requirement to reduce power to max cont after 5 mins with no level (third) segment so dist obstacle clearance performance with the flaps retracted would ALWAYS out perform flapped to 1500 feet. You would still need to fly a level segment to accelerate to enroute but it would be shorter than from the flapped condition (you're already going faster and there's no segment where you are raising the flap).

Still failing to see the downside..
I re-read the Bombardier AFM for a normal take off today for the 601. It states flaps up at 1.25Vs which is typically V2+4 when light to V2+7 when heavy. Flaps up at V2+20 (quoted in the Bombardier training notes and on the checklist) already has a margin built in.

every days a school day ...

[tommoutrie]

sillypeoples, my cruise climb is 250 kts, my enroute climb is 190, my final segment is V2+20, second segment is V2. Your grasp of whats going on here is astonishingly weak but I have a copy of Kippers Kite that you might enjoy now that my kids finished with it.

[tommoutrie]

deefer, you have summed up the issue very well. Can you explain it to sillypeoples?

one thing - this isnt my suggestion. Its whats in the AFM. I'm suggesting that some training organisations bang their own SOPs over the top and they don't enhance the performance of the aircraft - in fact they degrade it. Using the raw data it should become obvious if this suggestion is correct or not and the numbers I've just got from the graphs suggest it does. But we should not forget that using the manufacturers method give more benefits - no (or a shorter) third segment, lower fuel burn (not by much but a bit), less noise (because you will climb better as you accelerate), lower workload in the event of a failure (because you are going faster and are already clean), and I honestly can't see any downsides!

Actually, there is one (just to scupper my own argument). If you take off and climb into a strong tailwind the slightly increased speed (V2+20 as opposed to V2) would mean the gradient is very slightly worse but I cant be bothered to do the maths as the difference will be absolutely minimal and nobody else is bothering to wind the take off path at all so I dont see why I should bother!

[Kak Klaxon]

You don't see any downsides because you are not seeing the bigger picture in what a Perf A aircraft needs to be able to achieve. I guess you never had to suffer a Lawrie Benn 5 day Perf A course back in the day.
Look again at the NTOFP and tell me how bringing the flaps up on speed at an unknown altitude provides you with guaranteed obstacle clearance .

[apruneuk]

Tom

Just another thought for you; as I have already mentioned, for the Hawker, the manufacturer's recommended flap retract speed is VFTO, not V2 plus 10, for a normal take-off. One very good reason for this could be that V2 plus 10 is usually reached before the gear has started to retract. By the time the gear is fully stowed, VFTO (approx V2plus 30) has been achieved and the aircraft can be cleaned up.

The question now is, what speed would you pitch for if an engine were to fail clean below 1500'? The charts give profiles for a climb to 1500' at V2, however it is unlikely that you have calculated V2 flap less if you have just taken off flapped. Of course, you could approximate or continue at VFTO, however neither method would give you a provable second segment gradient.

Hence, it is far easier for operators to mandate a height of 1500' for flap retraction to allow for an engine failure at any stage prior to that point. All that would then be required would be a pitch to your calculated V2 to maintain a gradient guaranteed to keep you safe to 1500'. Or you could just take off flap less if your type allows it.

AP

[tommoutrie]

kak thats an interesting comment.

I did my exams at london guildhall up on the top floor and remember lauries lectures well

Remembering his lectures has convinced me even more that the problem lies in the teaching. The only case that was calculated was OEI at V1. Thats all you needed to pass the exam. All based on a Tristar from what I can remember. The legacy is that pilots believe they have to degrade the performance of the aircraft on normal take offs so that in the event of a failure they can re-capture the worst case scenario. But it simply isnt true. Because people misunderstand the segments and whats actually going on, they think they have to resort to a flapped climb in the event of a failure to comply and its just not true. Its a very significant failure in the training and testing regime.

Engine failures are rarely as benign as we experience in the sim and the shock of a powerplant letting go, shedding bits, and vibrating like mad is not realistically replicated in the box. I genuinely feel that we should be armed with the most appropriate and easiest aircraft to fly in this event and clean and fast is the easiest configuration. I haven't got a hawker manual to read but I'm assuming that what apruneuk has posted is correct and perhaps its written that way because the enroute climb gradient is good enough to meet the criteria. The 125 series is derived from the dominie which was a IMC and IFR trainer for the RAF for a long time so wouldn't be surprising if the aircraft has some basic design features which make it easy to handle with failures. For the Hawker, the default configuration for take off should be flapless anyway because of the superior 2nd segment and easier handling with a failure. The flaps shorten the roll and give an earlier lift off and mean lower brake energy in the event of a critical stop but that seems to have got lost in the mists of time too.

I think this matters because there's a mixture of ideas about what to do with a failure higher up the climb. I've flown 1200 sectors as a line trainer and simply discussing this with pilots seems to cause confusion - its never been explicit in a part B or an AFM for a pilot to read. Even on here its clear that pilots confident enough of what should happen have conflicting ideas. I'm still not clear on what some of your plans are in the event that you retract the flap at 400 feet "above V2+x" and then the engine quits. Would you pitch up to reduce the speed? Would you hold the pitch and let the speed bleed off more gently? Would you reduce the pitch and bleed the speed off really gently? I've never heard a pilot brief it and I don't tend to bother either. There's a complex drag argument to be had for doing each of those three things whether you are flapped or clean when you have excess speed and as the PM I'd like to have a really clear idea of what the HP's plan is before it happens because if the mental model is different to mine when an engine fails the discussion is going to be compressed..

[BizJetJock]

one thing - this isnt my suggestion. Its whats in the AFM.

Err.... no, it's not. The AFM for a 601 just says flaps up at not less than 1.25 Vs. Therefore either method meets the letter of the AFM. Other types, as has been pointed out, do have at or not below 400' mentioned.

why don't we sort the wheat from the chaff and forget about noise abatement!

Because we're not allowed to. The original question was why do people climb to 1500' before flap retraction - answer, because that's the noise abatement departure as required by the operating rules. I've quoted this previously, but it's EU-OPS1.235

[Kak Klaxon]

Tom,

Again, please tell me how you are going to guarantee obstacle clearance by raising the flaps at an unknown altitude. This is the whole crux of the argument.

[tommoutrie]

and you're right biz but a critical part about the noise abatement departure is ignored. Very few pilots adhere to the speed schedule for NADP claiming that the body angle is too high (and they are right) but climbing with excess power against the drag causes more noise and degrades the climb. Everyone keeps saying that the increased drag is minimal and its not for long etc but ANY increased drag is increased noise and increased footprint. Also, I have never seen charts for climb gradient at speeds above the minimum flap retraction speed so you don't know by how much you have increased the noise and footprint.

This is a good reason to start a proper discussion about noise abatement procedures and come to an agreement with the authorities with regard to noise because at the moment I think very few departures are compliant with the rules.

[mutt]

Tom you might enjoy reading this....

http://web.mit.edu/amarch/www/files/March_thesis_SM.pdf

Mutt

[BizJetJock]

I don't think I ever said the rules were right...;)

[deefer dog]

mutt,

anyone who might possibly enjoy reading that needs their head tested.

[BizJetJock]

Not sure about enjoy, but it was interesting. Basically said configuration (i.e. flaps up/down) makes stuff all difference to noise. The two biggest factors are:
Thrust setting - so all a/c that are capable of it should use reduced thrust for takeoff
Speed - We should be going for max body angle rather than letting the a/c accelerate.

Since bizjets not on reduced thrust will invariably accelerate to a fairly high speed even at 15 degrees of pitch, it bring it all back to the question of what procedure you should use for an EF at 500'. I am firmly in the camp of leaving the flaps at the takeoff setting, since you are then in the configuration you have done the OEI planning for, and guaranteed to be above and able to stay above the calculated flight path.
While there is some logic to Tom's suggestion for some a/c types, where even at max body angle you have reached Vfto or equivalent (note, it must be Vfto and not some lower speed that would subsequently require acceleration in the event of an engine failure), and the clean climb gradient is always better than the 2nd segment (again, not true for all aircraft), logic only gives you a "probably ok" which is not good enough.

