Category Archives: General Aviation

Roundtable Discussion About Loss of Control in Flight Yields Some Important Ideas

By Chairman Robert L. Sumwalt

On April 23, I had the privilege of moderating an important roundtable discussion on preventing loss of control (LOC) in flight in general aviation (GA), the leading factor of general aviation accidents and an issue on our Most Wanted List. LOC involves the unintended departure from flight and can be caused by several factors, including distraction, complacency, weather, or poor energy management.

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NTSB Chairman Sumwalt and Member Weener with LOC roundtable participants

 

I can say unequivocally that the NTSB LOC roundtable event—held in our Board Room and Conference Center at our Washington, DC, headquarters and webcast live—was a resounding success. We achieved what we aimed to do: bring together leading experts in government, industry, and academia to identify training and cockpit technology solutions that could make a difference, as well as dig into the challenges of implementing these solutions.

And I was thrilled to hear that about 1,000 pilots and GA enthusiasts watched our discussion, with many receiving FAA WINGS credit.

At our event, we saw an honest, open sharing of ideas among GA safety experts, as well as a willingness to collaborate to address and overcome the challenges associated with this problem, which is the cause of nearly 40 percent of all fixed-wing general aviation crashes. The 18 industry and government participants included a NASA astronaut, a world-famous aerobatics champion and trainer, GA associations, tech companies, the Federal Aviation Administration, as well as our own investigators and Board Member Earl Weener. I was also thrilled to welcome to our roundtable two bright young minds, Thomas Baron and Justin Zhou—high school students from Virginia. Baron and Zhou (Remora Systems) won the Experimental Aircraft Association’s Founder’s Innovation Prize for a product they developed for pilots to help avoid LOC. Their fresh, Generation Z perspectives on this issue enhanced our discussions.

The NTSB’s Director of the Office of Aviation Safety John DeLisi kicked off our discussion with these experts by reminding us that more than 1,500 people have died in the last 10 years due to loss of control and that “we are here to save lives.”

 

Our roundtable experts—all leaders in their organizations—discussed both the challenges and solutions to reducing LOC accidents, especially in the area of training and technology. I will recap just some of their key insights:

 On Training . . .

  • Address pilot weaknesses and skills requirements; pilots should always continue to improve their skills.
  • Reward pilots for additional training taken and ratings achieved, and incentivize new instructors to make sure pilots are taught correctly.
  • Teach students the importance of maintaining situational awareness during their initial training. The first 10 hours that new pilots spend with instructors can be some of the most important training time.
  • Recognize that technology is not a substitute for basic stick skills, nor should it compensate for poor training.
  • Incorporate more realistic scenarios into flight training regarding stalls. Ensure pilots have the confidence to do stall recovery.
  • Train for the startle factor so it doesn’t happen at low altitudes. The stall warning might be too late to recover.

 On Technology . . .

  • Find a responsible role for cockpit technology; it can make a big impact on safety.
  • Continue to responsibly innovate.
  • Reduce angle of attack (AOA); this is the key to recovery. AOA indicators can help.
  • Continue to quickly certify new technologies in a variety of plane types.

Other ideas . . .

  • Use data to improve GA safety; data monitoring programs can help us standardize safety.
  • Establish mechanisms where industry and government can continue to collaborate to collectively find solutions.
  • Recognize that regulation and mandates aren’t always the answer; education and outreach may be a better approach.
  • Utilize pilot social networks and type clubs to learn and grow.
  • Get involved in working groups; study best practices and incorporate outcomes.
  • Be aware of the limits of the airplane; pilots should not fear the capabilities of their planes.
  • Change the way we do outreach. Unifying around a single topic like LOC helps.

The statistics are trending in a good direction, thanks to the FAA’s and industry’s efforts to address LOC. However, from NTSB accident investigations, we know that much more can—and should—be done to accelerate the improvements in training and technology, because one death for what is largely a preventable problem is one too many.

For more information on the LOC roundtable, including the topics covered, participant’s list, and our LOC resources, see our events page.

 

Don’t Turn A Blind Eye on Risky Pilot Behavior

By Leah Read

This is the seventh blog in a new series of posts about the NTSB’s general aviation investigative process. This series, written by NTSB staff, explores how medical, mechanical, and general safety issues are examined in our investigations.

