Flap retraction
Join Date: Sep 1999
Location: ME
Posts: 5,502
Likes: 0
Received 0 Likes
on
0 Posts
By the way, can you post me a reference to a flap retraction height in a Boeing manual. Its not in the 757 manual because I've checked and I was on the phone to a guy doing a 737 rating earlier who has checked with his instructors and its not in the 737 manual either.
Mutt
Join Date: Nov 2005
Location: Eire/HK
Posts: 590
Likes: 0
Received 0 Likes
on
0 Posts
Tom
Cut and paste from the G550 MANUAL/ AFM
The obstacle clearance procedure is to climb with landing gear retracted,
flaps in takeoff position at a speed of V2 to at least 1500 feet above the
takeoff surface. Use of the obstacle clearance data in this section will
ensure that obstacles will be cleared by a minimum of 35 feet for dry
runway takeoffs. For wet runway takeoffs, 20 feet must be added to heights
read from the charts to assure 35 feet minimum clearance.
A Gross Level-off Height correction grid has been added to these charts
to account for the reduction in climb performance that results during the
climb from the airport pressure altitude to the recommended level-off
height. This Gross Level-off Height grid corrects the base climb gradient
capability at a height of 400 feet above the airport to the average climb
gradient available between the base height of 400 feet and the
recommended level-off height. Before the available climb gradient can
be determined, it is first necessary to determine the recommended leveloff
altitude from the Distant Obstacle Clearance chart. As indicated in
the title, these charts present available net climb gradient performance.
Per CFR 25.115 (Takeoff flight path) for two-engine airplanes, the gross
climb gradient is 0.8% greater than the net climb gradient.
In addition to criteria governing accelerate-go distance and the items
discussed above, the following procedures and assumptions also apply:
1. No configuration change, except gear retraction, is assumed to
be made prior to reaching a gross airplane height of 1500 feet
above the takeoff surface.
2. Gear retraction shall be initiated immediately after lift-off and
positive climb is indicated.
3. The airplane shall attain speed of V2 prior to reaching a height
of 35 feet above the takeoff surface and continue at a speed as
close as practical to, but not less than V2, until reaching at least
1500 feet above the takeoff surface.
4. Net takeoff flight path data shall be determined in such a
manner that they represent the airplane’s actual takeoff flight
path diminished by a gradient of climb equal to 0.8%.
5. Bank angle not to exceed 5°.
Cut and paste from the G550 MANUAL/ AFM
The obstacle clearance procedure is to climb with landing gear retracted,
flaps in takeoff position at a speed of V2 to at least 1500 feet above the
takeoff surface. Use of the obstacle clearance data in this section will
ensure that obstacles will be cleared by a minimum of 35 feet for dry
runway takeoffs. For wet runway takeoffs, 20 feet must be added to heights
read from the charts to assure 35 feet minimum clearance.
A Gross Level-off Height correction grid has been added to these charts
to account for the reduction in climb performance that results during the
climb from the airport pressure altitude to the recommended level-off
height. This Gross Level-off Height grid corrects the base climb gradient
capability at a height of 400 feet above the airport to the average climb
gradient available between the base height of 400 feet and the
recommended level-off height. Before the available climb gradient can
be determined, it is first necessary to determine the recommended leveloff
altitude from the Distant Obstacle Clearance chart. As indicated in
the title, these charts present available net climb gradient performance.
Per CFR 25.115 (Takeoff flight path) for two-engine airplanes, the gross
climb gradient is 0.8% greater than the net climb gradient.
In addition to criteria governing accelerate-go distance and the items
discussed above, the following procedures and assumptions also apply:
1. No configuration change, except gear retraction, is assumed to
be made prior to reaching a gross airplane height of 1500 feet
above the takeoff surface.
2. Gear retraction shall be initiated immediately after lift-off and
positive climb is indicated.
3. The airplane shall attain speed of V2 prior to reaching a height
of 35 feet above the takeoff surface and continue at a speed as
close as practical to, but not less than V2, until reaching at least
1500 feet above the takeoff surface.
4. Net takeoff flight path data shall be determined in such a
manner that they represent the airplane’s actual takeoff flight
path diminished by a gradient of climb equal to 0.8%.
5. Bank angle not to exceed 5°.
Last edited by B200Drvr; 20th Nov 2012 at 23:58.
