dvt
YIKES ! 30yrs of flying transport aircraft here. That is one manuever I've never seen and hope I never do. I would
respectfully suggest you consider limiting forward slips to
light aircraft and gliders.

That swept wing airplane you are flying can and will do strange
things to you when you least expect it. Fly it like you were taught.:D, and it will treat you nicely.

Slips
 

dvt is a little irritating. There are two possibilities, it seems to me.

(1) dvt is confident of being right. I.e. it's all right to slip a 737-800 to lose altitude nearing a runway. In which case he just does it, and is confident of not having to explain his actions to a supervisor.

(2) dvt is not confident of being right. In which case he would be hostile and oversensitive in responding to the expressed reservations and concerns of most of the other posting members of PPRUNE.

Obviously (2) fits the data better than (1).

Now as to the merits of the quite interesting issues dvt raises.

(1) Nothing should interfere with the stabilized approach concept for largish jets. A slip (in such an airplane) is a not good idea below 1,500 feet. Surely that's a fair comment.

(2) There are slips and there are slips. Full deflection of a rudder are a really stupid idea in a swept wing jet. Light or moderate deflection with enough cross-control on ailerons, might be fine. Don't know. More to the point, neither does dvt. Is he comfortable with discussing "crossover" speed etc?

(3) If ATC gives you "crap" vectors, etc, presumably one has the ability to either dirty up or slow up. That way the "crap" vectors aren't as "crap" since the turn radius is tighter. Hence, no need for the heroics at the bottom of the approach.

(4) Many airline and jet pilots do aerobatics for fun. In an airplane designed for it. Treating a passenger jet differently (and more conservatively) is hardly effeminate.

(5) dvt needs to be counseled by his Professional Standards Committee. It's not his colleagues' job to justify their discomfort with slipping a transport jet. It's his job to justify doing it (in the absence of a compelling need to do it, or in the absence of an emergency).

(6) A Captain can do absolutely whatever needs doing in an emergency i.e. no engines, smoke in cockpit, etc. Slipping is one such thing. But when the aircraft is otherwise in fine shape, I just can't see slipping on a regular basis. That one's testosterone permits one to do it is not sufficient explanation.

All,
For those of you a trifle reticent about “slipping” him bigfella balus, all B757/767/744 on an autopilot coupled approach, below 500 ft, handle cross wind by side/forward slipping ( take your choice) admittedly in the case of the B744 a combination of crab and side slip.

A B767 is all sideslip with the aircraft centreline aligned with the runway below 500’, in a max (A/P) crosswind the wing down is about 7 degrees, and it does it beautifully.

As for D.P Davies, with all due respect to his fans, I would strongly suggest you take some of his pronouncements with a grain of salt, in fact he had very limited experience on large aircraft, but that did nothing to moderate his views.

He also had a highly developed "not invented here" complex, that was not trans Atlantic limited, it also applied cross Channel. The Caravel was never certified in UK, ( the forward fuselages were originally built by Dh).

Furthermore, aircraft handling characteristics have improved greatly since the late 50’s and early 60’s, just fly your current party transport to it’s sops, not according to Dai Davies.

Quite frankly, some of the modification demanded to B707-300/320 on the G- register (non Boeing stab trim settings for T/O, modifications to the spoiler isolation system to solve a non problem, but making handling jam stab procedures far more difficult, stick pushers for aircraft that DID NOT deep stall, to name three) seriously degraded the safe handling of these aircraft. A stick pusher going off in the flare in strong gusty cross winds made for some interesting moments.

If my memory serves me correctly, for some time he would not even permit the use of Flap 50 for landing in the early BOAC 707. The claim was that the aircraft had a slight pitch up, before the nose pitched down, in a Flap 50 stall. This was quite true, it did, the slightest little nibble, but by that time the airframe buffet bordered on the frightening, there was no shortage of natural warning, quite apart from the fact that the stick shaker was also going crazy. But the fact remained, the nose always fell through.

I often wonder by how much we shortened the airframe lives of these aircraft in this kind of training ?? But it seemed like a good idea at the time. To my mind, given that any pilot doing this kind of type rating was already an experienced pilot, approaching stall buffet would have been enough, without doing full stalls.

AAAAAH !!, the Good Old Days. !!!

Tootle pip !!

