Non-standard touch & go technique.
 

Whilst in discussion with another instructor (somewhat more experienced than I) recently, he advocated a technique for T&Gs that was new to me. How about this (C152): On base leg, close the throttle and drop 20 flap, speed 65 kts, then trim for this state i.e. the glide. Thereafter add power as necessary to achieve the desired approach path, accepting the out-of-trim forces generated by the addition of power. This means the student will be pushing forward on the column all the way down the approach but as power is reduced in the flare the plane will then be back in trim at touchdown. OK so far? On the roll, full power, carb heat in, FLAPS LEFT AT 20 degrees (or reduced to 20 if 30 has been used), TRIM LEFT AS IT IS, and the takeoff made in this configuration, again entailing a substantial forward pressure on the column, this time in the climbout. The rationale here is that, should the engine fail, you are already set up for the glide and landing.
What surprised me most about all this was that, according to this chap, it is a technique practised by the CFS and if it's good enough for them etc. etc.
I'd welcome opinions, especially from anyone who uses this technique and any CFS or ex-CFS types.
I myself am far (very far actually) from convinced of the wisdom of this method but am open to argument.
What thinkest thou (and does the CFS really do this, and if so why)?

Firstly the CFS aspect. I started my career as a baby pilot with a RAF Flying Scholarship, standardised by CFS, and this was certainly not the approved light aircraft technique back then (1989).
Student pilots should be taught to fly the aircraft! Using the 'standard' techniques, if the student has an engine failure for real, then it shouldn't be too taxing for them to subsequently trim the aircraft for the glide. After all, isn't this what the rest of us practice on PFLs/EFATOs?
From an instructor's point of view, getting the average student to close the throttle fully on base leg and then having them select 20 flap and trim for the glide would put the aeroplane well below the ideal glide slope. Huge out-of-trim forces on the go-around, anyone?
Fairly recent echoes from my BCPL course: "Keep the aeroplane in trim at all times.". I doubt that CFS is teaching otherwise...

Most of the technique you (DB6) describe is totally incorrect. There was only ever one occasion when students were taught to make an approach with a deliberate out-of-trim force - in the Gnat under manual control following hydraulic failure. The tailplane incidence was set to a fixed value using the standby electric trim and the approach was flown with forward pressure on the control column until the flare purely because of the insufficient pitch authority using elevator unlock alone if the TPI was set to an in-trim value on the approach - it just wasn't possible to flare sufficiently accurately or quickly enough and using the standby trim to assist with the flare either meant you'd run out of hands trying to close the throttle, flare using the control column, assist the flare using the standby trim switches as well as tring to stream the brake chute - or if you used the '399 switches' to transfer the standby trim control to the stick top you would probably overcontrol to such an extent in the flare that you would pitch up and stall. Tricky little sod, the Gnat in manual!! But that was years ago - everything is now flown using the point-and-power technique. Touch and go landings are made without recourse to changing configuration or retrimming because most service aircraft have sufficient thrust for the drag of full flap to be immaterial during touch and go landings - and the out of trim force resulting from use of this technique is minimal. However, in aircraft such as the PA28, touch and go landings should be made with the flaps retracted for the take-off. It is NOT necessary to adjust the stabilator trim during such landings - in fact it can be positively dangerous as most students will take their eyes off the outside world to retrim with potentially catastrophic results. No service aircraft is ever retrimmed during touch and go landings - except for the Vulcan during 4-engined roller landings following double asymmetric approaches when it was necessary to lower the nosewheels onto the runway and trim the rudder to neutral before setting the thrust for take-off.
Hope this is of some help.

[This message has been edited by BEagle (edited 05 November 1999).]

I was taught initially on the C-152 during my RAF Flying Scholarship (1994) to retract flap during the ground roll to the take off setting (10 deg)

Whilst flying the Bulldog during 1994-1996, the technique from downwind was:

800' downwind

Downwing cx complete,

set 1800RPM and 75kts, trim
Call Finals, trim during finals to achieve correct attiude/speed.

1/2 way around finals should be 600'

adjust with pwr if neccessary

roll out 400'

select full flap

point and pwr etc until flare

throttle to idle

flare

touchdown on main wheels

Apply full pwr during roll, rotate, then retract flap after Vr and above relevant safety speed to Inter then up.

