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View Full Version : Initial training : Slip Yes ……Slip no


graziani
13th May 2024, 16:44
Consider a single-engine airplane , if you need to increase your descent rate during a simulated engine failure during initial training phase …..

I see 2 schools of thought :

1first : never never NEVER use and teach slip technics to loose altitude If high , during initial training …is it to dangerous for the student Pilot …and it is possibile to manage in bad way during solo flight and stall /spin can occur.


2 second ) slip techics is a important skill to learn …..even during initial training……….of course , the student Pilot must not use frequently slip technics every time is to high….but using the slip tech during simulated engine fail is a important task to learn ."……

I appreciate all opinions tks

visibility3miles
13th May 2024, 18:27
If you have to lose altitude before landing, you can always do S-turns, i.e., flying a zig zag pattern to increase the distance you fly before you reach your landing spot.

I was taught to crab in order to deal with strong crosswinds on approach then to slip for the actual landing/touchdown, but it never came up during training for an engine failure. In the latter case, it was always find a safe place to land, then do your best to land there safely.

A strong crosswind will typically have a strong headwind component as well, so your speed relative to the ground is decreased.

https://pilotheadquarters.com/crosswind-landings-crab-vs-slip-which-should-you-use/



The amount of rudder you can apply for a slip determines the maximum crosswind you can handle when landing.

I’m not an instructor nor an expert.

https://pilotworkshop.com/tips/slipping/
​​​Is slipping a good technique for losing altitude quickly on final approach? Is it best to slip to the left or right (or does it matter)?"​​​​

“Let’s back up just a little and talk about slips. There are two kinds of slips. One is a side slip and the other is a forward slip…

To lose altitude quickly you need a forward slip. To induce an effective forward slip, the pilot needs to drop one wing and apply a large amount of opposite rudder. Remember to keep the nose well below the horizon during the slip. Since you now have crossed controls, the last thing you want is a stall at low altitude. In addition, the airspeed indicator may be inaccurate as it is not traveling parallel to the direction of flight. Another reason to keep that nose down and maintain an extra airspeed margin is that you have a higher descent rate than normal and it will take some energy, as in extra airspeed, to fix that before touchdown.

You can slip with or without flaps unless prohibited by your Pilot’s Operating Handbook.

graziani
13th May 2024, 18:45
tks visibility3miles (https://www.pprune.org/members/67616-visibility3miles).....but my question is about a simulated engine fail in a single eng. ...... if a slip can be incuded in training task in a safe manner or it is better to cancel it in a training programme ???

MechEngr
13th May 2024, 18:51
Would slip training be given for gliders and sailplanes?

Whopity
13th May 2024, 21:11
If you plan your descent to arrive at a Low Key position at an appropriate height for your aeroplane then all you have to do is maintain the aspect to the aiming point. Use flap to increase the rate of descent to bring the aiming point towards you. If you don't have flaps then slipping will acheive the same thing.

B2N2
13th May 2024, 21:52
They shouldn’t solo if they can’t demonstrate a half decent forward slip.
What if they have a flap malfunction on their solo? Divert to a 14,000’ runway?
Student pilots should be able to land full/partial/no flap in a designated runway area.

Vessbot
14th May 2024, 02:50
In the US, training this maneuver is required by the regs.

RetiredBA/BY
14th May 2024, 08:24
Side, slip. why not. Saved the Gimli glider !

Bergerie1
14th May 2024, 10:37
I haven't tried it in the real aircraft but you could sideslip the 747 simulator just like a Tiger Moth. But I guess you would need to know how much in order to protect the podded engines. I used to practise deadstick landings in the sim - rather good fun!

Jhieminga
14th May 2024, 11:19
Having used Cessnas a lot, a forward slip with flaps extended is prohibited on several of their models. With that in the back of your mind you need to look elsewhere to adjust the descent profile for a forced landing. As Whopity said, flaps are a good tool to use and we trained the students to get to an appropriate 1000' point while aiming a third of the way down the strip, then use flaps to adjust as needed and bring the touchdown point nearer to the beginning of the strip.

Once you're in an actual emergency situation, anything goes of course. With that in mind I might use a forward slip if needed. I'm not too fussed about using the aircraft again if I can at least walk away from it in one piece.