 

“Turning a blind eye, makes nothing disappear.”  Anonymous

Leah Read
Leah Read, Senior Air Safety Investigator

When air safety investigators arrive at the scene of a fatal aircraft accident, we meet with law enforcement officers, witnesses, friends of the pilot, and family. During these critical interviews, we start to get a bigger picture of the circumstances surrounding the accident and those involved. It’s very common to hear almost immediately that the pilot was very “conscientious,” “thorough,” and an “excellent pilot.”

But there are also times when no one seems to be saying anything much at all about the pilot…until we dig deeper. That’s when we hear things such as, “The pilot never maintained his airplane right.” or “Everybody knew he was going to crash eventually.”

There are also times when the investigator will get a call via our communications center that a witness must talk to someone “right away.” The witness then tells us that the pilot had a LONG history of “maverick-like” behavior, was known to “buzz” a friend’s house, or used illegal drugs—as just some examples. In these situations, we will ask the witness if they had talked to the pilot about this behavior or contacted the Federal Aviation Administration (FAA). They sometimes tell us, “I tried to talk to him, but he wouldn’t listen. He was too prideful.”

But more often, they tell us that they didn’t say anything to the pilot or FAA. Sometimes, the pilot was a friend whom they didn’t want to embarrass or cause any trouble. Personally, as a fellow pilot, I can understand the concerns.

But what if you see something, and don’t step up and say something? The reality is that nonreporting can put people at risk.

Many don’t realize that there are actions the FAA can take if risky pilot behavior is reported. The FAA has established a hotline for confidential and anonymous reporting. As noted on the FAA website, “The FAA Hotline accepts reports concerning the safety of the National Airspace System, violation of a Federal Aviation Regulation (Title 14 CFR), aviation safety issues…. The FAA Hotline provides a single venue for…the aviation community and the public to file their reports.”

As one FAA inspector told me, “We can’t investigate what we don’t know.” If a complaint was made via the FAA Hotline, the FAA would be obligated to investigate. Remember, you may not only save the life of another pilot but also an innocent passenger or bystander.

The NTSB, unfortunately, has seen the tragic consequences of turning a blind eye to a known hazard. I have seen accidents that have occurred in someone’s front yard, skimmed the roof of an apartment building, or crashed near a school. If the airplane had impacted just a few yards in either direction, the damage and loss of life could have been so much worse. This was the case in an accident I investigated where the pilot lost control of the airplane, crashing into a front yard just feet from an occupied house. Thankfully, there was no fire, and no kids were playing in that front yard.

Within moments of arriving on scene and being debriefed by law enforcement, I was handed a witness statement. Very quickly, I realized the witness was quite credible—and what he had to say about the pilot was alarming. The pilot had a known history of reckless behavior. Further investigation revealed that people knew of the pilot’s behavior but didn’t want to report him for several of the reasons I mentioned above. Not surprisingly, the FAA had no negative history on the pilot. He had a clean record and was never on their radar.

Sadly, in this accident, the pilot and his innocent passenger died. But what if he had other passengers onboard? What would have happened if he had crashed into the house, or, worse, a crowd?

A colleague of mine investigated an accident where a pilot was flying an airplane he was not rated to fly, in instrument conditions without holding an instrument rating. The pilot had recorded numerous notes in his logbook that provided compelling evidence of his own unsafe flying, by his own admission. The pilot noted landing on a major highway and flying low over a crowd during parades. He was also known for unsafe low-level flights over airshows and having a general disregard for proper communication procedures. Yet nothing was done about his behavior; people turned a blind eye to it. Tragically, the pilot and three occupants died in the accident when the airplane encountered instrument meteorological conditions and impacted terrain.

In the big scheme of things, we need to ask ourselves, who are we really protecting by keeping quiet?  As active pilots, mechanics, airport personnel, friends, and family members, you are the eyes and ears to what’s going on out there. You know your airport and the people who use it. You know when your friend or family member seems risky or unsafe. If you identify a hazard, then speak up. Or, file a report with the FAA Hotline. Just remember, we all share the same airspace or may be nearby if their plane crashes.

Stay safe and don’t turn a blind eye!

