Flap retraction
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Flap retraction will be initiated at the most critical level-off height
while the aircraft accelerates to V SE. Upon reaching V SE, continue climbing with flaps retracted at Maximum Continuous Thrust until all of the other obstacles are cleared.
Taken from G4 AFM, it clearly shows that if you can clear the obstacles with a 400 feet acceleration height, then go ahead, if not increase the acceleration height. Thats why we stick with a Flap Retraction height rather than a speed.
How do you calculate your obstacle clearance?
Mutt
while the aircraft accelerates to V SE. Upon reaching V SE, continue climbing with flaps retracted at Maximum Continuous Thrust until all of the other obstacles are cleared.
Taken from G4 AFM, it clearly shows that if you can clear the obstacles with a 400 feet acceleration height, then go ahead, if not increase the acceleration height. Thats why we stick with a Flap Retraction height rather than a speed.
How do you calculate your obstacle clearance?
Mutt
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I use Flugprestansa to get the close in obstacles and use the SID gradient for the gradient.
From your own AFM
Flap retraction will be initiated at the most critical level-off height
while the aircraft accelerates to V SE. Upon reaching V SE, continue climbing with flaps retracted at Maximum Continuous Thrust until all of the other obstacles are cleared.
What your manual says is retract the flaps at the most critical level off height (once you are clear of close in obstacles you can retract the flaps - this is what your manual is saying). Once you have achieved Vse (regardless of height, I added that bit because the bloke that wrote the manual thought it was clear) you can retract the flaps because THERE ISNT A CRITICAL LEVEL OFF HEIGHT ANY MORE and continue climbing WITH THE FLAPS RETRACTED until all the other obstacles are cleared. You calculate the weight you can carry for the temperature you intend to take off at. You take off. When you have cleared the close in obstacles and acheived the flap retraction speed you can retract the flaps. Then you can keep climbing. Thats it. Not complicated. In your own manual.
The tough bit is getting hold of the obstacle information and making sure that database is correct - ie have notam'd cranes and tethered balloons and the like been accounted for. Generally, obstacles are under the SID gradient so you just don't care about them because you're going to be above them anyway.
From an FGP of EGTE
Obstacles included in calculation: (Height above runway end / Distance from brake release point)
Oa: 488 ft/6687 m Ob: 185 ft/3965 m Oc: 174 ft/3900 m Od: 112 ft/3320 m Oe: 124 ft/3495 m Of: 63 ft/2785 m
Og: 88 ft/3142 m Oh: 48 ft/2645 m Oi: 275 ft/5530 m Oj: 36 ft/2517 m Ok: 242 ft/5304 m Ol: 952 ft/17567 m
Broadly speaking they are sorted in gradient order although I have come across anomolies before. This could be because FGP seem to sort the order from the start of the take off roll - obviously we are interested in the gradient from the DER so theres a bit of maths to do to correct the order but in this case its pretty much correct and the first obstacle is the limiting one at 3.2%. So I can choose to WAT limit my aircraft to comply with 3.2% and take off and actually know that I will clear any obstacle by the required amount because I've already calculated that the climb increment gained by my actual take off point will give me the clearance required (TCI). I do this as a cross check of the FGP data which simply gives me a weight limit and a QNH correction. I asked FGP to provide their data in a datastring form before because I wanted to perform further analysis but apparently its propriety. Also I mentioned the gradient sorting anomaly and they chap said they hadn't noticed that before so maybe that will change in the future.
Thus I have a way to comply with an engine failure at any stage. Before V1, V1 and above up to V2, V2 up to V2+20, and V2+20 and beyond.
By the way, have you found the bit in your G4 manual that says "you cannot retract the flaps below 400 feet because you cannot and you just cannot and don't ask why, you just aren't allowed" yet?
didnt think so..
From your own AFM
Flap retraction will be initiated at the most critical level-off height
while the aircraft accelerates to V SE. Upon reaching V SE, continue climbing with flaps retracted at Maximum Continuous Thrust until all of the other obstacles are cleared.
What your manual says is retract the flaps at the most critical level off height (once you are clear of close in obstacles you can retract the flaps - this is what your manual is saying). Once you have achieved Vse (regardless of height, I added that bit because the bloke that wrote the manual thought it was clear) you can retract the flaps because THERE ISNT A CRITICAL LEVEL OFF HEIGHT ANY MORE and continue climbing WITH THE FLAPS RETRACTED until all the other obstacles are cleared. You calculate the weight you can carry for the temperature you intend to take off at. You take off. When you have cleared the close in obstacles and acheived the flap retraction speed you can retract the flaps. Then you can keep climbing. Thats it. Not complicated. In your own manual.
The tough bit is getting hold of the obstacle information and making sure that database is correct - ie have notam'd cranes and tethered balloons and the like been accounted for. Generally, obstacles are under the SID gradient so you just don't care about them because you're going to be above them anyway.
