Alaska Airlines Flight 261 Student`s Name

Institutional Affiliation
Alaska Airlines Flight 261
Alaska Airlines Flight 261 was a 1992 McDonnell Douglas MD83 airplane operated by the Alaska Airlines that crashed in the Pacific Ocean on January 31, 2000 at approximately 1619 hrs (CNN, 2000).The airplane had 83 passengers on board, including two pilots, three attendants and the rest were passengers and all on board perished in the accident (CNN, 2000). This paper will investigate the causes of the crash, the role of human factors in the crash and possible remedial policy to avert similar situations in the future.
Facts of the Crash
The Alaska Airlines Flight 261 was a scheduled airline operating between Puerto Vallarta, Mexico (international Diaz Ordaz Airport) and Tacoma International Airport, Seattle, Washington. The plane was manufactured in 1992 and had done 26000 hours as at the time of the crash (Song, 2000). On January 31, 2000, at about 1337hrs, the plane left Mexico with 83 onboard. The nationalities of those present included 1 Mexican, 1 British and 81 had US nationality. In addition, 35 occupants were connected with the parent airline either as crew members or other employees. The airplane climbed to 31000ft, which was its intended cruise altitude and proceeded with the journey for about two hours before the crew starting experiencing problems with the horizontal stabilization mechanism (Song, 2000).
They immediately contacted the company`s offices in Seattle, Washington and the Los Angeles International Airport and explained how the jammed stabilizer was affecting the crew`s control of the trim mechanism, therefore making it very difficult to control the plane`s stability in flight (Holmes and Leeds, 2000). A lengthy discussion ensured, with crew suggesting that the route be diverted to Los Angeles to make an emergency landing, and the Airline Dispatchers suggesting that the pilots try to manage the situation and head to San-Francisco, the intended first destination (Song, 2000).
The crew finally decided to divert, and were en-route Los Angeles when the fatal accident happened. At about 1609hrs, the crew succeeded to release the jammed horizontal stabilizer, momentarily regaining control (Holmes and Leeds, 2000). However, the airplane started to lose altitude at a rate higher than 7000ft per minute, descending to 23000 ft. During this time, the crew contacted the Air Traffic Control (ATC) in Los Angeles International Airport and requested permission to emergency land the jet (Holmes and Leeds, 2000). The pilot requested to drop to altitudes of about 10,000 ft while still in the bay area, before proceeding to land the plane. The distance between Flight 261 and the LA runway was much longer than that in which a normal flight would lower its altitude in preparation for landing (Holmes and Leeds, 2000). At 1619hrs, the airplane was lost from the radar but the Cockpit Voice Recorder (CVR) registered thumping noises followed by a loud noise, possibly upon impact with the water, about 17 seconds later. The airplane totally disintegrated during the impact, and while it didn`t catch fire, its parts were completely damaged, and, sadly, all people on board perished (Holmes and Leeds, 2000).
Human Factors in Airplane Accidents
Airplane accidents happen due to several causes, notable among them being climatic factors, engineering factors, engine or other component failure, collision with objects, loss of control and wire strike among others (Song, 2000). While not all factors are associated with or directly as a result of human controlled factors, a significantly large percentage of fatal accidents in air have been associated with human factors (Gero, 1993). According to the Bureau of Air Safety Investigations (BASI), accidents often involve more than one factor, and may incorporate a sequence of otherwise distinct occurrences. The bureau, however, notes that there exists a typical pattern of occurrences in most fatal accidents. In a study of 75 major incidences in air safety, the bureau documented that about 22% of accidents involving fixed wing aero planes were attributed to loss of control (Bureau of Air Safety Investigation, 1996).
In addition, collision with terrain with control status unknown was the second most frequent source of accidents, accounting for 16% of all 75 accidents. Incidences of aircraft contacting power lines, with consequent damage from impact and electric sparks related explosions accounts for 15% of incidents (Bureau of Air Safety Investigation, 1996). Engine failure and mid-air collisions were equally responsible for 12% of all reported incidences. Collisions with objects, other than electricity wires which were classified separately, accounted for 11% of all accidents, while impact with terrain, with pilot control, accounted for 9% of fatal accidents. The bureaus also identified hard landing, airframe failure and undershoot to contribute about 1% each of all reported failures (Bureau of Air Safety Investigation, 1996).