And that also ignores the fact that the more different contingent procedures you bring in (EF here I do this, EF there I do that, EF over there I do procedure 3), the more likely people are to get it wrong. Even with 2 procedures, normal and OEI, a significant number of people get it wrong. So having the same procedure, the only difference between normal and OEI being the target speed, hugely increases the chances of success.

And finally, there is the factor that IMHO the drag and reduced pitch angle of flaps on the initial climb are a benefit from a handling perspective, especially with a low initial level off. By keeping the RoC low - only about 3000fpm! - it greatly reduces the chances of a level bust.

[Kak Klaxon]

Tom, answer my question, how do you ensure you can get over an obstacle if you raise the flaps at an unknown height.
Your a line trainer, you are teaching people to do this, what is the answer.

[deefer dog]

I didn't read it, but would bet my last dollar that one is gonna make less noise for less time climbing with less flap. For the purpose of this argument though, who gives a fcuk about the noise when you are climbing out on one engine? Noise will be the last thing on my mind, so could we get back to the topic in hand?

Seems to me that nobody has come up with a good argument to disprove Tommie's theory.... yet. It's all very well stating that it's not possible to define precisely the gradient he might make using early flap retraction, but if it is the case that the gradient will be better is that not enough to make his case?

[Kak Klaxon]

Sorry Deefer, unfortunately it's not, let's await Toms answer, We are doing facilitated learning here, Tom will know all about that as a good trainer.

[BizJetJock]

I didn't read it, but would bet my last dollar that one is gonna make less noise for less time climbing with less flap.

Enjoy your life of destitution... it concludes that climbing at a lower speed with flap is quieter than a higher speed clean.

For the purpose of this argument though, who gives a fcuk about the noise when you are climbing out on one engine?

Nobody - we're talking about the 2 (or more!)-engine profile, where you have to consider the highly likely case that all the engines continue working, as well as planning for the unlikely case of one stopping.

but if it is the case that the gradient will be better is that not enough to make his case?

With regards to obstacle clearance, yes. However for some a/c types you cannot prove that the overall gradient will be better, so it cannot be used as a general principle. And then there are the types where the AFM does give a minimum flap retraction height.

But all this also begs the question of what is the rush? Why are you so keen to have hands flashing around the cockpit close to the ground?
Personally I think the most immediate action is making sure the coffee maker is on.. :E

[Sillypeoples]

Tom,Why don't you explain to me what I am missing?V2 gives you a better climb gradient then V2+20V2 with flaps take off gives you an even better climb gradient.Retracting flaps means you started the third segmenet...pushing the nose over for a faster speed, a level off...something you might not want to do whilst trying to get over the hills...get it?I will assume that you fly in the real world with real hills to smash into...so explain to me why on a climb gradient restricted SID in the soup you would retract the flaps and push the nose OVER if the whole point of the exercise is to get over the obstacles?That makes sense right? I am all ears.

[deefer dog]

BizJetJock;
Enjoy your life of destitution... it concludes that climbing at a lower speed with flap is quieter than a higher speed clean.If that's what it states, then okay, I'll eat the humble pie and accept it. I don't have the time or inclination to read about noise abatement, and as non CAT, I don't give a fcuk about it either; I've never been busted for noise, but that is not the topic in hand.

Guys, I am prepared to learn here if that's what's needed, but so far nobody here is doing the teaching. Most are happy to quote "it aint in the AFM, so therefore it can't be right," but the fact remains that in the Hawker (which many of you have been quoting), the 900 does, under ALL conditions, provide a better OEI climb gradient with flaps retracted than it does with flap 15. All day long, and day, any WAT.

Unless one is runway length limited, any Hawker driver will, as a matter of course, choose to take off with zero flap. Why? Does it have anything to do with second segment? Er ...yes it does!!

Taking this just one step further. If you are runway length limited, what reason is there for NOT getting shot of the flaps at the earliest possible opportunity (provided all engines are operating) when by doing so you know know that your climb gradient is suddenly improved should an engine quit?

Now, on the other hand let's consider the engine failure, with take off flap selected, just after V1. This is an entirely different scenario, and in such a circumstance there is a very good reason why one should NOT retract the flaps too soon. It's not to do with the fact that you won't better the gradient with flaps retracted, but rather the reason is to do with the reduction in climb gradient while you accelerate to a speed that provides the margin for flap retraction.

As stated at the beginning I am prepared to learn if I have got it all wrong, but please if you want to teach please add some meat and gravy to your argument rather than amplifying the " it anit in the AFM, so therefore it can't be right."

If I hit V2 +20 with all engines operating, and it arrives before VFTO, please tell me why I should NOT retract the flaps in the knowledge that, in my aircraft, under any conditions, doing so will improve my climb gradient should en engine quit? Please teach me.

[mutt]

V2 gives you a better climb gradient then V2+20 are u sure about this ? If true, why do we have improved climb?

Retracting flaps means you started the third segmenet...pushing the nose over for a faster speed, a level off...something you might not want to do whilst trying to get over the hills...get it?I to begin with he has stated that he has achieved the required speed in his aircraft, so why does he need to accelerate! He isn't going to hit the hills.

As the Hawker appears to have 0 flap performance tables, is there any reason why he can't do what he wants in THAT aircraft.

For me, the lack of 0 flap performance information limits what we can do, we have no data to back up the theory that we will get a better gradient with 0 flaps and the appropriate speed and can guarantee obstacle clearance. We also have an issue with the higher speed increasing the takeoff path and possibly encompassing more limiting obstacles.

Noise, not rushing the configuration change, standard sop's across fleets, liability, are all external issues.

Mutt

[Sillypeoples]

Mutt -Only on this forum do the hills move out of the way when you retract the flaps and level off....lol.

[mutt]

when you retract the flaps and level off He has achieved the required speed, he doesnt need to level off, therefore as he has 0 flap peformance data he can ensure that he gradient is always equal to or greater than the planned profile with flaps extended.

Mutt

[mutt]

Tom, you came into this saying that you wanted to use Speed as the trigger for Flap Retraction rather than Height, we argued that you couldnt due to the acceleration portion of the takeoff and the height to initiate this acceleration. You are fixated on 400 feet an 1500 feet, but in reality we can use any altitude with the thrust limits.

Gross
Gross Track Gross X Lateral Gross
Distance Distance Offset Height
FEET FEET FEET FEET
-------- -------- -------- --------
Screen Height 7443 7443 0 35
Gear-Up 11320 11320 0 173
Level-Off 100000 100000 0 3175
Start Final Climb 136643 136643 0 3175
Or

Screen Height 6551 6551 0 35
Gear-Up 10565 10565 0 245
Level-Off 59064 59064 0 2855
Start Final Climb 82945 82945 0 2855

Both of these are clearing the same distant obstacle. So for aircraft like these, the only way that you can ensure that you will clear obstacles is by following the specifed flight path, you must use an altitude for flap retraction/acceleration and not a speed.

So to end, you have 0 flap performance data in the Hawker, so you can accelerate in the climb and retract the flaps. But for a lot of other aircraft that need to accelerate more than the Hawker does, then you cannot use a speed reference for Flap Retraction/Acceleration.

Mutt

[BizJetJock]

I've never been busted for noise,

I've never been busted for speeding; does that mean I can ignore the existence of speed limits?

What a stupid attitude..:ugh:

[BizJetJock]

Noise, not rushing the configuration change, standard sop's across fleets, liability, are all external issues.

Not sure what you mean by this - they are all factors that have to be taken into account when devising your takeoff/departure profile.