From an FGP of EGTE
Obstacles included in calculation: (Height above runway end / Distance from brake release point)
Oa: 488 ft/6687 m Ob: 185 ft/3965 m Oc: 174 ft/3900 m Od: 112 ft/3320 m Oe: 124 ft/3495 m Of: 63 ft/2785 m
Og: 88 ft/3142 m Oh: 48 ft/2645 m Oi: 275 ft/5530 m Oj: 36 ft/2517 m Ok: 242 ft/5304 m Ol: 952 ft/17567 m
Broadly speaking they are sorted in gradient order although I have come across anomolies before. This could be because FGP seem to sort the order from the start of the take off roll - obviously we are interested in the gradient from the DER so theres a bit of maths to do to correct the order but in this case its pretty much correct and the first obstacle is the limiting one at 3.2%. So I can choose to WAT limit my aircraft to comply with 3.2% and take off and actually know that I will clear any obstacle by the required amount because I've already calculated that the climb increment gained by my actual take off point will give me the clearance required (TCI). I do this as a cross check of the FGP data which simply gives me a weight limit and a QNH correction. I asked FGP to provide their data in a datastring form before because I wanted to perform further analysis but apparently its propriety. Also I mentioned the gradient sorting anomaly and they chap said they hadn't noticed that before so maybe that will change in the future.
Thus I have a way to comply with an engine failure at any stage. Before V1, V1 and above up to V2, V2 up to V2+20, and V2+20 and beyond.
By the way, have you found the bit in your G4 manual that says "you cannot retract the flaps below 400 feet because you cannot and you just cannot and don't ask why, you just aren't allowed" yet?
didnt think so..
Last edited by tommoutrie; 24th Nov 2012 at 10:17.
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You appear to have forgotten about DISTANT OBSTACLES? If you look at the AFM you will find a close-in and distant obstacle chart.
Nope, for us, this part is easy....... we use the actual data rather than the SID.
Which part of our previous statements that the AFM was based on FAR/JAR (etc) requirements didnt you understand?
OK, but Mr Gulfstream has this to say......
So are you basing your weights on single or dual engines? What about the part about two engine SID's should only be used in VMC?
Mutt
The tough bit is getting hold of the obstacle information and making sure that database is correct - ie have notam'd cranes and tethered balloons and the like been accounted for. Generally, obstacles are under the SID gradient so you just don't care about them because you're going to be above them anyway.
By the way, have you found the bit in your G4 manual that says "you cannot retract the flaps below 400 feet because you cannot and you just cannot and don't ask why, you just aren't allowed" yet?
Thus I have a way to comply with an engine failure at any stage. Before V1, V1 and above up to V2, V2 up to V2+20, and V2+20 and beyond.
WARNING
TWO-ENGINE SID CLIMB CRITERIA CAN BE EMPLOYED AT THE
OPERATOR’S DISCRETION. IF TWO-ENGINE SID CLIMB CRITERIA IS
EMPLOYED TO DETERMINE SID-LIMITED TAKEOFF WEIGHT AND AN
ENGINE FAILURE OCCURS EARLY IN THE DEPARTURE CLIMB,
CONTINUATION OF THE SID CLIMB ON ONE ENGINE SHOULD NOT BE
ATTEMPTED. INSTEAD, THE PILOT SHOULD DECLARE AN
EMERGENCY AND EITHER LAND OR ENTER A HOLDING PATTERN TO
GAIN SUFFICIENT ALTITUDE TO CLEAR OBSTACLES AND HIGH
TERRAIN. TWO-ENGINE SID CLIMBS SHOULD ONLY BE USED IN VMC
CONDITIONS WHERE OBSTACLES CAN BE VISUALLY ACQUIRED AND
AVOIDED.
TWO-ENGINE SID CLIMB CRITERIA CAN BE EMPLOYED AT THE
OPERATOR’S DISCRETION. IF TWO-ENGINE SID CLIMB CRITERIA IS
EMPLOYED TO DETERMINE SID-LIMITED TAKEOFF WEIGHT AND AN
ENGINE FAILURE OCCURS EARLY IN THE DEPARTURE CLIMB,
CONTINUATION OF THE SID CLIMB ON ONE ENGINE SHOULD NOT BE
ATTEMPTED. INSTEAD, THE PILOT SHOULD DECLARE AN
EMERGENCY AND EITHER LAND OR ENTER A HOLDING PATTERN TO
GAIN SUFFICIENT ALTITUDE TO CLEAR OBSTACLES AND HIGH
TERRAIN. TWO-ENGINE SID CLIMBS SHOULD ONLY BE USED IN VMC
CONDITIONS WHERE OBSTACLES CAN BE VISUALLY ACQUIRED AND
AVOIDED.
Mutt
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Two engine data is where you rely on a high climb gradient (as per Sion or similar) where you can accept the 13 odd percent climb gradient all engines operating but if you have an engine failure you must be in VMC conditions.
All engine operating data give you the all engine climbs. Thats why they say you must be VMC.
You appear to be a pretty knowledgeable and probably quite senior pilot. Either you must, by now, be happy to take my bet or somewhere, sitting at the back of your mind, is the niggling doubt that all this makes sense and actually we have all been really badly taught.
bet?
go on, you know you want to...
