Touchdown point
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Touchdown point
I wonder if anyone can confirm where students are taught to aim for as their touchdown point? e.g. on the numbers, 1/3 in etc.
There is a thread on the Private Flying forum about why people land long and this information would be very helpful.
There is a thread on the Private Flying forum about why people land long and this information would be very helpful.
Guest
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On the basis that runway behind you is of no use at all, where else should you land but the threshold ? If you train off large runways, teaching people to land well up becomes habit forming, don't do it, until they have mastered landing in the correct place.
Guest
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At cambridge we have a good long runway, I still ensure that my students can land in the minimum distance possible. We have shorter grass strips avaiable to assist with this technique.
However, on PFL training you select an aiming point 1/3 of the way in the field and use flap (and side slip but not in C152s) to bring the aiming point nearer the start of the field.
I have found that some students add 5 knots on the approach speed for mum, and then maybe another 5 knots because it is windy. This means they will never pull of a short landing. Before you know it you will be touching down at 90 knots!!
However, on PFL training you select an aiming point 1/3 of the way in the field and use flap (and side slip but not in C152s) to bring the aiming point nearer the start of the field.
I have found that some students add 5 knots on the approach speed for mum, and then maybe another 5 knots because it is windy. This means they will never pull of a short landing. Before you know it you will be touching down at 90 knots!!
Guest
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Don't forget that where you AIM for is actually the point where you flare, not touch down! Subtle difference.
'Aim' for a point 500ft-600ft before the spot where you want to put the wheels.
Don't know about Euro./CAA, but the FAA commercial training is hot on precision landings, and really teaches you to put the wheels exactly where you want them.
'Aim' for a point 500ft-600ft before the spot where you want to put the wheels.
Don't know about Euro./CAA, but the FAA commercial training is hot on precision landings, and really teaches you to put the wheels exactly where you want them.
Guest
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Landing distances are determined on the basis of a threshold crossing height of fifty feet. Given a three to six degree glide path, the latter being more appropriate for light training aircraft, touch-down will occur somewhere near five hundred feet in from the threshold.
Down here in OZ the fifty feet threshold crossing height is required to clear dead trees, single strand telephone wires, ant hills, barbed wire fences and all the other paraphernalia associated with an 'outback' airstrip. Some of the city runways are equally as challenging with delivery vans and the like crossing on roads in the undershoot.
Why teach a student to land on the threshold if you must ultimately re-train him/her to land properly in a later sequence. If the runway is not long enough to touch-and-go without planting on the threshold one must question the wisdom and the legality of conducting a touch-and-go.
Sure, the runway behind is of no further use, but the runway ahead would look mighty good if you were hanging from a strand of wire 100 metres short of the threshold!
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dragchute
email: [email protected]
Down here in OZ the fifty feet threshold crossing height is required to clear dead trees, single strand telephone wires, ant hills, barbed wire fences and all the other paraphernalia associated with an 'outback' airstrip. Some of the city runways are equally as challenging with delivery vans and the like crossing on roads in the undershoot.
Why teach a student to land on the threshold if you must ultimately re-train him/her to land properly in a later sequence. If the runway is not long enough to touch-and-go without planting on the threshold one must question the wisdom and the legality of conducting a touch-and-go.
Sure, the runway behind is of no further use, but the runway ahead would look mighty good if you were hanging from a strand of wire 100 metres short of the threshold!
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dragchute
email: [email protected]
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Most regional UK fields have PAPIs or VASIs so if you teach your student to fly these then he/she will round in the right place. Agreed that without these or from a flapless (flat) approach you need to use the threshold as your aiming point.
Your actual touch down point should be as far away from the round point as possible. The best touchdowns come from trying to keep the aircraft flying as long as possible, even in a trike configured undercarriage. Alas some pilots don't do this and end up in the accident reports with broken nose gear.
Vigi
Your actual touch down point should be as far away from the round point as possible. The best touchdowns come from trying to keep the aircraft flying as long as possible, even in a trike configured undercarriage. Alas some pilots don't do this and end up in the accident reports with broken nose gear.
Vigi
Joined: Jan 1999
Posts: 6,209
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From: north of barlu
Capt Crash has hit the nail on the head a lot of low time pilots fly the aproach to fast the speed should be 1.3Vs ,most flying clubs then round this up to the next eazy to remember number the low time pilot then adds his "safety margin" and a bit for the crosswind and the gust and because the aircraft is heavy so we now have a C172 with a 80KT aproach speed .
