After Take off climb attitude
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After Take off climb attitude
Gday!
I was told that after take off in a Light Twin (I fly c310) hold 7 deg pitch up till clean and then 10 deg pitch up would give you the right climb performance and it does seem to work well after acceleration it will hold about Best RofC speed.
However, since then I have been reading some Trevor Thom manuals and another Light Twin book and they say to accelerate aircraft to blue line in ground affect then climb away at blue line +10 to 15 kts (assuming no obstacles). ***Airspeed is everything***
Now the first option sounds more like what Airline type aircraft would need, and while the speeds work out well in the c310, would the latter approach be a safer option for GA light aircraft?
I was told that after take off in a Light Twin (I fly c310) hold 7 deg pitch up till clean and then 10 deg pitch up would give you the right climb performance and it does seem to work well after acceleration it will hold about Best RofC speed.
However, since then I have been reading some Trevor Thom manuals and another Light Twin book and they say to accelerate aircraft to blue line in ground affect then climb away at blue line +10 to 15 kts (assuming no obstacles). ***Airspeed is everything***
Now the first option sounds more like what Airline type aircraft would need, and while the speeds work out well in the c310, would the latter approach be a safer option for GA light aircraft?
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Scramjet (are you tied up with the QLD project by any chance),
Good meaty stuff.
I presume that you are referring to Dave Robson's book in the Trevor Thom series. Dave is a very experienced TP, instructor and a nice guy (as is Trevor) .. he took me for a chase plane ride in a somewhat faster aeroplane many years ago which was the highlight of my little life ...
I haven't had a chance to read his book although I did manage a 30 second skim through it some weeks ago and it appears to say the sensible sorts of things which I would expect. Certainly Dave's background warrants consideration of what he might have to say.
Some thoughts of my own directed to your questions/comments.
(a) try not to mix procedures relating to light and heavy aircraft. The certification bases are quite different and to do so generally creates more confusion that illumination.
(b) runway environments (lengths and splay obstacle profiles) will dictate what is the range of sensible and practical options for takeoff in a light twin.
(c) the general design, certification and operational requirements address the AEO case which, if the pilot hasn't given enough thought to the possible OEI situation, can lead to some degree of surprise.
(d) if the runway environment is benign .. ie lots of distance and a good end of strip gradient, consider the advantages of accelerating to a speed a little above blue line (actual or gross weight doesn't matter too much in this case) while you have both engines and then plan on cleaning up at a suitable height without too much delay ..
(i) hopefully, the available distance will permit the aircraft to be landed in the remaining distance or, at least, brought to a low speed overrun situation if something untoward occurs prior to achieving a useful climb speed. If the takeoff is continued OEI configuration can be achieved without delay. Much more importantly, the operational decision process can be made very much simpler for the pilot.
(ii) a big problem with an early airborne failure, especially if you don't do a LOT of OEI practice, is that you can lose an embarrassing amount of speed very quickly due to mishandling, indecision, and unnecessary delay. Given the marginal performance of this class of aeroplane with any decent gross weight and at any density height much above sea level, this is not a very desirable thing to have happen. Hence the reference to "airspeed being everything" ... the aircraft may only climb under stable conditions within a comparatively narrow airspeed band .. it is quite easy to lose speed, but a devil of a job to get it back without descending .. therefore, is it not better to start a little bit faster ? Leaves you with an ace up the sleeve.
(e) if there is plenty of runway, consider using nil flap for takeoff. Although there may be some certification issues overlooked by doing this, it does avoid the problems associated with reconfiguring at low level in a very dynamic situation following a failure. The question of approximate distance required can be addressed from first principles without too much trouble, keeping in mind that distance bears a relationship to speed squared. One would do this conservatively to allow for the fact that the piston installation provides a notionally constant power, not thrust, output. If this is desired for routine takeoff operation, it becomes appropriate to investigate a suitable STC to cover the non-standard takeoff configuration. This has been my preferred approach for many years and I prefer to stay on the ground, if that is appropriate for the particular aircraft, until I have a suitable higher takeoff speed in hand.
(f) consider pitching to the OEI body attitude during takeoff. Generally this works well in the event of a subsequent failure and gives an acceptable acceleration AEO. If there is no failure, once you achieve the desired AEO climb speed, then maintain it by adjusting body attitude to suit the conditions. For the range of light piston twins with which I have played over the years, a nominal 10 degrees seems to be a useful default target body angle.
(g) if the runway, by contrast, is tight (shortish and with a nasty obstacle profile) then you have very few options -
(i) can I use a longer runway ?
(ii) can I takeoff somewhat lighter or wait until the wind and/or DH is more favourable ?
(iii) can I go by car ? .. my preference in this case ...
If you decide that you are stuck with it, then there is little to be done other than follow the available book procedure until the obstacles are cleared, accelerate and clean up, and climb away at the desired AEO speed, preferably something in excess of blue line.
If the engine fails prior to this, you have a big problem .. one for which you must have decided your immediate actions prior to commencing the takeoff....
(i) can I land ahead without hitting something terribly hard ?
(ii) can I turn left or right to get over benign terrain and continue the takeoff ? If this is the case, why were you planning on a straight ahead takeoff anyway ?
