Takeoff Technique For Cessna's
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Takeoff Technique For Cessna's
Just wondering why my training organisation ask us to "Call 40 Knots" as were accelerating down the runway.
What were told is after were clear to take off, we advance throttle fully forward, accerelate down runway maintaining tracking, check airspeed is indicating and rising, check oil temp and pressure, call 40 Knots and then finally rotate at 55KIAS.
I understand all the other checks but not sure why we have to call out "40 Knots".
I will ask my instructor but my only guess is that 40 knots represents approx 2/3's Take Off Safety Speed (TOSS) which is what the theory books talk about with regards to taking off from short runways.
Thanks all....
Mr G
What were told is after were clear to take off, we advance throttle fully forward, accerelate down runway maintaining tracking, check airspeed is indicating and rising, check oil temp and pressure, call 40 Knots and then finally rotate at 55KIAS.
I understand all the other checks but not sure why we have to call out "40 Knots".
I will ask my instructor but my only guess is that 40 knots represents approx 2/3's Take Off Safety Speed (TOSS) which is what the theory books talk about with regards to taking off from short runways.
Thanks all....
Mr G
Is 40 knots reasonably close to your rotate speed?
Myself, when flying things like 172s, I call 50 knots and rotate at 60 knots. I use the preceding call to get myself prepared to rotate. Its sorta like a V1 call, but then in a 172 off the sort of runways I use, theres not going to be a critical speed.
Ask your instructor, she should have a good clear explanation for you.
Myself, when flying things like 172s, I call 50 knots and rotate at 60 knots. I use the preceding call to get myself prepared to rotate. Its sorta like a V1 call, but then in a 172 off the sort of runways I use, theres not going to be a critical speed.
Ask your instructor, she should have a good clear explanation for you.
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FYI, airline SOP's require the pilot to call out at "80kts." Of course, in the case of light aircraft, such a speed would not be relevant, as your typical bugsmasher would already be airborne.
Why the speed check? Airline crews make the call for verification of airspeed readout, and because the speed has a bearing on whether or not the take-off will be rejected under certain conditions. From 80kts up to V1 (consider "V1" as a last-chance decision speed, if you will, on which the take-off can be rejected), there are additional sets of conditions which may warrant a rejected take-off. However, above V1 it's balls to the wall, no matter what - unless you plan on using the fence at the opposite end as an arrester hook.
In the context of your type of operation, the considerations are much the same, albeit in a simplified form:
Recognition of airspeed (the ASI is/is not functioning), i.e. "my aeroplane is accelerating down the runway, thus my airspeed should be registering something by now." If it is, continue. If it's not, "how about I pull the pin before I get up close and personal with the fence at the other end?!" In other words, you don't want to find yourself having used up a good portion of the runway, only to realize you should have been at lift-off speed by now, but the ASI is acting all screwy. Recognition that something is amiss early in the take-off is much better than realizing the same thing after using up most of the available length.
As for the magic number 40, you'll notice your ASI is only calibrated from 40kts upwards (at least as far as I remember from the Cessnas and Pipers I used to fly), hence "40kts!"
Furthermore, it's good airmanship and teaches the right habits for when you do eventually get to fly heavier metal.
Why the speed check? Airline crews make the call for verification of airspeed readout, and because the speed has a bearing on whether or not the take-off will be rejected under certain conditions. From 80kts up to V1 (consider "V1" as a last-chance decision speed, if you will, on which the take-off can be rejected), there are additional sets of conditions which may warrant a rejected take-off. However, above V1 it's balls to the wall, no matter what - unless you plan on using the fence at the opposite end as an arrester hook.
In the context of your type of operation, the considerations are much the same, albeit in a simplified form:
Recognition of airspeed (the ASI is/is not functioning), i.e. "my aeroplane is accelerating down the runway, thus my airspeed should be registering something by now." If it is, continue. If it's not, "how about I pull the pin before I get up close and personal with the fence at the other end?!" In other words, you don't want to find yourself having used up a good portion of the runway, only to realize you should have been at lift-off speed by now, but the ASI is acting all screwy. Recognition that something is amiss early in the take-off is much better than realizing the same thing after using up most of the available length.