For more information on submitting a report of a risky pilot via the FAA Hotline, visit: https://hotline.faa.gov/

Leah Read is a senior air safety investigator in the NTSB Office of Aviation Safety.

Most Wanted List Progress Report: Aviation Safety

By Member Earl F. Weener

The NTSB is releasing a series of blogs highlighting the progress the transportation community is making in each mode to advance issues on our 2017-2018 Most Wanted List. This series sheds light on the progress made and what needs to be done going forward to improve transportation safety. This is the third blog of the series.  

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Member Earl Weener and John DeLisi, Director, NTSB Office of Aviation Safety, talk with attendees during the aviation session of the Most Wanted List midpoint meeting

Aviation is one of the safest forms of transportation—largely due to government-industry collaboration efforts such as the Commercial Aviation Safety Team and the General Aviation Joint Steering Committee. We have seen no passenger fatality in the domestic operation of a U.S. airline (Part 121) since 2009, and the accident rate is trending slightly downward in General Aviation-GA (Part 91 and Part 125). While we celebrate the safety gains made across the commercial aviation industry, there is still work to be done across all sectors, especially in GA.

On November 15, the NTSB brought together government, industry, and advocacy representatives from the transportation safety community to get a progress report on our Most Wanted List (MWL) of transportation safety improvements. Aviation Safety Director John DeLisi and I led the aviation portion of the discussion.

 

 

We learned that industry is taking the lead to improve safety, and, while some Federal Aviation Administration initiatives have been helpful, more may be needed. Yet the best path to getting NTSB recommendations adopted, most agreed, was encouraging a more aggressive voluntary, collaborative approach to safety.

Our focus on preventing Loss of Control (LOC) In Flight in General Aviation (GA)—the only aviation-specific issue on the MWL—was the primary focus of our conversations. Successfully resolving this problem requires continuing collaboration, which, so far, appears to be occurring widely and effectively. The GAJSC is one organization helping to facilitate this collaborative approach. At the mid-point meeting, we also announced that the NTSB will be collaborating with the FAA, industry associations, flight schools, technology manufacturers, and others in an upcoming April 24, 2018, roundtable on LOC solutions. The number of LOC and fatal LOC accidents are both trending down as of 2016, our last complete year of data. We won’t call that progress yet, but we might look back one day and say that it was.

The changes to Part 23 of the Federal Aviation Regulations reforming small aircraft certification standards have enabled streamlined adoption and installation of new technologies, such as AOA indicators that would prevent LOC, without a lengthy and costly supplemental FAA flight certification. Private industry can now do what it does best: innovate.

We also discussed another MWL issue, Expand Recorder Use to Enhance Safety. In particular, the NTSB would like to see more cockpit cameras, which aid in accident investigations and provide useful data for developing policies/procedures to prevent accidents. However, privacy issues, data protection challenges, and fears of punitive actions by companies appear to still hinder progress in this area.

Just as we have seen tremendous benefits in crash survivability on our highways with the use of seat belts and air bags, the aviation community so too must also recognize the significant safety benefits of enhanced occupant protection systems, such as five-point shoulder harnesses. While helicopter pilots appear to be buckling up, others in GA are not—including passengers. Child restraint systems (“car seats”) should also be used in planes; yet, they widely are not. The NTSB reported at this meeting that we are collecting more data on if/how seat belts are used in our accident investigations.

Progress is being made on the carriage of lithium-ion (LI) batteries. Heat from one battery can propagate to nearby batteries before a fire breaks out, introducing a challenge for fire detection and suppression. However, we expect the FAA to complete testing related to this risk within this MWL cycle. We also await the Pipeline and Hazardous Materials Safety Administration actions to harmonize its regulations with the International Civil Aviation Organization’s technical instructions regarding segregating lithium batteries carried as air cargo from other flammable cargo.

Just before the beginning of this MWL cycle, in 2016, the new flight and duty regulation went into effect, a huge win for managing fatigue in commercial aviation. We continue to fight for the small wins. We still need to apply the same level of safety to cargo flights, but we have seen progress toward applying it to maintenance personnel.

And, in 2017, the FAA communicated that they’ll research the prevalence of impairing drug use – OTC, illicit, and prescription – throughout aviation. Previously, we had studied their presence in pilots in fatal accidents, which revealed an alarming rate of OTC use in fatal accidents. It may be too early to discuss any changes to medical fitness in aviation due to BasicMed. However, one of the related concerns is the loss of flight time data that we previously gathered as part of the medical certification process.