If you don't have one of these two options available, and the AEO case was pretty limiting, then you are almost certainly about to become a statistic. In all cases it is worth keeping in mind that one is far better off crashing under control than out of control.
Good meaty stuff.
I presume that you are referring to Dave Robson's book in the Trevor Thom series. Dave is a very experienced TP, instructor and a nice guy (as is Trevor) .. he took me for a chase plane ride in a somewhat faster aeroplane many years ago which was the highlight of my little life ...
I haven't had a chance to read his book although I did manage a 30 second skim through it some weeks ago and it appears to say the sensible sorts of things which I would expect. Certainly Dave's background warrants consideration of what he might have to say.
Some thoughts of my own directed to your questions/comments.
(a) try not to mix procedures relating to light and heavy aircraft. The certification bases are quite different and to do so generally creates more confusion that illumination.
(b) runway environments (lengths and splay obstacle profiles) will dictate what is the range of sensible and practical options for takeoff in a light twin.
(c) the general design, certification and operational requirements address the AEO case which, if the pilot hasn't given enough thought to the possible OEI situation, can lead to some degree of surprise.
(d) if the runway environment is benign .. ie lots of distance and a good end of strip gradient, consider the advantages of accelerating to a speed a little above blue line (actual or gross weight doesn't matter too much in this case) while you have both engines and then plan on cleaning up at a suitable height without too much delay ..
(i) hopefully, the available distance will permit the aircraft to be landed in the remaining distance or, at least, brought to a low speed overrun situation if something untoward occurs prior to achieving a useful climb speed. If the takeoff is continued OEI configuration can be achieved without delay. Much more importantly, the operational decision process can be made very much simpler for the pilot.
(ii) a big problem with an early airborne failure, especially if you don't do a LOT of OEI practice, is that you can lose an embarrassing amount of speed very quickly due to mishandling, indecision, and unnecessary delay. Given the marginal performance of this class of aeroplane with any decent gross weight and at any density height much above sea level, this is not a very desirable thing to have happen. Hence the reference to "airspeed being everything" ... the aircraft may only climb under stable conditions within a comparatively narrow airspeed band .. it is quite easy to lose speed, but a devil of a job to get it back without descending .. therefore, is it not better to start a little bit faster ? Leaves you with an ace up the sleeve.
(e) if there is plenty of runway, consider using nil flap for takeoff. Although there may be some certification issues overlooked by doing this, it does avoid the problems associated with reconfiguring at low level in a very dynamic situation following a failure. The question of approximate distance required can be addressed from first principles without too much trouble, keeping in mind that distance bears a relationship to speed squared. One would do this conservatively to allow for the fact that the piston installation provides a notionally constant power, not thrust, output. If this is desired for routine takeoff operation, it becomes appropriate to investigate a suitable STC to cover the non-standard takeoff configuration. This has been my preferred approach for many years and I prefer to stay on the ground, if that is appropriate for the particular aircraft, until I have a suitable higher takeoff speed in hand.
(f) consider pitching to the OEI body attitude during takeoff. Generally this works well in the event of a subsequent failure and gives an acceptable acceleration AEO. If there is no failure, once you achieve the desired AEO climb speed, then maintain it by adjusting body attitude to suit the conditions. For the range of light piston twins with which I have played over the years, a nominal 10 degrees seems to be a useful default target body angle.
(g) if the runway, by contrast, is tight (shortish and with a nasty obstacle profile) then you have very few options -
(i) can I use a longer runway ?
(ii) can I takeoff somewhat lighter or wait until the wind and/or DH is more favourable ?
(iii) can I go by car ? .. my preference in this case ...
If you decide that you are stuck with it, then there is little to be done other than follow the available book procedure until the obstacles are cleared, accelerate and clean up, and climb away at the desired AEO speed, preferably something in excess of blue line.
If the engine fails prior to this, you have a big problem .. one for which you must have decided your immediate actions prior to commencing the takeoff....
(i) can I land ahead without hitting something terribly hard ?
(ii) can I turn left or right to get over benign terrain and continue the takeoff ? If this is the case, why were you planning on a straight ahead takeoff anyway ?
If you don't have one of these two options available, and the AEO case was pretty limiting, then you are almost certainly about to become a statistic. In all cases it is worth keeping in mind that one is far better off crashing under control than out of control.
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Forget about compairing techniques of light twins to transport jets there are too many differences. With that said let me continue.
In light twins, I fly a pitch attitude that holds Vy or Vyse+10 which ever is greater. This technique allows me to gain the most altitude in the shortest amount of time. Altitude is your friend! Flying Vy/Vyse+10 (the greater of the two) Allow a buffer above Vyse if an engine should fail. You may recall that drag increases with the square of airspeed> You don't want to climb at too fast of an airspeed becouse your climb performance decreases.
If an engine should fail when climbing at Vy/Vyse+10, airspeed and climb performace decrease very quickly. I have found that with a decrease of pitch of about 5 degrees (+/-), the airspeed will stablize very close to Vyse (right where I want it).
Now weather or not the airplane climbs the way you want it to depends on your preflight planning!
Since your in the Cessna 310, ever look at the accelerated go chart? Ever notice that chart leaves you hanging at 50 feet AGL at an airspeed below Vyse? (I don't recall how close the airspeed was to Vxse).
