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?

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

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".

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...

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:

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 .

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.

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

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.

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.

Mutt, can you try picking it up from here?

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

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.

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

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..

Now ,that makes sense:E

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...

Neidajob? 32? Look older?