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Old 25th Dec 2002, 00:16
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V2 cut

...we were doing V2 cuts recentley and the ip told us to input aileron initially after the cut. i've always used rudder initially and then aileron.
we tried it and i couldn't control it. i still think it's rudder initially...

'just want to know how the rest of the guys fly it.

thanks
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Old 25th Dec 2002, 00:42
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Can't comment about the more "modern" swept wing jet airliners, but on the B707 (and later on the L10), rudder first works best. Aileron first raises spoilers...not helpful.
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Old 25th Dec 2002, 03:38
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Definitely rudder first.
On the 747, you can control an engine failure almost with the rudder alone, no aileron input, but if you try it with ailerons only, you end up all over the place.
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Old 25th Dec 2002, 04:26
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Close to the ground with visual refrences, I "step on the centerline". Airborne, in the clouds I initially respond with airlerons, shortly followed by "stepping on the low yoke side". The above techniques are pretty idiot proof.

Rudder is an absolute necessity in an engine out. i believe a BA 747 almost clipped a hilltop in Oakland California, because the pilot controlled with all aileron and no rudder. The aircraft couldn't climb with all that aileron.
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Old 25th Dec 2002, 05:33
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dvt, i guess if you're airborne with runway in sight--"stepping on the centerline" would be rudder first. it's just so instinctive for me to step on the rudder with a loss of power. and if i don't have a runway to look at i just step on the sky pointer... i don't know...

you're technique of stepping where the control column is banked i use to "refine"...

i guess it's really just a matter of personal preference.

thanks
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Old 25th Dec 2002, 19:32
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Rudder!

Technique taught in the 744 is to use enough rudder such that the yoke (ailerons) is neutral in level flight. If you need ailerons to maintain heading, your rudder isn't trimmed.
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Old 25th Dec 2002, 20:22
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It depends a lot on what type you are talking about.

Certainly the end result of a well controlled V1 (or later) cut is to utilise rudder to counteract the resultant yaw, but how you get to that final condition may vary according to type.

For instance, the Boeing Flight Training Manual for the B737-200 recommends initially using aileron to counter roll, and then (as described by DVT) using the 'down going yoke' to prompt correct rudder input.

This is not the most 'beautiful' solution, and can lead to excessive aileron input (which is undesireable for the reason specified by 411A...i.e. spoiler deflection) but it is an almost idiot proof training tool. With practice most trainees soon grasp the idea and become quite adept at getting the right ammount of rudder swiftly, thus minimising spoiler deployment.

So your instructor wasn't wrong if we're talking Boeing 737.

Also don't forget that Vmca rules allows 5deg bank toward the live engine by definition, so aileron is not totally out of the question on other types. The Airbus 320 Flight Director actually leads you into a dual aileron/rudder input...because it is the minimum drag arrangement if done correctly!
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Old 25th Dec 2002, 21:12
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Rudder is an absolute necessity in an engine out. i believe a BA 747 almost clipped a hilltop in Oakland California, because the pilot controlled with all aileron and no rudder. The aircraft couldn't climb with all that aileron.


I believe that the reason for the pilot input this way was that they did not initially recognize a classic engine out, what with all the noise and rocking. The pilot was probably trained for a simple V2 cut without the noise and lurching around that goes with a surging engine.
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Old 26th Dec 2002, 03:15
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If I may put a slightly different slant on the discussion .. lightoutandarmed's instructor may have been a bit terse or the message may have been slightly misinterpreted.

(a) One of the pertinent considerations is the degree to which the particular Type exhibits yaw-roll coupling. For most aircraft I have a familiarity with, the engine failure case at higher speeds is a bit of a doddle. However, as the speed is reduced back towards V2, then the roll becomes increasingly pronounced. Particularly if the pilot is handflying the aircraft .. ie on instruments, often a significant initial indication of the failure is seen on the AH/ADI/EADI/whatever and a counter-roll input is quite natural .. and works well, provided that the trained response in the engine failure case is to follow up essentially simultaneously with rudder to centralise the wheel (horn down side = rudder input side). With a bit of practice in the simulator, this input sequence becomes very rapid and the flight path excursions can be controlled very well. In the initial I/F practice, it may appear that the aileron is being used as the primary control but this is only an intermediate skills development step ... especially in the case of an inexperienced pilot under training.