Anyway, this is the technique I use, It's kept me out of the dirt though 4 engine failures.
In light twins, I fly a pitch attitude that holds Vy or Vyse+10 which ever is greater. This technique allows me to gain the most altitude in the shortest amount of time. Altitude is your friend! Flying Vy/Vyse+10 (the greater of the two) Allow a buffer above Vyse if an engine should fail. You may recall that drag increases with the square of airspeed> You don't want to climb at too fast of an airspeed becouse your climb performance decreases.
If an engine should fail when climbing at Vy/Vyse+10, airspeed and climb performace decrease very quickly. I have found that with a decrease of pitch of about 5 degrees (+/-), the airspeed will stablize very close to Vyse (right where I want it).
Now weather or not the airplane climbs the way you want it to depends on your preflight planning!
Since your in the Cessna 310, ever look at the accelerated go chart? Ever notice that chart leaves you hanging at 50 feet AGL at an airspeed below Vyse? (I don't recall how close the airspeed was to Vxse).
Anyway, this is the technique I use, It's kept me out of the dirt though 4 engine failures.
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Scramjet, read and understand J_T's thoughts, they just might save your skin. Also realise that light twins and transport twins are NOT the same....forget the body angle business and look for that blue line....airspeed leads to directional control, very important where performance is not all that great.
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I was lucky enough to do a Cessna 340 training course at SIMCOM in Scotsdale Arizona. It changed the way I fly light twins. One of the big problems with light aircraft is the decision speed is not defined like the way it is in transport catagory aircraft ( ie you have definite go/ no go criteria which have been tested ) . This combined with the marginal SE performance of light twins makes an EFATO a pretty ugly thing to have happen. Their method takes the ambiguity out and really works.
The Drill
1. Use full lenght of Runway ALWAYS preferably with no flap
2. Apply full power and check engine Instruments,
leave hands on throttles, if any sign of engine problems while hands on throttle, retart both throttles and max brake.
3. Rotate at BLUELINE
4. AFTER rotation and with positive rate of climb verified your hand goes from throttles to gear handle which is immediatelly selected up , then hand goes to prop levers.
5. if engine fails control yaw with rudder , verify with dead foot and then immediately select apropriate prop lever to feather.
6. Do nothing further but fly the aircraft straight ahead at BLUELINE with yaw controlled and banked 5 deg into dead engine. At 500 AGL complete engine failure checklist.
A light twin will not accelerate from a speed below Blueline in level flight. Therefore an engine failure below blueline means an automatic abort. After blueline is attained the aircraft is climbing and the gear is retracting the only thing left is to feather the failed engine. Most twins will not climb with a windmilling prop prop so it is vital to get it feathered ASAP. In effect a blueline rotation ensures positive climb performance ( V1,VR ) and your hand becomes the auto feather system. This is as close as you can get to duplicating the performance guarantee you will get with transport catagory aircraft V1,VR,V2
calculations.
The Drill
1. Use full lenght of Runway ALWAYS preferably with no flap
2. Apply full power and check engine Instruments,
leave hands on throttles, if any sign of engine problems while hands on throttle, retart both throttles and max brake.
3. Rotate at BLUELINE
4. AFTER rotation and with positive rate of climb verified your hand goes from throttles to gear handle which is immediatelly selected up , then hand goes to prop levers.
5. if engine fails control yaw with rudder , verify with dead foot and then immediately select apropriate prop lever to feather.
6. Do nothing further but fly the aircraft straight ahead at BLUELINE with yaw controlled and banked 5 deg into dead engine. At 500 AGL complete engine failure checklist.
A light twin will not accelerate from a speed below Blueline in level flight. Therefore an engine failure below blueline means an automatic abort. After blueline is attained the aircraft is climbing and the gear is retracting the only thing left is to feather the failed engine. Most twins will not climb with a windmilling prop prop so it is vital to get it feathered ASAP. In effect a blueline rotation ensures positive climb performance ( V1,VR ) and your hand becomes the auto feather system. This is as close as you can get to duplicating the performance guarantee you will get with transport catagory aircraft V1,VR,V2
calculations.
Moderator
Some interesting observations here ... if I may stir the pot just a little more ...
(a) GAMA style POHs which include various sorts of go/stop data ought to be viewed more as a serious admonition to stop rather than encouragement to go. One needs to keep in mind the very litigious environment within which the US manufacturers operate and consider their need to provide a measure of defence during litigation while not making their aeroplanes look too down market in the performance arena.
The pragmatic operational view in a light twin at high gross and density height is that it goes fine on two (some obviously better than others) and, on one, not too badly once it is cleaned up at altitude and on speed. Low and slow continuation of flight OEI, especially in the hands of a marginally proficient pilot in conditions requiring extremely critical flying, is an invitation to an eventual Vmca departure and a crash totally out of control. Far better, I suggest, to consider in such extreme circumstances a controlled forced landing with a moderate degree of available thrust to provide some choice of crash site.