As for the magic number 40, you'll notice your ASI is only calibrated from 40kts upwards (at least as far as I remember from the Cessnas and Pipers I used to fly), hence "40kts!"
Furthermore, it's good airmanship and teaches the right habits for when you do eventually get to fly heavier metal.
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Some just say 'airspeed alive' - or something. Calling something out will give you an idea of what it 'feels' like. As for this V1, rotate stuff - well, maybe that's the next lesson. My old instructor used to cover up the ASI and the other clocks (Not for take off) but guess what, you find you can get by without an ASI at all in a Cessna. Once you learn what it feels like at certain speeds, attitudes and configurations etc, its amazing what you can do without when you really have to. E.g. Great fun and no problem when you have a total electrical failure - at night.
The Bunglerat
Not all airlines, mainly a Boeing type call, other people call 100 knots.
Ummm, no TOGA is not always selected in the case of an engine failure, derated takeoff setting should give adequate performance under normal circumstances.
Mr Garrison
Ask your CFI, I would also suggest it was adapted from either RAAF or airline two crew procedures and introduced as a good habit as suggest above.
The airspeed call is also used as a pilot incapacitation check in some airlines.
Keep asking questions, its what this forum is for, no such thing as silly questions.
FYI, airline SOP's require the pilot to call out at "80kts."
However, above V1 it's balls to the wall
Mr Garrison
Ask your CFI, I would also suggest it was adapted from either RAAF or airline two crew procedures and introduced as a good habit as suggest above.
The airspeed call is also used as a pilot incapacitation check in some airlines.
Keep asking questions, its what this forum is for, no such thing as silly questions.
The manufacturer's POH for the C150, 152, and 172 and no doubt similar types do not mention a check or call of 40 knots during the take off run.
Similarly there is no mention of specific checking of temperatures and pressures in the middle of the take off run. It is just another GA gimmick. Those who think it is yet another GOOD IDEA to foist upon a hapless student these personal theories, should have the courage of their convictions and direct your theories to the aircraft manufacturer with the recommendation that they be incorporated in the POH as a matter of vital flight safety. The replies (if any are received) will be illuminating.
Similarly there is no mention of specific checking of temperatures and pressures in the middle of the take off run. It is just another GA gimmick. Those who think it is yet another GOOD IDEA to foist upon a hapless student these personal theories, should have the courage of their convictions and direct your theories to the aircraft manufacturer with the recommendation that they be incorporated in the POH as a matter of vital flight safety. The replies (if any are received) will be illuminating.
Silly Old Git
Absolutely..Centaurus.
Another distraction for our hapless tyro when he should be peering out the front anticipating the shove in the back and breathtaking 172 rotation and climb.
Another distraction for our hapless tyro when he should be peering out the front anticipating the shove in the back and breathtaking 172 rotation and climb.
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Yeah, 40 knot call probibly a bit of a waste of time. More appropriate to call 'airspeed active' during a short feild takeoff - and have an abort point. This allows for the possibility of an unexpected tailwind or poor acceleration due to long grass ect.
I also dissagree with checking ts and ps during the roll, too much work for the poor student, and as stated - not required by the flight manual.
As for the 'rotate' speed. In most lighties you don't really need a certain speed, just hold the weight off the nosewheel and somewhere around 40-50 knots raise the nose to climb attitude - the aircraft will get airborne when it wants to. It's not a heavy jet and not designed to be kept on the ground to build up speed.
I also dissagree with checking ts and ps during the roll, too much work for the poor student, and as stated - not required by the flight manual.
As for the 'rotate' speed. In most lighties you don't really need a certain speed, just hold the weight off the nosewheel and somewhere around 40-50 knots raise the nose to climb attitude - the aircraft will get airborne when it wants to. It's not a heavy jet and not designed to be kept on the ground to build up speed.
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Just a thought
Being a student was only a few years ago for me so I remember well the early days of just about every takeoff there was a new thing to learn. One of the things that I picked up just from observing a really good instructor was when you check ASI, a quick look for Greens on the gauges just to verify you have what you should have, rather than discover it 300' and no runway left that is useful.