(b) Depending on the Type's characteristics, at lower weights, Vmca becomes either limiting or very relevant. In this case, if the initial coupled roll is not controlled both effectively and promptly, then (the real) Vmca increases rapidly and there is a very real risk of loss of control via a Vmca departure. For such circumstances, it may be very necessary to control the initial failure with rudder input and very significant control wheel rotation into the operating engine(s) .. the question of spoilers in this case is not really significant as the wheel rotation is only a short-lived transient input until the flight path excursions are under control. Once the sequence becomes a practised outcome, the dual control input (as appropriate to the Type and the circumstances of the particular takeoff) is quite tidy.

(c) Be aware that the 5 degree bank limitation is a restriction imposed to prevent unrealistically low Vmca determinations and ought not to be necessary for failures unless Vmca is a consideration. Furthermore, for continued OEI climb at V2, the use of 5 degree bank will not provide optimum (zero) slip conditions and is a significant increase in pilot workload for no significant gain.... and, realistically, unless one is in constant OEI climb practice, then there are more than enough workload annoyances more important than trying to fly a small bank angle.

Last edited by john_tullamarine; 26th Dec 2002 at 03:29.
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Old 26th Dec 2002, 14:16
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Zero Sideslip Technique?

John, I recall an article in Aviation Safety a decade or two ago advocating this technique in twins, especially light pistons where that extra 50 fpm may be critical.

One point in the article suggested a yaw string would give better information on sideslip with OEI than the ball.

I guess from your post that transport category a/c have fat enough margins that this potential gain is neglegible when there is already quite enough workload.
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Old 26th Dec 2002, 23:30
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JT, in the A320 (and I'm sure this applies to other A3XX series aircraft) the normally YELLOW coloured ROLL/SLIP pointer automatically changes colour to a BLUE 'Beta Target' when engine failure is sensed. The FCOM describes this 'Beta Target' as a 'minimum drag' indication...it is no longer a pure 'slip' indicator. The FD is normally 'on' for all takeoffs and if you engage the autopilot at 100' (as recommended in Airbus SOPs) the final arrangement is a zeroed 'beta target' with the FD commanding a 5deg bank toward the live engine. This occurs in all situations...not just the near VMCA scenario.

I accept your point about this being likely to be somewhat unnecessary except in the near VMCA condition, but I can still see the advantage in the arrangement even at higher weights/speeds although the VMCA margin is indeed larger.

Perhaps you are already familiar with this stuff.

One question for you.
Many instructors use the old 'step on the sky pointer' or 'boot in the ball' phraseology when teaching engine out to ab initio students in jet conversion. Do you know why Boeing prefers the 'diplaced yoke/aileron control' method? I have my views but would be interested to hear yours.
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Old 27th Dec 2002, 04:39
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To elaborate on what Lomapasea said about the 747-400, which almost hit the hill near SFO: one engine was vibrating so badly that the engine instruments were very difficult to read and if the little "ball" (supposedly different in a 400) which shows turn coordination was also shaking in the panel, then maybe both pilots were a bit confused at first. The two extra pilots sitting behind the flight crew were yelling at the Flying Pilot (FO) to push on a rudder instead of turning the yoke.

This might not have been a factor, but how often do most 744 FOs actually make a takeoff and approach/landing, other than in the simulator? On certain 'Interport' Asian trips, the basic crew flies several legs before returning to the US. Apparently, many of our senior FOs avoid these multi-leg trips and consequently rarely fly an approach in the real plane, because the two Captains share most of the approaches and landings, which is a result of our MEC's terror of having type-rated FOs (fewer 400 Captains needed ) ; and you thought that the French were terrified during the Revolution-that was nothing compared to the stark fear of an FO with a widebody rating! Mon Dieu Commissar, le Terror!! :0

Our 400 FOs normally go each six months back to the sim (can be concurrent with Annual Training) in order to meet the reg. for six approaches. landings per six months.
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Old 27th Dec 2002, 11:12
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RatherBeFlying,

Consider the other side of the story .. what did you do in basic trainers when the approach was way too high ? .. either go round, or orbit, or sideslip .. the last option increasing drag significantly and increasing the flight path angle. Doesn't matter which aircraft, the result is similar.

Conversely, best climb requires zero sideslip.