Join Date: Nov 2005
Location: Eire/HK
Posts: 590
Likes: 0
Received 0 Likes
on
0 Posts
Tom.
That does go to prove one thing about your theory!!
G550 obstacle clearance is based on an extended 2nd segment climb
(Flaps 10° or 20°, gear up) to at least 1500 feet AGL. Because of this
and the fact that the FAR and JAR Final Segment (flaps up) climb
requirement is never more limiting than the Second Segment climb
requirement, Final Segment climb speeds and climb gradients are not
presented in the AFM.
That does go to prove one thing about your theory!!
G550 obstacle clearance is based on an extended 2nd segment climb
(Flaps 10° or 20°, gear up) to at least 1500 feet AGL. Because of this
and the fact that the FAR and JAR Final Segment (flaps up) climb
requirement is never more limiting than the Second Segment climb
requirement, Final Segment climb speeds and climb gradients are not
presented in the AFM.
Last edited by B200Drvr; 21st Nov 2012 at 00:20.
Join Date: Mar 1999
Location: Australia
Age: 53
Posts: 207
Likes: 0
Received 0 Likes
on
0 Posts
Tom, I wholeheartedly agree with your logic and reasoning. You are not mad after all! Flap retraction should be speed related andspeed related only.
The starting point for all this must be obstacle clearance. The basic requirement is to ensure you have it. OEM’s provide information in their AFM’s in the forms of procedures and performancei nformation in order for you to be able to calculate it in advance. After you start the takeoff, however, your actual performance is what matters. There have been a few comments about becoming a test pilot, not so. The departurehas the gradients required and hence you know the rate of climb required for your speed. If you’re making that or better then you are meeting the climb requirements regardless of whether your aircraft has a graph to tell you in advance. If you are qualified on a type you know if you are flying an aircraft with loads of excess performance on one that is very limited. I have flown aircraft have sufficient excess performance available that an early flap retraction is possible and considered normal. I have also flown aircraft that are on the bones of their arse for climb performance and no-one in their right mind would start accelerating early.
In the case mentioned early on of setting 15 degrees nose upand letting the aircraft accelerate to V2+50 I can’t see any sound reason forthis choice. I can see why a pilot maywish to maintain V2+10 (or whatever your aircraft uses) until acceleration altitude but if you are limiting yourself to a deck angle and accelerating in the climb to well above that speed then you have the performance to retract theflaps. If you have thrust to be able to accelerate whilst maintaining your required climb gradient and you reach min flap retraction speeds then there is no reason not to retract. In fact you will be in a better placed if an engine fails at that point. If, however, you are in a more performance limited aircraft and you need a level acceleration segment then you can’t just throw that in whenever you feel like it.
The starting point for all this must be obstacle clearance. The basic requirement is to ensure you have it. OEM’s provide information in their AFM’s in the forms of procedures and performancei nformation in order for you to be able to calculate it in advance. After you start the takeoff, however, your actual performance is what matters. There have been a few comments about becoming a test pilot, not so. The departurehas the gradients required and hence you know the rate of climb required for your speed. If you’re making that or better then you are meeting the climb requirements regardless of whether your aircraft has a graph to tell you in advance. If you are qualified on a type you know if you are flying an aircraft with loads of excess performance on one that is very limited. I have flown aircraft have sufficient excess performance available that an early flap retraction is possible and considered normal. I have also flown aircraft that are on the bones of their arse for climb performance and no-one in their right mind would start accelerating early.
In the case mentioned early on of setting 15 degrees nose upand letting the aircraft accelerate to V2+50 I can’t see any sound reason forthis choice. I can see why a pilot maywish to maintain V2+10 (or whatever your aircraft uses) until acceleration altitude but if you are limiting yourself to a deck angle and accelerating in the climb to well above that speed then you have the performance to retract theflaps. If you have thrust to be able to accelerate whilst maintaining your required climb gradient and you reach min flap retraction speeds then there is no reason not to retract. In fact you will be in a better placed if an engine fails at that point. If, however, you are in a more performance limited aircraft and you need a level acceleration segment then you can’t just throw that in whenever you feel like it.
Last edited by Roger Greendeck; 21st Nov 2012 at 00:50.
Join Date: Jan 2005
Location: Your nearest Marriott
Posts: 1,127
Likes: 0
Received 0 Likes
on
0 Posts
What is your flight director telling you to fly? Speed or pitch? And when does this change?
