When should carb heat be turned off in the landing sequence?

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Re: When should carb heat be turned off in the landing sequence?

Unread post by Mustang » Tue Nov 12, 2019 8:14 pm

From PA28-180E POH:

"Carburetor heat should not be applied unless there is an indication of carburetor icing, since the use of carburetor heat causes a reduction in power which may be critical in case of a go-around. Full throttle operation with heat on is likely to cause detonation."
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Re: When should carb heat be turned off in the landing sequence?

Unread post by jimdavis » Tue Nov 12, 2019 10:40 pm

Mustang wrote:
Tue Nov 12, 2019 8:14 pm
From PA28-180E POH:

"Carburetor heat should not be applied unless there is an indication of carburetor icing, since the use of carburetor heat causes a reduction in power which may be critical in case of a go-around. Full throttle operation with heat on is likely to cause detonation."
ABSOLUTELY Mustang =D> =D> =D> . I can't tell you how many times I have referred pilots and pupes to that paragraph! =D>

Sanity prevails. :D

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Re: WHEN SHOULD CARB HEAT BE TURNED OFF IN THE LANDING SEQUENCE ?

Unread post by Hunter » Wed Nov 13, 2019 9:28 am

jimdavis wrote:
Tue Nov 12, 2019 12:32 pm
Cherokee6 wrote:
Tue Nov 12, 2019 12:15 pm
TikkaT3 wrote:
Tue Nov 12, 2019 11:06 am

Base leg = C.C.P.P.F.T. (Carb-heat on, Cowls closed, Pitch full fine, Power 15 inches, Flap 30, Trim for 75 and 500fpm decent).

Finals = R.P.U.F.F.C. (Radio call final approach, Pitch full fine, Undercarriage down and locked 3 green, Fuel on both, Flap as required, Carb heat off).
:shock: That seems like an awful lot of acronym-flying to me. And very prescriptive - for example, 15 inches of manifold pressure on base? What if your downwind is a bit wider, or closer, necessitating a shallower or steeper descent on base, just as one example? I don’t know what my MP is on downwind, base or final - I know my prop is fine of course and mixture rich but power is applied by feel in order to maintain the correct sight picture. Sometimes I want a steep approach in order to dive through turbulence, in which case my base and final are adjusted accordingly. But I never even look at my MP gauge at those times. I also have no idea what my VSI is showing. Again, all I’m doing is looking at the sight picture and keeping it the way I want it, with my airspeed as desired.

Am I alone in this? Am I being sloppy? What do the experts say?
Ha ha ha, Cherokee 6. No you are certainly not alone. I guess that was a double transmission because I think I said exactly the same in the post before yours. :lol: :lol: :lol:

jim
I want to agree with you guys on this, but there is merit in knowing what your MP should be, at pitch full, on approach in case of an ASI failure. My instructor drilled many of these number into me whilst closing some of my gauges to simulate failures.
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Re: WHEN SHOULD CARB HEAT BE TURNED OFF IN THE LANDING SEQUENCE ?

Unread post by TikkaT3 » Wed Nov 13, 2019 11:44 am

Cherokee6 wrote:
Tue Nov 12, 2019 12:15 pm
TikkaT3 wrote:
Tue Nov 12, 2019 11:06 am

Base leg = C.C.P.P.F.T. (Carb-heat on, Cowls closed, Pitch full fine, Power 15 inches, Flap 30, Trim for 75 and 500fpm decent).

Finals = R.P.U.F.F.C. (Radio call final approach, Pitch full fine, Undercarriage down and locked 3 green, Fuel on both, Flap as required, Carb heat off).
:shock: That seems like an awful lot of acronym-flying to me. And very prescriptive - for example, 15 inches of manifold pressure on base? What if your downwind is a bit wider, or closer, necessitating a shallower or steeper descent on base, just as one example? I don’t know what my MP is on downwind, base or final - I know my prop is fine of course and mixture rich but power is applied by feel in order to maintain the correct sight picture. Sometimes I want a steep approach in order to dive through turbulence, in which case my base and final are adjusted accordingly. But I never even look at my MP gauge at those times. I also have no idea what my VSI is showing. Again, all I’m doing is looking at the sight picture and keeping it the way I want it, with my airspeed as desired.

Am I alone in this? Am I being sloppy? What do the experts say?
I can do these descriptive checks in my sleep. CCPPFFT, RPUFFC. Easy. And on downwind it's BUMPFFE. (breaks on and off, undercarriage down, Mixture set, power set, fuel to both and check quantity, flaps set, electrics -landing light on).