Now it realy gets interesting as the guy trys to touch down the aircraft wants to keep flying and the end of the runway is coming up fast so the guy trys to force the aircraft down it bounces up and the next thing we are into is a PIO two or three cycles of this and the nose gear gives way and the whole plot slithers to a to a stop with £10,000 of damage.
Now it realy gets interesting as the guy trys to touch down the aircraft wants to keep flying and the end of the runway is coming up fast so the guy trys to force the aircraft down it bounces up and the next thing we are into is a PIO two or three cycles of this and the nose gear gives way and the whole plot slithers to a to a stop with £10,000 of damage.
Guest
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Thanks for your very helpful responses.
The picture that I am forming is that there is good reason to teach students to land a little into the field initially (i.e. if the engine quits, the landing is made), but that they need to develop more control as their flying progresses and they wish to land in less forgiving fields. Possibly this includes steeper approaches and certainly tighter airspeed control.
I use 1.3vs as my final approach speed stabilised between 2-300'(63.7 kias with full flap on the PA28 I fly - rounded up to 65kias due to fortysomething eyesight!) and find that this is very comfortable. If there are more than slight controllability issues due to gusts etc., then I have chosen the wrong day to fly!
Thanks again for your kind assistance.
The picture that I am forming is that there is good reason to teach students to land a little into the field initially (i.e. if the engine quits, the landing is made), but that they need to develop more control as their flying progresses and they wish to land in less forgiving fields. Possibly this includes steeper approaches and certainly tighter airspeed control.
I use 1.3vs as my final approach speed stabilised between 2-300'(63.7 kias with full flap on the PA28 I fly - rounded up to 65kias due to fortysomething eyesight!) and find that this is very comfortable. If there are more than slight controllability issues due to gusts etc., then I have chosen the wrong day to fly!
Thanks again for your kind assistance.
Guest
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James G,
Speed control IS most important and your adherence to an approach speed of 1.3Vs is sound policy. Some years ago I operated Cessna 180 types into short fields (not really fields but claypans, roads, beaches or sometimes just a clear patch of ground). The approach speed was 1.1Vs as dictated in the ‘Precautionary Landing technique of our SOP’s (40 knots for a Vs of 36 knots in the landing configuration). The approach was stabilized with attitude and trim at precisely forty knots, and vigorous throttle application used to control the glide path to hit the aiming point. Prior to touch downpower was reduced to idle and full back stick applied for a firm three-point landing.(Getting out was usually another challenge – particularly with obstacles).
I do not suggest for one minute you or any other reader adopts this low speed approach technique. The point I make is that since 1.1Vs works (at least I got away with it on many occasions) then 1.3Vs must be perfectly safe with no requirement to increase for the ‘mum and the kids’ factor.
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dragchute
email: [email protected]
Speed control IS most important and your adherence to an approach speed of 1.3Vs is sound policy. Some years ago I operated Cessna 180 types into short fields (not really fields but claypans, roads, beaches or sometimes just a clear patch of ground). The approach speed was 1.1Vs as dictated in the ‘Precautionary Landing technique of our SOP’s (40 knots for a Vs of 36 knots in the landing configuration). The approach was stabilized with attitude and trim at precisely forty knots, and vigorous throttle application used to control the glide path to hit the aiming point. Prior to touch downpower was reduced to idle and full back stick applied for a firm three-point landing.(Getting out was usually another challenge – particularly with obstacles).
I do not suggest for one minute you or any other reader adopts this low speed approach technique. The point I make is that since 1.1Vs works (at least I got away with it on many occasions) then 1.3Vs must be perfectly safe with no requirement to increase for the ‘mum and the kids’ factor.
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dragchute
email: [email protected]
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G'day all,
I think an important consideration that should be taken into account is windshear on finals or a possible partial (or full) engine failure scenario (as JamesG noted a post or 2 above).
In either of the above situations, it really can save your bacon to be aiming about 250m (or 1/3 into the field, whichever is the lessor) rather than aiming straight at the threshold.
This, of course, depends on where you are operating from.
The school I work for is based at a large radar-controlled airfield with a 2,000m runway. In this location I've found pilots that fly an approach aiming at the threshold, w/flaps 40 (on a 172N) and 2200 RPM, seeming oblivious to the fact that if the engine decides to stop working they're going to lob into the sports field short of the runway.
For a short field landing, the method I'm most familiar with is to aim 1/3 into the field, close the throttle at 50ft (or once obstacles are cleared), fly down and land. It's the method given in the POH's and, whilst it may not deliver *really* short landings, most PPL's are able to get it consistently correct and land safely within the distances given in the POH.