After the quick scan its fly by attitude and feel and looking out for traffic or birds (feathered).
I don't know what the heavy metal boys do, but I guess now they have a computer that watches it for them and only flashes up a warning if the need arises!
J
After the quick scan its fly by attitude and feel and looking out for traffic or birds (feathered).
I don't know what the heavy metal boys do, but I guess now they have a computer that watches it for them and only flashes up a warning if the need arises!
J
The "80 kt" call used by airlines (100 kts on some types), is primarily used to check for any discrepancy between the Captain's and FO's airspeed indicators.
If there is a significant difference between the two,(most airlines SOP's state 10 kts) then a rejected T/O should be considered.
As for calling "40 kts" in single engine light aircraft, if it is not part of the aircraft opreating manual then the school teaching this technique should have a very good reason for doing so.
The reasons offered so far do nothing more than add an unnecessary distraction at a critical stage of flight.
A good question all the same Mr Garrison.
Cheers
If there is a significant difference between the two,(most airlines SOP's state 10 kts) then a rejected T/O should be considered.
As for calling "40 kts" in single engine light aircraft, if it is not part of the aircraft opreating manual then the school teaching this technique should have a very good reason for doing so.
The reasons offered so far do nothing more than add an unnecessary distraction at a critical stage of flight.
A good question all the same Mr Garrison.
Cheers
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SWH, I dunno what your flying....if I ever lose a hairdryer, the other lever(s) are gonna get bent forward..TOGA be buggered, 5 mins at rated thrust is going to save me and my passengers..
Just to say that there is more than one way to skin a cat, but strictly speaking all transport catagory aircraft are performance limited by their ability to fly away with a V1 critical power unit loss, hence TOGA is the promulgated thrust setting
Just to say that there is more than one way to skin a cat, but strictly speaking all transport catagory aircraft are performance limited by their ability to fly away with a V1 critical power unit loss, hence TOGA is the promulgated thrust setting
Grandpa Aerotart
but strictly speaking all transport catagory aircraft are performance limited by their ability to fly away with a V1 critical power unit loss, hence TOGA is the promulgated thrust setting
As to '40 kts'? If it's anymore than a way of signifying to the instructor that you have checked airspeed alive then it is, as mooted by others, a crock of ****e that stinketh.
Would I stop on a short, wet runway for no IAS in a lighty?
No...but then I was taught how to fly without one if the nead arrises.
There seems to be a lot of good usefull stuff that is not taught these days in primary flight training...and it seems, at times, it has been replaced with rubbish aped from 'the airlines'. Invariably the instructor has never been in an airline and actually has little idea of what he speaks but has read it somewhere.
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RE 80kt call
Just in regards to the "80 knots" call commonly heard in the bigger types, I believe I read somewhere that the performance charts for TO are based on TO power being set by 80kts. If it is not set by that stage, you risk cleaning up the fence.
Would probably be an ideal time to cross check/verfiy that both the capts. and FOs speed tape are both reading the same thing.
Just my 2 cents worth!
fnb
Would probably be an ideal time to cross check/verfiy that both the capts. and FOs speed tape are both reading the same thing.
Just my 2 cents worth!
fnb
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In a C182, i dont see a need to call 40, but i do check to see if the indicator is working, on more than 1 occasion, just because the ASI is working and climbing as you accelerate down the strip doesnt mean it HASNT failed. on 2 occasions in a piper Arrow, accelerating down 11R at YSBK, the airspeed worked fine (so i thought) rotated at 65, accelerated to 80, gear up. accelerated through 90, but heres where things went pearshaped, attitude OK, yet the ASI continued through 120Kts, then 140, through yellow and continued through 3 complete circles of the dial only to settle a few degrees before 0. a circuit was completed followed by a normal landing.
fortunatly my instructor, Brian wetless regulalry stuck bits of carboard over instruments.
ask your instructor if he/she can do some partial panel work with you.
fortunatly my instructor, Brian wetless regulalry stuck bits of carboard over instruments.
ask your instructor if he/she can do some partial panel work with you.
