I'm not a pilot ... so it might be:Why do I have to turn on pitot heat?I was driving home tonight in about 6 inches of Global Warming that is currently falling on my driveway and I looked at the external temperature gauge that is on my vehicle and it told me that the outside air temperature was 28 degrees.Now, how come my airplane doesn't have one of those? And when the thermostat says the outside air temperature is nearing freezing, why doesn't my pitot heat just fire up automagically?And fire up the cabin heat for me too, while it's at it?Am I stupid, or are airplane designers? (I'm asking for it, I know!)

The pitot heat requires a fair amount of amperage, and there really needs to be some moisture in the air. You can easily be at freezing temps with nothing to freeze.L.Adamson

LAdamson is right. You don't ALWAYS need pitot heat when it's below freezing. As I understand it, many times, if a plane is at, say, 22000 feet, it might be -20degF, but it's far too dry up there for any significant ice to form.Same for icing. Doesn't happen as much at high cold altitudes. At low altitude, where there is often more moisture, that's when you can ice up, or neet pitot heat.At least as I understand things.RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

Really?It puts that much pressure on the aircraft systems that turning it on is a factor?As a non-pilot that seemed really odd to me. I gather from just using flight simulators that NOT turning it on when it's needed can be rather unpleasant; so I was just wondering why it's left up to the human.

On my old Debonair-turning on the pitot heat or landing light could potentially over tax the alternator-I ended up putting a higher amp alternator eventually which took care of this . http://mywebpages.comcast.net/geofa/pages/rxp-pilot.jpg

Any time you add automation to a vehicle, you add weight. You are also adding something that can break. And on top of it, every single system in the plane has to run through an exhaustive approval process with the FAA assuring its reliability, which costs unimaginable amounts of money.The goal of every airplane designer is to design a plane that is as reliable and light as possible. Hence, even today the pilot still has to control the mixture of the gas/air going into the carburator and FADECs are still a thing of the future. When was the last time you saw such a thing in an automobile?Thomas[a href=http://www.flyingscool.com] http://www.flyingscool.com/images/Signature.jpg [/a]I like using VC's :-)N15802 KASH '73 Piper Cherokee Challenger 180

Also, when comparing car systems to airplane systems, think what the requirements are to drive a car and then compare that to the vigorous process of obtaining a PPL, and considering any idiot can drive a car, it makes sense that most systems are automated.Ian.

"Hence, even today the pilot still has to control the mixture of the gas/air going into the carburator and FADECs are still a thing of the future."The DA-42 that I was doing my multi in had a pretty nice FADEC setup. No mixture or prop levers here. We actually had to get clarification from the FAA that the hours flown in it can be logged as complex, since the prop pitch is not directly controlled by the pilot. And it runs on Jet A. How cool is that? :-)

Also understand that Flight Sim does not model the pitot heat function very well. The icing of the pitot is more on the temperature than on the moisture/temperature combination in the real world.In FS, turning on the pitot heat is required most of the time, especially for high altitude flight.As noted above - weight is everything in an aircraft - and the weight of the amount of money required to buy some automated systems is also a factor especially for small aircraft owners.

>>And it runs on Jet A. How cool is that? :-)Isn't a DA-42 one of those Diamond aircraft, like a Diamond Katana?That's weird! Or is that getting more common? A piston engine running off Jet A. Does it have a carb'ed engine or is it fuel injected?RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

The DA-42 is turbo diesels.

I don't think its a matter of being stupid. Some aircraft have auto heating of the pitot, etc. In the same token all airliners always have the pitot heat on while in flight.Most GA aircraft are not flying along at FL340 for 8 hours either. The vast, vast majority of GA aircraft fly VFR (since the vast, vast majority of private pilots are not IFR Rated). Flying VFR, you're not supposed to fly into any clouds, not supposed to be above FL180, and finding yourself in icing conditions will end up being the exception rather than the norm. So if we go on that premise, why bother to add the extra weight of an automated temperature sensing system when a 1 ounce manual switch would do the job just as well. And just as Geofa said, in most GA aircraft you have to pick your electrical "battles" quite carefully. If you are flying in with your landing lights on and the system decides to turn on your pitot heat, cabin heat and everything else you may find yourself declaring an emergency when your alternator can no longer take the load.Its much like the stupid automated headlights that come on when it thinks its dark enough and stay on while you walk into your house and similarly automated winshield wipers. While some people may well like these features, do I really need the car to turn its lights on and off or the winsheild wipers on and off...or am I not capable of seeing that its dark outside or its raining and take the appropriate action. Remember those automated seatbelts and talking cars that told you that your door was adjar and your parking brake was on? There is a fine line between automation and having one's intelligence insulted.As a matter of fact, most GA aircraft have so little automated features that an automated pitot heat would be the absolute last thing that one would think of when one would rather spend the money on a tricked out autoflight system with GPS slaving capability!

A diesel! Wow, the other diesel planes I know about were from the 1930's. Maybe some ag planes are diesel too?One thing about diesels, they have advanced a lot in recent years, and in many ways they are a nice design, capable of burning some interesting fuels. And today's turbo diesels are works of art.I knew a guy who burned used transformer (electrical transformer) oil in his diesel for years.Do you know how diesels react to air/fuel mixture in an aircraft? Just like any other internal comb engine?RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case

Not only has it to be autometd but in needs checking to demonatrate it's still functioning and hasn't failed. It would also probably need a manual backup to cope in the event of failure.It all gets just too complicated.

Thanks everyone, for your input.I hadn't considered the weight-to-necessity ratio, which is understandable. And I had no idea that the electrical systems in GA aircraft were run so close to the edge of disaster that turning on your pitot heat might result in the declaration of a landing emergency.I don't know why, but I'm just amazed by that.