(b) the 340, while being one of my fondest light twins, often is described in unflattering terms in respect of its reluctance to leave the ground. While the comments ascribed to a particular training organisation possibly make a lot of sense for that particular Type, I believe that it is dangerous to attempt to make the takeoff procedure too much of a rote sequence. Circumstances dictate appropriate procedure. The preferred procedure on a particular takeoff might well be quite undesirable for a different set of conditions. I guess that what I am saying is that
(i) many pilots receive inadequate instruction in asymmetric operation during their training
(ii) individual pilots need to read widely within competent literature to obtain a more detailed appreciation of the problems .. so that they are better able to make sensible decisions for particular circumstances.
(c) 5 degrees into the live (I do hope your post involved a typo) engine relates to Vmca determination limits in the certification process. For the normal continued climb at higher speeds, climb performance wings level is very similar to that achieved with 5 degrees bank ... there is little to be gained by making the flying somewhat harder by targeting the bank angle. However, a skilful pilot might squeeze just a little more climb out of the aircraft by using an intermediate bank angle sufficient to eliminate sideslip caused by the rudder force vector. This generally works out to be around 2-3 degrees into the live engine.
(d) one ought not just blindly climb ahead without very considerable thought to terrain problems. Again this must be part of the pre takeoff briefing process.
(e) in some circumstances, a failure a little below blue line might be handled better with a continuation. It all depends on the circumstances .. in this case the overrun environment compared to the terrain further out. Clearly, though, if the aircraft is at a decent weight and density height and the speed is much below blue line, then, in general, it is not going to go anywhere ... something about being between a rock and a hard place. Similarly, there may be circumstances where one would still abort from a speed above blue line. For instance, a takeoff from a very mountainous airstrip with close in good forced landing areas but high tiger country further out. Again .. horses for courses and an individual decision for an individual takeoff.
(f) I take the view that FAR25 performance is not necessarily a guarantee .. only information relating to specific conditions. The jet can easily find itself in circumstances where it may not be able to complete an OEI takeoff satisfactorily .. windshear being the most obvious.
(g) .. and, in all cases, there is little to be accomplished if undue haste in shutting down the engine involves shutting down the wrong one ....
[ 30 December 2001: Message edited by: john_tullamarine ]</p>
(a) GAMA style POHs which include various sorts of go/stop data ought to be viewed more as a serious admonition to stop rather than encouragement to go. One needs to keep in mind the very litigious environment within which the US manufacturers operate and consider their need to provide a measure of defence during litigation while not making their aeroplanes look too down market in the performance arena.
The pragmatic operational view in a light twin at high gross and density height is that it goes fine on two (some obviously better than others) and, on one, not too badly once it is cleaned up at altitude and on speed. Low and slow continuation of flight OEI, especially in the hands of a marginally proficient pilot in conditions requiring extremely critical flying, is an invitation to an eventual Vmca departure and a crash totally out of control. Far better, I suggest, to consider in such extreme circumstances a controlled forced landing with a moderate degree of available thrust to provide some choice of crash site.
(b) the 340, while being one of my fondest light twins, often is described in unflattering terms in respect of its reluctance to leave the ground. While the comments ascribed to a particular training organisation possibly make a lot of sense for that particular Type, I believe that it is dangerous to attempt to make the takeoff procedure too much of a rote sequence. Circumstances dictate appropriate procedure. The preferred procedure on a particular takeoff might well be quite undesirable for a different set of conditions. I guess that what I am saying is that
(i) many pilots receive inadequate instruction in asymmetric operation during their training
(ii) individual pilots need to read widely within competent literature to obtain a more detailed appreciation of the problems .. so that they are better able to make sensible decisions for particular circumstances.
(c) 5 degrees into the live (I do hope your post involved a typo) engine relates to Vmca determination limits in the certification process. For the normal continued climb at higher speeds, climb performance wings level is very similar to that achieved with 5 degrees bank ... there is little to be gained by making the flying somewhat harder by targeting the bank angle. However, a skilful pilot might squeeze just a little more climb out of the aircraft by using an intermediate bank angle sufficient to eliminate sideslip caused by the rudder force vector. This generally works out to be around 2-3 degrees into the live engine.
(d) one ought not just blindly climb ahead without very considerable thought to terrain problems. Again this must be part of the pre takeoff briefing process.
(e) in some circumstances, a failure a little below blue line might be handled better with a continuation. It all depends on the circumstances .. in this case the overrun environment compared to the terrain further out. Clearly, though, if the aircraft is at a decent weight and density height and the speed is much below blue line, then, in general, it is not going to go anywhere ... something about being between a rock and a hard place. Similarly, there may be circumstances where one would still abort from a speed above blue line. For instance, a takeoff from a very mountainous airstrip with close in good forced landing areas but high tiger country further out. Again .. horses for courses and an individual decision for an individual takeoff.
(f) I take the view that FAR25 performance is not necessarily a guarantee .. only information relating to specific conditions. The jet can easily find itself in circumstances where it may not be able to complete an OEI takeoff satisfactorily .. windshear being the most obvious.
(g) .. and, in all cases, there is little to be accomplished if undue haste in shutting down the engine involves shutting down the wrong one ....
