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deej(at)deej.net
Guest

Posted: Thu Feb 10, 2011 8:05 am Post subject: Pitot heat

On 02/10/2011 09:38 AM, George, Neal E Capt USAF ACC 505 TRS/DOJ wrote:

 	  Quote: 	
		   80-kts on downwind, 70-kts on base, and he falls out of the base-to final turn because the ice has changed his stall speed.

 

 The point is, an accurate indicated airspeed is of little use where it matters - near the stall end of the envelope - if you don't know what the stall speed is in the airplane's current iced-up condition.


	


	So assume Captain Super Stud realizes that his stall speed is affected,

and elects to maintain 90 kts on final because he is able to fly the

plane at 90kts (he just tested this on the downwind leg).  Could he do

this without a working airspeed indicator?  Possibly if he had a working

GPS onboard.  However, by using GPS now you've thrown another variable

into the equation and another thing to deal with that the pilot might

not be familiar with (trying to fly the plane with GPS indicated speed

rather than the normal airspeed indication, and the fact that GPS

indicates ground speed not airspeed).  It is just one more thing to add

to what is probably already a stressful situation.  Better to do a quick

comparison prior to pattern entry of the airspeed indicator to the GPS

indicated speed to make sure it is working, and then use the normal

instruments for landing to reduce pilot workload.



	IMHO a heated pitot is like insurance.  You hope you never have to use

it, but it sure is handy when you do.  In this case, it is pretty cheap

insurance, too.



-Dj



-- 

Dj Merrill - N1JOV

Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/



Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855

Kindly TRIM your email replies and post AFTER the relevant text

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Feb 10, 2011 9:42 am Post subject: Pitot heat

 	  Quote: 	
		           So assume Captain Super Stud realizes that his stall speed 

 is affected,

and elects to maintain 90 kts on final because he is able to fly the

plane at 90kts (he just tested this on the downwind leg).  Could he do

this without a working airspeed indicator?


	


   <snip>



 	  Quote: 	
		    Better to do a quick

comparison prior to pattern entry of the airspeed indicator to the GPS

indicated speed to make sure it is working, and then use the normal

instruments for landing to reduce pilot workload.


	


   Is that your advice to the 200 hr VFR pilot? Put

   on your CFI hat. Consider that the things we're

   taught in the 40-hr holy-watered curriculum are

   the things that work 100% of the time based on

   panel displays and views out the window that

   are not contaminated by an un-calibrated tightening

   of the airplane's performance envelope.



   It's much easier to hypothesize a course of

   action based on our personal experiences and

   understanding of how things work. But how would

   you advise a pilot with an extension to that

   40 hr curriculum? How would you demonstrate

   a process and then test the student for competency

   to carry out that process?



   How about:  No pattern flight. No impromptu "flight

   testing". Straight in. Keep nose well below horizon.

   If you cross the numbers at 100+kts (GPS or IAS) the

   probability of a controlled arrival with the concrete

   is high. Now the skill to be cultivated is directional

   control during a higher speed roll out. Do you

   NEED a working speed indicator to accomplish this

   maneuver?



   Which thought process and procedure has the

   highest likelihood of a comfortable outcome?

   I don't think anyone proposes to discourage anyone

   from having pitot heat or any other gee-whiz.

   The goal is to QUANTIFY the risk-reduction value

   for having a heated pitot.



   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Feb 10, 2011 9:50 am Post subject: Pitot Heat

 	  Quote: 	
		    Landing without an airspeed indicator is a distraction I can easily avoid.


	


    I've had one loss-of-airspeed experience. Turned out to

    be a spider nest. Initial indication was that I was

    using a LOT more runway to accelerate to take-off speed.

    I tentatively tested the airplane's willingness to fly

    and it hopped right off. Climb out was cautiously low

    in deck angle and I was still pondering what was going

    on. Pretty soon, IAS indications were more 'normal' and

    I turned attention to other piloting issues.



    A few minutes later leveled at 8K or so, IAS was showing

    190kts in a 140 horse Cherokee!  Okay, IAS is snorked.