After our progress report meeting, I felt optimistic that the improvements being made, especially by industry, will serve to make aviation even safer. I encourage all stakeholders and the general flying public to consider areas where we still need to make progress. Everyone has a role to play in improving aviation safety—whether you are a pilot, an operator, or sitting in the seats.

Thank You

SafetyCompassLogoBy Stephanie D. Shaw

We launched Safety Compass in March 2011 to provide you an inside-out view of the investigative and advocacy efforts we’re engaged in and the important safety issues we’re focused on. As we close out 2017, we want to say “thank you” to you, our readers. Thank you for your interest in the work we do and for sharing our safety messages and recommendations for improving transportation safety.

From teens and sleep to drones, autonomous vehicles to our investigative processes, we’ve given you an inside look at the NTSB and highlighted our comprehensive approach to improving transportation safety across all modes and for all people.

To wrap up the year, here’s a list of some of our most popular blogs of 2017:

Last month, we released data revealing that 2,030 more people died in transportation accidents in 2016 than in 2015. Of those fatalities, 95 percent occurred on the nation’s roadways. Many of those deaths were completely preventable! As we approach 2018, we call on each of you to help us reverse the trend of increasing transportation fatalities, especially on our roadways. Continue to read our blog, see the lessons we’ve learned through our investigations, and share the safety recommendations we’ve made to prevent transportation accidents and crashes, deaths, and injuries.

We encourage you to keep up not only with our blogs, but with other NTSB materials. Sign up to be on our Constant Contact list. Follow us on Facebook (@NTSBgov), Instagram (@NTSBgov), LinkedIn (@NTSB), and Twitter (@NTSB). And in case you missed it, we launched a podcast in 2017, too! Check out Behind-the-Scene @NTSB wherever you get your podcasts. If you’d like to suggest a blog topic, e-mail SafetyAdvocacy@ntsb.gov.

As 2017 comes to an end, we again extend our gratitude to you for working with us to improve transportation safety. We wish you safe travels this holiday season and in 2018.

Travelers, Put Safety First this Holiday Season

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By Chairman Robert L. Sumwalt

At the NTSB, we’ve investigated many tragic transportation accidents that could have been prevented with some planning, forethought, and good decision making. As we mark the beginning of the holiday travel season, we want to encourage all Americans to make it their goal to arrive safely at their destinations, so we’ve boiled down some lessons we’ve learned that the traveling public can use.

By Car

Fatigue, impairment by alcohol and other drugs, and distraction continue to play major roles in highway crashes. Here’s what you can do:

  • If your holiday celebrations involve alcohol, ask a friend or family member to be your designated driver, or call a taxi or ridesharing service.
  • In a crash, seat belts (and proper child restraints) are your best protection. Always make sure that you and all your passengers are buckled up or buckled in!
  • Make sure to use the right restraint for child passengers, and be sure it’s installed correctly. If you have doubts, ask a Certified Child Passenger Safety Technician.
  • Make sure you’re well rested! A fatigued driver is just as dangerous as one impaired by alcohol or other drugs.
  • Avoid distractions. In this newly released video, survivor-advocates share their stories of personal loss—and the changes they’re working for now: https://www.youtube.com/watch?v=7jNYECrlzGU&feature=youtube.
  • Don’t take or make calls while driving, even using a hands-free device. Set your navigation system before you start driving. If you’re traveling with others, ask them to navigate.

By Bus or Train

The NTSB has made recommendations to improve passenger rail and motorcoach operations and vehicle crashworthiness, but travelers should know what to do in an emergency.

  • Pay attention to safety briefings and know where the nearest emergency exit is. If it’s a window or roof hatch, make sure you know how to use it.
  • If you’re unsure of where the exits are or how to use them, or if you didn’t receive a safety briefing, ask your driver or the train conductor to brief you.
  • Always use restraints when they’re available!

 By Air or Sea

Airline and water travel have become incredibly safe, but these tips can help keep you and your loved ones safe in an emergency.

