forgot to turn pitot heat on… how to avoid / prepare for this happening again

[dominikos]

fair warning, this is a bit of venting post to help me to think what went wrong.

a quick background, I’m based in Houston, so don’t really deal with freezing levels. instrument rated, a few hours short of 400 flying hours.

We flew today to northern Arkansas for a college tour. With lower temps, I should have turned pitot heat on. I thought about it earlier but my checklist does not call it out. I checked POH right now, but does not call it out either. 

As we started the descent, at some point we got a bit of ice, but I knew that we will be shortly through the clouds and the temperatures were warmer below. Suddenly all indicators went berserk. Before I completely lost speed indication and got a message to check for pitot heat, the airspeed went through some extremes. I have Dynon HDX with a backup D10A (similar setup to G3X with G5) and kept the wings leveled but was completely thrown off. This went away as I completely lost airspeed and got a message suggesting to put pitot heat on. Fortunately for me, we just got into opening between the cloud layers and was able to see ground through a scattered layer below. It helped me to compose myself. I reported issue to ATC, got permission to circle while waiting for the pitot tube to heat up and continued on the approach once I regained air speed indicator. Rest of the approach went fine, a bunch of deer crossing runway didn’t faze me at all. 

what I’m thinking:

1. need to better understand how my HDX behaves when something goes wrong. I was definitely complacent and really got thrown off when this started. 
2. develop strategy for emergencies and practice them - pitot one is a hard one but perhaps can be done in simulator
   1. part of the strategy is to memorize and include engine settings in my flow. I don’t do it in any standardized way, roughly know the settings and what to expect but definitely could be more structured
3. update my checklist to include pitot heat as needed on take off and landing
4. be much more conservative when planning descent through clouds up north and/or in winter time

anything else? curious what others learned from similar experiences…

Thanks, Dominik

[Rwsavory]

My last significant icing event was in West Virginia some years ago in a Cardinal RG. Forgot to turn on the pitot heat. Noticed airspeed decreasing, thought “hmm that’s strange,” turned on the heat, focused on pitch and power. Airspeed indicator quickly went back to normal, but the plane was getting iced up, so I turned back and landed where I started. This was before all the fancy avionics, so no red X’s. I have a nice blue plastic cover on my Mooney’s pitot heat switch, but I try like the devil to avoid needing it. I recently scrubbed a trip for that very reason. Drove to our destination, looking at the cold clouds above the highway, thankful not to be in them.

Now, as far as advice, here it is. Do not plan on dealing with ice. Plan on avoiding it entirely.

[N201MKTurbo]

I usually see ice on the windshield before I notice it on the wings. 
 

My old Mooney had a thermometer in the windshield. It would show ice on it before the windshield.

When the airspeed goes berserk, ignore it and just fly attitude. Then turn on the pitot heat. The airspeed will go crazy until the ice melts and the water is blown out the drain hole.

The Mooney carries ice better than most people think, so don’t panic. My experience is don’t do anything drastic like declare an emergency until the stall strips disappear. If you pick up a trace on approach and you think it will get better on the way down just keep going. If the stall strips disappear immediately go missed and climb back where there is no ice. At this point you can’t stand any more ice. You will have to find a place to land with no ice. If you can get into the sunshine, it will go away in 15-20 minutes.

[Rmnpilot]

Knowing that you may fly into the freezing levels, is it really an issue to keep the pitot heat on from the time we depart until we land?   Has anyone had a pitot heater wear out?  I saw something similar to this on an aviation facebook group and the consensus was to leave it on.  Granted, most of those planes were probably known icing

[dominikos]

one more pointer, here is a table explaining where pitot is used by Dynon HDX. That’s quite a lot…

[carusoam]

Nice pirep Dominik!

1) Pitot heaters rarely wear out…

2) Be sure to test pre-flight before leaving…

3) They heat up pretty quickly…

4) They can get really hot… so another checklist item for once the plane is no longer moving quickly in air…

Thanks for sharing the details… 

Best regards,

-a-

[PT20J]

The AHRS part of all these systems use MEMS gyros and accelerometers which are accurate in the short term but have long term drift. So, they use other inputs to "aid" them and the common inputs are airspeed (pitot/static inputs) and GPS velocity. So, loss of pitot input can affect the accuracy of the attitude solution depending on the design of the system.