I fly by the numbers and with my checks, once the numbers are dialled in, I can adjust accordingly for the "picture" and approach. Flying the numbers makes life a lot easier, especially at night. If I hit a gust on short finals which takes up all my focus I can I can know that I won't land with carb-heat still on, the landing gear up, or try do a go-around with cruise pitch still set. I wouldn't have it any other way whether I'm flying a Bushbaby or a 210.
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Re: When should carb heat be turned off in the landing sequence?

Unread post by jimdavis » Wed Nov 13, 2019 12:45 pm

Hunter and Tikka, I am not trying to head butt with you, but may I suggest you fly with an instructor and drape a towel or jacket over the instrument panel - covering ALL your instruments.

Now do at least three circuits and landings. You will be horrified at first, then you will settle down and realise that you actually fly pretty well by the seat of your pants. You don't NEED the instruments. It's a wonderful feeling when you know you can do without them. And you will be a better pilot for it. :D

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Re: WHEN SHOULD CARB HEAT BE TURNED OFF IN THE LANDING SEQUENCE ?

Unread post by ddevos » Wed Nov 13, 2019 3:16 pm

TikkaT3 wrote:
Wed Nov 13, 2019 11:44 am
I can do these descriptive checks in my sleep. CCPPFFT, RPUFFC. Easy. And on downwind it's BUMPFFE. (breaks on and off, undercarriage down, Mixture set, power set, fuel to both and check quantity, flaps set, electrics -landing light on).
Mmmmm... I know you can break something off, but I didn't know you can break something on? #-o
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Re: WHEN SHOULD CARB HEAT BE TURNED OFF IN THE LANDING SEQUENCE ?

Unread post by Cherokee6 » Wed Nov 13, 2019 4:51 pm

Hunter wrote:
Wed Nov 13, 2019 9:28 am

I want to agree with you guys on this, but there is merit in knowing what your MP should be, at pitch full, on approach in case of an ASI failure. My instructor drilled many of these number into me whilst closing some of my gauges to simulate failures.
I don’t follow, Hunter.

Firstly, your MP required on any given day is not a static number. It is going to vary depending on the elevation of the field you’re landing at, the descent angle of approach required, the strength of the wind on final, the atmospheric pressure on the day, the size of the circuit you’ve flown, and so on. So memorizing some theoretical MP seems completely pointless to me.

Secondly, even if you’re flying the correct sight picture and you see the MP is different to what you expect, what are you going to do about it? Option a: put the MP where you think it should be and ignore the sight picture, which means you’ll either fly into the ground on approach, or land deeper than you should. Option b: Just ignore the MP and fly the correct sight picture? I know which I’d do...

Sorry but I’m really not seeing the point of looking at the MP during those phases of flight. I’d much rather have my eyes out the window looking for traffic/birds than obsessing about MP.
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Re: WHEN SHOULD CARB HEAT BE TURNED OFF IN THE LANDING SEQUENCE ?

Unread post by Hunter » Wed Nov 13, 2019 6:50 pm

Cherokee6 wrote:
Wed Nov 13, 2019 4:51 pm
Hunter wrote:
Wed Nov 13, 2019 9:28 am

I want to agree with you guys on this, but there is merit in knowing what your MP should be, at pitch full, on approach in case of an ASI failure. My instructor drilled many of these number into me whilst closing some of my gauges to simulate failures.
I don’t follow, Hunter.

Firstly, your MP required on any given day is not a static number. It is going to vary depending on the elevation of the field you’re landing at, the descent angle of approach required, the strength of the wind on final, the atmospheric pressure on the day, the size of the circuit you’ve flown, and so on. So memorizing some theoretical MP seems completely pointless to me.

Secondly, even if you’re flying the correct sight picture and you see the MP is different to what you expect, what are you going to do about it? Option a: put the MP where you think it should be and ignore the sight picture, which means you’ll either fly into the ground on approach, or land deeper than you should. Option b: Just ignore the MP and fly the correct sight picture? I know which I’d do...

Sorry but I’m really not seeing the point of looking at the MP during those phases of flight. I’d much rather have my eyes out the window looking for traffic/birds than obsessing about MP.
I think both you and Uncle Jim may have misunderstood what I was trying to say. I do not at all profess flying by some arb theoretical numbers. I merely said there is merit in knowing what these are in case you have instrument failure. During my PPL, my instructor would regularly close one or more of my instruments and then I would have to use the other ones to work out my correct approach speed / angle / path etc. This was during training. I know my plane reasonably well, so now I fly mainly by site picture and reference the speed to double check. I fully agree with you on eyes out the cockpit. Again - I am not professing obsessing about MP numbers.
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Re: When should carb heat be turned off in the landing sequence?