Fly the numbers, read your POH and, above all, keep current.
Cheers,
Grade 3
I think an important consideration that should be taken into account is windshear on finals or a possible partial (or full) engine failure scenario (as JamesG noted a post or 2 above).
In either of the above situations, it really can save your bacon to be aiming about 250m (or 1/3 into the field, whichever is the lessor) rather than aiming straight at the threshold.
This, of course, depends on where you are operating from.
The school I work for is based at a large radar-controlled airfield with a 2,000m runway. In this location I've found pilots that fly an approach aiming at the threshold, w/flaps 40 (on a 172N) and 2200 RPM, seeming oblivious to the fact that if the engine decides to stop working they're going to lob into the sports field short of the runway.
For a short field landing, the method I'm most familiar with is to aim 1/3 into the field, close the throttle at 50ft (or once obstacles are cleared), fly down and land. It's the method given in the POH's and, whilst it may not deliver *really* short landings, most PPL's are able to get it consistently correct and land safely within the distances given in the POH.
Fly the numbers, read your POH and, above all, keep current.
Cheers,
Grade 3
Guest
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I think that aiming 1/3 of the way in the runways because you may have an engine failure is misguided. It is SOOOO unlikely that your engine is going to fail at or about idle power. It is under the most stress on a go-around, with an engine failure at this point you will be grateful of any runway ahead of you!
Just my thoughts.
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WHOOP WHOOP
PULL UP!!!!!!
[This message has been edited by Capt Crash (edited 20 January 2001).]
Just my thoughts.
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WHOOP WHOOP
PULL UP!!!!!!
[This message has been edited by Capt Crash (edited 20 January 2001).]
Guest
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I don’t believe it is possible to come up with a one size fits all technique for landing with maximum safety. Pilot, aircraft, runway and weather all need to be taken into account to even establish the best plan, let alone the issues about teaching and executing the plan.
But we have to start somewhere.
Let us assume an inexperienced recreational student pilot and a light aircraft of a type that is in widespread use. We have now removed two major variables.
Such a combination should ideally not be going about their business where the runway is other than plenty long enough and the weather pretty benign. In such normal circumstances, the instructor will surely be tying to get the student to develop three skills;
A Correct visual judgement of the approach and landing that is going on
B Proper control techniques
C Flying accuracy.
Not separating out these three elements and just getting on with bashing the circuit in some generalised way and hoping it will all come good one day is not helpful for the student.
In my view these skills should be taught/honed in the order listed. A and C are at the heart of this thread.
By all means teach the inexperienced student to land 1/3 in when teaching A and B. That way you maximise the chances of leaving the student to appreciate errors and correct them without instructor intervention and also enhance solo safety.
Then when A and B are sorted (and not before) you really need to beat up on the student over C. For my money this includes a touchdown point well in (for the extra safety this provides against an engine problem on finals) BUT that does not mean you accept other than the chosen point of touchdown. If undershooting - sort it, if overshooting - go around.
Once A,B and C are sorted the available skills allow the pilot to CONVERT to a new runway type. (short, narrow, bumpy, slippery, sloping, different width/length perspective etc etc)
Such a new runway may well require the (now) available skills of C to be used to land at the threshold – or wherever is appropriate for the combination of all the factors present.
When subsequently faced with a new runway, aircraft and weather combination the inexperienced pilot can then talk to him/herself downwind about the need to consider A, B and C.
JF
But we have to start somewhere.
Let us assume an inexperienced recreational student pilot and a light aircraft of a type that is in widespread use. We have now removed two major variables.
Such a combination should ideally not be going about their business where the runway is other than plenty long enough and the weather pretty benign. In such normal circumstances, the instructor will surely be tying to get the student to develop three skills;
A Correct visual judgement of the approach and landing that is going on
B Proper control techniques
C Flying accuracy.
Not separating out these three elements and just getting on with bashing the circuit in some generalised way and hoping it will all come good one day is not helpful for the student.
In my view these skills should be taught/honed in the order listed. A and C are at the heart of this thread.
By all means teach the inexperienced student to land 1/3 in when teaching A and B. That way you maximise the chances of leaving the student to appreciate errors and correct them without instructor intervention and also enhance solo safety.
Then when A and B are sorted (and not before) you really need to beat up on the student over C. For my money this includes a touchdown point well in (for the extra safety this provides against an engine problem on finals) BUT that does not mean you accept other than the chosen point of touchdown. If undershooting - sort it, if overshooting - go around.