Secondly assume a hot and heavy day - you rotate, hit V2+20 and select flaps up by 150ft. Before the flaps are gone, you lose a donkey. Where do you now stand in terms of guaranteed obstacle clearance? And what would be your actions now?
Secondly assume a hot and heavy day - you rotate, hit V2+20 and select flaps up by 150ft. Before the flaps are gone, you lose a donkey. Where do you now stand in terms of guaranteed obstacle clearance? And what would be your actions now?
Join Date: Jul 2002
Location: A Marriott somewhere
Posts: 213
Likes: 0
Received 0 Likes
on
0 Posts
Hi Tom
Somebody beat me to it and posted the AFM for the G550.
I always question why we do things as well as you seem to do. So many things we do are left over from long ago with entirely different machinery.
If everything is normal I retract the gear and then do flaps at 400' as long as I have reached the required speed by then. If I am heavy and its hot I might not be there by 400'. (Our FD goes to a pitch that gives you V2 on one engine). Once flaps are raised the speed schedule changes and we can select a vertical mode. (FLCH, vnav or VS). I hate FLCH, so I usually go VS and enjoy hand flying the plane while monitoring speed.
If everything goes to hell we hold v2+ to 1500' or msa. Then level off and accelerate.
By leaving the flaps to 400' I am covered in case one quits. Other than that I like it and it works. Since I am the PIC I do it my way.
The other more interesting thing I have always argued is that if you need the performance why not start the takeoff with flaps 20 to get the shorter roll, then if an engine quits bring the flaps to ten and get rid of the drag. I have not gotten any traction with that at all.
Good luck with your arguments, you make some good points. Always ask "why".
I always question why we do things as well as you seem to do. So many things we do are left over from long ago with entirely different machinery.
If everything is normal I retract the gear and then do flaps at 400' as long as I have reached the required speed by then. If I am heavy and its hot I might not be there by 400'. (Our FD goes to a pitch that gives you V2 on one engine). Once flaps are raised the speed schedule changes and we can select a vertical mode. (FLCH, vnav or VS). I hate FLCH, so I usually go VS and enjoy hand flying the plane while monitoring speed.
If everything goes to hell we hold v2+ to 1500' or msa. Then level off and accelerate.
By leaving the flaps to 400' I am covered in case one quits. Other than that I like it and it works. Since I am the PIC I do it my way.
The other more interesting thing I have always argued is that if you need the performance why not start the takeoff with flaps 20 to get the shorter roll, then if an engine quits bring the flaps to ten and get rid of the drag. I have not gotten any traction with that at all.
Good luck with your arguments, you make some good points. Always ask "why".
Join Date: Mar 1999
Location: Australia
Age: 53
Posts: 207
Likes: 0
Received 0 Likes
on
0 Posts
The flight director tells you what you set it up for. In my last aircraft I had performance charts for clean and take off flap so the answer in that case is if the engine stops I had a known speed to slow to and could plan my performance in advance.
Whilst I would have done my planning based on the engine stopping at V1 and climbing at V2 to acceleration altitude if I was at V2+20 with the flaps up or even retracting when the engine stopped I was already above the profile for a V1 fail and my climb angle was better at V2 clean.
Whilst I would have done my planning based on the engine stopping at V1 and climbing at V2 to acceleration altitude if I was at V2+20 with the flaps up or even retracting when the engine stopped I was already above the profile for a V1 fail and my climb angle was better at V2 clean.
Thread Starter
Join Date: Jan 2002
Location: london, UK
Age: 57
Posts: 550
Likes: 0
Received 0 Likes
on
0 Posts
Hello cough
Which AA are you talking about? Lots of companies impose one (Ryanair for instance impose an MFRA of 1000 feet) and at Ryanair if you raise the flap before you have gone through that you'll get into trouble. But that's not a directive from Boeing. I have found a reference in the Boeing 737 classic training notes that suggests the minimum height for flap retraction is 400 feet but its the only manufacturers recommendations I can find.
If there are company imposed limits that's absolutely fine and you can't breech them but it's still okay to understand why they are there.
Which AA are you talking about? Lots of companies impose one (Ryanair for instance impose an MFRA of 1000 feet) and at Ryanair if you raise the flap before you have gone through that you'll get into trouble. But that's not a directive from Boeing. I have found a reference in the Boeing 737 classic training notes that suggests the minimum height for flap retraction is 400 feet but its the only manufacturers recommendations I can find.