The trouble is that if you train a student to use the manouvre on a regular basis, the student will continue to use it and may get him/her/itself into trouble later on. I am basing this on teaching on an integrated course. The situation is different in the gliding world and may be different in a strictly PPL/LAPL environment.

blind pew
14th May 2024, 12:42
During my initial training on an equivalent to the CPL general handling test I was given an engine failure over the largest field on the Isle of Wight ..my normal technique left me way too high and having been told never to turn away nor taught to side slip I failed miserably.
I later got into SE instructing and finally glider instructing including aerobatics and mountain flying.
on ALL of the gliders I flew it was impossible to stall when established in a full side slip..may be possible on other types but…the difficulty is a coordinated reduction of side slip without increasing the approach speed too much. I’ve actually kept sideslip on into the flare..took it off then put it back on on the ground as I was running out of field during a national competition.
I also tugged at a mountain site in a Raylle which required landing down wind/ up slope and not the longest strip of tarmac. The final turn (150ft) and approach again too the flare was with varying amount of side slip but with power to protect the engine from shock cooling.
Like many things in life one needs to find a decent instructor and practice at a safe height.

Fl1ingfrog
14th May 2024, 15:21
Side slipping is effective and simple to apply and safe. How effective it is depends on the rudder size as this can limit the amount of bank achievable and therefore can require a curving approach. Having said that the curving slipping approach is the more comfortable. The bonus of the slide slip is the steep descent achievable and that you can start and stop it at will to control the rate of descent. Of course it requires training and practice as do all manoeuvres.

I think Cessna have always regretted introducing the 'no slipping with flap' in the pilots manual of certain models (the legal department at it again). Cessna later withdrew this demand for later models but the idea has stuck and is applied as a general rule.

Sillert,V.I.
14th May 2024, 16:33
Something to bear in mind is that in a real forced landing situation you will likely be stressed. If you're wrongly positioned to the extent that you'll overshoot with full flap, you'll likely be very stressed.

If you've never practiced continuing an off airport approach below 500ft, you'll also be in an unfamiliar situation.

Is this the right time to be flying at low level with crossed controls and a potentially unreliable ASI?

If you've a shedload of experience, then perhaps, but I'd suggest that this is a good way for a low hours pilot to get into an unrecoverable situation.

In a real world emergency, I'd rather hit the far hedge under control than stall with crossed controls at 100ft.

Fl1ingfrog
14th May 2024, 17:54
In a real world emergency, I'd rather hit the far hedge under control than stall with crossed controls at 100ft.

14th May 2024 17:21

This is old cliché advice to dissuade pilots from stalling into the leading hedge/wall or worse. It is common in the US to sideslip but not to deploy flaps until late on and only when certain to reach your field. As always speed control is paramount. You are not going to stall during a slide slip I promise you.

EXDAC
14th May 2024, 18:51
In my opinion if you cannot handle a full rudder sideslip then you don't know how to fly the aircraft. Perhaps people who think slips are dangerous don't understand the difference between a slip and a skid.

+TSRA
14th May 2024, 22:00
Slips are a tool, nothing more, nothing less. Like any tool, you have to know how to use them properly - this includes not only knowing how to use it, but when to and when not to. If we teach students to never use the tool, we rob them of a potentially life-saving maneuver later in their career. If we exclusively teach them to use it, we rob them of the ability to think outside the box or to experiment with different techniques.

So, if a slip during a deadstick approach will be the difference between making the field or not making the field, then why limit our students? Certainly during training and after the fact, discuss the different options that were open to them. Did they manage it perfectly? Cool, what would we do if we hadn’t done it perfectly? Did we sideslip? What could we do to put ourselves in a better position next time? Did we do a S-turn? Awesome, but what are the benefits and disadvantages of doing that low level in an area which likely has not been cleared of obstacles like the airport environment and for which you might at best have had a cursory look at the area?

Genghis the Engineer
15th May 2024, 07:46
Having used Cessnas a lot, a forward slip with flaps extended is prohibited on several of their models.

So far as I know this statement is incorrect. Sideslip is DISCOURAGED with FULL flap in some Cessna models. I don't recall any type where it is prohibited, but happy to be corrected.

The problem, in my opinion, is that many instructors learned on C172s themselves, they took that advice as a prohibition, and then took that prohibition to other types. I did my UK CPL on an Arrow, and was taught that sideslipping was prohibited. Initially, until I showed the instructor the POH !

G

bingofuel
15th May 2024, 07:57
I am fairly sure sideslipping is in the UKCAA syllabus as part of exercise 8 , so it should be taught in the UK anyway.

Fl1ingfrog
15th May 2024, 10:01
So far as I know this statement is incorrect. Sideslip is DISCOURAGED with FULL flap in some Cessna models. I don't recall any type where it is prohibited, but happy to be corrected.