    Now what? Land? Call back to the FBO to bring me a

    replacement airplane? AAA wasn't answering the phone

    that day.



    We completed our trip out and returned the next day

    without discomfort after sorting out all the indications

    and developing a plan-B. I'll suggest that your

    chances of loss of IAS data due to effects OTHER than

    icing are far greater.

   Bob . . .

trigo(at)mail.telepac.pt
Guest

Posted: Thu Feb 10, 2011 10:14 am Post subject: Pitot heat

 	  Quote: 	
		     

 --> AeroElectric-List message posted by: "Robert L. Nuckolls, III"  

 <nuckolls.bob(at)aeroelectric.com>  

   

   

   

    Which thought process and procedure has the  

    highest likelihood of a comfortable outcome?  

    I don't think anyone proposes to discourage anyone  

    from having pitot heat or any other gee-whiz.  

    The goal is to QUANTIFY the risk-reduction value  

    for having a heated pitot.  

   

    Bob . . .  

   

   
	


With due respect Bob, there are some things in life that are NOT QUANTIFIABLE.  

And this is one of them… Like someone said, this is like insurance! Some of us value it, other don’t.  

   

Since this is a VERY subjective issue, neither is it quantifiable, nor anyone of those in this List from both sides of the barricade will be convinced by the other’s arguments.  

   

Carlos  

       [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Feb 10, 2011 11:29 am Post subject: Pitot heat

 	  Quote: 	
		   

  

 With due respect Bob, there are some things in life that are NOT QUANTIFIABLE.

 And this is one of them… Like someone said, this is like insurance! Some of us value it, other don’t. 	


    Which is exactly the point my friend. An

    IAS indicator is sold to us as a highly

    quantified display: "Thou shalt not snub

    thy airspeed indicator lest ye be cursed

    with untenable surprises." Once the numbers

    have been elevated to celestial significance

    it seems only natural that we protect the 

    integrity of those numbers with what ever

    means are available to us.



    The point is that no mater how good your

    speed numbers are, there are other other

    factors (thanks Neal) that degrade the

    celestial status of the best numbers. Heated

    pitot tubes protect numbers whose values

    are no longer celestial due to effects of

    the same ice we drove off the tube with

    heaters.

      

  	  Quote: 	
		    

 Since this is a VERY subjective issue, neither is it quantifiable, nor anyone of those in this List from both sides of the barricade will be convinced by the other’s arguments. 	


    Who is trying to convince anyone of anything?

    The utility and usefulness of accurate IAS is

    NOT a subjective issue. The simple-ideas that

    drive IAS indications and aerodynamic performance

    of airplanes are hard, cold fact. As successful

    pilots, we strive to connect every combination

    of simple-ideas into a plan of operation

    completely independent of personal perceptions,

    fondest wishes or misunderstanding of the physics.



    I'm sorry if you're feeling barricaded. This

    isn't about changing your mind about whether

    or not to have a heated pitot tube. It's about

    crafting a works-99%-of-the-time plan for 

    putting an iced airplane on the ground. How

    would you advise use of IAS readings for what

    might be a pilot's very first tense experience

    with ice? Yeah, I've seen the pictures and read

    the stories from pilots to lived to tell about

    it. Many more did not. When the crews get out

    to the pile of bent aluminum, the ice is often

    melted. Nobody is left to tell us how they

    screwed up shooting a 60 Kt approach with a

    perfectly believable IAS display that was

    heated for additional SAFETY.



 

   Bob . . .    [quote][b]

deej(at)deej.net
Guest

Posted: Thu Feb 10, 2011 11:56 am Post subject: Pitot heat

On 02/10/2011 11:37 AM, Robert L. Nuckolls, III wrote:



 	  Quote: 	
		     Is that your advice to the 200 hr VFR pilot? Put

   on your CFI hat. 


	


	Actually, it is absolutely the advice I'd give a low time pilot.

Putting on a CFI hat, the best possible thing to do for a low time pilot

is to give them an environment that they are familiar with.  The more

"out of the ordinary" things you throw at them, the higher the chances

that they will mess up the landing.



