do you keep carb heat on for landing?

korben88

korben88

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C172, prelanding checklist calls for carb heat on, and my instructor said to pull it on and check for ice then turn it off.

I've been watching touch and go landing videos and they often times say flaps up - carb heat off.

Are they landing with carb heat on and turning it off, or just verifying that it is off as part of the takeoff checklist?
 
I've always left it on in Cessnas. In the standard throttle layout, you just stick your thumb out to close it simultaneously with the throttle. Pretty easy.

At our altitude it will also show if I guessed a bit wrong at where the mixture should be. Full rich is way too rich around here and we don't depart full rich either, but if you apply carb heat and it's already really rich, it'll blub and sputter and carry on like me with a winter chest cold.
 
I'm guessing you are in Denver, and me being in Salt lake our altitudes are similar. We land and take off full rich though.
It used to be leaned for altitude until someone burned up an engine. Now the cfi/owner wants everything done at full rich except taxi and cruise.
 
I use Carb heat on every landing in airplanes that have carb heat! I turn the heat off when the plane is on the ground. What good does it do if you leave it off and the carb does ice up? Your instructor is a moron!
Turn it on to check for ice then back off???? When you turn it off and you are at really low rpm's on final is when ice happens. What happens if you are trying to clear some trees and the carb ices and you can't make the power to clear those trees? Or what happens if you must go around and you push power in and it does nothing because the carb is iced up?
 
I never land with carb heat on. I push it in on final in preparation for a go-around. I want the plane configured for maximum performance when I get close to the ground.
 
korben88 said:
I'm guessing you are in Denver, and me being in Salt lake our altitudes are similar. We land and take off full rich though.
It used to be leaned for altitude until someone burned up an engine. Now the cfi/owner wants everything done at full rich except taxi and cruise.
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You need to find a different owner. Taking off full rich there is not a good idea. Lean for best RPM, then enrichen slightly.
 
denverpilot said:
I've always left it on in Cessnas. In the standard throttle layout, you just stick your thumb out to close it simultaneously with the throttle. Pretty easy. QUOTE]

Agree! What I've always done and taught, especially in Cessnas which is what I've flown and taught in mostly.
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On my 182 I always land with the carb heat on due to the fact that my Conti O-470 is known to be prone to carb icing.

I never landed with carb heat on in Pipers that i flew previously.

Follow the POH and you should be good.
 
For Cessnas, I was taught that anytime one is operating at RPMs below the green band the carb heat should be on. Carb icing can happen in temperatures well above freezing.

carb-ice-potential-chart.jpg
 
As Bill said. Best to leave it on for the approach, as you're using low power settings, where if wx conditions are right could cause ice to form. No sense to just cycle the heat, you might not have ice at that moment since you were more than likely using higher power settings at altitude, but it could form during the approach if you have carb heat off. If you needed to do a go around, you may not have the available power do to so.
 
That chart looks right to me. I have an O-300 in my 172, and experienced carb ice while cruising at 2450 rpm at 4500 ft. That woke me up. I had an airport directly under me which was a bit comforting. It cleared itself up even before I had the chance to hit the carb heat. I now cruise with enough carb heat to maintain 40F at my carb, and the engine is much happier as well. EGTs are straight across the board.

If you remember to turn off carb heat short final, nothing wrong with that. Otherwise just push it in while going full power.
 
Believe it's somewhat aircraft dependent - Grumman AA5 has relatively little tendency to carb icing due to its carburetor mounting in aft position on sump. Owners I've talked to say they don't generally apply prophylactic carb heat. POH says "as required", or some such verbiage.

At full rich in pattern, carb heat always seems to lead to roughness in my plane, and think it advisable to remove carb heat rather than lean in pattern.

Would be nice to have carb temp gauge tho.
 
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Depends on the engine. Some have the carburetor mounted to the oil pan and thus always have a source of warmth. Others, like small Continentals, have the carburetor just hanging down from the intake manifold on its own.

I have flown mostly C-85s for the past 30 years. I once forgot to apply the carb heat on approach for a touch-and-go, and the engine iced up and refused the "go" part. Another time, I applied carb heat, but the carb didn't get enough heat during a long, power-off approach and the engine died during roll-out.

For production airplanes, the POH is the best reference as to whether it should be used on every landing.

Ron Wanttaja
 
Just another perspective:

In the 85hp J-3 I fly, I turn on the carb heat for every landing (and if I ever flew it high enough to make a descent other than for landing, I'd turn it on while descending as well). The carb heat control is recessed into the lower right wall near the rudder pedal for the rear set, which is where you sit when flying solo. There is a kitchen jar lifter tucked in the back pocket of the front seat, useful for pulling the carb heat knob back to open it. I close it with my right toe. On short final and roll-out, you don't want your foot anywhere but firmly planted on the rudder pedal and you can't really be bending forward over the stick to reach the knob with your hand or the jar lifter.