[ 30 December 2001: Message edited by: john_tullamarine ]</p>
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Big Pistons, I tend to agree with most of what you say except that we teach our pilots, in Cessna 310R's, to rotate at TOSS(takeoff safety speed)and to keep hands on throttles until blueline is achieved at which point gear is selected up. This Gear Up point is the Go, NO Go, decision point as far as continuing is concerned. Any engine failure prior to that point is going to result in the land straight ahead scenario. There is one other thing that we do. Keeping in mind that blue line is calculated for maximum weight we have calculated lower blue line speeds for lighter weights by interpolation. The only reason that I have pulled you up on this is that I'm sure you will agree that trying to hold a C310R on the runway till it reaches 107 kts and full power is a mission that some pilots may not be able to handle without damaging the aircraft. Also this is not the technique called for in the POH.
We use the technique Grogmonster outlined on the Twin Comanche. While for many aircraft it's natural to associate the rotation speed with the speed at which the decision to fly or land ahead is made, it just doesn't work practically for others. In the case of the Twin Comanche, it wants to fly a good 10 to 15 knots below blue line, and trying to keep it on the runway, particularly in a crosswind, is exciting. So we accelerate after rotation before climbing. I don't think it has to be "in ground effect" as such, as long as the action in the event of an engine failure can be to close both throttles and land ahead.
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Large (old) piston twins of yesteryear (Convair 440, Martin 404) used autofeather to ENSURE that the windmilling propellor was feathered. Even these aircraft would NOT climb if the prop was not feathered at high weights, and if autofeather was inop, the MTOW was reduced by a large factor.
These aircraft were certified to CAR4b (now FAR25)and generally had good engine out performance. Most light piston twins, sadly, do not.
Now, if you have turboprops (Cessna 441 is a good example), the picture changes greatly.
These aircraft were certified to CAR4b (now FAR25)and generally had good engine out performance. Most light piston twins, sadly, do not.
Now, if you have turboprops (Cessna 441 is a good example), the picture changes greatly.
....all of which makes one wonder why the Trislander wasn't more of a success!
These comments about the marginal peformance of light twins (an aeroplane class I actively avoid having anything to do with!) remind me of the brief I received when flying in the back of a 3 tank Meteor 7: "I will plan to take-off and accelerate to a speed at which it'll climb on one, holding it on the ground for as long as I dare. Once airborne, I'll climb at the least gradient I can until we achieve SE climb speed - if we lose an engine before then, I'll close both throttles and we'll force land straight ahead, I'll dump the ventral if I've got enough hands. Once we've achieved SE climb speed, we should be able to climb if we lose one; however, it won't be easy. After my initial blasphemy, I'll say 'Left' or 'Right' and I want you to push the rudder fully forward in that direction. I'll dump the ventral, get us away from the ground, shut down the offending engine and complete a cautious circuit. Committal height will be around 650ft, once we're below that it'll be more or less a glide landing. We will then bravely bug ger off to the Mess and get thoroughly pi$$ed!!"
Lift is a gift, but thrust is a must!
These comments about the marginal peformance of light twins (an aeroplane class I actively avoid having anything to do with!) remind me of the brief I received when flying in the back of a 3 tank Meteor 7: "I will plan to take-off and accelerate to a speed at which it'll climb on one, holding it on the ground for as long as I dare. Once airborne, I'll climb at the least gradient I can until we achieve SE climb speed - if we lose an engine before then, I'll close both throttles and we'll force land straight ahead, I'll dump the ventral if I've got enough hands. Once we've achieved SE climb speed, we should be able to climb if we lose one; however, it won't be easy. After my initial blasphemy, I'll say 'Left' or 'Right' and I want you to push the rudder fully forward in that direction. I'll dump the ventral, get us away from the ground, shut down the offending engine and complete a cautious circuit. Committal height will be around 650ft, once we're below that it'll be more or less a glide landing. We will then bravely bug ger off to the Mess and get thoroughly pi$$ed!!"
Lift is a gift, but thrust is a must!
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The other problem about trying to compare GA and airline type aircraft techniques is that the pilot skill level is different. Airline pilots get to practice OEI operations under a variety of conditions on a regular basis, in simulators that, for the most part, pretty accurately reflect the real aeroplane.
How often does the average GA twin pilot get to practice the same thing? I believe that this must be part of the planning for each take-off. The only way to incorporate it safely, IMHO, is by reference to speed, but not speed alone.
Speed is the first important factor but, as has been said already, there are many GA twins that want to leave the ground well below "blue line" speed. This pretty much ensures that you are going to have a portion of your airborne time devoted to the consideration to close both throttles and crash as gracefully as possible.
I've personally found that "gear up" speed really is the most practical "decision speed" in most circumstances. The major operational problem that I've faced over the years is that the strips in Papua New Guinea are never long enough and often don't have good obstacle-free climb paths.
This presents the "horses for courses" scenario that means just about every take-off is going to be that bit different. That's really what GA flying is all about, when you come right down to it. And it's one major reason why airline techniques shouldn't be confused with GA twin techniques.
How often does the average GA twin pilot get to practice the same thing? I believe that this must be part of the planning for each take-off. The only way to incorporate it safely, IMHO, is by reference to speed, but not speed alone.
Speed is the first important factor but, as has been said already, there are many GA twins that want to leave the ground well below "blue line" speed. This pretty much ensures that you are going to have a portion of your airborne time devoted to the consideration to close both throttles and crash as gracefully as possible.