[tommoutrie]

Hello again all

Make yourself a coffee and read this properly - have a biscuit on me..

The reason you will clear obstacles is that you are always above the gradient required to clear them. (before you stop reading and just bang out another post, just hear me out).

I will ignore all the benefits which you can't account for because either you don't have the data or we do but currently don't account for it.

I am not suggesting for a moment that anything at all changes in terms of planning. We have to plan for a failure at any stage, obviously, so lets all be absolutely clear that in the event of a failure from V1 up to flap retraction, nothing changes. So lets just think a little more about that case? What is the reason we don't retract the flaps at a lower height in the event of a failure at V1? The reason is we don't have the performance to climb at the calculated gradient AND accelerate at the same time. So we plan to accelerate at a known height and accelerate there. The only point of this acceleration is to raise the flaps. What is the point of raising the flaps? If we can achieve a better gradient with the flap at the take off setting, what would be the point in raising the flap? Why would we not continue climbing at V2 with the flaps set at take off? If the aircraft does not produce much drag, why is it so important to remain in that rather narrow band (V2 to approx V2+10 or maybe a bit more) with the flap at the take off setting in order to achieve the stated gradient?

The reason we accelerate raise the flap at 1500 feet in the event of an engine failure at V1 is to improve the climb rate and for many aircraft 1500 feet is the certified platform at which we do this. It is desirable to raise the flap not only because it improves the gradient and also the rate of climb but the aircraft is also easier to fly.

So here's the thing. If you don't agree that the aircraft climbs better and is easier to fly, what is your justification for raising the flap at 1500 feet? Do you do it only because thats what the manufacturer says or because thats what the bloke that taught you perf A says you should do? If so, noddy pilot, need to think more. Consider how much easier the aircraft is to trim, how much less rudder you need because you've moved the centre of lift, how much more effective the fin is, and how (because its easier to fly) the auto-pilot will now manipulate the controls effectively enough for you to deal with the screaming captain who's just wet himself and can start working the problem.

Does everyone agree that raising the flap at 1500 feet in the event of a failure at V1 has benefits? Or does anyone think the aircraft performs better with the flap down? If anyone thinks the aircraft will continue to climb better with the flap down then you need to lobby the manufacturer and your company to change your OEI V1 procedures to leave the flap down.

Right..

Now lets think about what the 1500 feet is for. It is absolutely not a flap retraction height. It is a level platform which you can use and plan for which will allow you to accelerate and ONLY IF YOU ACHIEVE THE SPEED raise the flap. I'm just going to reiterate that point for sillypeople. You don't raise the flap because you achieve a height. You only retract the flap because you achieve a speed.

Does anyone disagree with that?

So hopefully we have all got to three agreed points so far.

1 - the aircraft climbs and performs better if you retract the flap otherwise you are certifiably insane for raising the flap at 1500 feet.

2 - the 1500 foot platform is for accelerating not for retracting the flap.

3 - we only retract the flaps because we have achieved the correct speed.


The gradient clean is normally called the final segment gradient and should be in all AFM's because you use it to complete a climb to 1500 feet in the event that you run out of time with the remaining engine at max thrust and have to reduce to max continuous. You also can use it to determine reduced acceleration altitude procedures which will enable you to clear distant obstacles which you may otherwise hit. This is all basic perf A and there was always a question in the PerfA exam which was to do with the maximum take off weight you could go with and it was a sneaky trick question because you could take slightly more if you reduced the AA. Nobody ever bothered to work out the answer to this question - it was the slightly higher of the two close weights...

Lets get back to the original question - am I nuts to suggest that we can do what the men that build the plane say and raise the flaps at V2+x. Once we have accelerated to V2+x we have achieved part of the purpose of the level (third) segment and we have attained the speed at which we can retract the flaps. Tremendous! Now, as agreed above, we can trend the aircraft from the slightly poorer gradient that we have with the take off flap to the better gradient achieved clean. You cannot disagree with that statement because if you do you have to leave the flap down at 1500 feet and come up with a good reason to raise them at all.

What happens if the engine fails just as we flick the switch, move the lever, that makes the flaps travel? It doesn't matter - we are already at the speed we need to make the thing climb at the better gradient so all the time the flaps are travelling the gradient is actually getting slightly better. There is a feeling that we are sinking because we have to change the angle of attack but in reality, as long as the speed remains at V2+20, the gradient will remain as good or better than we had with the flaps at take off. Again, if you don't agree with this, don't raise the flaps at 1500 feet as you will obviously not climb so well.

Ok so now we have all agreed, without using any of the extra factors like shorter take off roll than a failure at V1 or take off climb increment because we need the gradient from the end of the runway not our take off point, or the improved climb to wherever the failure actually occured at V2+20, that we have achieved at the very least the same gradient that we would have had in the event of a failure at V1.

By the way, I haven't forgotten what the rest of the job of the 1500 foot acceleration altitude is for - to accelerate to Venr. At the enroute climb speed you will definitely get a better rate of climb than at V2+20 but now your forward speed is greater so the gradient may be less. If you need the gradient for distant obstacle clearance you can continue the climb at V2+20 clean (extended final segment) at max continuous rather than max thrust. This is why final segment climbs are quoted at max continuous (OEI). This is also why we will always exceed the final segment climbs when we use them at low level (ie when we look at the gradient following a failure at V2+20 we will exceed the quoted gradient because we can still have the engine at max thrust rather than max continuous). This is another bonus that we can't quantify but is good to have in your back pocket.

So now we can be sure that at the very worst we will achieve the same climb gradient that we would have achieved if the engine failed at V1. Not a guess - absolutely certain because its in the manuals as I posted. If you don't think its in your manual I'm happy to have a look at the manual but bear in mind that the manufacturer would not certify the aircraft to have the flaps retracted at V2+x unless it were true. There would be big bold letters saying "you have to achieve this height, you have to reduce speed in the event of a failure to V2" blah blah blah and we've already seen from lots of other posts that no manual says that (except perhaps Coughs in his airliner and I completely agree that if it says it in the manual then that's what you do).

(dammit, lost my thread, had to read Hairy Maclary to my daughter)

oh yes. The AFM - the one published which was written by the people that certified the aircraft - doesn't say that. I think its a good plan to do what it actually says. All the benefits are on our side should the worst happen if we do what it says.

Tom

ps.. not facilitation learning because the audience is far too hostile and unwilling to consider an alternative idea. This is called primacy, and its the reason this subject needs to be taught better at an early stage.

pps.. call me odd but that paper Mutt posted is very interesting indeed. The footprint reduction calculation far exceeds what I expected. Its especially interesting that modelling techinques have advanced so much since I left uni as it wasn't possible to model turbulent flow that accurately when I was an undergraduate. This may mean we can develop a more appropriate noise technique for business jets that we can actually fly!

[deefer dog]

For me, the lack of 0 flap performance information limits what we can do.

I thought this was obvious from the outset, and assumed that Tommie had such data related to his type.

BizJet, the point I meant to make (but didn't type) was that if I was struggling to clear an obstacle I wouldn't give a fcuk about noise.

[deefer dog]

I read it Tommie, but have two questions before I go out.

What actual gradient will you make with the flaps up, and what speed will you aim for depending on the WAT? And what gradient do you lose during the acceleration?

If you have the data to provide an answer, and it exceeds the numbers for climbing out on one engine with take off flap selected, I see no reason to disagree.

[tommoutrie]

I posted both of the required tables in post 274 and 285. In all cases that I've checked the final segment climb gradient meets or exceeds the 2nd segment gradient. As mentioned before, the final segment gradient is with the engine at max cont rather than max thrust which is the case for 2nd segment. So where we are only able to match the 2nd segment climb (which would be good enough anyway) we will actually substantially exceed it because for the remainer of the time available we will remain at max thrust.