  • When flying, make sure that you and your traveling companions have your own seats—even children under age 2.
  • Don’t forget your child’s car seat. The label will usually tell you whether your child car seat is certified for airplane use; the owner’s manual always has this information.
  • If you don’t know the rules for using a child’s car seat on your flight, call the airline and ask what you need to know.
  • Pay close attention to the safety briefing! Airline and marine accidents have become very rare, but you and your family can be safer by being prepared.
  • Whether you’re on an airplane or a boat, know where to find the nearest flotation device.

No matter how you travel, you deserve the benefits of the lessons we’ve learned through our investigations, but you need to play an active part to take advantage of them. This holiday season, make a commitment to put safety first.

 

Inside the NTSB’s General Aviation Investigative Process

The Nuts and Bolts

By Aaron Sauer

This is the sixth blog in a new series of posts about the NTSB’s general aviation investigative process. This series, written by NTSB staff, explores how medical, mechanical, and general safety issues are examined in our investigations.

 

The public’s image of our agency is often based on the iconic blue and yellow NTSBNTSB Investigators Onscene jacket they see at accident scenes. What’s less well known is that examining and documenting on-scene evidence is just one step in an exhaustive process to gather all available information, determine a cause, and recommend any changes that can prevent similar accidents.

Since 2014, 12 percent of general aviation accidents—about three accidents every week—have involved a power plant malfunction. These malfunctions may include a fuel issue, component failure, or improper maintenance.  As an NTSB air safety investigator, I investigate such mechanical malfunctions, gather the facts of the investigation, and ultimately help determine the probable causes of accidents.

After the on-scene phase of the investigation is complete, the airplane wreckage is often recovered by professional recovery services and stored in a secure location until we determine if further NTSB investigation is needed. When circumstances, such as a large hole in the engine crankcase or the in-flight loss of a propeller, indicate that further examination is necessary, we work with the airframe, engine, and component manufacturers. These entities serve as parties to our investigation, providing technical expertise on their product. If required, we coordinate a follow-up plan to examine the aircraft wreckage in greater detail. At the accident scene or recovery facility, our investigators examining the machine determine the scope of follow-up based on any anomalies discovered.

In some accidents involving a reported loss of engine power, the initial examination (typically a 100-hour inspection) turns up no obvious anomalies. At this point, one of the best and most telling follow-up activities is to attempt an engine test run. Engine test runs may be performed at a recovery facility or at a manufacturer’s facility. A successful engine test run is a critical piece of information that may lead the investigation down another path.

When, upon initial examination, the investigator observes an engine issue consistent with an internal mechanical failure, it’s typical to disassemble the engine at the manufacturer’s facility or the recovery facility under NTSB supervision. Examining an engine at the manufacturing facility often provides the advantage of having available engineering staff, historical data and drawings, and proper test equipment for the engine components.

Once at the manufacturer’s facility, the investigation team (typically including NTSB, FAA, and airframe, engine, and component manufacturer personnel) determines the plan or approved test procedure for the detailed investigation. The scope of the investigation is determined based on the known facts and circumstances of the accident, the condition of the engine and components, and the work required to confirm the failure. It’s important to note that, although the parties work collaboratively, the NTSB has the final say if there is any disagreement in the investigation process.

Engine functional testing, partial disassembly, and full engine disassembly are the most common investigation techniques used to determine the cause of a failure or malfunction. Disassembly helps us identify fractured or broken parts, which are then documented and set aside for even further examination.

Most manufacturers have their own materials laboratory, metallurgists, and engineers. At this point and with the team present, our investigators may elect to use the manufacturer’s material laboratory for a preliminary examination to obtain a quick analysis of the failure mode, then forward the parts to our materials laboratory in Washington, DC, for a detailed metallurgical examination.

Even observers with a solid understanding of our processes beyond the on-scene images might not understand the many ways that NTSB investigations can improve safety. Even when all signs point to a mechanical malfunction, our investigative process still looks at two other factors: human and environment. When an accident involves reported loss of engine power, we gather information about the pilot and aircraft owner—documentation from the scene, aircraft records, and Federal Aviation Administration (FAA) records. We interview witnesses, visit and examine maintenance facilities, and meet with manufacturers. When necessary, we conduct follow-up examinations and interviews. If FAA inspectors handle the initial on-scene observations, we work hard to guarantee that our two agencies communicate effectively.

