Trimming under 300 feet
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A more likely reason why trimming below 300ft is not taught [at least to the ab initio] is simply to keep the workload to a minimum. A new guy has enough to think about in the initial stages of takeoff and climb without him trying to remove a bit of control force.
As time and experience progresses, he will have the mental capacity to safely do more and more.
As time and experience progresses, he will have the mental capacity to safely do more and more.
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Trying to fly an out of trim aircraft increases workload significantly because every time that the pilot relaxes the force on the stick, the attitude changes. Thus most of their effort (both physical and mental) is taken up with simply keeping the required attitude.
A quick adjustment to the trim can remove the out of trim forces and thus reduce the workload!
Regards,
DFC
A quick adjustment to the trim can remove the out of trim forces and thus reduce the workload!
Regards,
DFC
I taught to trim anytime the a/c was out of trim, except if a deliberate untrimmed state was desirable eg turns or, for some types/pilot combinations, a slight nose up trim on short final.
I know I trim within seconds of the wheels leaving the ground if it's not correct. I also do so on approach up to the point where I commence the flare, if necessary eg flying a reducing speed profile. As far as I can see, altitude is irrelevent. The major factors are task priority & pilot capacity to attend.
I know I trim within seconds of the wheels leaving the ground if it's not correct. I also do so on approach up to the point where I commence the flare, if necessary eg flying a reducing speed profile. As far as I can see, altitude is irrelevent. The major factors are task priority & pilot capacity to attend.
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your hand is on the throttle!
You should have your hand on the throttle during the climb out!! The throttle friction is ok, however some throttles still slide back, and its quite hard to detect. Also your aeroplane should be trimmed on the ground anyway during the pre-take off checks, to ensure that there isnt too much force on the controls during the climb out.
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Green Dinosaur,
IMHO, the main reason for keeping one's hand on the throttle is so that one can close it asap if necessary during the take-off.
During the climb it is true that a worn friction lock can result in the power reducing. However, unless you have fabulous noise cancelling headset equipment, any significant reduction is highlighted by a change in sound when flying an aircraft with fixed pitch prop.
If one was to teach no trimming below 300ft then would also have to teach that the gear should not be retracted below that height despite what effect that can have on performance. After all, it takes about the same time to move the gear leaver through a few centimetres as it does to move the trim wheel by the same or less.
Yes the aircraft trim should be set to the take-off position before take-off. However you may have noticed that while aircraft like the C172 have a single position for take-off trim, the loading can vary by more than a bit. If you don't believe me, ask your back seat pax to lean forward for a minute and see what that does to the trim setting during the cruise.
Thus unless that POH gives a specific setting for every position of the C of G, there is probably going to be some trim adjustment required shortly after take-off and more so if the C of G is near any of the extremes!
Regards,
DFC
IMHO, the main reason for keeping one's hand on the throttle is so that one can close it asap if necessary during the take-off.
During the climb it is true that a worn friction lock can result in the power reducing. However, unless you have fabulous noise cancelling headset equipment, any significant reduction is highlighted by a change in sound when flying an aircraft with fixed pitch prop.
If one was to teach no trimming below 300ft then would also have to teach that the gear should not be retracted below that height despite what effect that can have on performance. After all, it takes about the same time to move the gear leaver through a few centimetres as it does to move the trim wheel by the same or less.
Yes the aircraft trim should be set to the take-off position before take-off. However you may have noticed that while aircraft like the C172 have a single position for take-off trim, the loading can vary by more than a bit. If you don't believe me, ask your back seat pax to lean forward for a minute and see what that does to the trim setting during the cruise.
Thus unless that POH gives a specific setting for every position of the C of G, there is probably going to be some trim adjustment required shortly after take-off and more so if the C of G is near any of the extremes!
Regards,
DFC
Is he an airline pilot? Maybe he copied some procedures: no trim until gear up (the reason would be to prevent trim runaway with the gear hanging out on jets).
But still, I hate it if the aircraft is nose heavy in the climb and it requires forces to keep the nose up... trim it. Even on landing, on some Pipers (Archer/Seneca), we give 2 "bursts" up short final, while maintaining some forward pressure to keep it's attitude, then releasing it in the flare, which makes it a lot easier to land (especially on the Seneca this is really helpfull).