This is from the CESSNA 1978 model 172N. PILOT'S OPERATING HANDBOOK

The placard to be fixed adjacent the flap indicator; AVOID SLIPS WITH FLAP EXTENDED

However below is the text from SECTION 4 NORMAL PROCEDURES

Crosswind landing
..........If flap settings greater than 20 degrees are used in sideslips with full rudder deflection, some elevator oscillation may be felt at normal approach speeds. However, this does not affect control of the airplane .......................

Later it was explained by the then retired chief test pilot in an interview; the placard wording was at the insistence of the legal department but doesn't truly reflect the explanation to the pilot in section 4. However the placard wording has become gospel and preached around the world.

jonkster
15th May 2024, 10:04
1. Personal opinion on if sideslipping should be taught: yes (and I do so - depending on aircraft and not necessarily solely for forced landing situations. In some aircraft, competency sideslipping should be a requirement for normal operation - eg Decaths, Citabrias, Pitts, Cubs etc)

2. Aircraft restrictions on sideslipping? Some aircraft may have comments on this in POH - eg some will either restrict or will recommend avoiding sideslips with certain flap extensions (some models of Cessna eg 180), others may (eg PA28) caution against prolonged sideslipping (eg for more than Xsecs or for more than X000ft altitude loss) not for aerodynamic reasons but due possibility of fuel starvation. The Piper Sport states in the POH that any sideslipping is not to be used on any approach/landing (irrespective of flap) and then recommends check flights/training on type to include sideslips in landing configuration... :confused:

Obviously teach student to follow POH and manufacturer's guidance.... although in case of sideslipping in a forced landing due engine failure, I would say any restrictions due fuel starvation no longer really apply :)

EXDAC
15th May 2024, 12:24
In a slipping PA-28 the high wing tank is capable of feeding the engine continuously but the low wing tank cannot feed the engine unless the slip is shallow and the tank close to full.

When providing instruction in sustained full rudder slips the instructor should be smart enough to ensure the appropriate tank is selected. There is no risk of fuel starvation with the high wing tank selected unless that tank is empty.

I flew 172 models before and after the flap extension was limited. They all are capable of a full rudder slip and nothing bad happens. I never considered the "Avoid" placard any more limiting than the maximum demonstrated crosswind. More on C-172 flaps and slips here - https://www.pprune.org/private-flying/472132-c172-flap-question.html

Rivet gun
19th May 2024, 10:26
See UK aircrew regulation PART-FCL, Subpart C, Section 1, AMC1 FCL.210, (c) (2) (x) (D).. Side slipping should be taught on light aircraft except where not allowed for the type.

However those teaching future airline pilots, CPL and especially UPRT should emphasize the guidance for transport aircraft handling found in AUPRTA Rev 3 and also reflected in FCTM for types such as B737. In transport aircraft side slip should not be used intentionally as a means of creating drag (Gimli glider not withstanding). Other than cross wind landings, transport aircraft should normally be flown in balance. In upset recovery handling, aileron is always the primary means of roll control. However, if you attempt to roll using ailerons but cannot achieve the desired roll rate, a small amount of rudder may be used to achieve the desired roll rate. Only a small amount of rudder is required. Too much rudder applied too quickly or held too long can lead to loss of control or structural damage. Rapid rudder reversals are to be avoided.

Heston
13th Jun 2024, 16:09
I find this discussion, which comes up from time to time, absolutely baffling and bizarre.
Not knowing confidently how to use a slip to reduce height in a glide approach or simulated engine failure means you don’t know how to fly the aeroplane. End of story.

Big Pistons Forever
13th Jun 2024, 16:25
Having used Cessnas a lot, a forward slip with flaps extended is prohibited on several of their models. With that in the back of your mind you need to look elsewhere to adjust the descent profile for a forced landing. As Whopity said, flaps are a good tool to use and we trained the students to get to an appropriate 1000' point while aiming a third of the way down the strip, then use flaps to adjust as needed and bring the touchdown point nearer to the beginning of the strip.

Once you're in an actual emergency situation, anything goes of course. With that in mind I might use a forward slip if needed. I'm not too fussed about using the aircraft again if I can at least walk away from it in one piece.

The trouble is that if you train a student to use the manouvre on a regular basis, the student will continue to use it and may get him/her/itself into trouble later on. I am basing this on teaching on an integrated course. The situation is different in the gliding world and may be different in a strictly PPL/LAPL environment.