Because airspeed may be more critical in these systems than older systems with a gyroscopic attitude indicator, it is probably a good idea to turn the pitot heat on as part of the pre-takeoff checklist if there is any chance of encountering ice. Some advocate not turning the pitot heat on when on the ground because the reduced airflow supposedly can cause it to overheat and burn out, but I have never seen this prohibition in an airplane flight manual. But, even if it were an issue, turning it on shortly before takeoff should not be an issue.

In a non-FIKI airplane any ice accretion should trigger an escape plan (hopefully one already made during planning) because there is no way of knowing how much worse it may get and how fast that may happen.

Skip

[Pinecone]

In the A-10, as we rolled onto the runway, we did a Heat - Seat - Skid checklist.

Turn on Heat - pitot and windshield.  

Arm Seat 

Turn on Anti Skid.

[dominikos]

30 minutes ago, PT20J said:

The AHRS part of all these systems use MEMS gyros and accelerometers which are accurate in the short term but have long term drift. So, they use other inputs to "aid" them and the common inputs are airspeed (pitot/static inputs) and GPS velocity. So, loss of pitot input can affect the accuracy of the attitude solution depending on the design of the system.

Thank you for explaining this. Somehow, I didn’t realize this dependency of AHRS. Regardless of my particular situation, there is always possibility of either pitot or static port getting clogged. In HDX manual, they explain how GPS ground speed is used as replacement. Have you ever came across emergency procedures for partial AHRS failure? What really got me today was how fast it happened and how confusing the indications were.

[0TreeLemur]

I know the feeling.  Here's another possibility (or stupid pilot trick):

Last weekend I took off to visit my A&P who is about an hour away to swap out the turn coordinator.  I'd been messing around in the hangar for a few hours before that looking things over. 

Rolling down the runway, airspeed not alive?   Engine making takeoff power.  Red X's on the Aspen.   CHECK PITOT HEAT on the Aspen.  Plane is new to me, so I'm trying to process this new weirdness.  I'm off the ground.  Fly the airplane. 

I immediately realized that for the first time in over 1000 hours I failed to take off the pitot tube cover.  Landed, shut down, and started over.  Took my time. 

Since the engine was running fine it didn't occur to me to abort the takeoff.

 

[PT20J]

28 minutes ago, dominikos said:

Thank you for explaining this. Somehow, I didn’t realize this dependency of AHRS. Regardless of my particular situation, there is always possibility of either pitot or static port getting clogged. In HDX manual, they explain how GPS ground speed is used as replacement. Have you ever came across emergency procedures for partial AHRS failure? What really got me today was how fast it happened and how confusing the indications were.

My setup is a G3X with a G5 standby. So, if one "fails" I have a backup. There are a couple of problems with that, though. Not all failures are "hard" and immediately obvious. Buried in the manuals is that the two units compare solutions and if they don't agree they annunciate a MISCOMPARE and leave it to the pilot to figure out which one to believe. The other problem is that both units were designed by the same team at the same company using the same technology. So, something that affects one is likely to affect both. To protect against this I bought an inexpensive third unit (AV-20-S) as a tie breaker. 

[PT20J]

13 minutes ago, 0TreeLemur said:

I know the feeling.  Here's another possibility (or stupid pilot trick):

Last weekend I took off to visit my A&P who is about an hour away to swap out the turn coordinator.  I'd been messing around in the hangar for a few hours before that looking things over. 

Rolling down the runway, airspeed not alive?   Engine making takeoff power.  Red X's on the Aspen.   CHECK PITOT HEAT on the Aspen.  Plane is new to me, so I'm trying to process this new weirdness.  I'm off the ground.  Fly the airplane. 

I immediately realized that for the first time in over 1000 hours I failed to take off the pitot tube cover.  Landed, shut down, and started over.  Took my time. 

Since the engine was running fine it didn't occur to me to abort the takeoff.

 

I did that once. In a hurry to fly to the avionics shop at a nearby airport before work one day years ago.

[Ragsf15e]

I know it’s warm in Texas, even in the clouds (I lived in Del Rio), but it’s smart to turn it on before takeoff any time you’ll be imc.  The pitot tube can ice before the wing.  You aren’t gonna hurt it.  Just turn it on.

I iced a pitot tube in North Carolina once.  It’s warm there too.  Your groundspeed still works, so you can get an idea from that until your pitot heat warms up.