I use this method religiously to date whether civ or mil (Adjusting heights as required) as it seems to work with fewer questions asked and with less bounce and time fiddling with switches during the ground roll.

As far as I am aware, this was standard CFS technique at the time!!!!

Still is!! But after rolling out of the final turn, it's WINGS LEVEL, FULL FLAP, TRIM, ADJUST TO APPROACH SPEED, RETRIM then only when all this has been done correctly do you AIM AT TOUCHDOWN POINT WITH CONTROL COLUMN AND ADJUST SPEED WITH THROTTLE, KEEPING TOUCHDOWN POINT FIXED IN WINDSCREEN!!
Glad that someone learned the technique properly - well done mate!!

Re Approach and landing technique in C152 et al. Keep the exercise simple. Turn base, and when you can comfortably glide in, close the throttle fully. Use flap as needed (not merely by rote)and aim to cross the fence at 54 knots with full flap. Immediately after touch down, raise the flaps fully and apply full throttle. Rotate at 54 knots. The trim forces in the 152 are dead easy to hold at any stage of flight. It is designed that way. Repeat exercise ad nauseum (or money runs out for the day) until solo.

The C152 was designed to be safe and simple to fly. Warriors too. The trim forces are minimal and the POH states that normal landing approaches can be made with power-on or power-off. Same as a Tiger Moth!!
You do not need flaps for take off or touch and go. Glide approaches taught from the first circuits teach early judgement skills which will prove useful in case of forced landing.
From a student's point of view, the myriad of combinations of throttle settings, versus incremental flap positions plus differing target speeds for each flap setting
that some schools teach, is bewildering and quite unnecessary. Avoid gimmicky techniques which abound at flying schools. Read the manufacturer's POH and be guided by the advice therein.

I have a friend who knows someone who thinks he may be a CFS Examiner! DB6 - your instructor colleague is wrong. CFS certainly do not advocate flying out of trim, at any time, let alone on final approach. Dunx and BEagle have pretty much got it right.

dlV, I think you missed the point. You're exactly right on how to carry out a GLIDE approach, we were talking about powered approaches. I would argue with your "cross the fence at 54 knots" though- while it's pretty close to 1.3 Vs (clean), to my mind (and that of my first instructing boss, who's been operating 152s since the early 70s) it doesn't allow enough of a mragin for the 152's high drag in the full flap config.
It's only my opinion, though....

Strangest technique I've ever heard! Nobody in their right mind would teach a student to deliberately fly an aircraft out of trim. How does this chap pass instructor renewals?

As for touch and goes and retracting flap after rotate, in an aircraft like a Bulldog with plenty of power this isn't a problem, but try it in a Cessna 150 (40 flap) and you'll struggle to get any climb at all.

Talking of interesting techniques, an instructor I knew always taught students to close the throttle at the threshold, regardless of how high they might be! Try that in a 150 on a dark night with 40 flap....oooh parachuting!!

Cheers

TJ;-)

Thanks for the responses, chaps. I think we are in agreement on this one. Love that stuff about the Gnat, BEagle. Wish I'd had the chance to fly one - the RAF rejected my kind offer of assistance.
Cheers DB6

Capt. Homesick. The manufacture's POH performance charts for C152 states that landing length is predicated at 54 knots over the fence (50ft) That is legal and quite safe and should be taught as the desired speed in calm wind. Exactly the same principle as a 737. The C150 POH states 52 knots with 40 flap. Legal and safe. Still 30% above the stall in landing config. These speeds would not be certified unless they were safe and capable of being flown by an average pilot. Boeing and Airbus aircraft use manufacturer's recommended threshold speeds, not individual instructors pet speeds. Why not the little Cessnas too?

dlV, I don't have the 152 book in front of me, but I accept what you say. For a short-field landing, I would use 55 knots over the fence (I think the one knot extra is acceptable, given the accuracy of the ASI).
However, for a glide approach, I was taught (by RAF instructors) to use a speed significantly higher, to allow for the high induced drag with the (larger than usual) flare at the bottom of the glide (especially with full flap, a low nose attitude and high RoD). At anything less than 60 knots over the fence, without any power to cushion the flare, I found the 152 drops like a brick! Not a good idea, when the undercarriage bends with the impact and the CFI and chief engineer are standing at the window 100 yards from the threshold watching!
I would be interested in your input, it's been too long since I flew a light aircraft, I'll need all the help I can get to get current again.