A forward slip is not prohibited on any Cessna SEP as far as I know. As was noted in an earlier post several models note in the "Normal Operating" section of the POH that slips with more than 20 degs of flaps should be "avoided" due to a possible pitch down moment generated and tail plane buffeting. These effects are completely controllable. It is unfortunate that so many instructors don't seem know what is in the POH and do not understand the difference between "limitations" and POH notes.

Ab initio pilots should be taught to use all of the controls to make the airplane do what they want it to do. I think the forward slip is required instruction for 4 reasons
1) It represents progressive learning and skill development from the initial attitudes and movements lessons. The required cross controlling in a slip builds skills in managing yaw and bank in both turns and straight line flight paths
2) The side slip works better for cross wind landings for many airplanes and should be in the tool box for every airplane, including some large aircraft. For example every cross wind landing I did in the Convair 580 was with a side slip.
3) The PPL is a license to fly any light airplane. Many don't have flaps so they need to know how to slip
4) If the engine fails a forward slip or even a slipping turn may be necessary to save a too high approach

lederhosen
13th Jun 2024, 16:58
I am also at a bit of a loss why some instructors seem so averse to slipping. My suspicion is that they may lack confidence in demonstrating it themselves and are happy to fall back on some spurious reasoning. I think it is a crucial skill particularly in the engine failure (landing in whatever field is available) scenario. I regularly instruct on an Aeroprakt A32 with just one flap setting (a limitation in Germany at least) and I think pulling off a reasonable field landing without being able to slip would be beyond most average pilots.

hugh flung_dung
16th Jun 2024, 15:28
As some others have said, being able to enter and adjust a slip is a perfectly normal, and useful, piloting skill. Some aircraft have limitations (which, obviously, must be observed in training) but, IME, virtually all aircraft are capable of being put into a controlled slip and this should be taught to students. In addition to slipping, students should also be taught that a lot of excess height can be lost by diving to Vfe with full flap, albeit with a slightly increased float. Separately, if they are falling short of the field, a well-timed deployment of flap may be useful in jumping a hedge.

Someone, upthread, said that it is not possible to stall in a slip - this is incorrect and is a dangerous statement. Some aircraft may not have the control authority to stall, but others do. Stalling when slipping can be rather disorientating because it is the rearward wing that drops, and it can be quite violent, although it's easily recovered by treating it as an incipient spin. If you haven't experienced this then find yourself a competent instructor (preferably one who teaches aeros), a suitable aircraft and go to a safe height.

Edited to add: I highly recommend Think Like a Bird: An Army Pilot's Story for an excellent description of army fixed wing pilot training, and of getting in (and out) of impossible fields

HFD (FI, FE Ret'd)

lederhosen
16th Jun 2024, 19:48
Good post!

BigEndBob
18th Jun 2024, 16:44
Only problem i have seen sideslipping any Cessna high wing, the flaps rattle like hell. I wonder what wear might occur. No wonder flap tracks and rollers get worn.
Twice i used side slip to get down with real engine problems, could be a life saver, well was.

On test i don't mind what speed, not below best glide, within limits or maneuver a candidate uses to get into a field.

beamer
19th Jun 2024, 18:53
The ability to side slip and an understanding of the difference between a slip and a skid should be fundamental.

EXDAC
5th Jul 2024, 18:22
On test i don't mind what speed, not below best glide, within limits or maneuver a candidate uses to get into a field.

Why would speed below best glide be any issue if the field was made? I'd prefer to land in an unknown area with minimum possible speed and that may be well below best glide speed.

Best glide speed seems to be given magic properties but few have any idea how it is influenced by aircraft mass, headwind, airmass sink etc. Best glide speed in only of use for making the best distance for the available altitude. It is of no value at all in planning the final approach speed unless the approach was judged so poorly it was the only way to make the field.

hugh flung_dung
5th Jul 2024, 21:29
EXDAC: I agree, the important thing is to arrive in a reasonable field in an orderly fashion.
here's a reasonable write-up here on adjusting glide speed for head/tail wind and sinking/rising air: https://www.faasafety.gov/gslac/ALC/course_content.aspx?cID=629&sID=1186

HFD

FlyingHigh976
8th Jul 2024, 17:27
Why would speed below best glide be any issue if the field was made? I'd prefer to land in an unknown area with minimum possible speed and that may be well below best glide speed.

Best glide speed seems to be given magic properties but few have any idea how it is influenced by aircraft mass, headwind, airmass sink etc. Best glide speed in only of use for making the best distance for the available altitude. It is of no value at all in planning the final approach speed unless the approach was judged so poorly it was the only way to make the field.