Hope I'm not being pedantic here Ledsled, but the B767 manual states "A/P systems initiate a slip with a maximum bank angle of 2 degrees when the crab angle exceeds 5 degrees"

There is a considerable difference between two degrees and seven. Also, the autopilot will be completely stabilised on the G/P and localiser, on speed and spooled up when executing it.

The other problem with sideslipping a swept wing aircraft is of course that the apparent airflow to the leading wing is much greater than it is to the trailing wing. If you have enough slip at low airspeed, I would imagine you could find yourself with an unexpected wingdrop.

Any expert comments on this?

Referring to the link explaining the difference between a side slip and a forward slip, and to some of the posts trying to explain the difference, I can't see any difference, except that in the so called side slip, the amount of slip will usually be limited to that amount needed to off set drift. Whereas the so called forward slip is limited by rudder v aileron/roll spoiler authority and the size of the pilot's gonads.

The aircraft doesn't know or care which way the wind is blowing, both manoeuvres involve crossed controls and a flight path into the lower wing.

For my money, they're one in the same manoeuvre.

Bally Heck,

With all due respect, read a little further ---- at 500 agl, the A/P “kicks” off the drift, and from there to touchdown it is all sideslip, the numbers you have quoted are very close to what the 744 does under the same circumstances.

Would anybody like to comment on the L-1011 A/P coupled in a cross wind, I seem to recall it had a much higher A/P coupled limit than the 767 or the 744, which is 26 kt or so.

Tootle pip !!

LeadSled

At the risk of going slightly off thread and also of repeating myself, I quote from the B 767 vol 2

ROLLOUT mode engages at 5 foot R/A so the aircraft will probably still be wing down at touchdown.

It does not at any time "kick" off the drift, and from the way I read it, a crab angle of much greater than 5 degrees would result from a strong crosswind once tha A/P had adjusted to 2 degrees bank angle. That however would probably happen at crosswinds outside the certificated limit for autoland.

Hey Gang,

Notch Johnson here. I've been away the past few days, with my girl BJ, slipping her other things besides airplanes. She likes to slip out to the country and ride the baloney pony with me. Anyways, I'm back and I'm truly astounded at the response of this thread. Though I think it has more to do with my charming personality than anything else. Right? I didn't want to discuss the merits of a simple flight maneuver, but you are right...I don't own this thread. So forgive me. Ok then.

Here's an excellent question on reader’s minds, submitted by Mouse...
"For the benefit of my curiosity when would you envisage needing this particular 'trick'?"

Well readers here my short response….”When going around is not the BEST option”.

I can hear you all now...."GASP! Oh the Horror! Murmur! Are you mad, man! Going around is ALWAYS the best option!" I’m my opinion; this is not always the case. Let me explain. It seems to me, many of you may only be familiar with flying into “flat and rolly" places like LHR. You can be forgiven for holding the view that Going Around is always superior to slipping it in. However, let me take you into some of the "Salad Bowls of Terrain" in places like Central/South America and the Caribbean. These places are scary enough in the daytime; try a visit at night. Many of these places have some of the most complicated and insane "Missed Approach" procedures you could imagine. Their "Engine-Out Missed Approach" procedures are even worse! You look at them and you say ..."You've got to be joking me! Right!" It looks like they were developed to satisfy some legal requirement knowing full well that Chuck Yeager might not be able to pull it off.

Anyways, case in point. I'm flying into one of these "Salad Bowls". I see that I'm high by a couple of thousand feet. I'm fully configured at final approach speed. There's a tailwind. My ND shows RED terrain all quadrants. So now I ask myself these questions. Can I “S” turn or 360...Hell NO! Shall I Go-Around and take a chance flying one of these widow-maker missed approaches...It depends. OR, can I perform a simple Forward Slip and be stable by 1000 ft AGL? Yes, I can. I would submit to you, given these circumstances, a Forward Slip can be a BETTER option than a Go-Around. Unless you want to give me a GREEN cockpit and a set of Night Vision Goggles, I think this maneuver is a good one to have in your "Bag of Tricks".

Don't get me wrong. I prefer a straight in same as anybody else. But I don't wish to debate the merits of a maneuver that has served me well, 5 or 6 times over the course of my career. It’s safe, it’s approved by the FAA, and it works. When someone tells me it’s unsafe, I get pissed cause I think it can save your @$$. One of the things I learned early on is " The PK (probability of kill) of a mountain is 100%”. Now, if you don't think you have the skills to do one, then don't. However, if you can’t do one of these, I don’t think your chances are much better on a “Window-Maker”. Put it this way…a simple Forward Slip is better than the potential CLUSTER !!!! waiting for you in the dark. And I’ll damn-well do again if I have too.

