Ever since the Wright Brothers took off in December 1903 with their first, crude heavier-than-air prototype, aircraft have followed gravity all the way to the ground, not always with good results. The wisdom of those early pioneers of traditional crewed aviation was to learn from every mistake, every incident and every accident in order to create a culture of fine tuning that has resulted, 122 years later, in the safest way to travel.
The foundation of modern aviation safety rests on these hard-won lessons from accidents, technological breakthroughs and evolving Federal Aviation Regulations (FARs). Despite recent events and a major multi-fatality accident in early 2025, commercial aviation (Part 121) continues to hold an incredible record of operational safety that is the envy, not only of the rest of the world, but other modes of transportation as well – yet general aviation (Part 91 and Part 135) faces higher risks. This reality has profound implications for emerging technologies like drones and air taxis.
The Three “Parts” of U.S. Aviation Regulation: A Safety Hierarchy
To set the stage, one must first appreciate the sliding scale of safety ensconced in FAA regulations.
Part 91 (General Aviation): The Flexible Foundation
Governed by the least restrictive rules, Part 91 covers private flights, corporate jets, and flight training. With no mandated pilot rest requirements, flexible maintenance schedules, and permission to operate in challenging weather, it offers maximum freedom at the cost of higher accident rates. In 2022 alone, Part 91 operations accounted for 1,152 accidents – 181 fatal – underscoring the risks of its autonomy-first approach.
Part 135 (Charter/Commuter Operations): The Middle Ground
Serving as the bridge between casual and commercial flying, Part 135 regulates air ambulances, cargo carriers, and charter services. Stricter than Part 91 but less rigorous than Part 121, it requires enhanced pilot training (sometimes including Airline Transport Pilot certificates), formal maintenance programs for larger aircraft, and shared operational control between pilots and operators. Despite these safeguards, Part 135 accident rates remain significantly higher than those of major airlines.
Part 121 (Commercial Airlines): The Gold Standard
The crown jewel of aviation safety applies to scheduled airlines and major cargo carriers. With mandatory twin-pilot crews holding Airline Transport Pilot certificates, FAA-approved maintenance programs, dispatcher oversight, and strict duty limits, Part 121 operations achieved a fatal accident rate of just 0.135 per million flights from 2018-2022. This regulatory framework transforms aviation into the world’s safest transportation mode – a status maintained even through 2025’s industry challenges.
The Birth of Commercial Aviation Safety: Trial and Error to Federal Oversight
But what is aviation operational safety? Traditional commercial aviation operational safety (Part 121) has three components: Aircraft, Pilot and Organization. It is no coincidence that these three emerged and evolved separately but connected and in tandem.
Originally, in 1903, the obvious first item to improve was the aircraft. Eventually with new players and new ideas, the hardware improved to the point where it was the pilot that was the part that needed improvement. Eventually it became the organization that was the problem. The following graph explains these steps in terms of decades.
The Early Years: A Bumpy Ride
From 1903 to the early 1950’s the emphasis of the new industry was to create aircraft and power plants that were safe and reliable. During this period, the world went through two world wars and pilots were mostly trained by the military and by ad hoc instructors without a specific or unified curriculum. Weather forecasting was in its infancy and airborne radar did not exist yet, at least in a practical, usable way.
Most flights were conducted using visual flight rules (VFR) and preferably during daylight hours. Night flying was dangerous due to the possibility of thunderstorms and the lack of a navigation infrastructure designed and built to support an entire industry.
With the invention of Instrument Flying in late 1929 by a young Lieutenant named James Dolittle, who later became famous for bombing Tokyo after Pearl Harbor in 1942. Aviation was now firmly poised to be a ‘24 hours a day’ industry, except that aircraft were still unreliable and noisy.
In the late 1930’s the Douglas Corporation introduced the aircraft that changed all that and became the foundation of the modern airline industry as we know it today: the DC-3. With the introduction of this upgrade from the disastrous DC-2, reliability went from 50% of chances of reaching your destination to 80% – and the industry took off (no pun intended!)
During these early years hundreds – if not thousands – of accidents forced Congress to act. In 1926 the Air Commerce Act was passed giving the Commerce Department the responsibility to investigate accidents and recommend corrective actions based on the findings.
The Next Phase: New Agencies and Technologies
In 1958 the Federal Aviation Agency (today Federal Aviation Administration – FAA) was formed and in 1967, President Lyndon B. Johnson created The National Transportation Safety Board (NTSB), as an independent agency within the Department of Transportation (DOT).
By this time, jet aircraft were the norm, especially in international and transcontinental flights and most were done using the new VOR (VHF Omnidirectional Radio Range), a ground-based navigation system that provides aircraft with accurate directional information. It’s essentially a radio beacon that transmits a rotating radio signal, allowing pilots to determine their bearing (radial) to the station and therefore their position relative to it. If the aircraft is not equipped with accurate DME (distance measuring Equipment), intersecting two or three of these radials emanating from different VOR’s will give an accurate enough position.
Building Better Pilots Through Standardized Training
It was time to introduce a more rigorous pilot training system that considered the number of hours flown and the certifications obtained, from student to private pilot, to commercial multiengine, instrument rated and eventually Airline Transportation Pilot (ATP). This system is based on periodic sessions in simulators, in which the emphasis is on each aircraft model flown and a deep knowledge of all systems involved, from air conditioning to pressurization to hydraulic systems, plus a constant repetition of simulated emergencies and strict adherence to the aeronautical decision making (ADM) process, a systematic approach pilots use to determine the best course of action in a given situation.