If there are company imposed limits that's absolutely fine and you can't breech them but it's still okay to understand why they are there.
Thread Starter
Join Date: Jan 2002
Location: london, UK
Age: 57
Posts: 550
Likes: 0
Received 0 Likes
on
0 Posts
B200, just to re-iterate. Putting your post in bold is the equivalent of shouting and it really doesn't help get your point across.
What you quote from the Gulfstream manual is all in accordance with part 25.115, the conditions of which are (amongst others) are for a failure of the most critical powerplant at V1.
In the extraordinary event that the powerplant doesn't fail a number of interesting things happen. One is that you rotate earlier in terms of distance along the take off roll. Another is that you overcome the initial drag of flap and gear more easily. If you get rid of the gear promptly and continue to accelerate to V2 you can then pitch for your initial climb and achieve a much better gradient than if you lose an engine at V1. Crucially you can also keep accelerating. Once you achieve the point (in terms of speed) where you can retract the flap you will further increase your rate of climb. Your gradient will depend on what speed you choose to accelerate to. However, if you choose to argue that raising the flap will somehow degrade either your rate of climb or gradient, why would you raise the flap at all? Why raise it at 1500 feet? Why not continue to climb in the flapped condition and benefit from the increased performance?
You only degrade the gradient if your forward speed becomes high - remember we are still all engines operating here so the gradient will only become an issue at the point where your forward speed is so high that you degrade the climb such that it impinges on the original required gradient.
Hopefully we are all on the same page so far - now what happens if you lose an engine?
If we lose an engine from V1 up to V2+20 I think we are all on the same page.
If I have started to retract the flaps - ie the flaps have just started to travel at the point where the engine fails - I am STILL in an improving situation and here is the reason. All the time the flaps are travelling, the drag is decreasing. Thats why we retract the flaps at 1500 feet as explained above. All thats happened is that I have used the extra energy of having two engines operating to retract the flaps and attain my final segment configuration at an earlier stage. The climb rate clean at my flap retract speed has to be as good or better than in the flapped condition at V2 because thats why I retract the flap at 1500 feet. All the time the flaps are travelling from the take off position to the up position the trend is towards this better configuration.
Next case. Lets say I'm now clean and climbing at 4 or 500 feet, speed is now above V2+20, more like V2+40 or 50 and increasing. I'm now quite a long way above the required gradient because both engines have been operating but I agree completely that I have no way of proving how much and I haven't factored that into my calculations because its an unknown. Now the engine fails. I need to reduce speed to V2+20 which will give me back the known gradient that I need. I'm in the final segment configuration and climbing with max thrust because I still have time available (I've got up to 5 minutes). After that I will reduce thrust to max continuous for the one engine I have left and now that things have settled down I'll deal with the problem.
At all times, I'm above the gradient. If you (or anyone else) believes that the climb is degraded by raising the flap and flying clean what is your justification for doing it at 1500 feet? Because if its "they told me to" you haven't thought through the problem. When we learn about this stuff we focus heavily on the most critical condition - the whole thrust of this from me is that I dont think we work through this correctly and at every stage. I think we should. I think the manufacturers do and thats why, for a substantial number of aeroplanes, the manuals are written the way they are.
There are advantages to doing what the AFM says. In the event of a failure of a powerplant higher up the initial climb, you are likely to be in a better configuration for the climb and have an aeroplane which is substantially easier to fly. Because you are faster the fin is more effective so the initial rudder correction will need to be less - if you don't recognise it immediately (and the majority of engine failures are not like the events in the sim - there's a high level of shock, stress, vibration, possibly noise, probably horrible smells etc) I believe that what I'm talking about gives you a better chance to deal with it.
I don't fly noise abatement departures at all in Africa because off the very high chance of birdstrike. I don't want to hit birds when I am 20 degrees nose high with all my focus on the artificial horizon, the ASI, and generally scanning in the cockpit. I want the aircraft in a sensible climbing attitude, accelerating sensibly, and I want to see the monitor birds, the herons, and the clouds of swifts etc so that I stand a chance of avoiding them. At 200 kts and climbing the way I do I have seen and been able to miss large birds on a number of occasions and when you are climbing out of Kinshasa and all thats beneath you is jungle and the Congo river you think carefully about how you are going to climb the plane.