But still, I hate it if the aircraft is nose heavy in the climb and it requires forces to keep the nose up... trim it. Even on landing, on some Pipers (Archer/Seneca), we give 2 "bursts" up short final, while maintaining some forward pressure to keep it's attitude, then releasing it in the flare, which makes it a lot easier to land (especially on the Seneca this is really helpfull).
>Is he an airline pilot? Maybe he copied some procedures: no trim until gear up (the reason would be to prevent trim runaway with the gear hanging out on jets).<
Done the airline pilot bit for circa 25 years on Boeing and Airbus and never heard of such a procedure!
Done the airline pilot bit for circa 25 years on Boeing and Airbus and never heard of such a procedure!
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A student with only 10 hours isnt going to be able to tell by the engine sound whether he's climbing at full power or only has 2200 rpm set, unless his hand is on the throttle.
Remember you are teaching students,not 500+ hour pilots here. Further, you can set the trim a little either side of neutral to take into account of pax size. Seems sensible to me!!
Remember you are teaching students,not 500+ hour pilots here. Further, you can set the trim a little either side of neutral to take into account of pax size. Seems sensible to me!!
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green dinosaur,
I would hope that your 10 hour student would have an instructor sitting beside them who would calmly ask them if they think the engine noise has reduced slightly. If the student states that they have noticed the change in engine note then the instructor can calmly point to the fact that the attitude, and speed relationship are not what is normally expected and then perhaps the student might think that if the attitude is OK then the speed is low because the power is too low and pushing the throttle forward might help.
Which is more dangerous in your book?;
1. A pilot who makes a guess at where the trim should be set and places it somewhere other than the position recomended in the POH and then struggles with an out of trim aircraft until well above the surface ( but at a lower than normal speed due to an incorrect trim setting)? or;
2. A pilot who sets the trim as per the POH and then struggles with an out of trim aircraft until well above the surface ( but at a lower than normal speed due to an incorrect trim setting)? or;
3. A pilot who sets the trim as per the POH and then once airborne, uses the correct technique to keep the aircraft in trim at all times during flight?
To adjust the trim takes seconds.
The problem I have with all these AGL heights given to some students these days is that when departing from an unfamiliar field using QNH, they never work out what the appropriate altitude is for these restrictions.
How many students and PPLs are told - no flap retraction below 300ft and no turn until 500ft and depart from a 200ft elevation field and retract the flap at 100ft agl and turn at 300ft agl? Answer......lots
The great gotch ya for PPL checks is to ask them to climb at the best angle speed all the way to 500ft in an aircraft that uses flap for that. Almost 100% of them will automatically retract the flap at 300ft regardless of what the speed is!!
How many light aircraft descend while the flap is being retracted?
Would it not be better to say no turns at a speed below XX and don't retract the flap until clear of obstacles and the speed is above XX
Regards,
DFC
I would hope that your 10 hour student would have an instructor sitting beside them who would calmly ask them if they think the engine noise has reduced slightly. If the student states that they have noticed the change in engine note then the instructor can calmly point to the fact that the attitude, and speed relationship are not what is normally expected and then perhaps the student might think that if the attitude is OK then the speed is low because the power is too low and pushing the throttle forward might help.
Which is more dangerous in your book?;
1. A pilot who makes a guess at where the trim should be set and places it somewhere other than the position recomended in the POH and then struggles with an out of trim aircraft until well above the surface ( but at a lower than normal speed due to an incorrect trim setting)? or;
2. A pilot who sets the trim as per the POH and then struggles with an out of trim aircraft until well above the surface ( but at a lower than normal speed due to an incorrect trim setting)? or;
3. A pilot who sets the trim as per the POH and then once airborne, uses the correct technique to keep the aircraft in trim at all times during flight?
To adjust the trim takes seconds.
The problem I have with all these AGL heights given to some students these days is that when departing from an unfamiliar field using QNH, they never work out what the appropriate altitude is for these restrictions.
How many students and PPLs are told - no flap retraction below 300ft and no turn until 500ft and depart from a 200ft elevation field and retract the flap at 100ft agl and turn at 300ft agl? Answer......lots
The great gotch ya for PPL checks is to ask them to climb at the best angle speed all the way to 500ft in an aircraft that uses flap for that. Almost 100% of them will automatically retract the flap at 300ft regardless of what the speed is!!