If you are "a couple of thousand feet high" then making the missed approach gradient would be a doddle, even with high terrain in the area - unless you began the approach at some massive overload.

One assumes dvt that your company forgot to tick the "speedbrake" option when ordering their Boeings?

(Anyone else flummoxed by the "baloney pony" remark, or is he just being crude?):confused:

Bally Heck,
Are you quoting from a Boeing Manual, or a company version of a Boeing manual, that could be the difference, unless Boeing has changed things since I last operated B767.

As I said before, those numbers are very B744.

To those who were brought up on wings level/crab cross wind approaches, the B767 came as quite a shock to some, as if Boeing had committed some kind of heresy. As the manual will tell you elsewhere, you almost can't scrape a pod on B767, short of "shortening" a main gear, you will ding the nose or tail cone and a wing tip before you get a pod, quite a change from the "good old" 707.

Where I was working, very strong cross winds in severe clear conditions were common, there was no mistaking the behavior of the aeroplane.

Tootle pip !!

Too right LeadSled, roaring forties mate, can’t handle a stiff crosswind, better go home and cry oily tears on mamma’s cotton apron lap.

So, dvt, you wanna a medal friend? Of course you can slip a large aeroplane, x-wind land or descend, all works the same, doesn’t take an idiot savant to put it together. Point is, friend, set her down on the first third, fuselage aligned with the centerline, on speed, that’s a good enough landing.

Anybody gotta serious a problem with that?

BS, a hearty I'm with you on this one!

If I remember the original query on this subject it was can you do it? I don't know, as I have never flown a Boing product. I do fly a Saab, however. The Saab manual specifically recommends a wing down landing, which if I understand anything means a forward slip technique (or else an ealiy arrival at the terminal). Maybe the Boing manual has a similar paragraph?

On the subject of 'slips'(aeronautical): as far as I can work itout there is little to choose aerodynamically between the foreward and the side versions, but do any of you remember slipping and sliding turns (not enough rudder/too much rudder)? You are all going to lose your medicals to ulcers if you don't relax a little.

And furthermore, tried it yesterday on an MD-11, no big deal. As far as I can tell, if you take into account airflow disruption to the downwind engine(s) and pitot/static ports by compensating with extra airspeed during the maneuver, it’s very benign stuff, my son’s kid sister could pull it off without wetting dvt’s drawers.

Can’t really believe the above garbage regarding fin sideloads (AA587 notwithstanding), surely the designers took into account the possibility of repeated heavy turbulence encounters and max-dem crosswind landings.

Also not really sure why Prof Davies aka Handling the Big Jets pens his cryptic warnings regarding this subject re large transport category airplanes. Anyone know if he’s still alive, willing, and able to provide a reasonable explanation? If not, surely the Cathay Old School Boys must know!? They know everything, bless their degenerate RAF hearts!!

Bug Smash -- I readily concede you may be right - that slipping larger aircraft for glide slope enhancement just doesn't matter as an airframe life-limiting issue, but ONE detail is a source of concern:

Tail strength, etc are related during design to anticipated max crosswind speed for a given aircraft. However, no clear principle limits forward slips to the max angle implied by max crosswind speed. When slipping 'for effect', one tends to want to crank it in hard to get the 'feel' and then back off somewhat for tuning the result.

Done some distance above ground and at the pilot's discretion, a controllable fwd slip could quite possibly present an angle to the relative wind of TWICE what the max crosswind landing will do. Furthermore, this will be happening at velocities well above touchdown speed.

So, given that aerodynamic loads often increase at the cube of the airstream (vector) velocity, in fairly normal slip speedbraking one might be looking at 4x the tail load of a max allowed crosswind manoeuver - and that is before increments for turbulence and handling induced load factors.