The people to talk to are in the soaring (and, I guess, the FJ) fraternity where the bit of string sticky taped to the canopy is pretty commonplace.

Does the ball give you any information on slip (other than indirectly) ? .... as it reacts to forces, not whence comes the wind ...

Big birds don't have much climb fat under critical circumstances .. it is a matter of balancing workload against benefit .. and, apart from the difficulty of flying a steady small bank angle, some systems don't like prolonged small bank .. if my recollection is correct, the B727 VG would re-erect to a false horizon in these circumstances ? .. perhaps others can offer pertinent systems comment ?

For most aircraft, the optimum bank angle is somewhere around 2-3 degrees with the performance wings level being somewhat similar to that with 5 degrees bank .. why put all that work into flying 5 degrees if you aren't going to get a useful benefit ? This doesn't suggest that you ignore the bank in a (near) Vmca situation while you are getting the beast back under your control.

maxalt,

I don't know enough about how Messrs Airbus Consortium go about their business to comment... perhaps some kind soul might fund a few endorsement-related research programs so that I can rectify that deficiency in my skillset ?

However, may I put the following thoughts ..

(a) with the level of computerised assistance/control available in a FBW machine, I would be very surprised if the OEM didn't extract every last ounce of performance out of the aircraft when the automatics are driving ...

(b) are you sure that the commanded bank angle is 5 degrees ? .. or might it possibly be a tad less ?

Optimum OEI climb will always require a touch of bank ... rudder input generates a side force .. and hence a small sideslip .. to kill that undesirable sideslip we need a counter bank to generate, in turn, an opposing slip .. in the ideal situation, the two cancel each other and we end up with zero slip conditions.

The concern is with flight workload/performance benefit, generally, and control in the low speed, (near) Vmca, situation. It is useful to keep separate the control and performance considerations in discussion even if, in practice, we roll them into the one procedural sequence.

I suspect that Boeing's suggestion for the I/F situation is to capitalise on the I/F scan's predominant emphasis on the AH (by whatever name known) .. the roll is obvious for aircraft with a significant yaw-roll coupling, especially at lower speeds, and the counter-roll pilot input quite natural and effective .. PROVIDED that the trained response in the failure case is a near-simultaneous rudder input .. it is probably not so important just how the appropriate control inputs are effected .. rather that they are generated quickly, predictably, repeatably, and effectively.

I presume that Boeing's thoughts are based on research into training methods effectiveness.

For what it may be worth, my observations from the back of the box suggest that the technique readily is adopted by students. The result (in terms of minimising undesired flight path perturbations) probably is better, overall, than using rudder as the initial input. I make this observation subject to three thoughts ..

(a) the greybeard, experienced veteran will get the required end result tidily either way

(b) due to yaw-roll coupling, indelicate rudder input (often associated with lesser experience or inadequate recurrent training) often results in very untidy yaw/roll oscillations as the wee beastie wends its way down a rollercoaster ride with the hapless pilot desperately doing his/her best to rein it in ....

Ignition Override's observations are very pertinent ....

(c) often, in the training situation, interim techniques are an effective way for the student to acquire a difficult skill in a reasonable timeframe.
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Old 27th Dec 2002, 13:02
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JT, on point (a) yes I agree...thats what they're there for! On point (b) yep, I'm sure the full 5deg is not applied/necessary at higher weights/faster speeds.

My own view on the 'stand on skypointer' term is that it can lead to confusion for ab-initios converting from a typical GA type where (usually) the AH uses a top mounted pointer...i.e. the index moves instead of the roll pointer. This sometimes causes confusion in the first sim session (the roll indication appears to be reversed), but soon becomes natural. Maybe Boeing worried that the inexperienced might revert to type in the engine fail scenario and apply the wrong rudder as a result?

The slip ball in older B732 sims is near useless and could be very misleading as a means of determining PRIMARY rudder input.
In the real world a surging engine failure could result in the ball shooting from one side of the indicator to the other. Not much use in controlling the situation if you've developed the habit of using it in isolation.

BTW, the trick to preventing the roller-coaster ride on engine failure is to apply the correct rudder per the approved method and then HOLD IT. Cycling the rudder just creates almost uncontrollable PIO.
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Old 27th Dec 2002, 17:27
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just to be more type specific...