[PeteMc]

15 hours ago, dominikos said:

need to better understand how my HDX behaves

Forget how the HDX behaves....

I totally get the flying in TX mentality, but I was taught that where you are means cr*p!!!  But the Subject of post "how to avoid / prepare for this happening again" is the real question you should be asking.

Icing can happen in any state and it can actually happen above "freezing" when you're talking Pitot Tubes, Induction Icing, etc.  So the basic rule your original CFII should have taught you is that if you see clouds in front of you, you turn on the Pitot Heat.  Doesn't matter if you're in in TX or AK, you just do it!!

As others have said, if you're not just sitting on the ramp, it's pretty hard to burn out the Pitot heating element.

 

ADDED: I said "if you see clouds" above, but what I was really thinking is what @GeeBee said below that it's ANY Visible Moisture.

 

 

Edited January 23 by PeteMc

[donkaye]

4 hours ago, N201MKTurbo said:

ice. If you can get into the sunshine, it will go away in 15-20 minutes.

That has absolutely NOT been my experience no matter what you read about sublimation.  I had an inadvertent experience with ice many years ago before I really knew better.  We were returning from a fly in at Coeur D'Alene, Idaho.  Clouds were forecast at between 11,000 to tops at 15,000.  I knew there was probably some ice in the clouds but figured with the power and climb rate of the M20M I'd only be in the clouds a few minutes before getting on top.  Well, the bases were correct.  Light rime ice started building slowly almost immediately upon entering the clouds.  12,000, 13,000, 14,000.  I was looking up expecting to break out at 15,000; 16,000, the ice was getting worse, but it was getting lighter looking up.  I considered descending, but knew I'd continue to build ice.  17,000, 18,000, 19,000.  Finally, at 20,500 I broke out into bright sunshine.  The right side of the airplane had more ice than the left.  After leveling out, I tried to return the rudder trim to neutral.  Not going to happen; it was frozen in place.  I thought the ¼" of ice would sublimate off.  After an hour, with a big "bang" the rudder broke free.  The ice remained until we got above the freezing level, as we entered California.  I learned my lesson those many years ago.  Without ice protection, STAY OUT OF THE CLOUDS below the freezing level.  Unless you are very near the freezing level, the ice isn't going to sublimate off.

[N201MKTurbo]

4 hours ago, donkaye said:

That has absolutely NOT been my experience no matter what you read about sublimation.  I had an inadvertent experience with ice many years ago before I really knew better.  We were returning from a fly in at Coeur D'Alene, Idaho.  Clouds were forecast at between 11,000 to tops at 15,000.  I knew there was probably some ice in the clouds but figured with the power and climb rate of the M20M I'd only be in the clouds a few minutes before getting on top.  Well, the bases were correct.  Light rime ice started building slowly almost immediately upon entering the clouds.  12,000, 13,000, 14,000.  I was looking up expecting to break out at 15,000; 16,000, the ice was getting worse, but it was getting lighter looking up.  I considered descending, but knew I'd continue to build ice.  17,000, 18,000, 19,000.  Finally, at 20,500 I broke out into bright sunshine.  The right side of the airplane had more ice than the left.  After leveling out, I tried to return the rudder trim to neutral.  Not going to happen; it was frozen in place.  I thought the ¼" of ice would sublimate off.  After an hour, with a big "bang" the rudder broke free.  The ice remained until we got above the freezing level, as we entered California.  I learned my lesson those many years ago.  Without ice protection, STAY OUT OF THE CLOUDS below the freezing level.  Unless you are very near the freezing level, the ice isn't going to sublimate off.

When I first started flying IFR the ice rules were a lot more lax, so I got a lot more ice experience than most get these days. I haven’t been in much ice since 1990. All my ice experience was in a NA M20F flying around the Rockies. Most flights were in the 9000 to 13000 for range. The ice did sublimate off in a reasonable time, but the OAT was around -5 or so. At 20000 feet your OATs are likely much lower. All these situations need to be evaluated individually. 
 

I’m not advocating flying in icing conditions with a non FIKI airplane, but the weather doesn’t always cooperate with the forecast. My point was if you pick up 1/8 inch of rime on approach it isn’t going to kill you. If you pick up 1/2 inch in a minute on approach you need to go missed and go back where there is no ice. If you go missed with 1/2 inch, you will have more than 1/2 inch by the time you get back to no ice and you will be in a jam because you cannot do another approach in that area. 
 