(Bureau of Air Safety Investigation, 1996)
In addition, the bureau also broadly investigated the in-plane factors during accidents. It realized that 72% of all factors were associated with the pilot, while other personnel were involved in 12% of all cases. Weather, power plant, terrain and airframe were also identified as significant factors in airplane accidents. The table below shows the relative contributions of these broad factors (Bureau of Air Safety Investigation, 1996).
(Bureau of Air Safety Investigation, 1996)
It is important to note that human factors include all actions instituted or not instituted by persons in direct control of the aircraft (crew) as well as similar actions whose responsibility lies with external parties such as control towers and aircraft maintenance personnel (Bureau of Air Safety Investigation, 1996). In the case of Alaska Airlines Flight 261, the paper will explore human factors in the three categories, including pilot and crew, ground control, and aircraft maintenance (Bureau of Air Safety Investigation, 1996).
The Alaska Airlines 216 Analysis
Using the human factors model, the analysis of the Alaska Airlines 261 incident reveals certain human traits that were responsible for the incident, both directly and by inference.
Loss of Control
As with most other aircraft accidents, the Alaska 261 incident was attributed to loss of control in the last 17 seconds of its ill fated journey (CNN, 2000). While it was clear from recorded conversations between the crew and ground control suggest a very competent and prudent pilot and co-pilot, it can also be noted that the catastrophic failure of horizontal stabilizer due to factors unrelated to the pilot`s activities was an important factor in the subsequent loss of control (CNN, 2000). The National Transportation Safety Board (NTSB) in its accident report showed an altitude graph for the last journey of the Alaska Airlines 261 flight.
(National Transportation Safety Board, 2000)
The altitude graph shows a steep descent from 17,800 ft just minutes after the pilots` discussion with ground control unit at the Los Angeles International Airport (LAX) in which the pilot requested permission to lower the jet`s altitude to 10000 ft in preparation for hard landing (Holmes and Leeds, 2000). No further communication was received from the rapidly diving airplane, but the Cockpit Voice Recorder (CVR) registered thumps and a very loud noise when the plane made impact with water. This last descent indicates, as was stated by pilots who witnessed the incident, a definite loss of control in the activities of the aircraft (Holmes and Leeds, 2000).
In the ordinary pilot activities analysis in the human factors theory, factors such as poor judgment, diverted attention, low experience, health issues, among others are considered (Bureau of Air Safety Investigation, 1996). BASI listed some of these factors in the graph below.
(Bureau of Air Safety Investigation, 1996)
Poor Judgment
The NTSB report indicated several instances where pilots acted out of procedure during the flight (National Transportation Safety Board, 2000). The first instance was failure by the pilots to seek redress when initially they realized there were problems with engaging trim motors a factor they knew was critical to horizontal and vertical stabilization. In addition, the crews repeated attempt to engage the trim motors while already aware of possible damage in the stabilization mechanism was out of order, and possibly aggravated the stabilizer unit failure during the final dive, which resulted in unrecoverable descent and impact with the ocean (Cable News Network, 2000).
It is critical to note, however that, most actions by the pilots were indeed commended by the incident investigations board. Even the last descent attempt, which may arguably be held as a possible cause for the final loss of control, was within a reasonable pilot`s judgment in preparation for a landing. On the other hand, it would be prudent to state that the pilots were forced to operate the jet beyond experience or ability, a factor responsible for 13% of all accidents, and their in-flight decisions (a factor responsible for 15% of accidents) may have affected the aircraft control. Both actions were considered as a last result, and blame may not be with the crew (National Transportation Safety Board, 2000).
Pre-flight Preparations
While all normal conditions for flight were observed and the plane was declared fit for operation, the maintenance personnel were found by NTSB to have been lax on their responsibilities (National Transportation Safety Board, 2000). It is notable that the specific part of the jet which was a leading factor to the accident was technical and beyond the ground testing capability of the crew. The horizontal stabilizer and trim mechanism can be tested only by qualified mechanics, and not during a flight. Therefore, the human factor in the pre-flight preparation will be discussed below under maintenance.
