My experience has been that I have done full pedal slips to a first wheel touchdown on several types. This results in an angry tire screeching down the tarmac, unless you do it to wet grass, or better yet, ice. I will consider IAS as I do this, and allow IAS to decay as I flare, considering the possibility of a wing drop. But if you're 6 inches off the surface, a wing drop is less critical, it's just an uneven landing. That said, I do not promote slipping an airplane into the flare, unless you're really familiar with how that type stalls in the slip. I've done a lot of that testing too, as it is considered "spin resistance" testing. That is a compromise with the Flight Test department to not have to demonstrate fully developed spins for a modified plane (particularly external loads). Spinning a Cessna floatplane with a canoe tied to the float struts is un nerving!

I have never flown a plane that I would not slip, though I have flown a few where I would not be keen to slip to really high angles (DC-3/King Air B200). Other types (C 150/PA-18 the most forgiving) I would happily fully slip as needed.

For most light GA aircraft, where you would use slip to steepen a glide (eg in a glide situation posed by the original video), I would think you would not need to be particularly concerned by airspeed inaccuracies.

If the slip is being used to steepen a glide approach, so as to hit an aim point, surely you would not be trying to maintain a set glide speed, More likely, if high on approach, I suspect you would be pushing the stick forward rather than pulling back and not be worried much about what the ASI was saying, rather you would be trying to avoid overshooting the aim point.

And if you were pulling back - say to avoid undershooting the aim point - you probably would not be using sideslip.

In that situation ASI inaccuracies due position errors, would seem to me to be of small import.

my 2c

I’m not lecturing anyone. Sorry if I hurt your feelings, but you’ll have to take it up with the FAA. They are making the distinction.

The crosswind or lack thereof is the difference. We are in agreement that the maneuver is the same.

Btw, no one’s laughing, and you have provided nothing from any source to say that the two names are incorrect either. Ease up on the caffeine maybe.

Just read the video comments. 1st prize goes to this one.


https://yt3.ggpht.com/ytc/AKedOLTxAw...00ffffff-no-rj

Ozgrade3 Australia

Sorry people, as a 5000 hr flight instructor I have to strongly disagree. The approach was appalling. To be that high on profile in an aircraft with gobs of drag available from the flaps is very very poor. No side slip or anything used to get on the ground at the 1/3 touchdown aimpoint on the runway is unforgivable. It's easy to achieve if you have the right technique. You can make the Cessna descend like a bag of sand. To be landing that far into the runway, like at the very end is incompetent. I have taught this scanario hundreds of times, both in the Cessna and Warrior which has lots less drag available. I imagne a proficiency check and remedial training with the Chief Instructor of her flying school will be on the cards. This was not well handled in any way

The tailwind at the surface of 7knots was a significant contributory factor to this deep landing.
If ‘sight angle’ & then ‘shapes’ appearing on the windscreen were used, then the initial 1/3 aiming point would have been achieved, followed by further ‘fine tuning’ to bring the touch point towards the start of the runway. The greater groundspeed & gliding range were ignored. Judicial sideslip was clearly called for.
If however the instructor hasn’t been taught such techniques during the various training courses, it is hardly surprising that this close shave occurs.
Bottom line: Quality training of the potential instructor is absolutely vital. Otherwise, how are their perspective students going to benefit.
Call me old fashioned…

I have followed the discussions over sideslipping with great interest. I have been flying for almost 50 years, mainly in the UK, with much of this time being involved in flight test and instruction and I had never before heard the phrase 'forward slip'! So, a few thoughts from my background on these discussions.