I've personally found that "gear up" speed really is the most practical "decision speed" in most circumstances. The major operational problem that I've faced over the years is that the strips in Papua New Guinea are never long enough and often don't have good obstacle-free climb paths.
This presents the "horses for courses" scenario that means just about every take-off is going to be that bit different. That's really what GA flying is all about, when you come right down to it. And it's one major reason why airline techniques shouldn't be confused with GA twin techniques.
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Lots of good stuff in this thread. A couple of points. I guess my original post was not very clear. When the pilots hand is taken off the throttles it selects gear up and then goes to the props. Engine failure means pull back what ever handle you are touching, throttles = abort, props equals fly. The placement of your hand in effect performs the same function as the V1 call in a multicrew transport aircraft. I think it is important to emphasize that in transport catagory aircraft no thinking is required, if below V1 you stop if above V1 you go. If the regulatory agencies and industry has decided that it is unrealistic for a 30000 hr 747 Capt to think through what are the approrpriate actions at such a stress filled and critical time , I don't think a light twin driver is any more equiped to adjust his actions in real time.
Also you are right I did situate the actions to the airplane I usually fly in the winters, A VG equiped C340 ( VMC=100 kts ) . A 100 kt rotation works very well in this aircraft, however it would be more accurate to say rotation speed is not that important , what matters is that a engine failure below blueline means the throttles are automatically retarded. I still think delaying the rotation to the highest possible speed is desirable because you are more likely to still be on the runway when the failure occures and therefore will have an easier time controlling and stopping the plane. Certainly airplanes which have signinicant nose up attitude on the ground like Twin Comanches or Seneca's this speed will be lower. Also this is not practicle for aircraft with a high blueline speed like Aerostars ( 115 -118 ks ). SIMCOM's 1.5 million $ US simulator has what is in my experience very good performance fidelity to the actual aircraft. I am convinced it is a practicle impossibilty to reliably be able to get the aircraft to accellerate from a speed below blueline , to blue line and then climb away for an engine failure during the takeoff run even at loadings significantly below gross weight. And this was with me primed to expect a engine failure. Therefore in my opinion
you must treat this scenario the same as an engine failure in a single engine aircraft. Obviously good airmanhip also applies. If there is a mountain in front of you don't climb straight ahead and short fields will require flap and lower rotaion speeds. But I stand by my original assertion. If you don't have blueline, positive rate, gear selected up, and hand's on the prop levers ready to feather then continuing with the flight in the event of an engine failure is unlikely to be sucessfull. It is far better to crash wings level in control with the no thrust than to lose control stall and spin as seems to happen all too frequently. If your hand is on the prop lever than by my definition you are past decision speed and will keep going, now the MOST important thing to do is feather the failed engine, Nothing else matters as a light twin WILL NOT climb away from the runway with a windmilling prop. I would also suggest that all your attention should be focused on controlling the aircraft, that is the rational to so far as possible climb straight ahead and not worry about any other engine failure drills untill the aircraft is at 500 feet AGL. Even if you do everything perfectly the aircraft may still not climb thereby forcing you to close the throttles and do your best in the ensuing forced landing. I believe however that this method wil give you the best chance of sucess.
[ 30 December 2001: Message edited by: big pistons forever ]</p>
Also you are right I did situate the actions to the airplane I usually fly in the winters, A VG equiped C340 ( VMC=100 kts ) . A 100 kt rotation works very well in this aircraft, however it would be more accurate to say rotation speed is not that important , what matters is that a engine failure below blueline means the throttles are automatically retarded. I still think delaying the rotation to the highest possible speed is desirable because you are more likely to still be on the runway when the failure occures and therefore will have an easier time controlling and stopping the plane. Certainly airplanes which have signinicant nose up attitude on the ground like Twin Comanches or Seneca's this speed will be lower. Also this is not practicle for aircraft with a high blueline speed like Aerostars ( 115 -118 ks ). SIMCOM's 1.5 million $ US simulator has what is in my experience very good performance fidelity to the actual aircraft. I am convinced it is a practicle impossibilty to reliably be able to get the aircraft to accellerate from a speed below blueline , to blue line and then climb away for an engine failure during the takeoff run even at loadings significantly below gross weight. And this was with me primed to expect a engine failure. Therefore in my opinion
you must treat this scenario the same as an engine failure in a single engine aircraft. Obviously good airmanhip also applies. If there is a mountain in front of you don't climb straight ahead and short fields will require flap and lower rotaion speeds. But I stand by my original assertion. If you don't have blueline, positive rate, gear selected up, and hand's on the prop levers ready to feather then continuing with the flight in the event of an engine failure is unlikely to be sucessfull. It is far better to crash wings level in control with the no thrust than to lose control stall and spin as seems to happen all too frequently. If your hand is on the prop lever than by my definition you are past decision speed and will keep going, now the MOST important thing to do is feather the failed engine, Nothing else matters as a light twin WILL NOT climb away from the runway with a windmilling prop. I would also suggest that all your attention should be focused on controlling the aircraft, that is the rational to so far as possible climb straight ahead and not worry about any other engine failure drills untill the aircraft is at 500 feet AGL. Even if you do everything perfectly the aircraft may still not climb thereby forcing you to close the throttles and do your best in the ensuing forced landing. I believe however that this method wil give you the best chance of sucess.