Airspeed is mentioned in the quote above and other places in this thread. What I have not seen is much mention about what the accuracy of the airspeed is which presumably is influenced by
factors that have not been mentioned including:
Is the static port on the left or right side or both? Rephrased, is the pitot port on the same side or the
opposite side of the rudder pedal that is being pushed. (Seem to recall one plane that had it on both sides)
The effect of the pitot tube being displaced from the line of flight should impact the indicated airspeed.

In addition no mention is made of not hastily moving into and out of the slip (forward or side) since one wing
will be advancing and the other retreating. A rapid change might be interesting on the retreating wing considering
the speed of the airflow referenced to that wing during that momentary transition if the speed is already low and
the airspeed indication is not as accurate as is normal.

Comment based on general aviation experience that is decades old and am decades passed being
current. An attempt at humor: take my comment(s) with a grain of salt: your choice whether the salt is
plain, iodiized or the sea version.

EXDAC
8th Jul 2024, 19:02
I flew about 1,500 hours in an ASW-19B glider in which the airspeed went to zero in a slip. It was no concern at all. Simply maintain the pitch attitude in the slip that existed before slip entry.

I don't think this thread was about how to slip but rather whether slips should be taught. The majority of posters seem to think they should be. Next step is to find a competent instructor.

what next
9th Jul 2024, 14:44
Next step is to find a competent instructor.

It is really not rocket science. I was taught to sidelsip in gliders when I was 15 years old by someone who was maybe three or four years older...
But other than that I am of the "not so sure that it is an essential skill to teach future airline pilots"-fraction as this is the kind of instructing I mainly do. The "Gimly glider" incident has been mentioned but I would rather emphasise to teach the students proper fuel calculations instead because then you will not need to sidelsip your Boeing in the first place.

And one little anecdote about the possible stupidity of sideslipping: Many years ago I was coming for a landing in a Piper Seneca with some passengers. It was a longer flight with just the legal IFR reserve of fuel, maybe 1/5 of the tanks, remaining. We were coming in high over some mountainous terrain when the airfield offered us a visual direct approach to the nearest runway. Without giving that a single thought I happily accepted and my glider pilot muscle memory immediately put the aircraft into a "massive" sideslip because we had to get rid of 2000 or 3000ft within a short distance. Of course I never had sideslipped a Seneca and neither had any of the passengers experienced that manoever before so they were pretty scared. And for a good reason, because if the low fuel level would have exposed a tank drain an engine might have stopped a few hundred feet above ground. And I guess (I have yet to try it) that if the wrong engine stops in a twin during a sidelip the departure from controlled flight can be quite spectacular and certainly require a lot of height to recover from. Once on the ground I became aware of how stupid and lucky I have been...

BEagle
9th Jul 2024, 16:03
Having spent ages demanding that students 'keep the ball in the middle' and fly in balance, I don't think that deliberate 'out of balance' flying, i.e. sideslipping, should be taught until around the time when forced landings are being taught. But even then it should be a 'last resort' - using the 'constant sight line angle' technique for a forced landing, together with appropriate use of flap, normally obviates the need for sideslipping.

Bergerie1
9th Jul 2024, 16:21
But, you have to admit, that side slipping down the approach into a short field, and then straightening it out for a nice three-pointer was fun!!!

421dog
9th Jul 2024, 19:10
A C-120 without a slip and a 1500’ field just won’t work

ZeBedie
14th Jul 2024, 11:04
I think Americans call a sldeslip a 'forward slip'? But there is at least one person in this thread using both terms. There isn't any difference, is there?

EXDAC
14th Jul 2024, 12:46
I think Americans call a sldeslip a 'forward slip'? But there is at least one person in this thread using both terms. There isn't any difference, is there?

Both terms are used in FAA terminology and cause much confusion. A forward slip and a side slip are aerodynamically the same. The distinction only applies when the slip is ground referenced.

See "Intentional Slips" in https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/airplane_handbook/10_afh_ch9.pdf

selfin
15th Jul 2024, 13:53
https://www.langleyflyingschool.com/Images/Handbook%20References/Slipping.gif


David St George will present a webinar (https://www.faasafety.gov/SPANS/event_details.aspx?eid=131332&caller=/SPANS/events/EventList.aspx) as part of SAFE's CFI-PRO Clinic (https://safepilots.org/safe-cfi-pro/), eligible for FAA Wings credit, entitled Slips/Skids and 'Cross-Coordinated' Using Your Rudder Effectively! on Sun 11 Aug at 20:00 EDT (Mon 12 Aug, 0000 UTC).