'Sideslip' is defined as the angle between the relative airflow and the aircraft's longitudinal axis. The manoeuvres flown on an approach involving the use of sideslip to generate drag are 'steady heading sideslips', a phrase that is used for a specific flight test technique but also is valid in this context. A rudder input generates a sideslip angle and a yaw rate ,and the yaw rate is reduced to zero (ie. a constant or steady heading) by the use of bank angle in the opposite sense to the applied rudder. Note that all of the discussion here is relative to the aircraft as the frame of reference and its motion with respect to the airmass. The flightpath vector of the aircraft can then be resolved with the wind vector to generate a velocity with respect to earth axes ie. where it is tracking over the ground. The pilot can control the path over the ground by varying the rudder input or bank angle in order to turn the aircraft and when the desired track is achieved he can re-establish the sideslip and bank angles to maintain the desired path with zero yaw rate/on a constant heading. Aerodynamically, this is a single case. What has been discussed in many of the earlier posts is just the difference between the frames of reference ie. the air mass or the ground. In my opinion, the use of the phrase 'forward slip' only serves to cause confusion.

I agree, and appreciate Lomcevak's good review of the definition.

In my opinion. an airplane flies through air, either straight, or a little sideways. If it's deliberately sideways, it's a slip (or skid). If the air mass, through which the plane is flying is moving relative to the ground, that's a different thing, and doesn't change what the pilot is controlling the airplane to do - it's either flying forward, or being slipped.(flying a little sideways), so just call it a sideslip, and then be assured that the pilot is still flying the plane relative to the surface also and trust that they will compensate for that too!

If you google forward slip aircraft, you will find an explanation of what it is and the difference between a forward slip and a sideslip. Pilots should be familiar with both terms and the difference between them. Admittedly, some posts here(including mine which have now been corrected) used the incorrect terminology(sideslip instead of forward slip).

Here is what the FAA has to say about it(if you scroll down)

Activities, Courses, Seminars & Webinars - ALC_Content - FAA - FAASTeam - FAASafety.gov

If you, an instrument qualified and current, were in the RHS, with a hood on, could you tell if the pilot was doing a side slip or a forward slip?

I am struggling to see why the terminology is so important.

I had never heard of the term "forward slip" until quite recently and am not getting what extra value making the distinction is.

In fact there are obvious situations where you seem to be doing both!

Just teach people how to sideslip - no need to make it over complicated. It is an easy technique to teach. If people want to give it a different name depending on how the aircraft is oriented to the ground, fine, but what value does it add? How does it help?

Happy to be shown the value if I am missing something - maybe I have been doing it wrong for decades.

Probably just have not known the proper terminology for the two different maneuvers for decades. No big deal as long as you know the different techniques.

Bottom line for newbies: Be able to perform and do a proper slip if required in the type of scenario that was in the video.

Flyingmac, how dare you ;), the guy is an expert, he even tells us so.The one thing wrong with any attempted analysis of the long landing is we don't know the details, how's this for a scenario, engine failure, instructor knows they can make the field, to instill confidence in the student the instructor allows student to make the force landing, whilst keeping a watching brief as things progress. Though overshooting the desired touch down the instructor is confident in a successful completion. Outcome, student debriefed on how things could have been done better, side slipping, S turning on final, a big pat on the back to restore students perhaps flagging confidence in airborne petrol powered contrivances. Having the opportunity to get things wrong in controlled conditions is one of lifes greatest lessons, after you have the license in hand you have no one to hold the other.

I have to say that I think that the FAA document does not explain this very clearly. The two pictures are identical except that they are orientated differently on the page which surely causes confusion to an inquisitive mind. The paper also implies that bank angle is the prime parameter here with rudder then used as required as the secondary input. I believe that when teaching about sideslip (and I use that word in the aerodynamic sense that I defined in a previous post) it is important to stress that rudder is the primary control input and that is what determines the sideslip angle. Lateral control input to vary bank angle is the secondary control input which determines the subsequent turn rate/heading/ground track. In practical terms both inputs are made simultaneously but this emphasis really helps to understand the mechanism. All that is then needed is to understand the manoeuvres where sideslip is used. First, full rudder to generate drag and lose energy. Secondly, in a wing-down crosswind landing to generate a sideslip angle which equals the drift angle such that the aircraft is pointing straight down the runway at touchdown; this will invariably require less than full rudder pedal. Thirdly, in an aircraft with a high pitch attitude on the approach such that the runway and touchdown point cannot be seen sideslip can be used such that the nose is not pointing down the runway on the approach such that the threshold can then be seen. Again, this typically will not require full rudder pedal and the sideslip will be removed before touchdown. As for the term 'forward slip', is this used on both sides of the Atlantic? I think that it is a very ambiguous and meaningless phrase and I wonder why the phrase 'wing down crosswind landing' is not used instead, which is what I and my colleagues have always used and is much clearer?