Once A,B and C are sorted the available skills allow the pilot to CONVERT to a new runway type. (short, narrow, bumpy, slippery, sloping, different width/length perspective etc etc)
Such a new runway may well require the (now) available skills of C to be used to land at the threshold – or wherever is appropriate for the combination of all the factors present.
When subsequently faced with a new runway, aircraft and weather combination the inexperienced pilot can then talk to him/herself downwind about the need to consider A, B and C.
JF
Guest
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Capt Crash: Perhaps it is unlikely to have an engine failure due to mechanical failure on short finals, but there are other possible causes (e.g. carby icing, fuel starvation / contamination). It also comes down to the philosophy of minimising the risk. You aim a little way into the field for the same reasons you don't fly single engine over water (you don't do you ? 
)- just in case !
JF: Thanks for the description of the method in your post. I found it very enlightening and most useful.
Cheers,
Grade 3
)- just in case !JF: Thanks for the description of the method in your post. I found it very enlightening and most useful.
Cheers,
Grade 3
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Grade 3
I understand what you are saying, but I just hate leaving runway behind me. At the school I teach at we leave carby heat ON until we vacate the runway. Fuel provided at Cambridge is checked daily and as for running out of fuel....
And, yes I do fly over water all the time in a single engine aircraft.
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WHOOP WHOOP
PULL UP!!!!!!
[This message has been edited by Capt Crash (edited 21 January 2001).]
I understand what you are saying, but I just hate leaving runway behind me. At the school I teach at we leave carby heat ON until we vacate the runway. Fuel provided at Cambridge is checked daily and as for running out of fuel....
And, yes I do fly over water all the time in a single engine aircraft.
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WHOOP WHOOP
PULL UP!!!!!!
[This message has been edited by Capt Crash (edited 21 January 2001).]
Guest
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If you were to aim to land anywhere else other than the tochdown zone which is generally 300 metres past the threshold on an instument runway and marked with the 'chequered' paint markings either side of the centre line, or failed to follow the glideslope information provided by approach path indicators (papis, vasis et al ) to landing on non instrument runways, then you would not get past day one of your initial conversion course with an airline. Surely it is best to tech the correct technique for each type of runway that could be used, short fields, grass strips etc require different techniques, but if you can land on the TDZ on a large runway, then you must have the skill to land just past the threshold on a short strip if required.
From experience, if you do not need to land on the threshold, then the extra fifty feet height you will have over it is an extra safety margin aginst windshear etc. It's for free as well - and I'm all for that.
BTW, regarding leaving the carb heat on until you are runway vacated - does not the carburettor heater on most piston engines bypass the airfilter and it's use decrease the volume of charge in the cylinders due to the warmer air being induced?.
I thought the proper way to use it was to turn it off prior to landing so that full power will be available for any go-around and to prevent engine damage on the ground due to f.o.d. ingestion.
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"How can we soar like eagles when we're surrounded by turkeys"
[This message has been edited by The Growler (edited 21 January 2001).]
From experience, if you do not need to land on the threshold, then the extra fifty feet height you will have over it is an extra safety margin aginst windshear etc. It's for free as well - and I'm all for that.
BTW, regarding leaving the carb heat on until you are runway vacated - does not the carburettor heater on most piston engines bypass the airfilter and it's use decrease the volume of charge in the cylinders due to the warmer air being induced?.
I thought the proper way to use it was to turn it off prior to landing so that full power will be available for any go-around and to prevent engine damage on the ground due to f.o.d. ingestion.
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"How can we soar like eagles when we're surrounded by turkeys"
[This message has been edited by The Growler (edited 21 January 2001).]
Guest
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Growler,
The approach speed for a C152 is around ‘55-65 KIAS with flaps and reducing to 54 KIAS at fifty feet’ (Model 152 Information Manual). Given that a stabilized approach is achieved with a rate of descent of about 500 feet per minute, this equates to some five degrees gradient – steeper when a head wind is considered. Assuming that a threshold crossing height of fifty feet is achieved, touchdown will occur at a point 600 feet or 182 metres from the threshold. Other factors applicable to light aircraft pilots include the possibility of engine failure and approach obstacles existing on many GA runways particularly those surveyed just 150 metres from the threshold.
Most approach aids such as PAPI, T-VASIS and ILS achieve a three degree glideslope. Given that a performance type will approach at or above a Vref speed double the approach speed of the C152 but still stabilized at about 500 feet per minute the ‘aided’ glidepath will work. A three degree touch down zone will intersect the runway based on 50ft TCH precisely 1000 feet from the threshold – hence the markers.
