Guest Editorial:

Human Error Vs. Airborne Terrorism

By Robert Baron (


On September 11, 2001...

Four terrorists hijacked United Airlines flight 93, which departed Newark and was destined for San Francisco. The plane crashed in Somerset, Pennsylvania killing all 45 persons on board. The intended target of that hijacked plane may never be known, but it is believed that it was bound for the White House. It is important to point out that due to the bravery of the passengers in overpowering the hijackers on that doomed flight, the aircraft was prevented from being used as a missile.

Five terrorists hijacked American Airlines flight 77, which departed Washington Dulles Airport and was destined for Los Angeles. The plane was flown directly into the Pentagon. A total of 189 persons were killed, including all who were onboard the plane.

Five terrorists hijacked American Airlines Flight 11, which departed Boston and was destined for Los Angeles. The plane was flown directly into the north tower of the World Trade Center. On board the aircraft were 81 passengers, nine flight attendants, and the two pilots.

Five terrorists hijacked United Airlines Flight 175, which departed Boston and was destined for Los Angeles. The plane was flown directly into the south tower of the World Trade Center. On board the aircraft were 56 passengers, seven flight attendants, and the two pilots.

In the end, more than 3000 persons were killed in these four heinous attacks. I'm sure that each and every one of us has thought about what it must have been like for those passengers in their final moments on each of those four ill-fated airliners on September 11th, 2001.Thousands of innocent lives were lost because of fanatic martyrs who believe in some sort of a fantasyland after-life. Unlike hijackers of the past, there are no demands to be met or negotiations to be had. These people have only one motive; to kill as many Americans as possible and be willing to die for the cause. That is scary. 

Thanks to 9/11, and for the foreseeable future, passengers will board commercial airliners with a newfound type of anxiety. After all, our domestic security was breached and our air transportation system was violated. We can't help but wonder if the passenger sitting next to us has been properly screened and is not armed with a box cutter, knife, or other weapon with the explicit intent to harm Americans. Things are different today, that's for sure.

The following pictures depict the aftermath of the worst terrorist attacks on U.S. soil.

In the aftermath of the 9/11 attacks, we have stepped-up security at airports and have become extra vigilant for suspicious activities in our aviation environment (as well as other high-risk environments). Today, when boarding an aircraft, the average passenger fears a hijacking more than any other element of flight. However, if we put we things in perspective, an airline passenger has at least a 100 percent higher risk of being seriously injured or killed by human error than by terrorist activity. Therefore, the gist of this article is not about terrorism, per se, but how serious the consequences can be when human error is left unchecked. 

THE HUMAN ELEMENT: That by which we have physical or mental control to recognize, change, prevent, or mitigate a situation. Approximately 80 percent of all air crashes fall into this category. While the previous definition called it "pilot error," the term has been changed to "human error" to more realistically reflect that anybody who acts in a support capacity of a flight may contribute to the error chain. Not just the pilot. Of the previously cited 80 percent, the NTSB (National Transportation Safety Board) further breaks down human errors into the following categories:


Unprofessional Attitudes

Visual Perception Misjudgment 19%
Pilot Technique 21%
Inflight Judgment or Decision 5%
Improper Operation of Equip. 6%
Unknown Causes 4%





        Continuing with statistical data, the following two tables depict the causes of accidents (in percent) from the 1950's through the 1990's. Note that "pilot error" has, and still does, account for the highest percentage of accidents. 

Accident Causes by Category (percent)

Cause 1950s 1960s 1970s 1980s 1990s Total
 Pilot Error 41 34 27 28 27 31
 Pilot Error  (weather related) 9 17 14 15 14 14
 Pilot Error (mechanical related) 6 5 4 3 4 4
 Total Pilot Error 56 56 45 46 45 49
 Other Human Error 2 7 8 6 8 7
 Weather 16 11 15 15 14 14
 Mechanical Failure 20 19 19 19 24 21
 Sabotage 5 4 11 13 8 8
 Other Cause 1 3 2 1 1 1

The tables above and below are compiled from the accident  database, representing 1,834 accidents from 1950 thru 1999.  The table above uses 1,286 accidents where a cause can be identified and excludes accidents where a cause could not be determined. The table below includes all 1,834 accidents including those where a cause could not be identified.