In answer to the topic in question.....
Yes, the B737-800 can be forward slipped to increase descent rate on final approach but in 5000 hours of flying this aircraft I have only seen it done once and I am hoping that I never see it again. It is extremely uncomfortable - and not just for the passengers.
To end up in a situation where it would be verified is extremely unlikely and would be the result of incompetence on behalf of not only the ATC at the time but also both flight crewmembers.
Orbits on final have their own dangers (see the A320 crash in Bahrain whereby the circuit was performed with neither height loss or speed loss) however are alot more comfortable for aircraft and crew.
I am sure that Boeing recommendation for forward slipping as a way of increasing descent rate on finals would be the same as their recommendation for using speedbrake with flaps more than 15 or maintaining flap limit speed when extending flaps (using flaps as speedbrakes)...... i.e. NOT.

Do it once if you don't believe me. After doing so I am sure you will not do it again if your airline wants to keep their passengers.

Point taken arcniz. Surely, however, the designers must take into account the possibility of a heavy turbulence encounter at high speed (something that would potentially generate stresses far higher than a max x-wind landing), violent yaw-damp failure induced dutch roll, or engine-out maneuvering at high power settings when considering maximum lateral loads to be withstood by the fin assembly.

redturk, I agree, the maneuver is not a pretty one, but for the purposes of understanding large aircraft behaviour and design limits, a very interesting one.

bugg smasher,

One ought to be VERY circumspect in presuming just what the design team does and does not consider.

The design standards, as frozen for the particular design, determine the minimum set of requirements for which compliance must be shown.

There are many areas where additional work would be very nice to have ..... whether the design group addresses such matters is difficult to determine. Having been involved in such things, I can only say that one ought to be a little cautious on the line ......

This is one of the reasons that we ought to operate, to the maximum extent reasonably practicable, in sensibly strict compatibility with the manufacturer's AFM and crew manual data.

It may be a bit too late, at the time, to discover that you have pushed the boundaries a little too far ...........

LeadSled
It's odd how the memory plays tricks on one - I would also have said, from memory, that the L1011 had a higher x-wind limit. Just dug out the Big Airways/Callie F.M. and the only reference to x-wind limits appears in the A/P engaged to 50' RH limits, which gives "reported wind not greater than 26kts, x-wind component not greater than 20 kts, tailwind not greater than 10 kts and no abnormal turbulence". For Tristar x-wind operation the forward slip was, of course, the ONLY way to do it and the other relevant entry in the F.M. is in the section on x-wind landings ...
"Touchdown on one main landing gear is permissible and recommended"

j_t, if you were involved in aircraft design, perhaps you might be able to dig a bit and provide us with more information on fin design requirements. In addition to the above examples, I have been stuck on the ground in typhoon conditions in the Far East, and have seen from my hotel room window 747’s parked directly across the path of the oncoming storm. Those fins were subject to a sustained broadside (several hours) of 100 knots or more, with frequent gusts to 150, yet to my knowledge, those aircraft were not subject to any special inspection procedures afterwards. The only conclusion I can draw from this is that brick shathoose strength (technically speaking) is a basic design requirement for that particular aircraft structure.

Perhaps you can enlighten us with the facts.

Here's a link that gives some idea about the stresses Boeing engineers were thinking about when they design an aircraft's vertical fin...So long as you're not abrupt with th flight controls, a forward slip is well within the design limits. Which answers the intent of this post. Design limits can be exceeded when "Over Yaw" is induced by abrupt inputs to the rudder. What's far worse is to abruptly cycle the rudder in both directions. However, I think a Boeing would BEND but not BREAK with such inputs. Just a guess. But perhaps, Bugg Smasher, our resident test pilot will try this one on for us on his next trip.

It's reassuring to know that Boeing aircraft are designed to handle full rudder (steady state sideslip) in one direction, followed by full deflection in the opposite direction from steady state sideslip times a factor of 150%!!! That's one tough bird. What must be avoided is aburptness and the resulting "Over Yaw" that being abrupt creates. It would be Gameover on an Airbus. I believe an Airbus is designed to handle the stress of sideslip in one direction only.

http://www.ifalpa.org/sab/03SAB001_U...n%20Boeing.pdf

Excellent link dvt, a must read for everyone. As can be seen from the bulletin, the sideslip maneuver produces no unusual stresses on the tail whatsoever.

With that, I now stow my ‘resident test pilot’ wings safely in my desk drawer, and go out to drone along the night skies secure in the knowledge that if something is going to break, it’s not likely to be the fin. Anyone out there who wants to give multiple full rudder reversals a go, please make sure someone on the ground has a video camera.
:cool:

buggsmasher,

Not an easy question to address and certainly one wherein generalisation may be more distracting than illuminating. While the present thread has, as its interest, fin loads, the following more general comments may be of some use ...