All engine operating data give you the all engine climbs. Thats why they say you must be VMC.
You appear to be a pretty knowledgeable and probably quite senior pilot. Either you must, by now, be happy to take my bet or somewhere, sitting at the back of your mind, is the niggling doubt that all this makes sense and actually we have all been really badly taught.
bet?
go on, you know you want to...
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Actually, the high performance SID out of sion is exactly this issue. You stand no hope of achieving it one engine inoperative (thats what 3 engined business jets are for) but you can accept the high performance gradient because you are all engines operating. But you can only accept it in VMC conditions because then, if you have a failure, you can climb visually.
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no thats right - the CAA don't and I'm pretty sure you can't do this at Sion any more but its exactly why the two engine performance data exists for some aircraft and thats what two engine data is. We don't use it under EASA as far as I know. Used to depart following the high performance departure SID the same way as Samedan - depart VMC and open the IFR plan once at the 13000 feet which was what you needed to be at, I think it was at 20 D SIO. If you lost an engine you were VMC so continued along the Sion valley and turned right to the lake.
at least we've established what OEI and two engine data is now though eh!
at least we've established what OEI and two engine data is now though eh!
Last edited by tommoutrie; 24th Nov 2012 at 21:30.
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If one was only looking at the difference between 35 feet and 400 feet based on all engines or 1-eng out, then even following an all engine takeoff, retracting the flaps at V2+X, and having an engine failure, the difference in the initial height gain and gradient "should" be sufficient to ensure that you are above the single engine profile..... however, as we have obstacle clearance heights significantly higher than 400 feet, then the concept of selecting flaps up at V2=X is not going to guarantee obstacle clearance, 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.
So I will continue to follow our present procedures, TT if you ever get an answer from Bombardier stating that they Guarantee that you will clear all obstacles in the flight path if you accelerate to V2+X and retract the flaps regardless of height, and have a subsequent engine failure, then please let us know.
Mutt
So I will continue to follow our present procedures, TT if you ever get an answer from Bombardier stating that they Guarantee that you will clear all obstacles in the flight path if you accelerate to V2+X and retract the flaps regardless of height, and have a subsequent engine failure, then please let us know.
Mutt
Last edited by mutt; 25th Nov 2012 at 01:43.
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mutt. 
Tom
This gas been an interesting thread and it took a long time to get to the OEI/SID swamp.
I'm with Bingo and Doug, there is a real danger this discussion is leading the innocents to perdition.
I showed where the 400/1500 ft references come from and why the AFM is constructed so.
So, IMHO and it seems Doug's, unless you have precalculated EVERY ONE of the early flap retraction scenarios for EVERY point of the takeoff path, so that KNOW where you are in (or out of ) the obstacle clearance basket, PRIOR to standing up the power levers on take off, you are a candidate for a Darwin Award.
Trying to achieve that ad hoc and in flight might be a bit of an ask don't you think.
So why not take advantage of the enormous amount of resources and brainpower applied to make you safe and efficient.
I'll bet Bombardier send you a copy of the relevant AFM pages, anything else and they effectively give every Bombardier operator license to have at it, I can see the buzzards licking their chops and the liquidators warming up their red pens as we speak. Without seeming to be over dramatic it might even cost the their Type Certificate, which automatically grounds every aircraft of that type.
But I've been wrong before.
Tom
This gas been an interesting thread and it took a long time to get to the OEI/SID swamp.
I'm with Bingo and Doug, there is a real danger this discussion is leading the innocents to perdition.
I showed where the 400/1500 ft references come from and why the AFM is constructed so.
So, IMHO and it seems Doug's, unless you have precalculated EVERY ONE of the early flap retraction scenarios for EVERY point of the takeoff path, so that KNOW where you are in (or out of ) the obstacle clearance basket, PRIOR to standing up the power levers on take off, you are a candidate for a Darwin Award.
Trying to achieve that ad hoc and in flight might be a bit of an ask don't you think.
So why not take advantage of the enormous amount of resources and brainpower applied to make you safe and efficient.
I'll bet Bombardier send you a copy of the relevant AFM pages, anything else and they effectively give every Bombardier operator license to have at it, I can see the buzzards licking their chops and the liquidators warming up their red pens as we speak. Without seeming to be over dramatic it might even cost the their Type Certificate, which automatically grounds every aircraft of that type.
But I've been wrong before.
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Gee you guys are getting yourselves tied up in knots (the nautical kind) 
tommoutrie :
400feet, v2+x, then the engine fails.
whats your plan?
where's your data?
whats your plan?
where's your data?
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: 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.
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.
FAILURE OCCURS EARLY IN THE DEPARTURE CLIMB, CONTINUATION OF THE SID CLIMB ON
ONE ENGINE SHOULD NOT BE ATTEMPTED.
…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!
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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
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
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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?
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?
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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?
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?
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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
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
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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".
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".
Last edited by Empty Cruise; 26th Nov 2012 at 11:06.