"Pilot error (weather related)" represents accidents in which pilot error was involved but brought about by weather related phenomena.  "Pilot error (mechanical related)" represents accidents in which pilot error was involved but brought about by mechanical failure.  "Other human error" includes air traffic controller error, improper loading of aircraft, fuel contamination, improper maintenance etc.  Sabotage includes explosive devices, shoot downs and hijackings.  "Total pilot error" is the total for all types of pilot error (on the fourth line in yellow).  Where there were multiple causes, the most prominent cause was used.

Accident Causes by Category (percent)

Cause 1950s 1960s 1970s 1980s 1990s Total
 Pilot Error 27 24 18 21 20 22
 Pilot Error  (weather related) 6 12 9 11 11 10
 Pilot Error (mechanical related) 4 3 3 2 3 3
 Total Pilot Error 37 39 30 34 34 35
 Other Human Error 2 5 5 4 6 4
 Weather 10 7 9 11 11 10
 Mechanical Failure 13 14 12 15 18 14
 Sabotage 3 3 7 10 6 6
 Other Cause 1 2 1 1 1 1
 Undetermined or missing 34 30 36 25 24 30
Odds of being on an airline flight which results in at least one fatality
Top 25 airlines with the best records
1 in 4.2 million 
Bottom 25 airlines with the worst records
1 in 186,000
Odds of being killed on a single airline flight
Top 25 airlines with the best records
1 in 12.4 million 
Bottom 25 airlines with the worst records
1 in 251,000

Source: BACK Associates and accident database, 1980 - 1999

Mortality Risk by Type of Scheduled Service
1987 - 1996

Advanced-world1 domestic jet

1 in 8 million

U.S. Commuter2

1 in 2 million

Developing-world3 domestic jet

1 in 500,000

International jet within advanced-world

1 in 5 million

International jet between advanced-world and developing-world

1 in 600,000

International jet within developing-world

1 in 400,000

1.  Advanced-world air carriers have home offices in economically advanced, technologically advanced and politically democratic countries (Australia, Austria, Belgium, Canada, Denmark, Finland, France, Germany, Iceland, Ireland, Israel, Italy, Japan, Luxembourg, Netherlands, New Zealand, Norway, Portugal, South Africa, Spain, Sweden, Switzerland, the United States and the United Kingdom).  

2  Includes service by reciprocating-engine aircraft and turboprop aircraft.

3.  Developing-world air carriers have home offices in countries other than those countries categorized for the purposes of this study as economically advanced, technologically advanced and politically democratic.

 Source: Arnold Barnett and Alexander Wang, Massachusetts Institute of Technology

 The following pictures depict the aftermath of human error.




        Let's start off by remembering the adage "to err is human." Errors can be diminished to a certain extent, but will always exist. It's just a fact we have to deal with. This holds true for all events in life, not just aviation. If you track the roots of any air disaster, there is bound to be some kind of human error in the equation, even if it is not apparent at first. An example of this would be the crash of United Flight 232 in Sioux City, Iowa in 1989. Sure, it was catastrophic failure and NOT pilot error. But...if you track the maintenance history back for a period of time you will come to realize that a mechanic was not doing his job properly and certain inspections were not complied with. Eventually, this lead to catastrophic engine failure and a total loss of hydraulic systems in that DC-10. The point is, even though the accident was classified as mechanical failure, the roots go back to a human who made an error. This error included a blatant violation of the Federal Aviation Regulations, a judgment decision, and possibly pressure to save time and money.