The Type Certificate Data Sheets will give an indication of the design standards which were applicable to a particular type. A review of the relevant issue (and the host of anciliary documentation) will give you an overview of the certification requirements applicable at the time ... Then there is the issue of design variations, concessions, equivalent safety determinations and the like .. Upshot is that, unless one is with the design organisation it is near impossible to find out just what was or wasn't done, especially in respect of matters extending beyond the minimum requirements. To a large extent the Industry relies on the professional integrity of the design organisation and the assessing regulatory body to give us some measure of protection .. and we have seen a few major screwups over the years where such reliance was proved to have been misplaced in the hard light of inservice experience.

It is important to realise that the people within the design and certification areas are just as human and fallible as everyone else. I have seen very competent engineers make assumptions which are quite reasonable to an engineer but which are materially at variance with what happens in the real world environment. Further, with modern design of large aircraft, as the projects become larger and discipline specialisations increasingly focussed .. there is the problem of overall design project management and what might slip through the cracks ....

To me the principal guiding light ought to be for the operator (and the operator's pilots) to follow the guidance which is laid down by the manufacturer (and ought to be in the operator's prescriptive documentation) .. for the simple reason that such guidance is based on the (usually unidentified) assumptions made in the design and certification processes. It really comes down to a matter of trying to walk through a minefield with marked safety pathways .. certainly you can step off the marked path and not have a problem ... or, conversely, do so and have a big problem ... difficulty is that you have no way of knowing outcome probabilities in the absence of data. It all comes down to a matter of sensible risk management and risk minimisation practices.

While being of sufficient modesty not to reproduce his comment here ... the earlier observation made by HOMER SIMPSONS LOVECHILD does, I think, sum up my thoughts precisely ....

My own worries tend to look less toward static strength problems (although the failure characteristics of composites can present some excitement) and more to the fatigue consequences of operation and maintenance practices which are at variance with the assumptions made within the original design and on-going MRB systems .. and we have seen a number of fatals over the years due to precisely this consideration. Having been involved in earlier lives as an engineer at both ends of the process I can only urge a conservative operation of the inservice article ... there are just too many imponderables and, as airframe lives are pushed out way beyond original life cycle projections, too many opportunities for spectacular outcomes.

In respect of your monsoonal observations, this is an example of the sort of situations which give rise to longer term cumulative structural concerns.

Scanning through the IFALPA/Boeing article in the link above suggests to me that Boeing, also, echoes HOMER SIMPSONS LOVECHILD's sentiments .....

This answer is probably not at all what you wanted ..... sorry about that... but, then again, if you have a TP background .. you know all too well all of what I have said above ...

I realise this thread started with reference to the B737-800, however Airbus has recently provided some timely information on the subject of JAR/FAR 25 certification of yaw control.
Basically, the most severe 'in service' encounter of lateral gusts, rolling maneouvre and asymmetrical engine failure must be taken into account. The aircraft structure must be able to sustain a design limit load of 1.5 without permanent deformation or failure over a period of 3 seconds.

There are further requirements/ considerations....

"Boy, if the manufacturer don't recomend doin' something,dont go stikin' yer dick in there!! "

I agree j_t, with all of your comments; proceeding with great circumspection in light of potentially significant hidden and/or known design flaws, cumulative airframe stresses and faulty maintenance practices, contributes greatly to a pilot’s potential seniority. Re Homer Simpson’s comment quoted above, however, most manufacturers do in fact recommend slipping the aircraft, albeit in the context of a crosswind landing. The Boeing bulletin kindly linked by dvt indicates that this maneuver may be safely accomplished throughout the flight envelope.

In my view, therefore, if dvt wants to side-forward slip his 737 till the cows come home, I see no safety-related reason not to. That the passengers might view things from a different angle is a horse, of course, of an entirely different color.

Here's what Airbus says about their design considerations...

http://www.ifalpa.org/sab/03SAB002_U...n%20Airbus.pdf

Basically, it seems they've designed their tail structures to the MINIMUM requirements specified by FAR/JAR 25. Boeing by contrast, has gone beyond the minimum requirements. I've always been partial to Boeings anyways. This is just one more reason to justify my prejudice.

