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Vectors for Safety - July 2021

Safety Initiative Update

Registration is Open! Next Avemco Webinar will be Tuesday, July 13

Our next free webinar in the Avemco "Pilot Talk" series will be on Tuesday, July 13 at 7:00 PM Eastern. The title, Avoiding the Summer Flight "Gotchas," describes the content. We are confident that just about any pilot will learn something new or at least be refreshed on something long forgotten. Click here to register or visit the Pilot Talk section for more information. Also, Avemco has been kind enough to sponsor a free online course based on the webinar material. The course shares the same title as the webinar. Click here to enroll in the course or visit the Online Courses section for more information. If you are flying to AirVenture, I highly recommend seeing this presentation.

Another Great Resource if Flying to Any Air Show or Fly-In

The latest issue of the NASA "Callback" publication is devoted to airshows and fly-ins. Read the reports from other pilots to help avoid getting into similar situations. Click here to view on the ASRS website.

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I received the following message from a colleague on Wednesday afternoon. His points are excellent, but the upcoming webinar has been completed and already had to be shortened to fit the schedule. He graciously accepted my suggestion to include his message in this issue of Vectors.

By John Townsley

I suggest you include some discussion time of wildfire smoke as it affects visibility, fire suppression aircraft, TFRs, and related issues.
FWIW, some of the worst visibility I've seen on PVFR (pretend VFR) flights occurs within valleys early and late in the day when looking toward the sun through wildfire smoke, or when flying toward high terrain where mountains and canyons have created shadows creates absolutely impenetrable visibility problems. During several summers over the past 25 years I've seen dense smoke affect flight visibility locally and at multi-state scales. Conditions can develop really quickly. Often the only way to fly anywhere during the summer is IFR, or for short trips a combination of barely VFR to MVFR. In a nutshell… Proficiency is essential. ADSB (In and Out) is really an essential tool since 'See & Avoid' is severely compromised.
Pilots really need to understand that all large wildfires will not have a TFR. And ALL wildfires won't get a TFR at first, but it's a strong bet that fire fighting aircraft are already there or are on the way. Especially in the unroaded back country huge, active fires may never get a TFR … but still have suppression aircraft either monitoring them and in some cases laying retardant lines to herd the flames away from sensitive areas.
Also, retardant aircraft (we used to call them retardant 'bombers') have to return to base to reload. Depending on fire activity and nearby (to the fire) structures, private property, ecologically sensitive, culturally important, or otherwise - it's not unusual for conga lines of loaded and returning to reload aircraft to be flying to/from hot fires and reload bases miles away.
Finally, I think it's safe to say that producers of EFB software universally include in their user manuals disclaimers that say something like 'this software is for planning purposes only… verify information blah blah before using in flight…'. So a big "heads up" on the importance of briefings.

Gene's Blog

I realize that carburetor ice and the use of carburetor heat does not apply to all my readers but many incidents and accidents are attributed to carburetor ice, so I think it is worth addressing.

Carburetor ice is a favorite accomplice of complacency. Many pilots learn about carburetor ice in their initial training and always follow the example set by their instructor. That works fine until it doesn’t. Flying in a different season, in a different climate, or in a different kind of airplane can create a scenario in which carburetor ice forms and goes undetected until it is too late. Of course, carburetor ice is limited to airplanes with a float type carburetor. That includes many of the most common small general aviation airplanes in use today.

Unlike structural ice that is associated with cold air, carburetor ice forms when flying in warm, humid air. Please beware that there is a substantial difference in the susceptibility to carburetor icing between different makes and models of airplanes, even though the same model engine might be used. Early in my instructing career, I moved from upstate New York to Florida. The same make and model airplanes, Piper Cherokee 140s, were the primary trainers at both locations. In New York, I had never experienced carburetor icing in any season and we followed the manufacturer’s recommendation to not use carb heat unless ice was indicated. That did not work in the much higher humidity in Florida. Carb ice formed not only at the expected times when operating at a low power setting, but at cruise flight also. Years later, I had a Beech Duchess in which the POH called for carburetor heat full on or full off as needed during descent and landing. I quickly learned that, at least in that particular airplane, landing without the carb heat on in just about any conditions, resulted in having both engines quit after landing but while still on the runway. Without the use of carb heat during the approach, an attempted go-around would have been disappointing.

The lesson that I learned over the many years of my flying is to apply full carburetor heat during reduced power operations, regardless of what the POH says. I understand the counter arguments that when carb heat is applied unfiltered air is entering the engine. I take issue with an aviation pop culture idea that it is a good practice to turn off the carb heat once landing is assured. Except for landing in an extremely dusty environment, I recommend leaving the carb heat on until there is no longer any possibility of needing to go around. I do not believe that landing is assured until the airplane has exited the runway. I have had several occasions in which I had to abort a landing at the last second. Once, I needed to abort a landing after I had already touched down. If a go-around becomes necessary, the recommended procedure of applying full power and immediately turning off the carb heat results in only a miniscule amount of time lost. Applying full power and having the engine not respond because the carb heat was turned off when landing was supposedly assured but was not, makes for a bad day.