	Think about the scenario that you painted in previous emails.  You have

a low time pilot that inadvertently ended up in icing conditions, and

there is visible ice on the airframe.  The flying characteristics of the

plane have changed due to the ice, and the pilot does not know exactly

how they have changed.  We have some "Top Gun Tough" pilots, but there

is a good chance that a pilot in this situation is going to be somewhat

shaken, or at least have increased anxiety.



	While this pilot is preoccupied with "flying the plane" to get it to a

safe landing, would you rather throw yet another workload item for them

to deal with (ie, using GPS speed instead of airspeed), or allow them to

use the very familiar scan with the airspeed indicator that they've been

using all along?  Remember, low time pilot.



	I submit that it is safer to allow the pilot to use the tools and

techniques that are familiar, and not throw more unknowns into the

situation if it is at all possible to do so.  That would include flying

a normal pattern to get them comfortable with the approach and mentally

prepare them for landing, but fly it at an increased speed that they

already know the airplane will fly at.  Change as few things as

possible, and only those that are necessary for the safety of the

flight.  For example, I'd recommend not lowering the flaps since you

don't know what affect that might have.



	We should all be able to land an airplane without any speed indication

at all, especially if that were the only thing you were concerned about.

 However, with an iced up airframe and completely unknown flight

characteristics, a relatively inexperienced and possibly scared pilot,

and a strong desire to get the plane on the ground, there is no need to

add the additional stress of an iced over pitot tube when it is

relatively easy and cheap to prevent it.



-Dj



-- 

Dj Merrill - N1JOV

Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/



Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855

Kindly TRIM your email replies and post AFTER the relevant text

riggs_la(at)yahoo.com
Guest

Posted: Thu Feb 10, 2011 12:03 pm Post subject: Pitot heat

I have had an icing experience in a U6A on an IFR flight plan.  Icing conditions were not forecasted but I started picking up ice on climb out. I was able to climb above the cloud layer so the icing stopped but I did not lose any ice either.  As I descended for approach I picked up more ice.   As the ice accumulated the air speed decreased so I added decrease in airspeed to my approach speeds plus a safety factor of a few knots.  When I landed the stall speed was about what I expected it to be.  If I did not have a heat pitot tube what turned out to be just a stressful event could have turned into a disaster. I would not own a aircraft without a heated pitot tube.  I have had experiences where pitot tube ice but there was no sign of structural icing.  It is just not worth the risk of not installing a heated pitot tube and needing it just once.



Lynn Riggs, Maj Ret

USA AVN



--

endspeed(at)yahoo.com
Guest

Posted: Thu Feb 10, 2011 12:40 pm Post subject: Pitot heat

Hi guys,



  I have lost at least two and I believe three pitot systems in my career of flying.  The first time I felt cold adrenaline and fear going down my spine, so it kind of gets your attention when the airspeed starts bleeding down to zero. All were heated systems in a jet ironically enough.  There is nothing that can take the place of training to remedy this scenario.  You MUST go out on a VFR day with a plan to learn some basic attitude flying.  What pitch attitude, power setting and configuration give you a desired performance.  I know 450 feet per minute descent, flaps 20 and 15 inches of power will hold a 3 degree glideslope at 90 knots in my old 182.  That would be a nice speed to fly to a suitable runway.  In some heavy icing situations I would approach at cruise speed or at least the lowest known flyable speed and land on a long runway.  Remember, if you find yourself in this scenario, you are a test pilot and that nice, docile Cessna could have the slow speed handling characteristics of the Space Shuttle. Don't change flap settings. Don't slow down until a safe landing is assured even if it has to shutdown O'Hare International! Ice avoidance and aircraft knowledge will keep you safer than pitot heat. But I do plan on pitot heat for my aircraft.  



Safe flying,

Bob S.

P.S. Angle of attack indicators are a fine backup for a pitot system should a pitot tube suddenly be clogged by bugs or mud but icing COULD take out the ASI and AOA gauge.

Neal.George(at)hurlburt.a
Guest

Posted: Thu Feb 10, 2011 12:55 pm Post subject: Pitot heat

Actually, it is absolutely the advice I'd give a low time pilot.