There is no acceleration (in the event of an engine failure at V2+20) - we are already at V2+20 so don't need any acceleration. All we need to do is keep that speed - while the flaps travel the gradient will change from the flapped to the clean gradient. We do not accelerate. We still have the 1500 foot level acceleration platform available to accelerate from V2+20 to Venr so that we can establish in the enroute climb when necessary.

That acceleration phase in the level segment will be shorter than in the calculate scenario where the engine failed at V1. So our obstacle clearance calculations are still valid.

In all cases we outperform the critical failure at V1 case. Thats without counting all the other factors which are actually in our favour.

[Kak Klaxon]

Wrong wrong wrong wrong, what does it say in the top left of the chart that you posted, did it say this chart includes loss of climb gradient from V2 to flap retract to final Single Engine climb speed? Keep it short man. X factor starts soon.

[tommoutrie]

right right right... we don't even commence the flap retraction until we achieve V2+20. So no acceleration, no loss of gradient.

X-factor? have some self respect man..

[Lord Spandex Masher]

Tom, what would your manuevering capability be if you're clean, at V2+20 and OEI?

[Kak Klaxon]

Tom, I have never flown an aircraft where flap retract and single engine climb speed have been the same, hand on heart I have not flown the 601 so that's where my confusion must of come from.
I am out of time, really sorry, maybe we can continue later, I don't know why this is getting me so involved as since I left the airlines I have turned into a proper cowboy with regard to stuff like this!
Have a good weekend.

[tommoutrie]

as per the posts before, V2+20 is the speed for the final segment climbs. At acceleration altitude I would accelerate to Venr (190 kts) and climb away at that unless a distant obstacle calculation prevented it.

So in the event of a failure at V2+20, yes I would hold that speed. If they both keep going I would keep accelerating to cruise climb, 250 kts and climb away at that. Actually, thats not quite true, I've been doing a load of maths and would climb away at my most fuel efficient speed but thats another story that I'm messing about with. And I don't fly enough to prove if thats right so I'm not going to mention it..

DOH!

[tommoutrie]

V2+20 clean is my final segment climb speed and configuration.
I can climb at that for as long as I like.
However, I can also accelerate to my enroute climb speed and achieve a better climb rate though not necessarily a better gradient because of the increased forward speed. If there are no obstacles we should climb at Venr because of the increased climb rate.



Recap. These are all the same - retract the flaps on schedule and you can't go wrong.

If we have an engine failure at V1 up to V2+20 - can't retract the flaps because we can't accelerate and climb. So climb to 1500 feet, reduce pitch to level flight and retract the flaps accelerating through V2+20. Keep accelerating to Venr, climb away.

If we manage to get to V2+20 with both engines running we can now retract the flaps WITHOUT a level segment or pitching to accelerate.

So if we have an engine failure V2+20 up to Venr we're clean now (or in the middle of reconfiguring to clean). Keep the constant pitch and gently allow the speed to reduce back to V2+20. Its important not to pitch up because again the drag will increase (from the elevator) so just let the speed bleed back naturally. You are still well above the pitch for V2+20 clean so you'll still be trading speed for extra height and therefore definitely above the required gradient. The speed will bleed back to V2+20 and you pitch to maintain that. At 1500 feet (the platform we've all agreed on for a level acceleration) you can lower the pitch to accelerate to Venr and when you get there, climb away. There are conditions on this which you already do calculations for (I'm sure). Far out obstacles may require you to stay at your final segment climb gradient so you may have to do that but you're still in a much better position than the guys who left the flap selected as you don't have to pitch level and accelerate to get rid of the flap.

Engine failure after Venr up to cruise climb speed. Gently slow down to Venr because that gives you (roughly) the best climb clean OEI.

This is what isn't explained during perf lessons. It is, however, what the manufacturer thinks you're going to do. It leaves you in all cases after V2+20 with an aircraft thats climbing better and easier to fly than leaving the flap down past the flap retraction speed. It means you do the same thing whether all engines keep running or one fails ie:-

Take off, Retract the flap at V2+20, if you need a level acceleration platform to achieve flap retraction and a Venr climb use 1500 feet (subject to normal perf constraints)


its the same plan for every take off whether an engine fails or not.

Spandex (cool name) asked what maneuvering limitations we have at V2+20 clean. I can retract the flaps at 1.25Vs which is V2+4 when light and V2+7 when max weight and that will give the same maneuvering protection as flap 20 and V2 so there's already improved maneuvering margin but I'll look up the limits in the manual tomorrow.

[Kak Klaxon]

Good morning Tom, I now realise that your 601 has the magical powers upgrade so you can do what you like in it, who is your CAA ops inspector, Harry Potter?

[BizJetJock]

am I nuts to suggest that we can do what the men that build the plane say and raise the flaps at V2+x

Yes - because they don't say that!! I've posted the manual quote directly for you several times and it says not less than.

Re accelerating at 400 or 1500 feet - a history lesson:
1500 feet is an arbitrary number that marks the change from the takeoff phase to the enroute phase in terms of required obstacle clearance. It's the lowest height where you're likely to meet the enroute requirement of 1000' above obstacles.
Early jets couldn't climb at all with flap down OEI at max continuous; and because of their poor climb and acceleration even at takeoff thrust with water injection, they could only make it to 400' before having to level off and start accelerating to be clean before their 5 minutes ran out. I understand that the 400' figure was a battle between manufacturers and regulators; manufacturers wanted lower and were told "no".
Later, we get jets like your 601 that can get straight to 1500 (just); this allows them to take more weight in a scenario with distant obstacles below 1500 by delaying acceleration until you are above them.
More modern still a/c (604/5) can get higher still - and we have graphs in the manual for extended second segment climb. So we quite often are climbing above 1500' before accelerating if it is required for obstacle clearance. Zurich RW28, for example, AA is 3410', which is 2020' above the runway.
So the answer to your question is that we use 1500 normally because at 95% of airports we are clear of obstacles and are only interested in rate of climb, not angle.

Your logic for your profile appears to work for the 601, but only because it is a special case on two counts;
1) that the flap retraction minimum speed and the final segment climb speed are the same - on most aircraft there is still acceleration required. Of course, if you adopt my logic this problem goes away, because you leave the flaps down until you have reached Vfs ;)
2) because the final segment gradient is always better than the 2nd segment. There are plenty of aircraft where this is not the case, because the reduction in thrust from TO to MCT reduces the performance by more than the gain of getting the flaps up.

And on aircraft like the Hawker with flaps up performance data, if you've looked up the appropriate clean V2 then you could use that in case of an engine failure after flap retraction but below AA; But that comes back to introducing too many variables to expect the average pilot to cope with.

BizJet, the point I meant to make (but didn't type) was that if I was struggling to clear an obstacle I wouldn't give a fcuk about noise.
Yes, and quite right too. However, the original question was why do we fly the profile we do on all engines. And the answer is because as well as planning for an engine failure at any stage, we have to comply with the normal operating rules (noise abatement, etc) and make the whole thing reasonable to expect people to fly - which should in the process cover any liability issues!

This may mean we can develop a more appropriate noise technique for business jets that we can actually fly!
I agree that the current framework is written entirely around airliners, and is in many ways not appropriate for bizjets; however, until it is changed (oh, look , there's a pig flying past my window...) we have to work with the rules we have.

Enjoy the rest of the weekend. :ok:

[tommoutrie]

Hello Biz

I just need to deal with a couple of points that you've made because you're trying to make the 601 a special case. The final segment climb is not the same as the enroute segment climb and I'm not sure what type you fly but I strongly suspect the same will be true for your type. What do you fly? I'll have a look at the manual to see if its any different to the 601 in this respect.