[ 30 December 2001: Message edited by: big pistons forever ]</p>
Moderator
BPF ..
I think that we are basically aligned in our operational thinking.
I would take issue with the claim that the FAR25 situation is a totally programmed decision process. There are situations which can arise where the pilot has to think laterally. However that starts to get dreadfully off the original topic ...
... and surely we would all agree that the Trislander is one of the best noise generators around ...
[ 30 December 2001: Message edited by: john_tullamarine ]</p>
I think that we are basically aligned in our operational thinking.
I would take issue with the claim that the FAR25 situation is a totally programmed decision process. There are situations which can arise where the pilot has to think laterally. However that starts to get dreadfully off the original topic ...
... and surely we would all agree that the Trislander is one of the best noise generators around ...
[ 30 December 2001: Message edited by: john_tullamarine ]</p>
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I have another question:
How many instructors teach light twin pilots to leave the gear down until there is no runway left ahead to land on?
...............
The hardest thing about flying is knowing when to say no.
How many instructors teach light twin pilots to leave the gear down until there is no runway left ahead to land on?
...............
The hardest thing about flying is knowing when to say no.
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I used to, but now I teach the method outlined in my earlier post. The problem is how do you make the judgement? In any case it doesn't matter. If the airplane won't fly after it is cleaned up, land it on the runway or any other suitable place gear up. I think the important thing is to minimize the number of decisions because I am sure the shock of an actual failure will not allow you the luxury of puzzling out the best course of action is. And the simulator showed me how important it was to quickly get the aircraft properly configured if contiuing the flight is a realistic possibility. The other problem is training is unfortunately somewhat unrealistic in that the student is expecting a failure and for obvious safety reasons you are not going to kill an engine close to the ground. The advantage of a good simulator is ALL of my engine failures were in the ugly area close to the ground and at or near blueline. Incidently I crashed on the first one the sim instructor gave me using the traditional: Control , Power ( check throttles full forward ), Drag ( check gear and flaps up) , identify ( dead foot dead engine ), Verify (with throttle), Feather . By the time I got to the Verify with throttle, it was all over. He suggested I use their method and I was sucessfull on the next 20 + . Rapidly feathering the failed engine was the key. He said that almost all first time SIMCOM students crash but most of the graduates of the course who are back for recurrent training do not. Obviously he is biased but I believe him, Their method works.
[ 31 December 2001: Message edited by: big pistons forever ]
[ 31 December 2001: Message edited by: big pistons forever ]</p>
I used to, but now I teach the method outlined in my earlier post. The problem is how do you make the judgement? In any case it doesn't matter. If the airplane won't fly after it is cleaned up, land it on the runway or any other suitable place gear up. I think the important thing is to minimize the number of decisions because I am sure the shock of an actual failure will not allow you the luxury of puzzling out the best course of action is. And the simulator showed me how important it was to quickly get the aircraft properly configured if contiuing the flight is a realistic possibility. The other problem is training is unfortunately somewhat unrealistic in that the student is expecting a failure and for obvious safety reasons you are not going to kill an engine close to the ground. The advantage of a good simulator is ALL of my engine failures were in the ugly area close to the ground and at or near blueline. Incidently I crashed on the first one the sim instructor gave me using the traditional: Control , Power ( check throttles full forward ), Drag ( check gear and flaps up) , identify ( dead foot dead engine ), Verify (with throttle), Feather . By the time I got to the Verify with throttle, it was all over. He suggested I use their method and I was sucessfull on the next 20 + . Rapidly feathering the failed engine was the key. He said that almost all first time SIMCOM students crash but most of the graduates of the course who are back for recurrent training do not. Obviously he is biased but I believe him, Their method works.
[ 31 December 2001: Message edited by: big pistons forever ]
[ 31 December 2001: Message edited by: big pistons forever ]</p>
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B.P.F.
Its nice to see you changed your teaching methods, any idea where the goofy idea of not cleaning up a multi engine airplane as soon as safe came from?
There is one other facror that comes into the equation when flying any airplane and that is inertia, when training waterbomber pilots I used to be amazed at how fast some of them would immediately go through their rote learned engine failure exercise with no thought process at all.
Here is the engine failure checklist I teach.
(1) What the fu.. is this thing doing now.
(2) Fly it under control, and really identify what the fu.. it is doing.
(3) When the problem is identified carry out the procedure that will solve the problem.
A fully loaded PBY waterbomber with the critical engine failed and propellor windmilling would only lose approximately two knots in the first five seconds, providing the speed at failure was at or above best single engine climb speed.
Five seconds will give you time to think, all you do is fly it straight while thinking and looking. Of course it is always easier with a well trained and co-ordinated crew of two.
Bottom line is do everything right the first time, dont just rush into something you may not be able to fix.
.................
The hardest thing about flying is knowing when to say no.
Its nice to see you changed your teaching methods, any idea where the goofy idea of not cleaning up a multi engine airplane as soon as safe came from?
There is one other facror that comes into the equation when flying any airplane and that is inertia, when training waterbomber pilots I used to be amazed at how fast some of them would immediately go through their rote learned engine failure exercise with no thought process at all.