When the fact-gathering phase of the investigation is complete, our investigators compile all the relevant factual information, complete a detailed factual report, and create a public accident docket. For an engine failure accident, the docket may include engine reports, materials laboratory reports, aircraft records, and historical engine safety information in the form of service bulletins and airworthiness directives.

Many people understand that we may make recommendations at any point during an investigation, but sometimes our investigations also result in other actions to improve safety. For example, depending on the nature of the material failure, an NTSB investigator may work with the FAA or the manufacturer to issue a manufacturer service bulletin, service letter, safety notice, or a potential airworthiness directive. The safety action taken by the FAA or manufacturer depends on the failure’s cause, fleet exposure, and the potential safety awareness benefit of each product.

Over my 17 years as an NTSB investigator, I’ve investigated numerous engine-failure–related accidents that resulted from human error and material failure. Despite the varied causes and outcomes of these accidents, one fact stands out: proper maintenance is the best way to avoid catastrophic consequences. Following manufacturer-recommended maintenance practices and procedures and adhering to basic maintenance principles can prevent accidents.

Remember: SAFETY is NO ACCIDENT!

All accident reports and public accident dockets are available on the NTSB website:  www.ntsb.gov.

 

Inside the NTSB’s General Aviation Investigative Process

An Aeromedical Mystery Solved

By: Clint Johnson, Chief, Alaska Region, Office of Aviation Safety

This is the fifth blog in a new series of posts about the NTSB’s general aviation investigative process. This series, written by NTSB staff, explores how medical, mechanical, and general safety issues are examined in our investigations.

Clint Johnson
Clint Johnson at industry event

After nearly 20 years of investigating hundreds of aviation accidents, I recently encountered an invisible killer.

I was enjoying a late summer Saturday afternoon with my wife in Anchorage, Alaska, when my phone rang. My wife – a 20-year-veteran NTSB spouse – knew from the look on my face that our quiet weekend at home had just ended.

An Anchorage Fire Department dispatcher was calling. She reported that rescue crews were on the scene of a fatal airplane crash in a residential neighborhood only 20 minutes away.

When I arrived, I was briefed by a small army of Anchorage Police and Fire Department

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Hefty Polar Cub airplane crash site

crews. Behind the wall of fire trucks, police cars, stunned residents, and TV cameras, I caught a glimpse of the inverted and burned remains of what looked like a float-equipped Piper 11 in the middle of the residential roadway.

We continued to talk as we walked toward the wreckage site. The pungent smell of burned aircraft wreckage filled the air as we proceeded past the yellow police tape. Finally, I was close enough to see that only the welded steel-tube structure and engine remained, with the fuselage and wings barely recognizable. The postcrash fire had incinerated much of the wreckage.

Witnesses had told the police that just before the accident they watched in amazement as the airplane completed two, low-level, high-speed, 360° right turns over the neighborhood – the first 150-200 feet above ground level, and the second much lower. One homeowner stated that the airplane passed over his home about 50 feet above his roof.

Witnesses also reported that the airplane’s bank angle increased significantly on the second 360° right turn; one pilot-rated witness estimated the bank at more than 60°. Witnesses also reported hearing the airplane’s engine operating in a manner consistent with high power settings throughout both 360° turns.

One man was mowing his lawn as the airplane completed the second, steep, 360° right turn. He said that the airplane flew directly over his yard, then the nose of the airplane pitched down and it began to descend rapidly. The engine rpm then increased significantly, and the wings rolled level just before the airplane impacted a stand of tall trees adjacent to his home, severing its floats.

It crashed on a neighborhood road, coming to rest inverted. About 30 seconds after impact, a fire ensued, which engulfed the entire airplane before any of the witnesses made it to the wreckage.

Sadly, after the fire department crews extinguished the fire, they found the remains of the 75‑year-old pilot and his dog still inside the incinerated wreckage.

While we all waited for the medical examiner to arrive, I began interviewing witnesses. Most concluded, or were well on their way to concluding, that the pilot was “just showing off” to someone on the ground. But the NTSB sets a high bar for conclusions. It was way too early for me to go there.