However, Boeing points out, that while their tails are designed to handle a great deal of sideslip stress, the engine mounts are not designed to that same level. Cyclical over yaw, may overstress the mounts. Large sideslip angles, via abrupt inputs, may cause engine surge and stall at high power settings. Reason enough to be smooth on the flight controls at all times. This does not mean, that a forward slip can't be a smooth, controlled and useful manuever. I still see no reason to remove it from my "BAG". At least on Boeings. However, those of you flying Airbus' "made of glass", may want to keep your bank limiters set to 10 degrees and ask for long finals.

"If it ain't a BOEING, I ain't GOING."

Sorry dvt, didn't mean to step on your prejudices! For myself, I've had a choice for years as to which type to fly, but after sifting the B.S. have decided to eat my meals in comfort with a tray table and sidestick readily to hand.
However you do make a good and valid point that the Boeing is capable of rudder reversal from the steady state sideslip...
My reservations on slipping large, swept wing aircraft are the same as others have stated; largely concerned with control response, material fatigue, airmanship and comfort.
Dire circumstances notwithstanding, perhaps it is better to recognise the 'high and hot' situation earlier and do something more appropriate than resorting to side/forward-slipping. A go-around could be pro-active management of an unstable approach.

spleener,

You do not provide details of the Airbus data to which you refer. However, your description suggests that you are referring to design static loads. Some problems relate to whether the prescribed loads are, in fact, the most severe or merely presumed extreme loads .. quite apart from the potential for dynamic responses giving rise to higher loads than are obtained by steady or smooth/steady control inputs ....

bugg smasher,

I have no problem with slipping .. quite clearly the manoeuvre is a necessary function of getting from A to B. My concern is only with some of the thread's comments which infer that ill-considered pilot control inputs do not present a potential problem ... as to whether the SLF might be adversely impressed by substantial slipping is another consideration altogether.

dvt,

Again the problem (regardless of flight loads under consideration) relates to whether the design standard prescription is, or is not, sufficiently conservative to cover all reasonably expected real world situations. There have been instances in the past where the design standards have been found wanting and beefed up somewhat ... tailplane ice-related stalling, prescription of sharp-edged gust profiles, and earlier fatigue spectra assumptions come to mind, for instance. I wouldn't suggest that one ought to avoid slip manoeuvres .. merely that one ought to be conservatively cautious in large aeroplanes ... small trainers, such as the beloved SuperCub and like ilk on the other hand, are far more suited to heavy handed slip inputs.



As to the situation where the aircraft is held high or whatever ... if one cannot reconfigure to a higher drag and achieve a steeper profile at lower speed, then a precautionary early miss or orbit is probably the better option. My experience is limited to dinosaur Boeings .... there was no problem in achieving 1-1.5 nm/1000 when that was necessary ... provided that one was well ahead of the game plan and dirtied up early ... this might need to have been effected at 10,000-12,000 feet on occasion ... but it works just fine. The pilot who is just along for the ride and enjoys surprises, however, is an accident just waiting to happen sooner or later.


This has been a fun thread, though .....

People - inside aviation and otherwise - have grown more conscious of tail loads and airframe life issues after AA587. Metal fatigue and corrosion-related accidents in a maturing fleet amplify this awareness.

As J_T observes, the ability of an airframe to reach maximum service life is directly relates to how much abuse it has taken along the way.

I predict a move toward 'life-history' FDRs in nearly all future-build transport airframes, accumulating a 'perpetual' trail of g-loads and impulse events which may then be used to make refurb decisions along the way and then, finally, to determine the final flight date for the aircraft chassis. This use of LHFDRs will give 'tail-cover' for regulators, operators and insurers at a lower cost than the alternatives of 'excessive maintenance' or operation until a fatigue related accident/incident occurs.

Should make it MUCH harder to gloss over the barrel rolls.:p

arcinz

I like the concept of life-history FDR's, it seems logical to not only track maintenance but also the loads the airframe has experienced over its life. For smoother operators this could reduce costs and increase resale and for those who perform such sideslip manouvers - well lets just say you would know what you were insuring or buying.

dvt,

Why are you so agro that no one else supports the use of this technique. Did you do it on a check and are now having to answer to your company Gods?