Unread post by Wayne Boonzaier » Wed Nov 13, 2019 6:53 pm

jimdavis wrote:
Wed Nov 13, 2019 12:45 pm
Hunter and Tikka, I am not trying to head butt with you, but may I suggest you fly with an instructor and drape a towel or jacket over the instrument panel - covering ALL your instruments.

Now do at least three circuits and landings. You will be horrified at first, then you will settle down and realise that you actually fly pretty well by the seat of your pants. You don't NEED the instruments. It's a wonderful feeling when you know you can do without them. And you will be a better pilot for it. :D

jim
Jim where on earth are you going to find an instructor that can fly without instruments ?
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Re: When should carb heat be turned off in the landing sequence?

Unread post by Wayne Boonzaier » Wed Nov 13, 2019 6:54 pm

Wayne Boonzaier wrote:
Wed Nov 13, 2019 6:53 pm
jimdavis wrote:
Wed Nov 13, 2019 12:45 pm
Hunter and Tikka, I am not trying to head butt with you, but may I suggest you fly with an instructor and drape a towel or jacket over the instrument panel - covering ALL your instruments.

Now do at least three circuits and landings. You will be horrified at first, then you will settle down and realise that you actually fly pretty well by the seat of your pants. You don't NEED the instruments. It's a wonderful feeling when you know you can do without them. And you will be a better pilot for it. :D

jim
Jim where on earth are you going to find an instructor that can fly without instruments these days ?
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Re: When should carb heat be turned off in the landing sequence?

Unread post by Hunter » Wed Nov 13, 2019 7:00 pm

jimdavis wrote:
Wed Nov 13, 2019 12:45 pm
Hunter and Tikka, I am not trying to head butt with you, but may I suggest you fly with an instructor and drape a towel or jacket over the instrument panel - covering ALL your instruments.

jim
I have actually done that a few times in the 235, but I must honestly say I don't like it. It is good to do to stay sharp and I will do it again. I get it right no problem, but it does not feel lekker. However, flying a STOL taildragger "by the seat of your pants", is a great amount of fun.
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Re: When should carb heat be turned off in the landing sequence?

Unread post by Cherokee6 » Thu Nov 14, 2019 12:49 am

Wayne Boonzaier wrote:
Wed Nov 13, 2019 6:54 pm
Wayne Boonzaier wrote:
Wed Nov 13, 2019 6:53 pm
jimdavis wrote:
Wed Nov 13, 2019 12:45 pm
Hunter and Tikka, I am not trying to head butt with you, but may I suggest you fly with an instructor and drape a towel or jacket over the instrument panel - covering ALL your instruments.

Now do at least three circuits and landings. You will be horrified at first, then you will settle down and realise that you actually fly pretty well by the seat of your pants. You don't NEED the instruments. It's a wonderful feeling when you know you can do without them. And you will be a better pilot for it. :D

jim
Jim where on earth are you going to find an instructor that can fly without instruments these days ?
Any decent instructor will do this. And during the night rating it should be done again, in the dark. Mine did this, a number of times.
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Re: WHEN SHOULD CARB HEAT BE TURNED OFF IN THE LANDING SEQUENCE ?

Unread post by TikkaT3 » Thu Nov 14, 2019 7:23 am

Cherokee6 wrote:
Wed Nov 13, 2019 4:51 pm
Hunter wrote:
Wed Nov 13, 2019 9:28 am

I want to agree with you guys on this, but there is merit in knowing what your MP should be, at pitch full, on approach in case of an ASI failure. My instructor drilled many of these number into me whilst closing some of my gauges to simulate failures.
I don’t follow, Hunter.

Firstly, your MP required on any given day is not a static number. It is going to vary depending on the elevation of the field you’re landing at, the descent angle of approach required, the strength of the wind on final, the atmospheric pressure on the day, the size of the circuit you’ve flown, and so on. So memorizing some theoretical MP seems completely pointless to me.

Secondly, even if you’re flying the correct sight picture and you see the MP is different to what you expect, what are you going to do about it? Option a: put the MP where you think it should be and ignore the sight picture, which means you’ll either fly into the ground on approach, or land deeper than you should. Option b: Just ignore the MP and fly the correct sight picture? I know which I’d do...