Why would one wish to train a student in a C152 or similar to achieve a three degree glidepath when such is outside the recommendations of the POH? Airlines have the right to insist of achieving PAPI & G/S – flying schools have the right to insist upon achieving the criteria prescribed in the POH and that will probably include ignoring the PAPI or T-VASIS in day VFR operations.
Fully agree with your comments on the carburetor heat. Should be selected to cold when landing is assured. Engine life will be considerably extended if the ingestion of abrasive dust particles is avoided by filtering intake air.
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dragchute
email: [email protected]
The approach speed for a C152 is around ‘55-65 KIAS with flaps and reducing to 54 KIAS at fifty feet’ (Model 152 Information Manual). Given that a stabilized approach is achieved with a rate of descent of about 500 feet per minute, this equates to some five degrees gradient – steeper when a head wind is considered. Assuming that a threshold crossing height of fifty feet is achieved, touchdown will occur at a point 600 feet or 182 metres from the threshold. Other factors applicable to light aircraft pilots include the possibility of engine failure and approach obstacles existing on many GA runways particularly those surveyed just 150 metres from the threshold.
Most approach aids such as PAPI, T-VASIS and ILS achieve a three degree glideslope. Given that a performance type will approach at or above a Vref speed double the approach speed of the C152 but still stabilized at about 500 feet per minute the ‘aided’ glidepath will work. A three degree touch down zone will intersect the runway based on 50ft TCH precisely 1000 feet from the threshold – hence the markers.
Why would one wish to train a student in a C152 or similar to achieve a three degree glidepath when such is outside the recommendations of the POH? Airlines have the right to insist of achieving PAPI & G/S – flying schools have the right to insist upon achieving the criteria prescribed in the POH and that will probably include ignoring the PAPI or T-VASIS in day VFR operations.
Fully agree with your comments on the carburetor heat. Should be selected to cold when landing is assured. Engine life will be considerably extended if the ingestion of abrasive dust particles is avoided by filtering intake air.
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dragchute
email: [email protected]
Guest
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>Fully agree with your comments on the carburetor heat. Should be selected to cold when landing is assured.
I would agree also, BUT for a student, who may not feel assured, what is best to teach them? A longish final with power at idle and no carb heat has landed some 152/172 drivers in the far fence. The accident or incident reports have those wonderful vague comments about engine failure without any mechanical findings.
I wonder if the carb heat issue isn't more safely taught after licensing.
After all a license is only a permit to learn.....
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I would agree also, BUT for a student, who may not feel assured, what is best to teach them? A longish final with power at idle and no carb heat has landed some 152/172 drivers in the far fence. The accident or incident reports have those wonderful vague comments about engine failure without any mechanical findings.
I wonder if the carb heat issue isn't more safely taught after licensing.
After all a license is only a permit to learn.....
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-.-- --.- -..-
Guest
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Blue dude
I don't know where you fly but here in Canada knowing when & how to use carb heat is vital; we fly in the carb ice range a lot, and in extreme cold weather carb heat it can actually cause carb ice formation by heating the intake air to the icing range. There have been several engine failures caused by improper use of carb heat- the driver applied heat and the engine sputtered (indicating the presence of ice), and then panicked and closed the carb heat.
<font face="Verdana, Arial, Helvetica" size="2">I wonder if the carb heat issue isn't more safely taught after licensing.</font>
Guest
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Oh what have I started, the carby heat issue.
My employer has owned a fleet of 152s since the late 1970s and the aircraft have not suffered due to the carb heat being left on. The engine life may be reduced but they are replaced every 2000 hrs and as long as they last that long who cares. My employer is also a light aircraft maint organisation and they would let us know of any excessive FOD or ware.
When trying to teach landing we try to keep things as simple as possible, carb heat out downwind and in (using your thumb on right hand as you advance the throttle seems to work) on go-around or touch and go. If it is forgotten no big deal, the aircraft will climb at full flap with the carb heat on as long as the correct attitude is selected.
I DO understand that the way things are done are different but I don't think they are for the worse.
My employer has owned a fleet of 152s since the late 1970s and the aircraft have not suffered due to the carb heat being left on. The engine life may be reduced but they are replaced every 2000 hrs and as long as they last that long who cares. My employer is also a light aircraft maint organisation and they would let us know of any excessive FOD or ware.
When trying to teach landing we try to keep things as simple as possible, carb heat out downwind and in (using your thumb on right hand as you advance the throttle seems to work) on go-around or touch and go. If it is forgotten no big deal, the aircraft will climb at full flap with the carb heat on as long as the correct attitude is selected.
I DO understand that the way things are done are different but I don't think they are for the worse.