I've had a fellow pilot select FLT and cross it up on final - hot and high, CRM non-existent - it's not fun for the other bloke. I know the aircraft can do it, but it ain't a good idea for more than just structural reasons.

If operating as a crew then you shouldn't surprise the other half, even if you do inform him of your intentions I doubt (time is limited unless you planned this from ToD?) he has time you consent or undertands to what extent you intend to do. It really sounds like you would be better flying solo.

Granted the Vnav data of late has gotten worse and worse but how do you miss manage your energy state so badly that this manouver is required. OK so your flying into a "Salad Bowl", big deal, on this occasion just be a bit more reserved.

Good luck with the company if they are trying to haul your ass.


:rolleyes:

Thanks Mudd Skipper.

I post facts. You post opinion. I'll take your opinion for what it cost me. Squat! If you had any real experience in Central/South America you'd have understood my post better.

For all intents and purposes this thread is finished. Boeing and Airbus have stated their position on the appropriate use of rudder. See my previous links. A forward slip is WELL within the envelop on a Boeing and within the enevelop on an Airbus.

Fini non?

Good Bye All.

Bon Voyage dvt.

Now...... does anyone smell children...:rolleyes:

.. perhaps the sideslip issue has been well canvassed .. but, surely, the thread can move onto other new threads involving difficult approaches and ways and means of getting around the problems while still maintaining a high level of risk management ?

A quote from Air Publication 1979A, Cadets' Handbook of Elementary Flying Training !st Edition April 1943 - issued by command of the Air Council;

Page 85 chapter 14 entitled SIDESLIPPING.

"General Principles.
The manoeuvre known as sideslipping may be roughly described as making the aircraft descend through the air broadside on, while gliding. The direction in which the aircraft travels is at an angle to the direction in which the nose is pointing. We can sideslip in a turn as well as flying straight.
The advantage of the sideslip is that it permits us to increase our rate of descent, that is, to lose height more quickly, without increasing our forward speed.
By varying the amount of slip, we can vary the rate of descent......the degree to which any aircraft can be sidelipped depends on the extent to which the rudder is capable of overcoming the "weathercocking" of the aircraft, provided by the air pressure on the fin and keel surfaces This imposes a limit to the amount of bank which can usefully be applied and thus to the amount of sideslip....."

There is more - but by now you will have got the picture.

Reference to another old RAF manual of the World War 2 era, also has advice on sideslipping - but no trace can be found of the term "forward slipping".

Publication 129, the Royal Air Force Flying Training Manual - Part 1 Landplanes - dated November 1937 and reprinted June 1938, has this to say at Chapter 3 Basic Flying -paragraph 116 under the heading SIDESLIPPING.

"A sideslip means a state of equilibrium in which the aeroplane is travelling in a direction at an angle to that in which the nose is pointing. The unintentional slip is bad flying, but the intentional sideslip is a valuable manoeuvre to increase the rate of descent in a glide without gaining speed"....etc etc

So there you are. No such animal as a forward slip - not in those far gone days, anyway.

.. an Americanism, John .... I noted some FAA references in an earlier post ... if you like I can give you copies next week when I am back in town ....

Bring on life history DFR's.

It really is a brilliant idea. If there is one person operating foward slips and trying to justify it, then there is probably ten or more others doing the same.

No I have not flown in Central America, just a little country we call Papua New Guinea - short one way jet strips at several thousand feet and Wellington in NZ can be fun on good days too. Sorry not a pi*** contest but I would suggest things can become local SoP's but that doesn't mean they are good airmanship (whatever that means).

Personally I would not wish to fly or buy an aircraft which has been pushed harder than required, as an SoP. Fortunatly my ops generally buys new aircraft and we fly in a reasonable conservative world.


Cheers

My best to the Kids:)

"Life history recorders" are a fact of life in many operations and will likely increase in use.

The devices are generally called quick access recorders or similar and provide a convenient means for the operator to monitor such things as performance, engine operation etc ... and operational exceedances. The former are a great boon to tech services engineering people ... while the last, with sensible management and union practices, can be a useful flight standards management tool.

Interesting ENVELOP????? Spelled twice this way in the post.

Now it's time for DVT to go back to MS Flt sim and practice his/her short field landings in the Concorde.

At least this line of rationale is reassuring to a PPL who travels as pax rather a lot and would feel very uncomfortable about anyone needing to slip an airliner, certainly whe he should be stabilised.