Anyway

1) that the flap retraction minimum speed and the final segment climb speed are the same - on most aircraft there is still acceleration required. Of course, if you adopt my logic this problem goes away, because you leave the flaps down until you have reached Vfs


No acceleration will be needed for the final segment climb on any aircraft. An acceleration will be needed for the enroute climb. Leaving the flap down until you reach Vfs is gash because you are climbing against unnecessary drag. In the event of an engine failure you will ALWAYS be below the path you would be on had you taken the flaps up at the flap retraction speed.

2) because the final segment gradient is always better than the 2nd segment. There are plenty of aircraft where this is not the case, because the reduction in thrust from TO to MCT reduces the performance by more than the gain of getting the flaps up.


Which aircraft? Not adversarial, just interested. Its true for all the aircraft I have manuals for. Can you let me know which ones its not true for? Also, don't forget that in the event of a failure once you have cleaned up you still have max thrust (in the Challenger the APR would still trigger) so you will substantially outperform the published figures. By not cleaning up you are throwing away this advantage and I just don't get the logic behind doing that.

I'm busy downloading figures for a 605 and will look at the Global tomorrow because I'm in work and have the manuals available.

[deefer dog]

And on aircraft like the Hawker with flaps up performance data, if you've looked up the appropriate clean V2 then you could use that in case of an engine failure after flap retraction....

No need to...it's 1.2VS as indicated on AOA which of course is set prior to every departure irrespective of flap setting.

[awacs]

That the test pilots, aerodynamic engineers, and PhDs that built the plane could not figure this out and publish the data? Or is it possible that maybe your wrong?

AWACS

[tommoutrie]

not sure what the intention of that post was but I think the engineers etc know exactly what they are doing and they do publish the data. I don't think we read it properly and many of us don't understand it.

[His dudeness]

Which aircraft?

Sovereign:

2nd Segment at Flaps 7, V2, A/I off, T/O Thrust (limited to 10 min in OEI):

Sea Level / 15°= 6,3% with 30300 lbs (MTOM), 9,2% at 26000 lbs
5000 ft / 5° = 6,4% / 9,3%
10000ft / -5° = 5,2%/7,9%

Enroute Climb (Flaps 0, MCT, A/I off, at Venr = 180KIAS)

SL/ 15° = 5,7 / 7, 6 (-0,6 / -1,6, -> less than 2nd segment)

5000ft / 5° = 5,6 / 7,4 (-0,8 / -1,9 -> less than 2nd segment)

10000ft / -5 ° = 4,6 / 6,4 (-0,6 / -1,5 -> less than 2nd segment)

JFI: T/O Thrust vs. MCT, A/I off

SL: 96,0 / 94,8
5000ft: 100,0 / 98,6
10000ft: 102,5 / 102,3

[tommoutrie]

can't compare it to the enroute segment - groundspeed is too high. Don't you have final segment climb gradients (as opposed to the enroute segments)? If you have a manual that allows flap retraction at V2+x you should have a final segment gradient table that gives you the gradient at that speed.

[His dudeness]

No, Njet, Niente, Nada....

All there is is first segment, second segment and enroute.

What is there though is a distance table from reference zero (35ft) to end third segment (acceleration V2 to Venr)

[BizJetJock]

Leaving the flap down until you reach Vfs is gash because you are climbing against unnecessary drag.

Run this one past me again - we have two suggested profiles:

Profile 1
- complies with all regulations
- allows the handling pilot to concentrate on accurate speed and flight path control without interruption for the first 30 seconds after liftoff
- in the event of an engine failure requires the same profile all the way from liftoff to clear of obstacles, and the only difference from the all engines profile is the speed

Profile 2
- does not comply with at least two regulations
- requires configuration changes involving large attitude/trim adjustments almost immediately after liftoff
- in the event of an engine failure requires different profiles depending on where you are in the initial climb

and you think the first one is gash??!! You have seriously lost the plot there, I'm afraid.

You keep saying there's something wrong about leaving the flaps down for another 30 seconds because it causes drag. This on an aircraft that - if you have done your sums right - can clear all obstacles with the flap down on one engine, and on two is so embarrassingly overpowered that we can't fly a proper noise abatement profile. The flap drag allows us to fly a moderately sensible speed in the initial climb, allowing us to target a speed rather than just an attitude and makes a low level off much easier to handle. A benefit!

Which brings us to
In the event of an engine failure you will ALWAYS be below the path you would be on had you taken the flaps up at the flap retraction speed.
Sorry, just not true. It would be true if you maintained V2+20 or whatever on two engines after flap retraction, but I don't think even you are advocating 30 degrees of pitch. If you maintain a sensible attitude - let's say 15 degrees since that is about the pitch that gives us 190kts with flap 20 - basic aerodynamics tells us that for a given pitch the flight path will be a steeper climb with flaps.
For the Challenger we can even quantify it. If you fly level at 200 kts clean you need +5 degrees pitch. If you select flap 20, you need to pitch down to 0 degrees to maintain level flight; or conversely if you maintained the attitude you would start climbing at 5 degrees - over 8%. That is a huge difference in the flight path.

His Dudeness has posted an aircraft where the final segment is less than the second. From memory all the 500 series Citations are the same, but I haven't got the figures to hand.

Between all those, I think we can say that your theory is well and truly debunked. As I said before, it is not a new idea; such profiles were used when aircraft struggled to climb with flap even on all engines, but modern (i.e. within the last 30 years!) thinking is to take advantage of the better performance from modern aircraft to simplify the handling and cut down on noise.

[His dudeness]

BJJ, I think the discussion itself is a good one and I´m not too sure that Toms theory is complete bollocks....

The discussion has changed and in the beginning we were talking about all engine performance and noise footprint...now we are at OEI performance...

By the way, IIRC is the difference net to gross gradient 0,8 on the 2nd (2 engines) and 1,1 on the enroute climb (too lazy to look it up right know), so the difference is almost neglicable and if we bear in mind that the enroute climb is in MCT and the 2nd is T/O thrust then his theory has its merits. (I havenßt got the numbers to crunch it or prove it)

Also Cessna has elected to stick to one Venr for all weights. I would guess that this speed would normally also change with weight. Most likely Cessna has found the difference to be so small that for the benefit of the average stupid flying the C680 (such guys like me) it sticks with just one speed....

Manufacturers like to save money time and hassle and tend to make just the necessary documentation and I think the legal implications especially in the US might be a contributing factor.

The real question for me stays the same: what do I do when one donk goes awol after the flaps are retracted, I´m somewhere between V2+10 and Venr and there is an obstacle I still have to make. (what gradient am I doing) Our CL / AFM doesn´t give guidance here and I admit it, I haven´t thought about this scenario before and certainly have not trained it with FSI.
I think it is a valid question, OTOH its not a scenario that happens often and to the best of my knowledge there has not been one accident where this had played a role...

Its not practical to stay at V2+10 with both engines and flaps til clear (I´d block the departures at 120-130 KIAS...)

[BizJetJock]

The engine failure procedures are just one of the factors you need to take into account planning your all engines normal takeoff. Some people have got fixated a bit on that one aspect forgetting the rest.

No, it's not complete bollocks, just there are more ifs and buts involved than Tom is making out.

The main problem is that rather than being a great leap forward as he is suggesting, it is a great leap backward. As I have said, the airline world went through this discussion and came up with the current procedures 30 years ago. You wouldn't think it would take so long for the corporate world to catch up.

[tommoutrie]

Where in the airlines do they go blasting though the flap retraction speed? Which airline has an all engines operating policy of exceeding the flap retraction speed by 40 or 50 knots before retracting the flap at a pre-determined height?
The airline world is entirely consistent with what I've posted right from the start of this thread. The flap retraction schedules in all airline are based on speeds. There may be "not below" heights and MFRA's but the retraction of the flap is based on the speed schedule. The heights do not come from legislation (for all the bleating the only post relating to height is FAR/JAR 25 and that relates to OEI at V1).