Forging the Modern Commercial Airline Industry
The issue that jet flying made abundantly clear in the 1950’s is that at speeds of 400 miles an hour and more, aircraft tend to move faster than most pilots can handle, so new techniques and more automation were necessary. There was also the recommendation that a minimum of two pilots share the responsibility of each flight, so the workload at the critical phases of flight (takeoff and landing) were evenly divided.
With the introduction of Cockpit Voice Recorders (CVR) and Flight Data Recorders (FDR) plus an air traffic control (ATC) system that is constantly monitored and recorded, accident investigation could now determine if the mishap was the result of a mechanical failure, weather, pilot or ATC error or a combination of them.
The NTSB and the FAA combined forces to investigate every incident and accident in the U.S. They also collaborated with other nations in their respective investigations. The goal: to create a huge database of events that would contribute to a periodic set of recommendations for aircraft manufacturers, pilot training centers and ATC management, to fine tune a system that continued to grow exponentially.
The 1970s saw a period of consolidation of the airline industry and some of the existing names today such as United, American and Delta, emerged through organic growth and a great deal of mergers and acquisitions. These organizations combined operational safety teams that brought together weather forecasts, crew duty time, mechanical protocols, ramp operations and many other factors to create procedures that would be copied and perfected over the decades and throughout the entire commercial airline industry to the levels of safety that we have today.
But that is only the ‘Part 121’ of the story; Part 91 and Part 135 developed into a very different safety reality, one in which accidents were not as rare as those involving commercial airliner jets.
The General Aviation Divide: Part 91/135 Lag Behind
The largest general aviation membership organization in the U.S., AOPA (Aircraft Owners and Pilots Association) releases an annual report on the safety of the industry that is always helpful to understand the reality of Part 91 and Part 135, especially in contrast to Part 121.
A few weeks ago, the AOPA Air Safety Institute released the 34th Richard G. McSpadden Report (formerly the Joseph T. Nall Report) which presents users with near real-time accident analysis updated on a rolling 30-day cycle. The accident data used in the report is from 2008 to 2022, the last year for which the NTSB has officially released complete records. (Please note that the NTSB takes approximately two years to issue a probable cause statement, so only preliminary data is available for 2023 and 2024).
The picture for Part 91 or Part 135 is not as rosy as with Part 121. In this case, most if not all accidents occurred while operating under these two provisions. In 2022, there were 1,152 general aviation accidents, and of these, 181 were fatal. This was an increase of 32 accidents in comparison with 202. It was also 102 more than in 2020, the lowest number of accidents in over a decade, perhaps attributable to the Covid-19 restrictions.
In short, while Part 121 achieved near-perfection, 2022’s 1,152 general aviation accidents reveal persistent gaps:
- Training Variability: Part 91 allows pilots with just 40 hours’ experience to carry passengers
- Maintenance Flexibility: Owner-performed repairs permitted on many small aircraft
- Technology Gaps: 70% of GA planes lack terrain awareness systems mandated for airlines
The McSpadden Report also shows these sobering trends:
- Weather-Related Crashes: 35% of Part 135 fatalities involve continued VFR into Instrument Meteorological Conditions (IMC) conditions
- Loss of Control: 40% of Part 91 accidents stem from pilot mishandling
- Mechanical Failures: 2x more common in GA vs commercial aircraft
So, what lessons can we, in this new uncrewed aviation industry, learn from these most recent lessons – combined with the 120 years of accident/incident investigations?
Lessons for the Drone Age: Building Part 108’s Safety Foundation
One thing is for sure: as an industry, we are not starting from zero. We are joining an already thriving and safe aviation business. All we need to do is to understand how they managed such levels of operational safety and then adapt those practices to our business models.
The challenge would be that aiming at Part 121 operational safety levels would mean huge investments that could make the entire enterprise a losing proposition. Drones and air taxis will fly lower and at slower speeds than jet airliners and the distances, at least at the beginning, will be relatively short.
Aiming at the safety levels of Part 91 and 135 is probably unacceptable, because given the huge number of uncrewed aircraft crossing our skies, the accidents will be counted by the thousands.
The next three years will be decisive in terms of safety levels for the uncrewed aviation industry. The rapid developments in Artificial Intelligence (AI) technology and the final implementation of Part 108 sometime in 2026 or 2027 would mean that from the regulatory and technological points of view we will be ready to integrate with traditional aviation.
The big question remains: at what level of acceptable operational safety will this integration begin? The answer is simple. Drones and air taxis will have to rely a lot on automation and in some cases AI. The industry will have to be completely independent of ATC but act in coordination with it. We will need to perfect UTM systems and Detect and Avoid (DAA) technology to the point that they effectively replace the pilot on board and we will need to demonstrate these capabilities to the FAA in less crowded areas (rural) and slowly move towards areas of heavy traffic (urban). This crawl-walk-run approach will allow us to have a fully integrated, safe NAS in about a decade.
It is up to all of us in the industry to guarantee that this level will be closer to Part 121, but in an affordable manner. This presents a formidable challenge that the industry must be prepared to meet. As the industry stands at this crossroads, the lessons of Part 91, 121, and 135 remain vital. Lasting safety requires equal investment in hardware, human factors and organizational culture – no matter who (or what) is at the controls.
By: Juan B. Plaza