At the scene, I met a family member, along with a close friend of the pilot. Understandably upset, both reported that it was highly unusual and uncharacteristic behavior for the pilot to be flying as the witnesses consistently described to me. They went on to say that to their knowledge, the pilot didn’t know anyone in the area, but that, given the pilot’s anticipated flight route, he would have been flying over the neighborhood while on the return flight home.

Then, as the pair was preparing to leave the scene, the pilot’s friend said something in passing – something about his longtime buddy’s history of cardiac problems, which, in his opinion, caused the pilot’s erratic flight maneuvers.

I pressed him for more information, but it became clear that he wasn’t prepared to provide any additional information on the subject then and there, and I decided that this was neither the time or place to discuss it. As the pair got back into their car and slowly drove away, I knew that the following Monday morning I’d likely be attending the pilot’s autopsy.

For now, I needed to document and examine the wreckage before it was removed. This included determining control cable continuity to the flight control system, engine control continuity, and more.

The engine sustained significate impact damage, but only minimal fire damage. There were no mechanical problems that I could find on-scene that would explain what the witnesses reported. However, a much more detailed wreckage exam would be accomplished later, once the wreckage was moved to a more secure and suitable site.

On Monday morning, I found myself at the State medical examiner’s facility, meeting with the pathologist who would be working my case. I explained to her what I was looking for, and she started the exam.

The entire autopsy took over two hours to complete, and the pathologist found no conclusive evidence for medical incapacitation from an acute cardiac event. However, per standard protocol, the autopsy team took blood and tissue samples to send to the FAA’s Bioaeronautical Sciences Research Laboratory in Oklahoma City for a toxicological exam.

I knew I would not have the tox report for two to three months, but the autopsy yielded at least one more piece of valuable information: the pilot died from trauma, not the postcrash fire. Unbeknownst to me at the time, this would be an extremely important data point that would help solve the case in the end.

Over the next two weeks, I visited the wreckage two separate times at a local aircraft salvage yard. I looked for evidence that would support various theories, but nothing ever panned out. It was one dead end after another.

Then on a cold and snowy autumn afternoon, the FAA’s tox report on the pilot appeared in my e-mail. I opened it and scanned the results, and only then realized just what I had been missing all this time: Carbon Monoxide, an odorless, colorless and tasteless gas – and a silent killer of general aviation pilots.

The pilot’s carboxyhemoglobin (carbon monoxide) level was an extremely high 48%. To put these results in context, nonsmokers may normally have up to 3% carboxyhemoglobin in their blood, and heavy smokers may have levels of 10% to 15%. And according to family members, this pilot did not even smoke.

Since the pilot died of blunt-force trauma prior to the ensuing fire, it was not possible that this CO level was an effect of the fire. But it was possible that it was a cause of the crash.

I realized that over the last few months I had missed an important and somewhat elementary piece of evidence, the airplane’s exhaust system. I quickly reviewed my on-scene photos, and I could clearly see that the entire exhaust system sustained relatively minor damage in the accident.

Within 15 minutes of receiving the toxicology results, I was on my way back to the stored wreckage. I ended up bringing the entire exhaust system back to the office, muffler, heat exchanger/muff and all. Like the autopsy examiners I had met months earlier, I went to work on this simpler machinery, peeling back the heater shroud.

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Accident muffler can assembly

Inside I found a severely degraded muffler with portions missing, which allowed raw exhaust gases to enter the main cabin through the airplane’s heater system.

Unfortunately, neither the family or any of the pilot’s friends could find any maintenance logbooks for the accident airplane, so I was unable to determine just when the last muffler inspection was done (if ever). However, after talking with several friends of the deceased pilot, many said that he did his own maintenance, and he was not an aviation mechanic.

They went on to say that the pilot, with the help of a few other friends, installed the more powerful Lycoming O-320 engine about 5 years earlier, but none could provide any additional information about how the pilot maintained his airplane.

However, I could report directly to the family what circumstances led up to the death of their loved one, and I was able to show them the physical evidence that I found.

The NTSB’s probable cause summed it all up: “The pilot’s severe impairment from carbon monoxide poisoning in flight, which resulted in a loss of control, and a subsequent inflight collision with trees and terrain.”

Often, it takes time, patience, and knowledge of the human operator, the machine, and the environment to solve an accident mystery to provide answers.