Here is the engine failure checklist I teach.
(1) What the fu.. is this thing doing now.
(2) Fly it under control, and really identify what the fu.. it is doing.
(3) When the problem is identified carry out the procedure that will solve the problem.
A fully loaded PBY waterbomber with the critical engine failed and propellor windmilling would only lose approximately two knots in the first five seconds, providing the speed at failure was at or above best single engine climb speed.
Five seconds will give you time to think, all you do is fly it straight while thinking and looking. Of course it is always easier with a well trained and co-ordinated crew of two.
Bottom line is do everything right the first time, dont just rush into something you may not be able to fix.
.................
The hardest thing about flying is knowing when to say no.
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What I like about this board is the varity of techniques that come up. I few things caught my attention:
Rotation speed: I use what is recommended in the POH or a minimum of Vmc+5 which ever is greater. Depending on the type of day (hot) and load (heavy) I may bump Vr up to Vsse. Compare this speed with the speeds used on the performace charts (T/O dist, Acc stop, Acc go) notice that in some airplanes these numbers differ from the normal procedure section and the speeds used for performance. If an incident occures the investigating authorities will figure out you did not use the manufactures recommended procedures. Then you will have some explaining to do.
If you accelerate the airplane to Vyse before rotation you could encounter severial problems a pilot might need to deal with: Wheel barrowing, excessive tire speed (tires have limition speed above which a tire will fail), Brake energy limits (something transports use but light twins seldom discuss),reaction times and procedures and needless to say all performance numbers are thrown out the window.
If you rotate farther down the runway you miss out on the altitude above you, and reduce the climb gradient profile (obstical clearance).
When an engine failes in a light twin there is a decision to be made, to stop or to go. This decision needs to be made from all availble information. This means digging in the performance section of the POH and evaluating the departure profile before the flight. Take these numbers and add a safety factor. On some flights I have made my "go" point 500 feet AGL. This was based on available climb performance and the Obstical departure procedure.
Climbing at "Blue line": The Blue line as marked on the airspeed indicator is Vyse at sea level conditions at gross weight. Vyse changes with a change in altitude, tempature and weight. You compute Vyse from the POH before every takeoff (some rules of thumb exist for older aiplanes with out good POH info). When the engine quits fly this Vyse not Blue line.
First and formost Fly the airplane.
Think before you react. Most of us are wired for and engine failure. But wait, do you have a complete failure or an engine that is still producing reasonable power? Do I have a propeller overspeed or underspeed? If an engine is surging in and out, which engine is it? If I shut down that engine what other limitation/problems will I have to work with?
Fly, Think, Fly, Think..........
Rotation speed: I use what is recommended in the POH or a minimum of Vmc+5 which ever is greater. Depending on the type of day (hot) and load (heavy) I may bump Vr up to Vsse. Compare this speed with the speeds used on the performace charts (T/O dist, Acc stop, Acc go) notice that in some airplanes these numbers differ from the normal procedure section and the speeds used for performance. If an incident occures the investigating authorities will figure out you did not use the manufactures recommended procedures. Then you will have some explaining to do.
If you accelerate the airplane to Vyse before rotation you could encounter severial problems a pilot might need to deal with: Wheel barrowing, excessive tire speed (tires have limition speed above which a tire will fail), Brake energy limits (something transports use but light twins seldom discuss),reaction times and procedures and needless to say all performance numbers are thrown out the window.
If you rotate farther down the runway you miss out on the altitude above you, and reduce the climb gradient profile (obstical clearance).
When an engine failes in a light twin there is a decision to be made, to stop or to go. This decision needs to be made from all availble information. This means digging in the performance section of the POH and evaluating the departure profile before the flight. Take these numbers and add a safety factor. On some flights I have made my "go" point 500 feet AGL. This was based on available climb performance and the Obstical departure procedure.
Climbing at "Blue line": The Blue line as marked on the airspeed indicator is Vyse at sea level conditions at gross weight. Vyse changes with a change in altitude, tempature and weight. You compute Vyse from the POH before every takeoff (some rules of thumb exist for older aiplanes with out good POH info). When the engine quits fly this Vyse not Blue line.
First and formost Fly the airplane.
Think before you react. Most of us are wired for and engine failure. But wait, do you have a complete failure or an engine that is still producing reasonable power? Do I have a propeller overspeed or underspeed? If an engine is surging in and out, which engine is it? If I shut down that engine what other limitation/problems will I have to work with?
Fly, Think, Fly, Think..........
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Read in a Forum on AVWEB about a bloke who did some sim training at Flightsafety and reckons that instead of the "Dead Leg-Dead Engine" method used Engine Failure- "Nose Yawed right-Right Engine Failed, Nose Yawed Left -Left Engine Failed".
Any company's actually use this method as SOP??
Any company's actually use this method as SOP??
Moderator
I would hope not. If this technique involves significant yawed flight for a period during which the pilot works out what is going on ... and the failure occurs at a lowish speed, then there is likely to be generated an undesirable bank angle and a "gotcha" increase in Vmca.
It doesn't take too much adverse bank to see the aircraft continue yawing and then roll away into the ground.
It doesn't take too much adverse bank to see the aircraft continue yawing and then roll away into the ground.