The argument that this hasn't caused an accident or been a factor in the business jet world so it isn't a problem concerns me. Firstly, I don't know whether that's true. Business jets generally have very good performance on one engine so even if a failure is handled very badly the aircraft will still tend to climb away so there isn't really enough data to argue the point (well, I dont have access to that data). But the argument regarding noise and extra fuel burn applies to every take off - why is this invalid?

I'm hoping to get a 680 manual later today and I'm interested to see what it actually says. If there's genuinely no data between flap retraction and the enroute climb speed that will be a very big surprise to me - I have never seen a manual like that!

[CAPTAIN WOOBLAH]

On the B747 it's called the flap speed schedule! ;)

[Cough]

Tom,

Whats the max pitch you use on climb out?

[B-HKD]

http://img834.imageshack.us/img834/3411/screenshot20121204.jpg

[Kak Klaxon]

At the risk of sounding like a stuck record 400 feet does come from regulation, just because it does not fit with your theory does not mean it is not true.
I have manuals that state that 400 feet is the minimum for flap retract from Bombardier and Dassault. Good fun this.

[de facto]

The flap retraction schedules in all airline are based on speeds

True but you aint going to accelerate without the proper pitch..

[BizJetJock]

Tom, the airlines are 99% of the time using reduced thrust for takeoffs - i.e. matching the thrust used to the weight/altitude/temperature so the problem does not arise. If you have a lightly loaded airliner where they have to use TOGA for takeoff (contaminated runway, antiskid inop, etc.) then you will find that on reaching their pitch limit they allow the speed to increase. On reaching their acceleration altitude if they find that they are already above the minimum flap retraction speed they can do it straight away.
This technique is available on the 601, although interestingly because so few people used it Bombardier decided it wasn't worth the time and cost to certificate for the 604/5.
You are actually the only person on here who seems to think that when people refer to a flap retraction height that they mean that there is no reference to speed. Therefore it would appear that the only problem is your lack of understanding. Knowing the training at both your operator and their third party training provider, I would lay the blame for that squarely with them initially, but the more you refuse to listen to the evidence put forward on here, the more it appears that you are the problem.

[tommoutrie]

biz, try not to get personal with this. This is a legitimate thread to have raised and I find it surprising that you (and others) keep telling me that legislation exists which forbids flap retraction below 400 feet and yet nobody has posted it. I've now looked at the 604 as well and its exactly the same as the 601 -chart 06-05-2 applies, final segment climb gradient. Again, the gradient clean outperforms or matches the gradient flapped even with the APR off at Max Continuous so there is no level (third) segment required.

All thats been posted is CFR 14 part 25.111 so let me just deal with that quickly by posting it below. I'm going to state very clearly here that extracting little bits out of regulations like this is actually dangerous and by only quoting the bit that supports your argument and not quoting the stated conditions you are propogating a myth. If you believe that Part25 mandates no flap retraction below 400 feet then you must fail an engine on every take off. I've highlighted the critical statement below.


Sec. 25.111

Takeoff path.

(a) The takeoff path extends from a standing start to a point in the takeoff at which the airplane is 1,500 feet above the takeoff surface, or at which the transition from the takeoff to the en route configuration is completed and VFTO is reached, whichever point is higher. In addition--
(1) The takeoff path must be based on the procedures prescribed in Sec. 25.101(f);
(2) The airplane must be accelerated on the ground to VEF, at which point the critical engine must be made inoperative and remain inoperative for the rest of the takeoff; and
(3) After reaching VEF, the airplane must be accelerated to V2.
(b) During the acceleration to speed V2, the nose gear may be raised off the ground at a speed not less than
VR. However, landing gear retraction may not be begun until the airplane is airborne.
(c) During the takeoff path determination in accordance with paragraphs (a) and (b) of this section--
(1) The slope of the airborne part of the takeoff path must be positive at each point;
(2) The airplane must reach V2 before it is 35 feet above the takeoff surface and must continue at a speed as close as practical to, but not less than V2, until it is 400 feet above the takeoff surface;
(3) At each point along the takeoff path, starting at the point at which the airplane reaches 400 feet above the takeoff surface, the available gradient of climb may not be less than--
(i) 1.2 percent for two-engine airplanes;
(ii) 1.5 percent for three-engine airplanes; and
[(iii) 1.7 percent for four-engine airplanes.]
[(4) The airplane configuration may not be changed, except for gear retraction and automatic propeller feathering, and no change in power
or thrust that requires action by the pilot may be made until the airplane is 400 feet above the takeoff surface; and
(5) If Sec. 25.105(a)(2) requires the takeoff path to be determined for flight in icing conditions, the airborne part of the takeoff must be based on the airplane drag:
(i) With the takeoff ice accretion defined in appendix C, from a height of 35 feet above the takeoff surface up to the point where the airplane is 400 feet above the takeoff surface; and
(ii) With the final takeoff ice accretion defined in appendix C, from the point where the airplane is 400 feet above the takeoff surface to the end of the takeoff path.]
(d) The takeoff path must be determined by a continuous demonstrated takeoff or by synthesis from segments. If the takeoff path is determined by the segmental method--
(1) The segments must be clearly defined and must be related to the distinct changes in the configuration, power or thrust, and speed;
(2) The weight of the airplane, the configuration, and the power or thrust must be constant throughout each segment and must correspond to the most critical condition prevailing in the segment;
(3) The flight path must be based on the airplane's performance without ground effect; and
(4) The takeoff path data must be checked by continuous demonstrated takeoffs up to the point at which the airplane is out of ground effect and its speed is stabilized, to ensure that the path is conservative relative to the continuous path.
The airplane is considered to be out of ground effect when it reaches a height equal to its wing span.
(e) For airplanes equipped with standby power rocket engines, the takeoff path may be determined in accordance with section II of appendix E.

I'm getting the Soverign manual today so I'll look at that. Perhaps you could help me by posting the references in the Bombardier manuals that you mentioned.

Thanks

Tom

[BizJetJock]

I know perfectly well that Part 25 only addresses OEI performance; however since CS25.111 includes the paragraph

(4) Except for gear retraction and
automatic propeller feathering, the aeroplane
configuration may not be changed, and no change
in power or thrust that requires action by the pilot
may be made, until the aeroplane is 122 m (400 ft)
above the take-off surface.

then if you retract the flaps any earlier, in the event of an engine failure you have invalidated the performance calculations.

I have never actually said before in this conversation that there is a regulation about flap retraction per se, I have been pointing to other factors. But you don't seem to be interested in discussing the points raised, you just keep on about your idea without letting facts get in the way.

I'm sorry if you think that's personal, but I am only persevering with this thread because I am worried that there will be people reading it who think that you are advocating a legal, sensible procedure.

[tommoutrie]

You are extracting single lines from the regulations without taking into account the conditions. Thats the same as me quoting the line:-

"The airplane must be accelerated on the ground to VEF, at which point the critical engine must be made inoperative and remain inoperative for the rest of the takeoff"

and saying that you therefore have to fail an engine at V1 on every take off. And lets be clear. Are you stating that you can retract the flaps at 400 feet? If so, what are you using for data from that point in the event of a failure?

Yes I certainly am advocating the retraction of flap in accordance with the manufacturers manual. The minimum flap retraction on the 601 is actually 1.25Vs and on the 604 is Vfto+5. Both of these are always below V2+20 so there is already substantial margin built in to the flap retraction speed in the checklist. Biz I simply don't understand where you get the idea that the flaps care how high they are. Can you quote the section in the Bombardier manuals so that I can have a look? I've found the Flight Safety SOP's now which are applied across their training and I believe they are inappropriate for a number of types. Where is works (ie, 400 feet happens to be co-incident with V2+x) it sends completely the wrong message to the pilots about the reason for flap retraction. I don't understand why Flight Safety advocate the use of a 400 foot call to trigger flap retraction. I'll post the SOP so that you can make your own judgement.