        In the next few pages, we will take a look at a few actual human-error accidents in respect to the operation of an aircraft. More in-depth text summaries are included for most topics as a hyperlink (underlined text like this) for those who are either unfamiliar with the event or who would like to refresh their memory of a past event. Please note that these sample error categories comprise only a small percentage of all possible errors. In order to keep this article at a reasonable length, I have included what I feel to be very timely and/or important categories. 


        As a passenger on a commercial airliner, we should feel pretty self-assured that our pilots are not intoxicated. However, this wasn't the case on July 1st, 2002 in Miami when the crew of an America West Airlines Airbus 319 attempted to takeoff an aircraft while under the influence of alcohol. And while this situation is highly unlikely, the possibility does exist (as demonstrated recently by this flightcrew). According to CFR (Code of Federal Regulations) Title 14, Aeronautics and Space Part 91.17

§  91.17  Alcohol or drugs.

(a) No person may act or attempt to act as a crewmember of a civil aircraft --                                                                                

(1) Within 8 hours after the consumption of any alcoholic beverage;

(2) While under the influence of alcohol;

(3) While using any drug that affects the person's faculties in any way contrary to safety; or

(4) While having .04 percent by weight or more alcohol in the blood.

(b) Except in an emergency, no pilot of a civil aircraft may allow a person who appears to be intoxicated or who demonstrates by manner or physical indications that the individual is under the influence of drugs (except a medical patient under proper care) to be carried in that aircraft.

America West Airlines has an even stricter policy in regard to Item (1). They state that "no person may act or attempt to act as a crewmember of a civil aircraft within 12 hours after the consumption of any alcoholic beverage." Obviously, items (2), and (3) were disregarded by this crew. And as far as Item (4) is concerned, these two pilots far exceeded the .04 percent by weight in the blood. The captain of that flight registered a .091 while the copilot registered a .084. It's interesting to note that Item (b) gives the pilot the right to not let a passenger be carried on his aircraft if the situation were reversed!

        Although the aircraft had already pushed back from the gate and began taxiing towards the active runway, the ground controller told the crew they needed to return to the gate immediately. At that time both pilots were arrested and charged with not only operating an aircraft under the influence, but also with vehicular DWI since the state of Florida has a .08 threshold for operating a motor vehicle. Thanks to the observation of a security screener in Miami, that flight crew was apprehended and arrested before that aircraft took to the sky.

        This flight terminated with no injuries or loss of life. The pilots went to jail and the passengers were put on another flight and eventually arrived at their destinations. Could the outcome have been different and far more tragic? I think you know the answer to that question. But what about other flights? Do you think pilots learn from these lapses of reason or judgment? Apparently not. In January 2001, Northwest Airlines fired a pilot after discovering that he flew a DC-10 aircraft carrying 59 passengers from San Antonio, Texas, to Minneapolis-St. Paul, Minn. A Northwest employee smelled alcohol on the employee's breath after the plane landed. A Breathalyzer test showed that the pilot's blood-alcohol was .056, exceeding the FAA limit. In 1990, three intoxicated pilots were arrested after flying a Northwest Airlines Boeing 727 carrying 58 passengers from Fargo, N.D., to Minneapolis. Federal authorities were tipped off by an inspector who had learned the three had been drinking heavily at a bar the night before their flight.

        So how does this relate to human error? Take a look at the NTSB HUMAN ERROR CHART at the top of this page. Notice that Unprofessional Attitudes tops the list at 47%. Do you think piloting an aircraft drunk falls under that category? I'd say so! Another factor would be Inflight Judgment or Decision, which comprises 5% of the chart. A Judgment and decision-making rating would be considered poor for any of the aforementioned crews.


        One of the most disturbing and continuing errors committed by a flight crew is called CFIT (Controlled Flight Into Terrain). There are many definitions of CFIT, but all yield the same result. Your author defines CFIT as the following: "When a perfectly airworthy aircraft, under complete control of the pilot (s), is inadvertently flown into the ground, an obstacle, or water with little or no awareness by the pilot (s) until it's too late." CFIT accidents account for a large percentage of aircraft accidents and generally occur during the approach and landing phase of a flight. In light of the severity of this type of human error, I have included two examples. Korean Airlines Flight 801, and what's known in the business as the "classic" CFIT accident, Eastern Airlines Flight 401. You may be familiar with these. If not, hyperlinks have been included for full-text details.      