...we were practicing V2 cuts on a 767-300 sim.
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Old 27th Dec 2002, 21:46
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maxalt,

Have to agree ... "squeeze and freeze" is the 737 mantra when it comes to rudder ...

lightoutandarmed,

The principles are the same ...
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Old 28th Dec 2002, 16:02
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Just a couple of points:

1. It was a UAL B747-400 that almost whacked the hill coming of San Francisco, not BA. The F/O was flying and that’s why the heavy types go back to the sim a bit more often now than they did originally under the AQP program.

2. While I agree that using rudder first, and correctly, is the most aerodynamically efficient technique for a V-anything cut, it can also be the chanciest. AA was doing some training on big fast airplanes (757/767) for nationals of an un-named state a few years ago and discovered that they had a less than 50% hack rate in getting the correct rudder during high-body angle V2 cuts. If you stick in the wrong rudder, that can constitute the opening scene of the last act. The solution, from AA or Boeing I’m not sure, was to have them promptly pitch down to 12 degrees, while eliminating adverse lateral motion, initially, with aileron. Upon arrival at the new pitch attitude, the candidate should note where the yoke is pointing and make the appropriate rudder input, and subsequent trim arrangements. While far from elegant, it is not fraught with risk as is the more dynamic response. It also, as has been pointed out in earlier postings, leads to smoother and more accurate responses as experience grows.

3. Additionally, between the laws of physics and economics we are unlikely to ever have a simulator motion system that will accurately reproduce the cues of a major thrust loss, with all of the potential attendant motion and g cues. A procedure that is simple and relatively foolproof is the way to go for the majority of aviators. Boeing and Airbus recognized that in their collaborative efforts to simplify recovery from unusual attitudes, understanding that for most, the simulator was the only training vehicle available.

4. To that end, I would like to add one more amplifying comment. Maxalt correctly promotes reducing PIO through application of the correct rudder and HOLDING IT. The holding it part is spot on, but many folks get caught up in the CORRECT part and decide to refine that input before the motion fun has settled down. Better to stick a bunch of rudder in the correct direction until the initial control issue is resolved, and then refine it. This technique, from a sim point of view, is even more important on a twin than on the 747-400, which is a relative pussycat after the 757/767. This is really far less an issue in the airplane where the motion doesn’t have a software loop to get through, but a good drill will work in the real world too. All the Vmca and related discussion is appropriate in the context of flying away after the initial excitement has been resolved, but as per the initial entry, I reckon the aileron input was only intended for initial response in a particular circumstance.

PS. 'Squeeze and freeze' is a splendid phrase thanks; I'll remember to give the credit appropriately.
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Old 28th Dec 2002, 16:51
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Right-on madtrap;

After 35 yrs and 9000 hrs of mutiengine [ lt/med twin] flying and having been to many of the sim schools [Flt Safety, Simcom and RTC] I like the "pitch to five [or whatever is appropriate for the type], roll to the bug, step-on [and hold] the ball" approach which works every time particularly on the gauges. With the heading bug set to departure [rwy] heading it is very natural to roll to the bug and the follow-on rudder is also natural and rapid. Virtually eliminates initial incorrect response such as stomping on the wrong rudder at a high pitch angle.
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Old 28th Dec 2002, 22:45
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madtrap,

No credit due me for "squeeze and freeze" .. I picked it up from a checkie somewhere in the past in relation to 737 asy work.

But the approach is very useful with pilots new to the shorter 737s .. initial (guess) steady rudder input ... lock the legs ..... level the wings on aileron ..... small gentle rudder correction to level the yoke .(squeeze it, man) which covers either not enough or too much initial rudder .... lock it ..... aileron correction ... and so forth until the desired setup is reached. After a few practice runs, most students can catch a failure quite tidily ....

.... but ... rock and roll with the rudders .. and that is just what one gets as a result ....
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Old 2nd Jan 2003, 07:09
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MadTrap: In my sixteen years with this company, I've only once been trained for an engine failure at a high pitch angle (once at 15-18 degrees). All of the rest were either just after V1 before the nose came up, or maybe once or twice on downwind, possibly in holding. One of our FOs was a 737 Captain at the late Vanguard, and described how much rudder he needed to fly an actual 737 climbing out of Midway with the engine power surging back and forth.

Would it not be valuable training to have a flame-out at MDA on a LOC/VOR approach?
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