I am CEE trained. For the old Soviet-realm counties, the training was pretty much unified. Completely identical understanding to what LOMCEVAK posted, not only in the last piece but also higher up.

We called it just slip, to describe the aerodynamical state (ball off-centre). From the handling point, it is a cross-controlled flight.

The FAA seem to build separate names for the different use cases, have two discriminate manoeuvres described in the book. Well, it's 2 use cases after all, so why not. (the quoted description explaining why one is different from the other had me scratch my head until the point of losing interest).

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An excellent point. I've been happy to do this for a student, and certainly the recipient during my life long training. Another aspect is that it's also good "crew resource management" (such as it is with a student as the other crew member). The more experienced pilot can actually do a few other important things, while monitoring, rather than assuming all the workload.

About 45 years ago, I though I was an expert in a tiny, unimportant field of interest. I told someone that. I was wrong, and they promptly told me. I have never used that word to refer to my skills since - because I'm not, I'm still learning, even from people here.

I had a test flight to fly on a club airplane following an unusual repair. Their rules say that I have to take an instructor with me, as they're calling it a checkout flight. No problem... They send a proud ('cause he tells me) Class 1 to ride with me. After I have completed all my testing, and the plane is fine, I ask if there's anything he wants to see for my "checkout". He says, well.... your really have done everything already..... except a practice forced approach. I arrive to the circuit, it's empty, and I announce a practice forced approach over the runway intersections. I run my cause checks, and commit to a landing, as I have a suitable runway. As I slip in around base and final, I announce that I will clear at the intersection (which mean aiming a little further down the runway than would be normal), and that's where I roll off. As I taxi in, he asked "how did you do that!?". I explained. He asked if I'd teach him how to do that. Um, I probably shouldn't, I'm not an instructor, and I don't work here.....

The first time I heard it on this side of the Pacific was from a student who had been reading US material and promptly got tied in knots trying to demonstrate the difference.

I may be wrong but think it was never used here until the rise of the internet saw more US material become available.

'Two nations divided by a common language'

Boils down to this for U.S. pilots: forward and side slip are terms used by the FAA. It's in the FAA handbooks and it's in the FAA airman certification standards. These terms are used by U.S CFIs and DPEs. If you want to get an FAA license, you need to speak and understand the FAA language.

Illuminating thread in many ways. I've taken away two key points:

Practise slipping in case I ever have the luxury of being too high on approach following an engine failure
Carry enough cash to ensure whoever films my efforts doesn't upload the footage anywhere...

If you have an engine failure it is far, far better to be too high than too low. It may not be that obvious that in fact you are not really high at all particularly if there is a wind gradient. This summer I was on approach to the runway in the club glider (PW5) and was sure I was way high without really watching for a definite overshoot (i.e. touch down point moving down in the windshield/canopy). In this case it turned out that after the application of spoiler when I actually started paying attention the touchdown point was going up fast :uhoh:
I ended up fully closing the spoilers to regain the correct approach path. This is essentially equivalent to going to full power on final in a powered airplane....not good. :=

The bottom line is if you are too high you go off the end of the runway or hit something at a relatively low speed. If you are too low you will probably hit something not on the ground and at flying speed greatly increasing you risk of serious injury or death

That being said I encourage all my students to mix things up after they got their license. Traffic permitting try a gliding approach high and close in. Try a long straight in starting the final approach path at cruise speed and slowing down progressively on final, and yes practice slipping, not only could it help you if things go badly but it will improve your crosswind landings.