Sorry but I’m really not seeing the point of looking at the MP during those phases of flight. I’d much rather have my eyes out the window looking for traffic/birds than obsessing about MP.
Who's obsessing about MP? Your're missing the picture. You reduce power to a certain MP, go through the other 5 seconds of memorized checks and get the plane SET for approach. Once this has been done and I'm sure I'm not going to do a wheels-up or land with carb-heat still applied, then I fly the approach "outside" all the way down, glancing at my ASI, pitching for airspeed and using MP for altitude. Again, it takes 5 seconds (for all the checks) and by the time I get back to it, the plane is already at a nice stable speed and a 500fpm decent. It makes life so much easier, especially on fast and complex machines. I never said that I set some arbitrary MP setting and fly it all the way to touchdown, its ridiculous to think that. "Oops, too shallow approach, better just fly into the ground short of the threshold instead of touching that throttle!".

Just as it's been pointed out here that one should do a few circuits with the instruments covered, you should also try flying a few proper circuits by the POH numbers, especially on a calm, still night. The aircraft almost lands itself.
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Re: When should carb heat be turned off in the landing sequence?

Unread post by southside » Thu Nov 14, 2019 3:35 pm

TikkaT3 wrote:
Thu Nov 14, 2019 7:23 am
Cherokee6 wrote:
Wed Nov 13, 2019 4:51 pm
Hunter wrote:
Wed Nov 13, 2019 9:28 am

I want to agree with you guys on this, but there is merit in knowing what your MP should be, at pitch full, on approach in case of an ASI failure. My instructor drilled many of these number into me whilst closing some of my gauges to simulate failures.
I don’t follow, Hunter.

Firstly, your MP required on any given day is not a static number. It is going to vary depending on the elevation of the field you’re landing at, the descent angle of approach required, the strength of the wind on final, the atmospheric pressure on the day, the size of the circuit you’ve flown, and so on. So memorizing some theoretical MP seems completely pointless to me.

Secondly, even if you’re flying the correct sight picture and you see the MP is different to what you expect, what are you going to do about it? Option a: put the MP where you think it should be and ignore the sight picture, which means you’ll either fly into the ground on approach, or land deeper than you should. Option b: Just ignore the MP and fly the correct sight picture? I know which I’d do...

Sorry but I’m really not seeing the point of looking at the MP during those phases of flight. I’d much rather have my eyes out the window looking for traffic/birds than obsessing about MP.
Who's obsessing about MP? Your're missing the picture. You reduce power to a certain MP, go through the other 5 seconds of memorized checks and get the plane SET for approach. Once this has been done and I'm sure I'm not going to do a wheels-up or land with carb-heat still applied, then I fly the approach "outside" all the way down, glancing at my ASI, pitching for airspeed and using MP for altitude. Again, it takes 5 seconds (for all the checks) and by the time I get back to it, the plane is already at a nice stable speed and a 500fpm decent. It makes life so much easier, especially on fast and complex machines. I never said that I set some arbitrary MP setting and fly it all the way to touchdown, its ridiculous to think that. "Oops, too shallow approach, better just fly into the ground short of the threshold instead of touching that throttle!".

Just as it's been pointed out here that one should do a few circuits with the instruments covered, you should also try flying a few proper circuits by the POH numbers, especially on a calm, still night. The aircraft almost lands itself.
I always have to giggle when people refer to fast/high performance /complex aircraft on light aeroplanes. None of the light Cessnas/Pipers/Beechcraft ect are complex or high performance....a Boeing/Airbus/CRJ/Dash 8 ect is complex and high performance :roll:
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Re: When should carb heat be turned off in the landing sequence?

Unread post by jimdavis » Thu Nov 14, 2019 5:46 pm

southside wrote:
Thu Nov 14, 2019 3:35 pm
I always have to giggle when people refer to fast/high performance /complex aircraft on light aeroplanes. None of the light Cessnas/Pipers/Beechcraft ect are complex or high performance....a Boeing/Airbus/CRJ/Dash 8 ect is complex and high performance :roll:
SS you are technically correct. However, seldom is a "Boeing/Airbus/CRJ/Dash 8 ect" captain as busy as a Baron charter pilot returning to Johannesburg in a busy late afternoon during summer thunderstorm time. He has to plan the descent, cope with traffic, talk to ATC, change frequencies, read back clearances dodge thunderstorms and be nice to difficult pax - ALL ON HIS OWN - no copilot, no hostie, no one to negotiate with ATC, possibly no glass and a pretty ordinary autopilot.

To my mind that is the busiest pilot in the world - despite his humble aircraft. Its the very lack of what you see as complexity, makes it an extremely complex aircraft to operate. Actually nothing to giggle at. 8) :wink:

jim
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