So I keep the carb heat on until the plane is nearly stopped on the ground or established in a climb to go around. I probably lose a little power that way, but the Taylor Cub flew on 35hp and the J-3 itself was certified with as little as 37hp. So when I'm flying light, the power I give up while transitioning from approach to go-around is not nearly as important as maintaining control of the plane. If someone is sitting in the front seat, he can close the carb heat by hand easily enough and, if anyone is ever foolhardy enough to get into the J-3 with me, I'll brief that task.
 
wanttaja said:
Another time, I applied carb heat, but the carb didn't get enough heat during a long, power-off approach and the engine died during roll-out.
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That's another thing to consider. Carb heat only supplies so much warm air. Closed throttle plates can, according to the chart that Bill Jennings posted above, make ice in the carburetor in 105-degree air. I think that the Cub owner's manual says to open the throttle to clear the carburetor occasionally during long descents even with carb heat on, and I think I've seen the same advice in other sources including POH's and maybe the FAA's publications.
 
I always use carb heat below the green arc in my Skyhawk... I was taught that way and haven't had a reason to change my thinking... On a go-around, its a simple push with the thumb while simultaneously pushing up the throttle.
 
Stewartb said:
I never land with carb heat on. I push it in on final in preparation for a go-around. I want the plane configured for maximum performance when I get close to the ground.
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That ^

Beat me to it, only thing I'll add is carb head is UNFLITERED air, so another good reason to turn it off on short final is the closer you get to the dirty earth the more you're going to be wanting to suck and through a filter.
 
korben88 said:
C172, prelanding checklist calls for carb heat on, and my instructor said to pull it on and check for ice then turn it off.

I've been watching touch and go landing videos and they often times say flaps up - carb heat off.

Are they landing with carb heat on and turning it off, or just verifying that it is off as part of the takeoff checklist?
Click to expand...

An NTSB recommendation, ignored by the FAA, was to have all owner's manuals, handbooks, etc tell users to use full carb heat any time throttle is reduced below cruise. This is the "action" part of the recommendation: My emphasis.

"Accordingly, the Safety Board believes that pilots need more definitive guidance from airplane manufacturers concerning the use of carburetor heat on the descent and/or before-landing checklists. Descents in most carburetor equipped general aviation airplanes can be conducted without adverse consequences to the powerplant with full carburetor heat on when power is reduced below the normal cruise flight engine power setting (that is, below the green arc on the tachometer or the manifold pressure gauge. The use of this procedure would preclude the formation of carburetor ice when detection of such formation could be difficult, in lieu of more specific guidance or procedures from manufacturers concerning designated airplane models "

[FONT=Arial, sans-serif]Bob Gardner[/FONT]
 
James331 said:
That ^

Beat me to it, only thing I'll add is carb head is UNFLITERED air, so another good reason to turn it off on short final is the closer you get to the dirty earth the more you're going to be wanting to suck and through a filter.
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Meh....it isn't all that important to worry about filtering the air. I'd be more concerned about having a clean carb free of ice....should one need to perform a go-around.

Turn the carb heat off once you perform your after landing check....at the first turn off.

.....and I recommend using carb heat when ever the rpms are lower than 1,700.
 
Checkout_my_Six said:
Meh....it isn't all that important to worry about filtering the air. I'd be more concerned about having a clean carb free of ice....should one need to perform a go-around.

Turn the carb heat off once you perform your after landing check....at the first turn off.

.....and I recommend using carb heat when ever the rpms are lower than 1,700.
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Short final, 500ish AGL, for that amount of time you're really not going to have a huge risk of ice, much higher risk of needing to do a go around, and at that late in the game any go around is going to be one where you need 100% power like right now
 
James331 said:
Short final, 500ish AGL, for that amount of time you're really not going to have a huge risk of ice, much higher risk of needing to do a go around, and at that late in the game any go around is going to be one where you need 100% power like right now
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what does altitude have anything do with ice?.....it's humidity that forms ice.

Sorry....I disagree.

One needs a good go-around discipline of turning off the heat while applying full power....not a big deal for one who is trained to do it.
 
korben88 said:
C172, prelanding checklist calls for carb heat on, and my instructor said to pull it on and check for ice then turn it off.

I've been watching touch and go landing videos and they often times say flaps up - carb heat off.

Are they landing with carb heat on and turning it off, or just verifying that it is off as part of the takeoff checklist?
Click to expand...