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Mayby some clarification here....
Tin......why would reducing t/o thrust increase M/tow...by reducing V1?..surely you reduce V1 to balance a shorter field.
V1 is a decision speed to fly, and therefore cannot be less than Vmc(a), V1 is calculated (in the company I work for) based on field length/slope, optimum flap setting, regulated & actual take off mass, temperature, and pressure altitude, VMC is always less than V1 in these calculations.
Chimbu...explain where and why Im wrong, I was refering to JAR Ops jet transports rather than T/Props.
Personally I think an airspeed alive check is sufficient in light a/c..most will tell you when they are gonna fly.
Tin......why would reducing t/o thrust increase M/tow...by reducing V1?..surely you reduce V1 to balance a shorter field.
V1 is a decision speed to fly, and therefore cannot be less than Vmc(a), V1 is calculated (in the company I work for) based on field length/slope, optimum flap setting, regulated & actual take off mass, temperature, and pressure altitude, VMC is always less than V1 in these calculations.
Chimbu...explain where and why Im wrong, I was refering to JAR Ops jet transports rather than T/Props.
Personally I think an airspeed alive check is sufficient in light a/c..most will tell you when they are gonna fly.
Haughtney1,
If you use assumed Temperature to reduce your take-off thrust, you are correct. However, if as swh and tinnie stated you use the derate, you are wrong.
In essense assumed temp considers the same engine performance but on a hotter day. The derate, treats the engine as being a totally new one at reduced thrust. So the VMC and V1 when using a derate is calculated at the reduced thrust. So, if you were to push all the levers forward after a failure as you stated, things may well go askew. The derate is not an option on smaller jets I guess.
Also of note, there is really no requirement to push everything up even when using the assumed temp method, as takeoff perf has been done at the reduced thrust. On a larger and bigger thrusted airplane, it is sometimes better just to leave the levers where they are as performance is not limiting when they are light, but the foot work might be. However when you are hot and heavy, the assumed temp and the outside temp will probably be close so the little extra thrust might be helpful.
Don
If you use assumed Temperature to reduce your take-off thrust, you are correct. However, if as swh and tinnie stated you use the derate, you are wrong.
In essense assumed temp considers the same engine performance but on a hotter day. The derate, treats the engine as being a totally new one at reduced thrust. So the VMC and V1 when using a derate is calculated at the reduced thrust. So, if you were to push all the levers forward after a failure as you stated, things may well go askew. The derate is not an option on smaller jets I guess.
Also of note, there is really no requirement to push everything up even when using the assumed temp method, as takeoff perf has been done at the reduced thrust. On a larger and bigger thrusted airplane, it is sometimes better just to leave the levers where they are as performance is not limiting when they are light, but the foot work might be. However when you are hot and heavy, the assumed temp and the outside temp will probably be close so the little extra thrust might be helpful.
Don
haughtney1,
Looking at your profile, I assume your a 757 F/O.
As Tinstaafl eluded to, reduce the rated thrust value and you can get a lower Vmcg-limited V1. If the rated thrust is reduced the Vmcg and Vmcg-limited V1 reduce, which means V1 can reduce, or an increase in MTOW to keep the same ASDR.
Reducing rated thrust, FLEX, assumed temperature are all about the same thing, not using all the performance available from the engine to extend service life, while assuring adequate climb performance. Selecting TOGA is not always necessary for all types, however it is always a consideration.
If you remember you B200, it even had derated engines.
Looking at your profile, I assume your a 757 F/O.
As Tinstaafl eluded to, reduce the rated thrust value and you can get a lower Vmcg-limited V1. If the rated thrust is reduced the Vmcg and Vmcg-limited V1 reduce, which means V1 can reduce, or an increase in MTOW to keep the same ASDR.
Reducing rated thrust, FLEX, assumed temperature are all about the same thing, not using all the performance available from the engine to extend service life, while assuring adequate climb performance. Selecting TOGA is not always necessary for all types, however it is always a consideration.
If you remember you B200, it even had derated engines.