I have also learned to check periodically for the presence of carb ice during cruise. Complacency can again cause a problem. The check at cruise is simple. Just note the power output via the tachometer if the prop is a fixed -pitch or via the manifold pressure gauge if the prop is constant speed. Now apply full carburetor heat. If the engine sputters, there is significant ice present. The carb heat is melting the ice and the water is going through the engine. A natural reaction is to immediately turn the carb heat off. That would be the worst course of action. Let the engine sputter and take care of itself. The ice will be melted very soon and the engine will return to smooth operation. Since ice was present, leave the carb heat on to prevent the formation of more ice. Since the warm air from the carb heat is less dense, the mixture will need to be leaned to adjust for that. If the engine does not sputter during the carb heat check, note the power output as compared to the reading prior to applying carb heat. There should be a reduction in power noted, again because the warm air is less dense. If the power output remains at the lower level, no ice is present and it is probably safe to turn the carb heat off. If the power output is gradually increasing, some ice is present and it is being melted. It is advised to leave the carb heat on and again, adjust the mixture.

It is important to note that if the engine quits because of carb ice, it may not be possible to restart it. The source for the carb heat is from a heat shroud around part of the exhaust system. Once the engine is no longer producing power, it is no longer producing hot exhaust and the system will cool down very rapidly, depriving the carb heat system of its heat source.

In summary, there are charts available regarding the probability of carburetor ice forming. When an accident involving carburetor ice is analyzed by the NTSB, they cite the probability of carb ice forming according to the chart. I have found the charts to be of little use in flight planning or in conducting the flight. Unless the ambient temperature is quite low, the chart will show that carburetor ice is possible. I just always assume that ice is possible and take the proper precautions. It took me a few years, a few thousand flying hours, and a few anxious moments to get that point. Everybody finds their own comfort zone, and that is mine.

Accident  Analysis

Accidents discussed in this section are presented in the hope that pilots can learn from the misfortune of others and perhaps avoid an accident. It is easy to read an accident report and dismiss the cause as carelessness or as a dumb mistake. But let's remember that the accident pilot did not get up in the morning and say, "Gee, I think I'll go have an accident today." Nearly all pilots believe that they are safe. Honest introspection frequently reveals that on some occasion, we might have traveled down that same accident path.

This accident happened in February of 2019 at Vero Beach, Florida. The airplane was a Piper PA28-161. It is called the Cadet, which is the training version of the Piper Warrior. The NTSB accident report includes the following: "The pilot was flying in the airport traffic pattern practicing touch-and-go landing maneuvers. On his third approach, the air traffic controller directed him to extend the downwind leg of the traffic pattern. On final approach, the engine rpm dropped, and the pilot felt the airplane "sinking." The pilot did not perform any checklists but advised air traffic control that he would be making an emergency landing and advanced the throttle lever. The engine momentarily produced more power but then lost total power
when the airplane was about 500-600 ft above ground level; the propeller windmilled. The pilot did not
attempt to perform any other remedial actions, such as applying carburetor heat, to restore power and
executed a forced landing on a nearby gravel road. During the landing, the airplane impacted a utility
pole and trees and sustained substantial damage to the wings and stabilator."

The NTSB probable cause finding states, "The pilot's failure to use carburetor heat while operating the airplane in weather conditions and at engine power settings conducive to the formation of carburetor ice, which resulted in a loss of engine power due to carburetor icing and the subsequent forced landing."


Photo Source: NTSB

If anything, this accident illustrates the importance having a solid understanding of the various airplane systems, how they work, and why they are there. Passing the FAA Knowledge Test most certainly does not guarantee that. This accident pilot, though apparently enrolled in a professional pilot program, seemed to have little understanding of carburetor icing. This accident pilot held a private pilot certificate, indicating that he had successfully competed the FAA Knowledge Test. The NTSB accident report also includes the following: "In a post-accident interview, when asked when he typically applied carburetor heat, the pilot responded that the it was appropriate to apply carburetor heat when practicing a simulated engine out procedure. When asked if there were other instances when it might be appropriate to use carburetor heat, he reiterated that it was only appropriate for simulated engine out procedures."


Photo Source: NTSB

Fortunately, the 21 year-old private pilot with 128 hours total flight time, all in this make and model,  was not injured but the airplane was substantially damaged. As a 40+ year flight instructor, I am curious about the quality of the ground training received by the pilot, the competency of the flight instructor(s) who provided endorsements, and the thoroughness of the examiner who issued the private pilot certificate. I am not accusing anyone of anything, I am just raising some questions.

Click here to download the accident report from the NTSB website.

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