Putting on a CFI hat, the best possible thing to do for a low time pilot

is to give them an environment that they are familiar with.  



===============



I expressed it poorly, but it's my contention it is exactly that

familiar environment that gets our subject pilot killed.  



With pitot heat on and accurate airspeed indications, our pilot is in

the klag gathering ice.  Descending to land, he breaks out of the cloud

deck and anxiety levels drop dramatically - simply because he can see,

but nothing else about his predicament has changed.  But it's still cold

and the airframe is not shedding ice - or maybe it's "warm", but the

airframe is not shedding ice fast enough to be clean before he turns

final.



Our young pilot gets himself established on the 45-deg entry leg and

relaxes - got it made.  He's back in a familiar environment and reverts

to his primal training and rote memory of the POH performance charts.

And those charts don't apply to his iced airframe.   



A heated pitot might ensure that the ASI continues to function; maybe -

are the static ports heated, too?  Even if the ASI is displaying

accurate data, the data is not useful because the airframe is altered

from its "tested, approved and published" configuration.



neal

deej(at)deej.net
Guest

Posted: Thu Feb 10, 2011 1:38 pm Post subject: Pitot heat

On 02/10/2011 03:48 PM, George, Neal E Capt USAF ACC 505 TRS/DOJ wrote:



 	  Quote: 	
		   I expressed it poorly, but it's my contention it is exactly that

 familiar environment that gets our subject pilot killed.  


	


	Let me offer an example:



Q. Why is it that accident rates are higher for pilots transitioning to

a new (to them) aircraft?



A. Because it is different from what they are used to, and is why

insurance companies require transition training with an instructor

before allowing solo flight.

 	  Quote: 	
		   Our young pilot gets himself established on the 45-deg entry leg and

 relaxes - got it made.  He's back in a familiar environment and reverts

 to his primal training and rote memory of the POH performance charts.


	


	I can't speak for any other pilot than myself, but I would not be

relaxed until I had the plane safely on the ground with the engine shut

down at my parking spot.  Knowing that the airframe is iced, I can't

imagine anyone simply going back to rote and doing everything exactly

the same as an everyday landing, unless that person is completely

clueless and in which case they should probably not be piloting an

aircraft (and probably won't be for long...).



	One or two things different and most pilots can probably handle it.

Keep adding different items, and eventually the pilot gets to a point

where they can no longer handle it, which is now approaching the case

where someone is transitioning to a new aircraft.



	The idea is to only change the things that have to change for the

safety of the flight, and keep everything else as close as possible to

the same so it does not add additional distractions to flying the plane.

 	  Quote: 	
		   A heated pitot might ensure that the ASI continues to function; maybe -

 are the static ports heated, too?  


	


	Indeed, which is why I mentioned comparing airspeed to GPS speed to

verify its working condition.



	Does the plane have an alternate internal static port?  If not, we were

taught to smash the VSI to make one.  That would be hard to do with a

glass panel, but chances are likely if you are building a plane with an

EFIS you are probably also installing an alternate static port.

 	  Quote: 	
		   Even if the ASI is displaying

 accurate data, the data is not useful because the airframe is altered

 from its "tested, approved and published" configuration.


	


	I strongly disagree - knowing the airspeed is VERY useful.  Otherwise,

our low time inexperienced pilot might slow to 50 kts without even

knowing it.



	It seems we have enough statistics to show that pilots have enough

problems with the base to final turn WITH a working airspeed indicator,

let alone without one.



-Dj

-- 

Dj Merrill - N1JOV

Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/



Please use Netiquette Guidelines http://tools.ietf.org/html/rfc1855

Kindly TRIM your email replies and post AFTER the relevant text

flyboybob1(at)gmail.com
Guest

Posted: Thu Feb 10, 2011 3:53 pm Post subject: Pitot heat

As Bob  K so aptly stated:

  

 <<"Thou shalt not snub thy airspeed indicator lest ye be cursed with untenable surprises.">> 

  

 This  is the dogma that is taught at every flight school and reinforced at every  Biannual Flight Review.  Unfortunately, it's a hoaks!  Aircraft don't  stall at a particular airspeed, they stall at a specific angle of attack.   If you don't agree with me just roll in a 45 degree bank and haul back to your  aircraft's stall speed.  Long before you get to the stall speed you will be  on your back and wondering what happened.  The point that Bob K keeps  making is that with ice build up on the airframe the AOA (angle of attack) that  the wing will stall depends on the nature of the particular ice  build-up.