Once again I’m NOT advocating flying into ice, I’m trying to give advice about what to do if you end up in that situation. Just saying “don’t fly in ice” doesn’t help those who stumble into it.

[GeeBee]

When I was a Check Airman on the B737NG I had a lot of new Captains checking out after a several years on the heavies as F/Os. They always had a hard time remembering engine heat because most the heavies had ice detectors connected to the "auto" function of the engine heat. Thus anytime ice was detected, the engine heat would come on. To increase their "muscle memory" I briefed three items.

1. If you forget the engine heat, you owe me a beer.

2, To remember the heat anytime you are about to enter visible moisture in the air or on the ground regardless of temperature say to yourself "Heat?"

3. If you forget the engine heat twice in the same flight, you owe me dinner....medium rare please.

 

Now on the Mooney I have it on the Before Takeoff checklist and I have "TKS and Pitot Heat" on the After Takeoff checklist to verify correct  operation of the systems once airborne. But most importantly before I enter visible moisture I say "Heat?"

[jlunseth]

I fly in the north. When I penetrate clouds and if temps are approaching freezing the pitot heat and the hot prop go on. Just from experience, temperature changes in a cloud deck are not very predictable. The rule of thumb is -2.5 dC or -4dF for every thousand feet, but it is a rule more often broken than honored by Mother Nature. Most of the time it works in our favor. Penetrating a relatively thin stratus layer in the winter with CAVU above, it will often be the case that temps are stable or even rise during an ascent through the deck, so if you expected to hit freezing level somewhere in the middle of the layer it does not happen. On the other hand, the reverse happens often enough that I always take precautions. Sometimes the temp drops much faster and does so abruptly, not on the gradient that the rule of thumb predicts. So pitot and hot props always go on before penetrating clouds where there is any question of what might happen. Just habit by now. Certainly not going to hurt anything.

Edited January 23 by jlunseth

[Fly Boomer]

2 hours ago, jlunseth said:

The rule of thumb is -2.5 dC or -4dF for every thousand feet, but it is a rule more often broken than honored by Mother Nature.

I've heard from others that Mother Nature can be a bi+ch if provoked.

[midlifeflyer]

14 hours ago, dominikos said:

• update my checklist to include pitot heat as needed on take off and landing
• be much more conservative when planning descent through clouds up north and/or in winter time

These are good. I think updating your climb, cruise, and descent checklists to include pitot heat can help too. So can a standard SOP to switch pitot heat on in the clouds regardless of temperature. I'm a big fan of the power of creating habits.

[Hank]

My habit is Pitot Heat ON when entering clouds, regardless of OAT. Because the clouds don't always follow the rules . . . .

[A64Pilot]

On 1/23/2023 at 1:05 PM, Hank said:

My habit is Pitot Heat ON when entering clouds, regardless of OAT. Because the clouds don't always follow the rules . . . .

I don’t “do” ice, and fortunately in my Civilian flying I’ve only encountered it a couple of times and then not severe. I’ve taken off in shirt sleeve Wx and seen light icing in clouds at altitude.

But I too turn on pitot heat prior to getting into clouds. Had an ice detector on the AH-64, but it wasn’t always perfect, we noticed ice build up on the windshield first. Many aircraft have two different types ice systems, engines are usually anti-ice, that is they prevent ice formation and should be on prior to an icing encounter, wings, blades etc are often de-ice, that is they shed ice after it’s formed.

 In my opinion Pitot is an anti-ice system, best turned on prior to encountering ice

[Sue Bon]

I learned that pitot heat is obligatory for all IFR flights, regardless of season or temperature. 

That being said... I usually don't use it in summer (unless I'm doing my annual IR check flight in August). The second that temps drop close to zero, with or without clouds, my pitot heat is always on.

[jaylw314]

On 1/22/2023 at 8:32 PM, 0TreeLemur said:

I immediately realized that for the first time in over 1000 hours I failed to take off the pitot tube cover.  Landed, shut down, and started over.  Took my time. 

I'm guessing a significant fraction of us have had an encounter with orange icing 

[whiskytango]

2 hours ago, jaylw314 said:

I'm guessing a significant fraction of us have had an encounter with orange icing 

I haven't had Orange Icing but I have had Mud Dauber Icing.  It doesn't go away when it warms up or when you remove the pitot cover