Capt. H. The 54 knots at the flare off a glide approach is quite safe in my experience based on the POH assertation at page 4-21 that you can land power off or on at any speed between 55-65 knots with flap down. I suppose that is because the 150 is a light weight trainer with effective elevator control. Certainly when flying more advanced and heavier trainers (the Harvard comes to mind), the glide was done at 10 knots higher speed at flare, to allow for the inertia.

Capt.H. I hope I haven't doubled up on this thread as I am having trouble knowing if it is transmitted. Re glide approaches in the 152. The extra speed advised by your RAF instructor seems at variance with the recommendations at page 4-21 of the 152 POH.
Personally I see no problem with 54k at flare from a C152 glide. Heavier trainers such as the Harvard (in the good old days) certainly required a higher approach speed on a glide approach to allow for inertia at round-out. But I don't think that you can tar all trainers with the same brush, unless there is a specific technique for glide approaches in the manufacturer's POH. But with your CFI and Engineer chappies glowering from the crew room, maybe you would be wise to add a couple of knots to make sure you don't sprong in at the flare. Good luck!

D.L.V.

I can't but help question why you would teach your students glide approaches from the 1st circuit and I'm afraid the arguement that it will teach early judgement in cause of a forced landing / or just like a Tiger Moth doesn't really wash with me. There are more requirments in this day and age for a correct landing than a correct forced landing.

I would think that a powered approach would teach early judgment which would prove useful in case of a NORMAL landing, bearing in mind that just about every aircraft the student goes on to fly will be landed after a powered approach rather than an glide approach.

A forced landing does require judgment skill but those should be taught at the appropriate time in the syllabus and if memory serves me correctly there are several lessons devoted to fullfilling that sequence, which include EFATO, Glide approaches and PFL's. From your post I would have to wonder if and where normal landings fit in and if it is after PFL's would it not cost the student more.

IMO I feel that sometimes it is too easy to focus on one picture but lose sight of the the movie.

In regards to your advice re reading the manufactures POH, good advice, but just as pertinent, sit down and discuss it with your CFI and find out how he/she expects it done because when it all boils down, they are the Boss, have the experience, the authority, and also the shoulders that take the blame should something go wrong.

Cheers

I suppose needing a few extra knots for the flare in a glide might just be nature's way of telling me I'm too fat.......

I've just had the pleasure of 6 months with CFS.

They certainly wouldn't advocate flying out of trim. However, your man may well be on to something.

Given how hard it is to persuade pilots to fly in trim, a bit of double bluffing on the instructors part may well work.

Tell the guy from day one that all he needs to do is have painful out of trim forces. Inevitably by trip 2 he will have sorted himself out.

Perfect! ;)

Gen Ties, your romantic idea's of Tiger Moths and glide approaches is touching and probably a good idea in the perfect world. However we no longer have the benifit of a large open field in the country to land. We have concrete and cross-winds. Also residential area adjacent to the airfield, these factors mean that the modern day pilot has to be considerate towards the public and fly larger than perfect paterns.
Also with many ex-wartime airfields having now closed there x-wind runway we cannot land into wind, which means it is better for the student to be stablised, in trim and on track for the final stage of the cct.
Glide approaches also have there own problems in the form of carb-icing!!

It has been a while since I taught primary instruction, but the laws of aerodynamics hanen't changed (at least to my knowledge). How do you explain crashing in a congested area with an engine out; glide landings are the way to go. When your student graduates to "heavies" they'll be taught the appropriate techniques. Teach them basic airmanship skills. They'll obtain the heavy airplane skills later and be much better off for learning how to fly first.--CY

[This message has been edited by Corporate Yank (edited 20 November 1999).]

Okay, I take your point but in the UK we have had several big General Aviation airfields closed down in the last few years.
The supermarket chains and other developers would love to get their hands on these properties, let's face it they don't even have to stomach the cost of building roads, just use the runways and taxiways. With strong residents comittees full of wrinklies taking the fight to the land owners, usually the local council. The large pound signs from the sale cause the airfield to close.
We therefore are forced into a corner having to give our students the best training we can, whilst taking into consideration the general public. There is nothing as good at headline grabbing as light aircraft skimming rooftops with apparently no power available. I know that this isn't the case but the public don't.