I fly a C-162 SkyCatcher. in the pattern the carb heat is on when abeam the numbers or when airspeed indicator is in the white (whichever comes first) on downwind and stays on until wheels on the ground.
 
Do whatever your instructor says. Although the DE MIGHT complain if you don't follow the pilot operating handbook. Ask the instructor about it if the way he is teaching you is different than the POH.
 
Yep carb heat on the whole time I operate bellow the green arc. There is no reason not to and many reasons to use it. The last thing I would want is to be at 500' agl descending over an obstruction with the carb heat off and need a little power to slow my descent rate and have it stumble over some ice.
 
Short final to a narrow short strip. Big trees all around. You're already fighting the wind but when you get to the treetop level the bottom drops out. It requires an immediate response. Do you think you'll remember to push in carb heat? I bet you won't. Been there several times. I've adjusted my carb heat procedure accordingly.
 
Stewartb said:
Short final to a narrow short strip. Big trees all around. You're already fighting the wind but when you get to the treetop level the bottom drops out. It requires an immediate response. Do you think you'll remember to push in carb heat? I bet you won't. Been there several times. I've adjusted my carb heat procedure accordingly.
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That's why I always think of a go around as my first option so I have the go around procedure running through my mind. Same thing they teach us here at my airline. Go around is your first option. Go around, set thrust, flaps 8. You won't be surprised if you have to go around.
 
Many days my landing are nothing more than aborted go-arounds. I may make 5-6 passes trying to catch the gusts just right. There's zero threat of ice forming on short final in my experience. My experience is more important to me than what the book says.
 
Checkout_my_Six said:
what does altitude have anything do with ice?.....it's humidity that forms ice.

Sorry....I disagree.

One needs a good go-around discipline of turning off the heat while applying full power....not a big deal for one who is trained to do it.
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I mentioned the 500AGL thing because the amount of time between 500' and touchdown isn't much time for ice to form, well unless you're dragging it in from miles out lol.

For me, when I fly carbs, which I don't really anymore, when I'm a minute from touchdown I take the carb heat off, it's a risk matrix, what more likely to kill me in the non carb heat 60 seconds before landing, a act of God amount of ice, or a go around type event.
 
coloradobluesky said:
Do whatever your instructor says. Although the DE MIGHT complain if you don't follow the pilot operating handbook. Ask the instructor about it if the way he is teaching you is different than the POH.
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Valuable phrase for pilots getting conflicting advice instructors: "Show me where it says that in writing." Instructors can be wrong, or passing on old-wives tales, or just parroting what they were taught.

Bob Gardner
 
Fuel injection is my co-pilot :D

When I owned the Warrior2 I didn't use carb heat at all. Only time I had anything close to carb icing was a stumbled engine on intial climbout out of OKC at night in the 30s with a looooong chilly taxi. It coughed and came back alive just as quickly. Could never prove it but figured it was the ice bit dislodging and getting swallowed as the sump got hot enough to be transmit effective heat. Carb'ed Piper/Lycos are toasty installations, they way a carb was meant to be installed really.

Cessnas and side draft carbs are a whole different ball of wax. When I owned the C-150 I did put in carb heat as part of any descent , but did attempt to push in carb heat before short final. Admittedly sometimes would forget.

Ultimately I just went with FI and never looked back.
 
hindsight2020 said:
Fuel injection is my co-pilot :D

When I owned the Warrior2 I didn't use carb heat at all. Only time I had anything close to carb icing was a stumbled engine on intial climbout out of OKC at night in the 30s with a looooong chilly taxi. It coughed and came back alive just as quickly. Could never prove it but figured it was the ice bit dislodging and getting swallowed as the sump got hot enough to be transmit effective heat. Carb'ed Piper/Lycos are toasty installations, they way a carb was meant to be installed really.

Cessnas and side draft carbs are a whole different ball of wax. When I owned the C-150 I did put in carb heat as part of any descent , but did attempt to push in carb heat before short final. Admittedly sometimes would forget.

Ultimately I just went with FI and never looked back.
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True, FI is nice for this, but it can be a little more of a pain mx wise if something F's up, also I find teaching proper carb heat usage far easier than how to start a hot FI engine, especially a big bore conti ;)
 
Instructors teach students basic skills. Every pilot has heard that the PPL is a license to learn yet veteran internet pilots reference student pilot practices as gospel. If I fly an unfamiliar plane I refer to the POH. In a plane I've flown for 20 years the POH isn't as important. Every opinion has an experience set behind it. Anyone considering these comments needs to remember that.
 
Below 20" manifold pressure and carb heat is on. POH and check list says so and it works. Right next to throttle so go around is flat hand to firewall which pushed both throttle and carb heat.
 
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