This Korean Airlines Boeing 747 crashed while attempting to land at Guam in heavy rain. Crew error was blamed on the accident. Two-hundred-twenty-eight out of 254 aboard were killed. (August, 6, 1997)


Realvideo animation of Flight 801 descent [3.5M]

The first example of a CFIT accident involves a Boeing 747 operated by Korean Airlines. A classic example of a perfectly airworthy aircraft being flown inadvertently into terrain (in this case, Nimitz Hill).

    As is so typical of a CFIT event, this one occurred only a few miles from the airport. The weather conditions at the time included heavy rain and low visibility. The pilots had to rely on instruments for the approach to landing, since there were no outside visual cues. To compound the situation, part of the ILS (Instrument Landing System) was inoperative. Instead of a gradual, fixed descent to the runway, the pilots had to perform a series of letdowns at prescribed points. If you look at the transcripts of this accident, you will notice that the crew was uncertain about the status of the ILS during the entire approach. Mountains are not very forgiving. And in this case, flying at the wrong altitude caused this 747 to clip the top of that mountain.        

   There were a series of other factors that contributed to this accident as well, including pilot fatigue. When an aircraft is involved in an accident, there is going to be a "chain" of factors involved. This is referred to as the "error chain." No single factor may have caused that 747 to crash. But when you sum those factors up, that is when the likelihood of an event of this magnitude can occur.

   After its formal investigation, the NTSB released the following official official conclusion in reference to KAL 801. Note how much human error played a role in the accident sequence:

   In its official conclusion as to the probable cause of this accident: "The National Transportation Safety Board determines that the probable cause of the Korean Air flight 801 accident was the captain's failure to adequately brief and execute the nonprecision approach and the first officer's and flight engineer's failure to effectively monitor and cross-check the captain's execution of the approach. Contributing to these failures were the captain's fatigue and Korean Air's inadequate flight crew training. Contributing to the accident was the Federal Aviation Administration's (FAA) intentional inhibition of the minimum safe altitude warning system (MSAW) at Guam and the agency's failure to adequately manage the system."

   "The safety issues in this report focus on flight crew performance, approach procedures, and pilot training; air traffic control, including controller performance and the intentional inhibition of the MSAW system at Guam; emergency response; the adequacy of Korean Civil Aviation Bureau (KCAB) and FAA oversight; and flight data recorder documentation. Safety recommendations concerning these issues are addressed to the FAA, the Governor of the Territory of Guam, and the KCAB."

An Eastern Air Lines Lockheed Tristar crashed into the Everglades killing 100 of 176 people aboard. In the darkness, the crew, preoccupied with a landing gear problem, failed to notice the autopilot had become disengaged and the plane was losing altitude. (December 29, 1972)


   Eastern Airlines Flight 401 has come to be known as the "classic CFIT" case study. This was the point in time that airlines began to recognize the need for crew coordination, delegation and cockpit resource management.

   In this example, we have three highly qualified flight crewmembers (captain, first officer, and flight engineer), each with a substantial amount of flight time and experience. This flight, from New York to Miami,  was routine and uneventful until arriving in the Miami vicinity. At that point, when the landing gear was extended, the nose gear light failed to illuminate. The main gears were confirmed down. All three crew members became so fixated on the landing gear light, no one noticed that the autopilot had disengaged at 2000 feet and the L1011 was slowly descending towards the Everglades. At the time the air traffic controller asked "how are things coming along out there" (in reference to working on the nose gear problem), the aircraft was at 900 feet. By the time the crew had recognized how dangerously low they were, it was too late. The aircraft had impacted the ground.