Poor Equipment Maintenance
The National Transportation Safety Board (NTSB) attributed the Alaska 261 incident to a failure horizontal stabilization mechanism owing to faulty, de-threaded jack screws and faulty nut. In their report, the NTSB gave a detailed description of the failure situation, including the mechanical failure, material composition, manufacturer and the operating specifications of the horizontal stabilizer (National Transportation Safety Board, 2000).
(National Transportation Safety Board, 2000)
The report established that the acme nut, which is an essential component of the horizontal stabilization mechanism, was rusty and containing white deposits identified as a mixture of sand and grease (National Transportation Safety Board, 2000). In addition, the screw was largely de-threaded with lose threads coiling around the shaft in a manner as would stop free rotation of the mechanism. This obviously made control of the aircraft difficult, and the last thirty minutes of the flight was difficult with the pilots applying torque forces as high as 500N/M just to maintain horizontal control (National Transportation Safety Board, 2000). It was while attempting to reduce altitude with the aim of landing that the control mechanism totally failed, leading the plane to nose-dive inverted. The pilots attempted to use the rudder and bring it upright but failed. They also attempted to use air-brakes to control descent speed but did not succeed. At this point, the aircraft was swaying upside down as it rapidly descended, hitting the ocean at 1620.57.1 hrs (National Transportation Safety Board, 2000). The diagram below shows the acme thread and nuts recovered from the hull.
Figure 1: Thread Screw Recovered from the Hull
(National Transportation Safety Board, 2000)
Poor Design of Parts
The reports established that the Airline had substituted certain parts in the screw harness assembly as designed by Boeing with its own, thereby altering the assembly`s structural and operational capabilities in extreme load conditions. In the picture, two Alaska Airlines restraints (top) against Boeing`s original design (bottom) (National Transportation Safety Board, 2000). The report did not rule out variations in the operational deficiencies due to the design variation, as a result of which the Airline was held responsible for the accident on the counts of negligence in maintenance and design alteration for which it paid compensation to victims` families (National Transportation Safety Board, 2000).
Figure 2: Alaska Airlines Resigned Boeing`s parts in their Aeroplanes
(National Transportation Safety Board, 2000)
In addition, Boeing was held liable for the frequent failure of the screw and nut assembly in most of its aircrafts, as additional assemblies retrieved from similar Alaska airlines showed similar wear designs, even with proper maintenance. This was further aggravated by a 1997 mechanics work card reports on the state of the end play in the flight 261 screw and nut assembly (Cable News Network, 2000). While one mechanic suggested immediate replacement of the nut and screw, the lead mechanic objected, saying that the wear and end play was (at 0.038 inches) within the 0.040 inches limit, not withstanding that it would be another two years before the next check was done (Cable News Network, 2000).
The report found that while grease of two types (Aeroshell 33 and Mobigrease 28 ) was present in the screw and acme nut, the grease was mixed with several particles, mainly sand and metal shavings (Cable News Network, 2000). It was also established that Alaska Airlines had at the time been using Aeroshell 33, instead of the manufacturer recommended Mobigrease 28 for lubrication. The frequency and nature of lubrication was insufficient (National Transportation Safety Board, 2000).
Management Failures
A task force mandated to investigate Alaska Airlines operations management between April and June 2000 found that the airline lacked a proper vacancy for director of operations, and lacked a comprehensive operations manual, where vital maintenance was often in the presiding officer`s discretion (Cable News Network, 2000). Incidences of aircraft being released from C check routines were revealed in two instances. There were other discrepancies, and the taskforce recommended suspension of the airline`s heavy maintenance unit. Reports of falsification of maintenance records were alleged by witness mechanics, although the board failed to quantify them after investigations (Cable News Network, 2000).
The Federal Aviation Administration
The FAA failed to oversee the maintenance at Alaska Airlines, a step which would have resulted in discovery of the less than average maintenance standards (National Transportation Safety Board, 2000).