I'm not really enjoying the thread any more because I feel that some of you are so entrenched in one way of thinking that you don't even read the posts properly and simply sign on to have a gang mentality rant. Thats not why I started this - it was actually to discuss why some operators go blasting through the flap up speed and only retract flaps because they achieve a certain height and I don't understand that mentality.
I wanted to provoke a discussion and perhaps uncover something interesting and I have other things I'd like to discuss with regard to noise abatement (my first job was as an Acoustic Engineer for a company called Bruel and Kjaer) and I think with some cohesive discussion and effort we can present sensible noise solutions for business jets which are much easier for us to fly.
but I'll only get shot down so whats the point!
What you quote from the Gulfstream manual is all in accordance with part 25.115, the conditions of which are (amongst others) are for a failure of the most critical powerplant at V1.
In the extraordinary event that the powerplant doesn't fail a number of interesting things happen. One is that you rotate earlier in terms of distance along the take off roll. Another is that you overcome the initial drag of flap and gear more easily. If you get rid of the gear promptly and continue to accelerate to V2 you can then pitch for your initial climb and achieve a much better gradient than if you lose an engine at V1. Crucially you can also keep accelerating. Once you achieve the point (in terms of speed) where you can retract the flap you will further increase your rate of climb. Your gradient will depend on what speed you choose to accelerate to. However, if you choose to argue that raising the flap will somehow degrade either your rate of climb or gradient, why would you raise the flap at all? Why raise it at 1500 feet? Why not continue to climb in the flapped condition and benefit from the increased performance?
You only degrade the gradient if your forward speed becomes high - remember we are still all engines operating here so the gradient will only become an issue at the point where your forward speed is so high that you degrade the climb such that it impinges on the original required gradient.
Hopefully we are all on the same page so far - now what happens if you lose an engine?
If we lose an engine from V1 up to V2+20 I think we are all on the same page.
If I have started to retract the flaps - ie the flaps have just started to travel at the point where the engine fails - I am STILL in an improving situation and here is the reason. All the time the flaps are travelling, the drag is decreasing. Thats why we retract the flaps at 1500 feet as explained above. All thats happened is that I have used the extra energy of having two engines operating to retract the flaps and attain my final segment configuration at an earlier stage. The climb rate clean at my flap retract speed has to be as good or better than in the flapped condition at V2 because thats why I retract the flap at 1500 feet. All the time the flaps are travelling from the take off position to the up position the trend is towards this better configuration.
Next case. Lets say I'm now clean and climbing at 4 or 500 feet, speed is now above V2+20, more like V2+40 or 50 and increasing. I'm now quite a long way above the required gradient because both engines have been operating but I agree completely that I have no way of proving how much and I haven't factored that into my calculations because its an unknown. Now the engine fails. I need to reduce speed to V2+20 which will give me back the known gradient that I need. I'm in the final segment configuration and climbing with max thrust because I still have time available (I've got up to 5 minutes). After that I will reduce thrust to max continuous for the one engine I have left and now that things have settled down I'll deal with the problem.
At all times, I'm above the gradient. If you (or anyone else) believes that the climb is degraded by raising the flap and flying clean what is your justification for doing it at 1500 feet? Because if its "they told me to" you haven't thought through the problem. When we learn about this stuff we focus heavily on the most critical condition - the whole thrust of this from me is that I dont think we work through this correctly and at every stage. I think we should. I think the manufacturers do and thats why, for a substantial number of aeroplanes, the manuals are written the way they are.
There are advantages to doing what the AFM says. In the event of a failure of a powerplant higher up the initial climb, you are likely to be in a better configuration for the climb and have an aeroplane which is substantially easier to fly. Because you are faster the fin is more effective so the initial rudder correction will need to be less - if you don't recognise it immediately (and the majority of engine failures are not like the events in the sim - there's a high level of shock, stress, vibration, possibly noise, probably horrible smells etc) I believe that what I'm talking about gives you a better chance to deal with it.