   So you say "how could this happen?" Very easy. Before CRM (Crew Resource Management) training became mandatory for airline crews, pilots tended to work on a more autonomous level. Group climate, synergy, coordination, and delegation were non-existent. The captain was considered "God" and what he said went! In this case, the captain did not delegate responsibility at all. The way this should have been handled, and the way it is taught nowadays, is somebody must always be flying the aircraft. The other pilot...or in this case pilots...should be troubleshooting the problem and offering solutions. Input! Working as a team to arrive at a solution and then have the captain make the final decision. That was not the case here.

   Air traffic control also took part of the blame for their part in not effectively monitoring the progress of the flight. When the controller asked "how are things coming along out there," what he should have said was something to the effect of "Eastern 401, I'm showing you at 900 feet...altitude are below my minimum vectoring altitude...climb immediately." That very statement could have possibly prevented this whole tragedy. A more assertive command by the controller  is what we were looking for there.

   So again, we have an accident where a perfectly airworthy aircraft, under complete control of the pilot (s), was inadvertently flown into the ground, with little or no awareness by the pilot (s) until it was too late.


   One of the requirements of becoming a pilot in the United States is to be able to read, speak, write, and understand the English language. Although flight crews in other nations (in this case Colombia) are also required to have these English language skills when flying into the United States, there is much room for improvement. The following case identifies language barriers coupled with non-assertive behavior by the crew. The hesitancy of the crew to recognize a fuel-critical situation and be able to verbalize this situation with US air traffic controllers contributed to this accident.

This Avianca Boeing 707 ran out of fuel and crashed in the woods of Cove Neck, New York after the crew, which spoke very little English, failed to declare an emergency after running low on fuel.  Seventy-three of the 158 aboard were killed. (January 25, 1990)


   This accident spurs a flashbulb memory for your author. I was born and raised on Long Island and was living there on January 25th, 1990. I remember that night vividly. It was raining about as hard as I had ever seen and it was very windy as well. My home was located about 50 miles east of Cove Neck. When the news broke in and informed us of that tragic crash, my stomach dropped to the floor. I knew that the weather had to have something to do with the crash. I couldn't even believe that aircraft were even attempting to land at JFK that night.

   Although the weather was bad that night, it was not the single factor that caused that 707 to run out of fuel. But, when you combine fatigue, language barriers, and non-assertive behavior with the weather, you have the ingredients for human failure.

   In its official conclusion as to the probable cause of this accident: "The National Transportation Safety Board determines the probable cause(s) of this accident/incident as follows."

   "The failure of the flightcrew to adequately manage the airplane's  fuel load, and their failure to communicate an emergency fuel situation to air traffic control before fuel exhaustion occurred. Contributing to the accident was the flight crew's failure to use an airline operational control dispatch system to assist them during the international flight into a high-density airport in poor weather.  Also contributing to the accident was inadequate traffic flow management by the FAA and the lack of standardized understandable terminology for pilots and controllers for minimum and emergency fuel states .The Safety Board also determines that windshear, crew fatigue and stress were factors that led to the unsuccessful completion of the first approach and thus contributed to the accident."


   CRM (Crew Resource Management), or lack of it, played a huge role in this example. With CRM training, crews are taught how to use all available resources for a safe and efficient flight. That training was obviously not provided to the crew of this Lockheed L1011.

   Amongst other things, CRM training teaches pilots how to communicate, delegate, work as a team, and use all available resources in making decisions. Although the captain is still the final authority as to the final decision, there is equal input to make that decision from all available people and resources. Crews that have been through CRM training have proven to be safer, better pilots. (particularly during adverse or abnormal situations). 

Burned out hull of a Saudi Arabian Lockheed L-1011. Although the plane landed safely, all 301 aboard died before rescue crews could reach them. The fire started in the aft cargo compartment and the crew failed to take immediate steps to evacuate the plane after landing. (August 19, 1980)


   This tragic accident brought about many questions. One of the most pressing issues was why didn't the crew evacuate the aircraft after landing? Instead, all aboard died while smoke and fire consumed the cabin.