[tommoutrie]

http://farm9.staticflickr.com/8477/8247353804_7f833f640f_m.jpg

[tommoutrie]

woo hoo!! posted it! my technical skills are getting better..

Biz you need to tell me why you don't think this is safe or legal. Can you post the regulation please or give an explanation of why this isn't safe? Its what the manuals for many, many aircraft say so if it isn't safe this needs changing immediately.

[First.officer]

woo hoo!! posted it! my technical skills are getting better..


nah, your not.....it's far too small.......:E

[Kak Klaxon]

Tom its me who has the sections in the Dassault and BD manuals. Can I suggest that you pass your ideas onto your chief pilot who can if he is unable to explain why you are wrong pass them to your CAA ops inspector.

If the CAA ops inspector can't help then he will pass it to SRG, or whatever they are called now, if they can't help then they can pass it up the line to EASA/ ICAO. It would seem that you are not going to get the answer you want from this thread.

You are playing a spooky game, I like many have been involved in training and examining for a long time, you are on an open forum telling your colleagues in the business world that we are not flying properly. I have often thought some SOP s and Part B stuff was weird but I never taught against it, I have taken it up the chain of command, normally no higher than a fleet manager who has shown me why it's like that.

If your Part B has a profile where you bring the flaps up below 400 feet then your ops inspector agrees with you, sorted, but you would not be posting here if that was the case I guess.

[BizJetJock]

I have done so several times already, but to summarise:

Your profile is illegal because it does not comply with
EU-OPS1.085 f.8 - "The Commander shall....ensure that all operational procedures and check lists are complied with in accordance with the Operations Manual" and I know that your OMB says acceleration altitude is 1500 feet above takeoff.
EU-OPS1.235 - noise abatement procedures. Too long to publish here, but says you need to follow the ICAO profiles, none of which has flap retraction below 800 feet.

I do not think it is sensible because in the first 30 seconds after liftoff the handling pilot should be concentrating on smooth accurate flying without distractions, and I consider configuration changes to be distractions; and people have enough trouble with one engine out procedure without having to remember different ones depending on where they are in the initial climb.

My post from CS25 is not disingenuous, I am merely pointing out the conditions that your performance calculations (for OEI) are based on; if you end up on one engine flaps up below the height that is specified in the calculations, then welcome to the world of test flying.

[tommoutrie]

well you don't know my (possibly your) ops manual that well then.

4.2.3 which is entitled Company Standards gives my company minimum flap retraction height as 400 feet.

What I've discussed and the manufacturer suggests is entirely in accordance with both noise abatement profiles. If you fly a correct noise abatement procedure you don't achieve V2+20 (and therefore flap retraction) until 3000 feet. Surprisingly enough, the ICAO noise abatement profile is absolutely in line with the manual. Whats very odd is that hardly anybody actually complies with it!

for those that think the image of the flight safety SOP's was a bit small...
http://email.dropsend.com/wf/click?upn=h413JQpvtnO0rWHPCtzS8DVISu7H8cmXDmErIJXBru0Uan8AvZ lmktmodFueICuTWW23VezG8QZKYUozUDVGkQ-3D-3D_-2FJE3iHtNasAMh1o3ani60qoPz3-2Bc9LeZg4KIWeFPhxAXWcUSpHehl5FysL8oy686K91gQ7oj3vRYSDM5KwqzD 37kxST76tku33z71wsI9tG0ZBgIBXgwtbD-2Bf-2FisE7T8kssMJIkU-2F1-2Bq91FMFcYvnGh5sXflPYI8OaSJuorTyc4-3D

[BizJetJock]

Sorry, I was looking at Part B, normal takeoff procedure which says accelerate and retract flap at 1500'. This does not conflict with the Part A policy of not below 400' for any type.
But since you've spent 377 posts advocating retracting the flaps as soon as the speed reaches V2+20 regardless of height I'll take that as you agreeing that height is a factor.

I think your reading of the NADP's is a bit creative. From DOC8168:

3.3 The initial climbing speed to the noise abatement initiation point is V2 + 20 to 40 km/h (10 to 20 kt).
3.4 On reaching an altitude equivalent to at least 240 m (800 ft) above aerodrome elevation, decrease aircraft
body angle/angle of pitch while maintaining a positive rate of climb, accelerate towards Vzf and either:
a) reduce power with the initiation of the first flap/slat retraction; or
h) reduce power after flap/slat retraction

To be read in conjunction with:

k) The maximum acceptable body angle specified for an aeroplane type shall not be exceeded.

This is for an NADP 2, that has the lowest flap retraction height specificed. NADP1 says reduce thrust and keep climbing with flap to 3000' Also the speed for NADP1 is just "not less than V2+20km/h (10kt)". So I'm not sure how you conclude that V2+20 is not reached until 3000'

And I don't see how whipping the flaps up as soon as the speed reaches V2+20 at 2-300 feet is even remotely compliant.

But regardless of that, you have agreed that your procedure doesn't comply with your Ops Manual, therefore you can't do it. End of story.

[Cough]

Tom, the airlines are 99% of the time using reduced thrust for takeoffs - i.e. matching the thrust used to the weight/altitude/temperature so the problem does not arise. If you have a lightly loaded airliner where they have to use TOGA for takeoff (contaminated runway, antiskid inop, etc.) then you will find that on reaching their pitch limit they allow the speed to increase. On reaching their acceleration altitude if they find that they are already above the minimum flap retraction speed they can do it straight away.

TOGA or FLEX. Light weight or heavy. We pitch to maintain a stable climb in the second segment. Highest seen by me is 25deg NU, but stable climb speed.

We fly the profile as depicted on the charts, because that is what is expected of us by the airline, the regulator and the passenger.

[tommoutrie]

That reference is in our part B. Its not from the part A. Its in all our part B's because they were copied from a Citationjet part B and nobody ever bothered to change it even though I pointed it out on all three types I have flown for the company. The Citationjet is certified with a 400 foot platform in the event of an engine failure at V1. Thats why its there.

The point thats been raised about "concentrating on a smooth climb out" and "potentially moving the wrong lever" are only valid if you modify your procedures to leave the gear down until then and change your ops manual to not allow a go-around under 400 feet because the argument just isn't consistent otherwise. Height has nothing whatsoever to do with flaps. Only speed. If you have lost thrust and can't climb at the same time as accelerating you climb first and then use a certified or agreed platform to accelerate then you raise the flaps. This is badly taught, you clearly don't understand it, and neither do quite a lot of others. Some aircraft are actually certified to continue to accelerate to flap retraction in the event of an engine failure (Hawker 4000) but its never taught like that. This means that the pilots lose out on the extra performance gained. Aircraft climb better clean. Aircraft get off the ground in a shorter distance and at a lower speed with flaps. Once away from the ground it is desirable to get rid of the drag and climb. I don't know how to make it any simpler!

My suggestion is absolutely compliant with noise abatement. In a noise abatement climb I hold V2+10to20 therefore I don't raise the flap. At 800 feet I reduce power. At 3000 feet I accelerate through V2+20 and retract the flaps.

Absolutely consistent with every post I have made. Retract the flaps at V2+20. What is your justification for blasting through V2+20 on a noise abatement climb and leaving the flaps down? Body angle? Then reduce the power! Climbing against the excess drag is contrary to the spirit of the noise abatement rules. If you are going to ignore the rules on the basis that body angle and therefore safety is compromised, reduce the power early which will at least reduce the noise and keep with the spirit of the legislation. Everything I am suggesting we do is in the operators manuals, and is supported by the NADP1 and 2. What is your justification for exceeding V2+20 when its clear in the regs and in the ops manual?

[FCS_TEST]

Tom, don't get me wrong but aren't you just spending all your energy and momemtum at re-inventing hot water ?

[tommoutrie]

Perhaps.

But think about this. I'm not trying to re-invent anything. I am suggesting that we do what is in the manual for the aircraft we fly.