I don't fly noise abatement departures at all in Africa because off the very high chance of birdstrike. I don't want to hit birds when I am 20 degrees nose high with all my focus on the artificial horizon, the ASI, and generally scanning in the cockpit. I want the aircraft in a sensible climbing attitude, accelerating sensibly, and I want to see the monitor birds, the herons, and the clouds of swifts etc so that I stand a chance of avoiding them. At 200 kts and climbing the way I do I have seen and been able to miss large birds on a number of occasions and when you are climbing out of Kinshasa and all thats beneath you is jungle and the Congo river you think carefully about how you are going to climb the plane.
I'm not really enjoying the thread any more because I feel that some of you are so entrenched in one way of thinking that you don't even read the posts properly and simply sign on to have a gang mentality rant. Thats not why I started this - it was actually to discuss why some operators go blasting through the flap up speed and only retract flaps because they achieve a certain height and I don't understand that mentality.
I wanted to provoke a discussion and perhaps uncover something interesting and I have other things I'd like to discuss with regard to noise abatement (my first job was as an Acoustic Engineer for a company called Bruel and Kjaer) and I think with some cohesive discussion and effort we can present sensible noise solutions for business jets which are much easier for us to fly.
but I'll only get shot down so whats the point!
There has been 194 posts so far!
Of which 84 are from tommoutrie, the thread originator!
I think you could safely say he has hijacked his own thread!
Of which 84 are from tommoutrie, the thread originator!
I think you could safely say he has hijacked his own thread!
Join Date: Nov 2005
Location: Eire/HK
Posts: 590
Likes: 0
Received 0 Likes
on
0 Posts
Tom,
Now you have lost me, firstly typing in caps is considered shouting, bold is distinguishing between what is quoted out the 550 manual and what is my own opinion, everybody knows that!!
Secondly,There are advantages to doing what the AFM says. with that statement you went from being sensible to being a cowboy, You yourself said the AFM is the bible, I fly by the AFM, that is what is quoted there. Read post 187 you will see that I have no quibble about the second segment climb issue and I understand that the performance of final segment is always better than second segment. However, you have missed on vital piece of information in your quest to conquer all, the performance is calculated from 400 ft AAL, as stated in the G550 AFM, thats they way I read it.
Now you have lost me, firstly typing in caps is considered shouting, bold is distinguishing between what is quoted out the 550 manual and what is my own opinion, everybody knows that!!
Secondly,There are advantages to doing what the AFM says. with that statement you went from being sensible to being a cowboy, You yourself said the AFM is the bible, I fly by the AFM, that is what is quoted there. Read post 187 you will see that I have no quibble about the second segment climb issue and I understand that the performance of final segment is always better than second segment. However, you have missed on vital piece of information in your quest to conquer all, the performance is calculated from 400 ft AAL, as stated in the G550 AFM, thats they way I read it.
Join Date: Jan 2008
Location: MAN
Posts: 769
Likes: 0
Received 0 Likes
on
0 Posts
So now we have a handful of posters here who don't understand the different segments of climb.
This thread is proven to be highly entertaining, though slightly worrying if any of you guys are real pilots and not just 16 year old flightsim drivers....
This thread is proven to be highly entertaining, though slightly worrying if any of you guys are real pilots and not just 16 year old flightsim drivers....
Join Date: Nov 2005
Location: Eire/HK
Posts: 590
Likes: 0
Received 0 Likes
on
0 Posts
I don't fly noise abatement departures at all in Africa because off the very high chance of birdstrike. I don't want to hit birds when I am 20 degrees nose high with all my focus on the artificial horizon, the ASI, and generally scanning in the cockpit. I want the aircraft in a sensible climbing attitude, accelerating sensibly, and I want to see the monitor birds, the herons, and the clouds of swifts etc so that I stand a chance of avoiding them. At 200 kts and climbing the way I do I have seen and been able to miss large birds on a number of occasions and when you are climbing out of Kinshasa and all thats beneath you is jungle and the Congo river you think carefully about how you are going to climb the plane.
I am sorry, I don't buy that either, although my profile says IE and HK, I am actually from Africa and you have more chance of being shot at in the Congo than hitting a bird, maybe you should re-evaluate your departure profile!!
I am just saying!!
I am sorry, I don't buy that either, although my profile says IE and HK, I am actually from Africa and you have more chance of being shot at in the Congo than hitting a bird, maybe you should re-evaluate your departure profile!!
I am just saying!!