   The confusing part of this scenario is that the crew managed to fly the aircraft back to Riyadh safely and perform a normal landing, but after they landed, they did not stop the aircraft as soon as possible and begin an emergency evacuation. That was what the standard operating procedure and checklist called for. Instead, they let the aircraft roll down the runway for almost 3 minutes. The engines weren't shut down for approximately another 3 minutes, preventing the rescue personnel from entering the aircraft. Additionally, because of the unfamiliarity of the emergency exits, the rescue personnel required even more precious time to enter the aircraft. In all, 23 minutes elapsed after landing before rescue crews could access the fuselage. But it was too late...all 301 people aboard had perished.

   Contributing factors in this accident included a lack of crew coordination, the failure of the captain to delegate responsibility to the other crew members, the First Officers limited experience on the L1011 and lack of support to the captain, and the Flight Engineer (who was dyslexic) rifling through the operations manual the whole time repeating to himself "no problem."


   The Federal Aviation Administration defines a runway incursion as “Any occurrence at an airport (with an operating control tower) involving an aircraft, vehicle, person, or object on the ground that creates a collision hazard or results in a loss of separation with an aircraft taking off, intending to take off, landing, or intending to land.”

   For additional reading on runway incursions by your author, you can click here.

The remains of a KLM 747 in Tenerife, Canary Islands in the worst aviation disaster in history, which killed a total of 583 people. The KLM 747 collided with a Pan Am 747 after the captain of the KLM plane started his takeoff roll without clearance. (March 27, 1977)


   Runway incursions are another hot topic in the aviation world these days. The example that is used here illustrates the worst air disaster to date as far as loss of life goes, with 583 people killed.

    How did those highly experienced pilots for two major airlines (at the time) manage to bring a pair of jumbo jets together right on the airport and kill that many passengers? Human error played a huge role in this event. Once again, we go back to the accident chain of events. weather, crew fatigue, and language (phraseology) were all factors. If just one of those factors were omitted or mitigated from the sequence, perhaps the outcome would have been different? We'll never know.

  In its official conclusion as to the contributing factors in this accident, the Secretary of Civil Aviation, Spain reports:

"The fundamental cause of this accident was the fact that the KLM captain: 1. Took off without clearance. 2. Did not obey the "stand by for take-off" from the tower. 

3. Did not interrupt take-off when Pan Am reported that they were still on the runway. 

4. In reply to the flight engineer's query as to whether the Pan Am airplane had already left the runway, replied emphatically in the affirmative. 

Now, how is it possible that a pilot with the technical capacity and experience of the captain, whose state of mind during the stopover at Tenerife seemed perfectly normal and correct, was able, a few minutes later, to commit a basic error in spite of all the warnings repeatedly addressed to him? 

An explanation may be found in a series of factors which possibly contributed to the occurrence of the accident. 

1. A growing feeling of tension as the problems for the captain continued to accumulate. He knew that, on account of the strictness in the Netherlands regarding the application of rules on the limitation of duty time, if he did not take off within a relatively short space of time he might have to interrupt the flight - with the consequent upset for his company and inconvenience for the passengers. Moreover, the weather conditions in the airport were getting rapidly worse, which meant that he would either have to take off under his minima or else wait for better conditions and run the risk of exceeding the aforementioned duty-time limit. 

2. The special weather conditions in Tenerife must also be considered a factor in themselves. What frequently makes visibility difficult is not actually fog, whose density and therefore the visibility which it allows can be fairly accurately measured, but rather layers of low-lying clouds which are blown by the wind and therefore cause sudden and radical changes in visibility. The latter can be O m at certain moments and change to 500 m or 1 km in a short space of time, only to revert to practically zero a few moments later. These conditions undoubtedly make a pilot's decisions regarding take-off and landing operations much more difficult; 

3. The fact that two transmissions took place at the same time. The "stand by for take-off ... I will call you" from the tower coincided with Pan Am's "we are still taxiing down the runway", which meant that the transmission was not received with all the clarity that might have been desired. The whistling sound which interfered with the communication lasted for about three seconds. 