How many light aircraft descend while the flap is being retracted?
Would it not be better to say no turns at a speed below XX and don't retract the flap until clear of obstacles and the speed is above XX
Regards,
DFC
No difference between taking your hand off the throttle for a few seconds to adjust the trim than doing the same to raise the gear or raise the flaps or select/deselect carby heat or use a handmike (remember them?) or adjust the sunvisor or adjust a volume or set a heading bug or OBS etc etc etc ad nauseum.
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Two (2) very good reasons for keeping the hand on the throttle during T.O. & Climb-Out:
1) Throttles do creep out. Rare, but it does happen.
2) Training. Remember the Law of Primacy? Later, when you are flying Multi-Engine, the hand must be on the throttles to quickly snatch them back in case one fails on the T.O. roll, or after lift-off, and landing runway is still available in front. The hand must be on the throttles to effect a quick abort. If you don't do this in primary training, it will take a lifetime to instill at alater date.
But, the hand can move swiftly and purposefully to the trim control for a couple of seconds, then swiftly back to the throttle.
1) Throttles do creep out. Rare, but it does happen.
2) Training. Remember the Law of Primacy? Later, when you are flying Multi-Engine, the hand must be on the throttles to quickly snatch them back in case one fails on the T.O. roll, or after lift-off, and landing runway is still available in front. The hand must be on the throttles to effect a quick abort. If you don't do this in primary training, it will take a lifetime to instill at alater date.
But, the hand can move swiftly and purposefully to the trim control for a couple of seconds, then swiftly back to the throttle.
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Rubber Dagger
I think your question contains all the key words, you were training for your CPL and your local school was teaching students (as they do). Each to his or her own level.
IMHO there's no point fighting it, and a certain height AGL doesn't really matter. If you've got a higher priority (like controlling direction in twins and feathering the dead engine), then deal to that, but if everything's tickety-boo then why not make it REALLY easy?
Also, sometimes it's easier overall to not trim fully. For example, in bigger twins that can, on one engine, actually accelerate at acceleration altitude (all alliteration) it's easier in the overall scenario of EFATO to initially leave a bit of back pressure on the C/C so that when it accelerates by 10-20kts, it naturally tends to pitch up/reduce back pressure required, all meaning you don't have to retrim. This makes it easier to fly whatever the procedure is while mentally going through the problem, memory items, ATC, QRH, etc.
My two cents,
1. Do what your instructor says, with the caveat dont' do nuthin dumb. If your instructor tells you something different to someone else at the same organisation ASK WHY. Someone's not standardised. Go to the Chief if you have to, it's their playground.
2. If it makes life easier, do it. When it gets hard it gets really hard, really quickly, and you need all the cards stacked in your favour.
Enjoy
C6
I think your question contains all the key words, you were training for your CPL and your local school was teaching students (as they do). Each to his or her own level.
IMHO there's no point fighting it, and a certain height AGL doesn't really matter. If you've got a higher priority (like controlling direction in twins and feathering the dead engine), then deal to that, but if everything's tickety-boo then why not make it REALLY easy?
Also, sometimes it's easier overall to not trim fully. For example, in bigger twins that can, on one engine, actually accelerate at acceleration altitude (all alliteration) it's easier in the overall scenario of EFATO to initially leave a bit of back pressure on the C/C so that when it accelerates by 10-20kts, it naturally tends to pitch up/reduce back pressure required, all meaning you don't have to retrim. This makes it easier to fly whatever the procedure is while mentally going through the problem, memory items, ATC, QRH, etc.
My two cents,
1. Do what your instructor says, with the caveat dont' do nuthin dumb. If your instructor tells you something different to someone else at the same organisation ASK WHY. Someone's not standardised. Go to the Chief if you have to, it's their playground.
2. If it makes life easier, do it. When it gets hard it gets really hard, really quickly, and you need all the cards stacked in your favour.
Enjoy
C6
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My instructor once asked me, at about 300' after takeoff, to 'check your trim'... naturally (despite the aircraft being trimmed pretty well) I took my hand off the throttle... which he promptly closed saying 'engine failure!' 
- later he confessed that it was just a ruse to get my hand off the throttle so he could close it... b@stard! 
Adam
- later he confessed that it was just a ruse to get my hand off the throttle so he could close it... b@stard! Adam