Join Date: Nov 2005
Location: Eire/HK
Posts: 590
Likes: 0
Received 0 Likes
on
0 Posts
Cldrvr, If that is aimed at me, please read my post again properly, you will see it is related to a statement that Tom made regarding basically converting 2nd segment into final segment, a statement that I agree with because that is basically what He is doing, furthermore, the bold print is quoted out of the 550 manual.
Last edited by B200Drvr; 21st Nov 2012 at 11:02.
Join Date: Mar 2004
Location: schermoney and left front seat
Age: 57
Posts: 2,439
Received 0 Likes
on
0 Posts
This thread is proven to be highly entertaining, though slightly worrying if any of you guys are real pilots and not just 16 year old flightsim drivers....
Join Date: Jan 2008
Location: MAN
Posts: 769
Likes: 0
Received 0 Likes
on
0 Posts
What is your flight director telling you to fly? Speed or pitch? And when
does this change?
Secondly assume a hot and heavy day - you rotate, hit
V2+20 and select flaps up by 150ft. Before the flaps are gone, you lose a
donkey. Where do you now stand in terms of guaranteed obstacle clearance? And
what would be your actions now?
Thread Starter
Join Date: Jan 2002
Location: london, UK
Age: 57
Posts: 550
Likes: 0
Received 0 Likes
on
0 Posts
Pitch. It changes when I make a mode selection.
If you choose to take the flaps up at 400 feet at V2+20 the aircraft is still compliant. It has to comply with the climb gradient and I think its clear from all the posts on here that everyone agrees that if you take the flap up at 400 feet it will still comply with the climb. Thats what most people think the normal take off is - flaps up at 400 feet with a speed check of V2+20 (for my plane, different on others). Everyone seems happy that its compliant from 400 feet - well lets check that.. is everyone happy? Or is anyone of the opinion that once clean, if you have an engine failure you should reduce speed to V2 and reselect the take off flap? I've had that one sent privately too..
The flaps neither know nor care how high the aircraft is. If the gradient clean from 400 feet is good enough it will be good enough from wherever you actually select the flaps up because it will be the same gradient because the speed is correct.
I'm really open to the flaws in this but its exactly whats in the Bombardier manual and various Cessna manuals and the Embraer manual. The problem is that they don't explicitly deal with the engine failure after flap retraction in the climb case. They only deal in detail with the engine failure at V1 case.
I've got no issue with using 400 feet as a platform below which there should not be a flap retraction but I think its important that pilots retract the flap for the correct reason. I also think that its important that people understand whats happening. Close inspection of the 737 manual discusses reduced acceleration altitudes in the case of hot and high performance precisely because the gradient and climbs achieved once clean are better than the flapped gradients and climbs.
I'll be completely honest here. I've received a couple of fairly unpleasant emails regarding my professionalism and its not the sort of thing I enjoy reading so its time for me to call a halt to this. I'm sorry I brought it up!
If you choose to take the flaps up at 400 feet at V2+20 the aircraft is still compliant. It has to comply with the climb gradient and I think its clear from all the posts on here that everyone agrees that if you take the flap up at 400 feet it will still comply with the climb. Thats what most people think the normal take off is - flaps up at 400 feet with a speed check of V2+20 (for my plane, different on others). Everyone seems happy that its compliant from 400 feet - well lets check that.. is everyone happy? Or is anyone of the opinion that once clean, if you have an engine failure you should reduce speed to V2 and reselect the take off flap? I've had that one sent privately too..
The flaps neither know nor care how high the aircraft is. If the gradient clean from 400 feet is good enough it will be good enough from wherever you actually select the flaps up because it will be the same gradient because the speed is correct.
I'm really open to the flaws in this but its exactly whats in the Bombardier manual and various Cessna manuals and the Embraer manual. The problem is that they don't explicitly deal with the engine failure after flap retraction in the climb case. They only deal in detail with the engine failure at V1 case.
I've got no issue with using 400 feet as a platform below which there should not be a flap retraction but I think its important that pilots retract the flap for the correct reason. I also think that its important that people understand whats happening. Close inspection of the 737 manual discusses reduced acceleration altitudes in the case of hot and high performance precisely because the gradient and climbs achieved once clean are better than the flapped gradients and climbs.
I'll be completely honest here. I've received a couple of fairly unpleasant emails regarding my professionalism and its not the sort of thing I enjoy reading so its time for me to call a halt to this. I'm sorry I brought it up!
Last edited by tommoutrie; 21st Nov 2012 at 12:54.