The following must also be considered factors which contributed to the accident: 

Inadequate language. When the KLM co-pilot repeated the ATC clearance, he ended with the words, "we are now at take-off". The controller, who had not been asked for take-off clearance, and who consequently had not granted it, did not understand that they were taking off. The "O.K." from the tower, which preceded the "stand by for take-off" was likewise incorrect - although irrelevant in this case because take-off had already started about six and a half seconds before. 

The fact that the Pan Am airplane had not left the runway at the third intersection. This airplane should, in fact, have consulted with the tower to find out whether the third intersection referred to was C-3 or C-4, if it had any doubts, and this it did not do. However, this was not very relevant either since the Pan Am airplane never reported the runway clear but, on the contrary, twice advised that it was taxiing on it. 

Unusual traffic congestion which obliged the tower to carry out taxiing maneuvers which, although statutory, as in the case of having airplanes taxi on an active runway, are not standard and can be potentially dangerous. 

Although contributing to the accident, the following occurrences must not he considered direct factors in it: the bomb incident in Las Palmas; the KLM refueling; the latter's take-off at reduced power; etc."


   A mid-air collision is almost always caused by human error. Basically, two aircraft come in contact with one another in flight and almost always fall to the ground in an uncontrolled fireball. However, this is not always true. There are many documented cases where two aircraft collided in flight and both were able to be flown to a safe landing (although these are mostly smaller aircraft).

   When an aircraft is flying at high altitudes (above 18,000'), it is on an IFR (Instrument Flight Rules) flight plan. It is positively controlled by air traffic controllers, who assume the responsibility of separation between aircraft. Below 18,000' some aircraft may also be separated by air traffic control but they are mixed in with VFR (Visual Flight Rules) aircraft which are responsible for their own separation from other aircraft. In either case, below 18,000 feet, all aircraft are responsible to "see and avoid" other aircraft. For reference purposes, most mid-air collisions occur near an airport during a clear day! Most of these involve small, general aviation aircraft.

   Statistically, mid-air collisions are not very common or likely on a commercial airline flight. But, from the next example of human error, the possibility does still exist. 

The airliner and cargo plane collided over southern Germany at 35,400 ft. Debris was spread across a 20 mile radius. Fifty-two children on a beach holiday were among the 69 aboard the Tupolev. The Tupolev pilot received contradictory instructions. The collision avoidance warning system (TCAS) told the pilot to ascend followed by an order from the Swiss air traffic controller to descend one second later. The Russian plane did not immediately respond to the tower's order to descend, so it repeated the command 14 seconds later. Thirty seconds later the two planes collided. The Swiss air traffic controller that guided the planes had no way of knowing the Russian pilot was receiving contradictory instruction from his cockpit TCAS unless told so by the pilot. Russian aviation officials said the pilot correctly gave precedence to the control tower, but Western aviation experts said pilots are trained to give precedence to the cockpit warning. (July 1, 2002)


   This is a relatively new accident. Therefore this accident is still under investigation and subject to months or even years of analysis before a final, unbiased conclusion is reached.

   One thing is certain though: Human error has again showed its ugly face in this accident. A large percentage of blame could be spread to the air traffic controllers. The Swiss are known for their systematic work ethic and precision of their craft. Unfortunately, it looks like there may be a big glitch in this case. We will just have to see where this case goes over the next few months.


(celebrities are not immune to human error)

   In our final example of human-error accidents, I've decided to use a small, charter aircraft carrying a celebrity for our case study. This is to illustrate the point that human-error occurs in big and small airplanes and it doesn't matter who you are or how much money you have.

   This was indeed a tragic crash that took the life of Aaliyah Haughton and eight others in August of 2001. This was a combination of errors that not only involved the flight operation, but involved corporate management and decision-makers as well.