  

 If you  think knowing the airspeed will help you in an icing situation you are kidding  yourself unless you have tested the airspeed under the exact conditions you are  curently flying.  Now that we know that, what's your plan B for no airspeed  indication or more likely, irronious airspeed indication.  There are many  more causes of invalid airspeed indication than ice and they all require a plan  B to get safely on the ground.

  

  

Regards,

Bob Lee

N52BL  KR2

Suwanee,  GA  USA

92% done only 67% to go! 

   [quote][b]

ralphmariafinch(at)gmail.
Guest

Posted: Thu Feb 10, 2011 4:33 pm Post subject: Pitot heat

On my RV-9A I’m installing both a heated pitot and an AOA indicator. Belt and suspenders if you will. It’s little extra trouble or expense in the build process.

 

Really, I don’t see why the arguing about this. Why not have a heated pitot tube if it can be done easily? On a manufactured/certificated aircraft, sure, it’s a hassle to install one after the fact. On our experimentals—especially during build—rather easily done.

 

I think this thread has reached the angels-dancing-on-pinheads stage.

 

Ralph Finch 	  Quote: 	
		   	


  [quote][b]

earl_schroeder(at)juno.co
Guest

Posted: Thu Feb 10, 2011 5:03 pm Post subject: Pitot heat

--------

40950(at)rv10.net
Guest

Posted: Thu Feb 10, 2011 7:15 pm Post subject: Pitot heat

I  have to say, reading this great exchange of pitot heat discussion and icing has been informative but humbling. Frankly, I just never gave it that much thought. I bought a heated pitot for my RV-10 only because I had always flown with one. Many of them were automatically turned on with weight off wheels. These were all military jets that could eliminate airframe icing by adding power. At 400 kts or more, ice melts right off the jet.

I have approximately 3000 hrs, mostly military, but i know little about general aviation. Icing in GA aircraft scares me. I don't want anything to do with it. I will turn around when icing is first encountered. Thus, Bob's discussion is wise. It's all about cost / benefit. What is the risk reduction to heated pitot when encountering icing particularly if you are a low time pilot.

Myself, as stated, I'd turn right around and attempt to find warmer air to melt it off. If not, then prior to decent, after coordinating with center or approach of course, check the slow flight handling qualities of the airplane. Pattern altitude is the last place I want to experience unexpected behavior of the airplane. But this might be a little too much to ask of a low time pilot not being exposed to flying qualities evaluation as Bob stated. I really like the idea of teaching the student that nose at or below the horizon will not result in departure from flight. I'm going to go out and play with this some and get familiar with this instruction approach. It has simple, valid techniques that can be instructed to the low time pilot that will probably alway work and result in less low experience accidents.

Keep talking because I need the education,

Tom

RV-10 wings construction

On Feb 10, 2011, at 12:46 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	

 At 12:57 PM 2/10/2011, you wrote:

> 

> 

> do not archive

> 

> Any thoughts on the idea of flying around in clear air for some period after an icing encounter with the intent of decreasing the amount of ice on the aircraft before trying to land?  Sufficient fuel, etc.

   Absolutely. Ice will sublimate (evaporate directly)

   under the influence of flight winds. You can also

   seek higher temperatures which further enhances

   shedding. I think MOST icing encounters don't bring

   iced airplanes all the way to the runway.

   But I do recall pictures in Flying (or similar mags)

   showing amazing collections of mixed ice on the leading

   edges of just-arrived aircraft. It's a sure bet that

   this guy's arrival wasn't a gracefully executed,

   nose high, 3-point flare aided and abetted by

   an accurately calibrated and trustworthy airspeed

  display.

  Bob . . .

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