Accident Report The NTSB summarized about 46 statements with regard to the accident, most of which were with regard to human factors (National Transportation Safety Board, 2000). The result of the accident was loss of control due to the disengagement of the screw and acme nut in the horizontal stabilizer assembly due to low-cycle fatigue of the acme nut. It recommended the regulation of maintenance personnel practices so as to meet the set safety standards. The Alaska Airlines was also directed to institute proper training for greasing and replacement mechanics involved with maintenance of the screw and acme nuts, as well as regulation of the type and amount of grease used for lubrication (National Transportation Safety Board, 2000). The FAA was required to regulate all licensed airlines and ensure that they meet the required standards in terms of training, equipment, and maintenance practice (National Transportation Safety Board, 2000).
Effectiveness of the Recommendations
The board established that, while the recommendations put across to Alaska Airlines with regard to the Flight 261 were necessary to ensure safety of the airline operations, the company was yet to institute the recommendations laid out in the initial report in 2000 (Song, 2000). Carol J. Carmody, the Board Chairperson, regretted in a personal statement that Alaska Airlines had failed to upgrade greasing and end-play measurements in subsequent tests. Another board member altogether proposed a new jackscrew design for similar airplanes (Song, 2000).
Recommendations for the Accomplishment of a Safer Air Environment
Computer Aided Design Formulation
Reliance on mechanics for regular maintenance is often open to neglect, as it usually falls in the discretion of a few parties. For instance, the lead mechanic inspecting the report filed by a junior mechanic in 1997 regarding the Flight 261 overruled the junior mechanic`s recommendation to replace the nut/screw assembly (National Transportation Safety Board, 2000). Had this been done, the accident would most probably been avoided. Even better, installation of early computer aided warning systems for parts failure of malfunction would have revealed the failing nut and the low-cycle fatigue in the column years before the incident, prompting replacement (Song, 2000). These warning systems should be such that they are immediately displayed in the console, and possibly sent to a regulatory authority instantly without control of the company`s maintenance authorities (Song, 2000). Such a system would be standardized for all modern equipment and installed in every aircraft, and should transmit comprehensive system status to a central facility managed by the FAA periodically. Such an arrangement will ensure a centralized enforcement of air safety practices, bypassing non-corporative Airline owners such as the Alaska incident (National Transportation Safety Board, 2000).
Phasing Out Old Equipments
Another recommendation would be to phase out older equipment gradually through non-renewal of operation license for older models with demonstrated safety issues. Such a process would be gradual in order to allow investors to recover their capital expenses in the older vessels, while at the same time revitalizing the air transport safety (Song, 2000).
The other recommendation is with regard to training. The FAA, together with other related bodies, should institute a centralized training for maintenance crew of modern aircraft, and issue a joint certification of competence, in line with the requirements of modern air security standards. Establishment of such a body would layout an operation platform which would show better accountability and responsibility for individual actions (National Transportation Safety Board, 2000). For instance, local mechanics work only according to their employer`s specifications regarding parts maintenance and replacement, and are freed from any liability if an oversight within covered in the internal code or regulations lead to a safety incident. Thus, engineers fail to take responsibility for safety issues which they already know exist because it is not their job, or if such omission is within their mandates (National Transportation Safety Board, 2000). Such a scenario would be changed if each mechanic, repairperson or maintenance operator would be held liable for their actions by the central government, no matter the rank or employer.
Bureau of Air Safety Investigation (BASI) (1996). Human Factors in Fatal Aircraft Accidents. Accessed on 10 February 2013,
Cable News Network (CNN) (2000). Alaska Airlines maintenance records raise new questions. Accessed on 10 February 2013,
Gero, D. (1993). Aviation Disasters. Haynes Publishing Group P.L.C. Accessed on 10 February 2013,

Holmes, S. & Leeds, J. (2000). THE CRASH OF FLIGHT 261 For Airline, Loss Feels Like Deaths in Family. Los Angeles Times
National Transportation Safety Board NTSB. (2000). Aircraft Accident Report. Accessed on 10 February 2013

Song, M. (2000).Alaska Airlines copes with `saddest, most tragic day. The Seattle Times.