   In aviation, we are trained to perform during times of normal, abnormal and emergency operations. We are trained on how every system works in our aircraft and what procedures to follow if those systems become inoperative. We learn how to execute instrument approaches in bad weather. We learn how to file a  flight plan, check on weather, compute our weight and balance and performance. In ground school, we learn what regulations we have to abide by to be safe and proficient pilots. If we are flying for hire, we learn how many hours we can fly during a 24-hour period, how much rest we have to have, and what the rules are concerning the consumption of alcoholic beverages.

   What we don't learn and what can't be taught is JUDGMENT. Judgment is individual, and some people have a good command of it and some don't. In this case, the pilot of that chartered Cessna 402 used poor judgment when he knowingly and blatantly violated the rules, regulations and ethics that are required by a professional aviator.  

Singer/actress Aaliyah Haughton was killed, along with eight others, when the Cessna 402 she was flying on crashed while attempting to take off from Abaco Island, Bahamas. Pilot error was to blame.  (August 25, 2001)



   Just like the accident on the mid-air collision you read about, this one is still under investigation. Therefore, we can only work with the facts. Conclusions will come out after the NTSB finishes the investigation, which may be a while.

   But what we do know is that:

   1. The pilot had traces of cocaine in his body.

   2. The pilot had traces of alcohol in his body.

   3. The pilot was sentenced to three years probation on charges of crack cocaine possession 12 days before the crash.

   4. Routine maintenance was not likely being performed on the aircraft.

   5. The aircraft was 700 lbs overweight on takeoff.

   6. The aircraft was certified for 8 passengers including the pilot. There were 9 on board.

   7. There was no evidence of a malfunction in the aircraft itself.

   It is this type of "accident," and in this case I use the word "accident" loosely, that causes a great amount of concern. Just like our example of the alcoholic pilots in the beginning of this article, we want to think that the crew of the aircraft we are flying in is professional, safe, and ethical, and will abide by the rules. After looking at this example, it's obvious that some pilots have a disregard for other peoples lives. The most disturbing of all is the pilots connection with crack cocaine. I wonder if Aaliyah would have wanted to fly on that airplane if she knew more about the pilot?

   In any event, this is another example of a perfectly good airplane being destroyed and 9 people loosing their lives because of human error and bad judgment.

you have it. Just a few examples of human error in aviation. The purpose of this article wasn't to scare anybody or say that aviation is not a safe form of transportation. It always has been and always will be the safest modes of travel. Statistically, you stand a much greater chance of being killed in a car accident than you do in a plane crash during your entire lifetime.

         Conclusions were based on facts and findings of investigations. It is not the author's intention to point fingers or judge the outcome of an event with a tragic ending. I simply wanted to present the facts and make some additional comments for each example.

         Additionally, the crux of this article is to show that although most people fear a terrorist attack on their aircraft since 9/11, the chances are much higher that human error could play a bigger role in the outcome of your flight.


Robert Baron is the president and chief consultant of The Aviation Consulting Group, an aviation consulting firm with a core specialization in CRM/Human Factors training and research, and expert witness support for aviation law firms. He holds an Airline Transport Pilot Rating and has over 16 years of aviation experience, including a Line Captain, Instructor and Check Airman in Learjet aircraft. He's also type-rated in the Cessna Citation and holds a Flight Engineer Rating for Turbojet aircraft. His academic achievements include a Bachelor's Degree in Professional Aeronautics/Aviation Safety, a Master's Degree in Aeronautical Science with dual specializations in Aviation Safety/Human Factors, and is currently working towards a PhD in General Psychology with an emphasis on Aviation/Aerospace Psychology. Mr. Baron is also an adjunct professor at Everglades University, where he teaches Graduate and Undergraduate courses in Aviation Safety and Human Factors.  Mr. Baron can be reached at 1-954-803-5807. Company website is

July, 2002

Robert J. Boser    


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The Editor of this Web Page, now retired, was an airline pilot for 33 years and holds 6 specific Captain's type-ratings on Boeing Jet Airliners, including the Boeing 747-400.



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