I have a concern that current noise abatement procedures are not appropriate for some of the aircraft that we all fly and that many of us do not adhere to the regulations when flying a noise abatement departure. I don't blame the pilots for that at all - the relatively high power to weight of many business jets gives resultant performance which simply does not allow practical adherence to the regulations.

It is abundantly clear even from this thread but also from having worked as a line trainer for many years that the majority of pilots do not understand performance. It is not explicit in flight manuals what actions a pilot should take in the event of an engine failure above flap retraction speed whether the aircraft is clean or still has take off flap selected and many pilots have never even thought about it. I completely accept that I don't know whether it has ever been a factor in an accident but I don't think that's a reason not to consider it. Even discussing it seems to raise a high level of aggression in the responses and I think this is because I am questioning the actions of what pilots do every day. Everyone has got comfortable doing something that I think is flawed - they have been badly taught and do not clearly understand what is going on during the early part of an all engines operating take off. Exceeding the flap retraction speed by a significant amount degrades the take off path performance. This manifests itself as increased noise footprint when operating with all engines or as a degraded flight path in the event of a failure above the flap retraction speed.

I started this thread because I have been flying for an operator who has attempted to mandate climbing to 1500 feet holding the take off flap setting whilst accelerating to near Vfe. Quite clearly this is bonkers but in trying to get this situation changed I became aware of how deeply ingrained the idea that a flap retraction height controls the retraction of flaps is.

There is no such thing as a flap retraction height. This idea is actually dangerous. Acceleration altitudes exist which allow you to accelerate the aircraft should you require it in order to retract the flaps but a pilot does not retract the flaps because they are at a specific altitude. The flaps are retracted because the aircraft has achieved a specific speed.

My argument is that you do the SAME THING with regard to the flaps regardless of whether you lose an engine at V1, V2, V2+20, V2+50, on a noise abatement departure, on a normal (non noise) departure. I am certain that this is what is intended by manufacturers and it fits all the written legislation.

I am astonished that so many pilots have come back with initially fierce arguments without even beginning to carefully consider what we are really talking about. Its been clear that some pilots think you keep the flap set at take off and climb to 1500 feet, some think you can retract the flaps at 400 feet but have not been specific about what data they are using for this. Very few have been specific about their actions in the event of a failure above V2+20 and where they have done so I believe those actions are not supported by the flight manual.

So that's why I'm bothered about it. I've met too many pilots who don't really know what they would do in that phase of flight and don't understand the noise implications and fuel implications should everything go to plan. Worse than that, I've met trainers who will positively teach the wrong thing simply because they don't really understand it. And it all goes back to how they were taught in the first place.

[Cough]

The point thats been raised about "concentrating on a smooth climb out" and "potentially moving the wrong lever" are only valid if you modify your procedures to leave the gear down until then and change your ops manual to not allow a go-around under 400 feet because the argument just isn't consistent otherwise. Height has nothing whatsoever to do with flaps. Only speed.

Lots of pilot actions on the flight deck are based on motor actions, ie rehearsed items repeated again and again with the smooth professional grace that all of us use to operate aircraft.

What I was tying to suggest was de-linking the action of retracting the gear along side retracting the flap would be a good thing. If you take off safe in the knowledge that you have excess performance and in the knowledge that you can normally retract the flaps as soon as the gear is up, thats what you will start (subconsciously) doing. How do you then know that on a go-around you won't retract gear and flaps (entirely) at the same time? This is human factors and where I was coming from with my first post, a long time ago.

In our operation on the go around, gear and flaps are de linked with SOP's. We perform G/A actions (power+pitch), then move flaps, then check the aircraft has entered correct modes, then raise gear. Nothing is done in a rush...

Lets face it, gear up is normally 2-3 seconds after take off. If you climb at (guess mode) 4000 fpm, it will take you 6 seconds to get to 400'. Why are you in such a hurry to get anything done in that 6 seconds? Maybe, your 1500' operator just simply wants concentration on the initial climb ensuring stability over a rushed operation and in doing so they have made a choice of safety over outright efficiency...

BTW, from a purely performance perspective, I can't disagree with anything you are suggesting. From a flight safety one I most certainly do... And that's my opinion! :p

[tommoutrie]

gents I certainly don't mean to offend anyone by saying that we've been taught badly. I think there is a systemic fault in the training of pilots which tends towards teaching the minimums. Its an exam passing mentality that's becoming worse the more the industry relies on individuals to pay for their training. Even once we've passed and got jobs the emphasis of training is only to repeat the standard we achieved the day we scraped through the IR. And for subsequent courses there is a massive amount of repetition - how many courses have you sat through that are exactly the same stuff you sat through the year before. The emphasis should always be on continual learning rather than an annual LPC hurdle. Most pilots are expected to learn all the periphal information by osmosis. Ask most guys where do download OPS1 or how to look at ICAO 8168 or what it even is and you'll end up with a blank look. How EASA is supposed to work, what comes under the remit of the DFT, the list of things we could actually learn about is endless.

I also think that various bits of legislation are invented without real consideration to operational practicality (noise being one). I have 5 years experience as an acoustic engineer and I understand enough about noise and vibration to know that the current rules are daft. I don't even know who sit's round a table and makes these rules up. Where did the "land within 60% of the LDA" for turbo jets come from and whats the maths behind it? Why is it 70% for turboprops? I just don't understand the maths and the logic.

Anyway, I thought I'd start with this and your suggestion of talking to SRG is a good one so I'm happy to end the rather pointless bickering on here and let you know how I get on.

Cheers all

Tom

[His dudeness]

It is abundantly clear even from this thread but also from having worked as a line trainer for many years that the majority of pilots do not understand performance. It is not explicit in flight manuals what actions a pilot should take in the event of an engine failure above flap retraction speed whether the aircraft is clean or still has take off flap selected and many pilots have never even thought about it. I completely accept that I don't know whether it has ever been a factor in an accident but I don't think that's a reason not to consider it

You´re mixing up me and the majority. IIRC I was the only to say that I have never thought about it really.

[tommoutrie]

dood, you're definitely a minority.. ;)

[deefer dog]

Tommie, I think you've won the argument, but there are some vociferous posters who will never accept anything unless it's quoted in the regs that they seem so anxious to quote.

If you have the charts to back up your knowledge that the airplane will make a better gradient with the flaps retracted should an engine quit, in my opinion it makes good sense to retract the flaps as soon as you gain the known advantage. Doing so may even reduce the noise footprint, but even if it doesn't one could surely argue that you are enhancing the performance of your aircraft as a preemptive safety measure to increase the obstacle clearance margin should an engine quit. Who could possibly argue with that?

On the other hand it isn't really fair to criticise those who like to highlight obscure, non performance related regulatory text - these posters, in the main, are likely to be the product of a training regime that prioritises the teaching of regulatory compliance above the practicalities of "real world" aircraft operations. Unfortunately we live in a blame culture bubble, and its quite easy to see why the regulators have to cover their backsides too.

Rules are for the guidance of the wise, and the obedience of fools.

[Regulation 6]

It's so disheartening to discover that, after 20,000hrs, I am one of the fools that have been doing it all wrong by climbing out on the recommended vertical profile.

Of course! I should have ignored the AFMs, the test pilots, the company SOPs and those stupid regulatory authorities, and listened to these real experts on pprune.

It must be pure bloody luck that I haven't hit that mountain on climb out.

6

[1Bingo]

Reg 6, I concur.

All this pontification on the nebulousness of criteria bandied about, which confuses that established by aviation authority and the manufacturer of any given platform. I just hope the new guy reading all this doesn't try to inject this philosophical banter when executing a time critical emergency procedure.

Bingo

[1Bingo]

PS - give it up dudes.

[Tamer]

If you are departing an airfield with high terrain/elevation and very tight turns at low speeds, when would you retract flap?