Case Report of the Alaska-Airline Disaster

This case report discusses about the Alaska-airline crash that has occurred on Jan, 31, 2000 at California. The causes, contributing factors, potential hazards and safe- guards that were ignored in accordance with air crash were discussed. This incident teaches a great lesson to the world to prevent future air- accidents and the inadequacies in policies to prevent loss of life and property.   Ã‚  Ã‚   The most miserable disaster of Alaska-Airline took place on 31 st January, 2000 at approximately 1621 Pacific- Standard time. The flight 261 that involves MD (McDonnell Douglas) - 83, N963AS was crashed at approximately 2.7 miles in the Pacific Ocean specifically at the north side of Anacapa- island of California. All the people in the flight that includes two pilots, three crew-members of cabin as well as 83 passengers were killed with destruction of the flight by impact forces (Carmody, 2002). There were dozen causes that have contributed to this disaster and have taught a great lesson about flight maintenance.    The main cause is that the in-flight failure of the acme- nut threads that is present on the jack-screw assembly (trim system) of the horizontal-stabilizer of flight has occurred. This has lead to the loss of pitch control of the flight. NTSB (2003) has stated that the jack-screw assembly is the most integral as well as crucial part of the trim- system of horizontal-stabilizer that acts as a critical airplane system and the destruction of this jack-screw assembly has caused the flight disaster. Moreover, the thread failure has occurred due to the insufficient lubrication that has lead to the excessive wear of the Alaska Airlines (Cockpit database, 2000). Basically, there was a fault in the fundamental MD- 83 flight design as it has no fail-safe design to counteract the thread loss of the total acme-nut that has lead to the catastrophic effects. In this disaster, improper adherence to the maintenance process as well as inspection of the jack-screw parts has exacerbated the design fault and has resulted in crash (Carmody, 2002). Another factor that has contributed was the extended interval for lubrication process. The Federal aviation-administration (FAA) has approved the extended lubrication interval that has contributed to the missing or improper lubrication. This has resulted in the complete wear of the threads of acme-nut. Further, increased interval for end- play check with approval from FAA for extension has allowed to the excessive wear that has progressed to failure without detecting the flaw. The horizontal-stabilizer has stopped working to the commands of the pilot and they were unable to rule out the cause. The acme- nut threads have worn inside the horizontal stabilizer and were sheared off completely. Then, the acme-screw and nut has jammed that has prevented the movement of horizontal-stabilizer. Later, the jam was overcome that has allowed the acme-screw to pull acme-nut causing the airplane to pitch downward (NTSB, 2003). It had lead to the (low- cycled fatigue) fracture of the torque tube again lowering the pitch from which regaining is impossible.   The use of auto-pilot at the time of horizontal stabilizer jam was inappropriate. Moreover, lack of checklist to land at these circumstances is an additional drawback. The pilots were not provided with clear guidelines to avoid experimenting with improper troubleshooting measures (Woltjer, 2007). The slats and flaps should have extended by the captain when the flight was controlled by the configuration after initial drive. The acme-nut threads were found to have worn extensively due to ineffective lubrication on the acme parts that have lead to the disaster. The recovered acme showed dried degraded grease that suggests that, it was not greased recently. The post-accident interviews of SPO-mechanic indicated that they had no knowledge to lubricate acme (NTSB, 2003). The safety board concluded that inadequate lubrication and lack of standard measures have lead to the accident. Fig: 1 shows acme-nut with plugged grease Increased pressure in the flight maintenance area in correcting, maintaining and delivering the flight in given time has contributed to this disaster. In this disaster, they have falsified the records that the flight has passed through the inspection process due to the increased pressure on them to make a scheduled return (Carmody, 2002). The measurements have showed that the jack-screw was in the brink to wear out and requires to be replaced by a newer jack-screw: but as it may delay the departure time, they have altered the record to be airworthy (ATEC, 2005).  The maintenance persons don’t have assertiveness to speak about the importance of lubrication and replacing the wear to the company.   The maintenance personnel have not helped the pilots when they were at horizontal-stabilizer problems. The safety issues in this accident include improper lubrication with inspection of the jack-screw, extended end-play check-intervals, over-haul procedures of jack-screw and design with certification of horizontal-stabilizer, maintenance program and FAA’s inadequacies has lead to disaster. Standards should be issued to pilots with the instructions to handle mal-functioning situations. NTSB (2002) ordered MD flights to replace dried greases with fresh grease. The size of the access-panel was increased to lubricate the jack-screw properly (FAA, 2002). The lubrication procedure for jack-screw was established as an inspection item to be signed by an inspector. The existing intervals were reviewed to identify the fault in the flight components. NTSB (2002) has conducted an evaluation and has issued a report with recommendations for maintenance. Improving fail- safe mechanism in MD design, promoting end-play check interval, issuing newer certification regulations and policies for horizontal stabilizers ensures safe air-travel. ATEC. (2005)  Incorporating Air Transport Association Codes into Maintenance Curriculum, ATEC Journal, 26 (2). Available from Aviation Technician Education Council [Accessed 28/02/17] Carmody, C.J. (2002)  Aircraft Accident Incident Report. Loss of Control and Impact with Pacific Ocean Alaska Airlines Flight 261 McDonnell Douglas MD-83, N963AS About 2.7 Miles North of Anacapa Island, California January 31, 2000, National Transportation Safety Board, Washington, DC:   National Transportation Safety Board. [Accessed 28/02/17] Cockpit database. (2000) Cockpit voice recorder database. Available from https://www.tailstrike.com/310100.htm [Accessed 28/02/17] FAA. (2002) Accident Board Recommendations, U.S.  Department  of  Transportation. Available from https://lessonslearned.faa.gov/ll_main.cfm?TabID=1&LLID=23&LLTypeID=4 [Accessed 28/02/17] NTSB. (2003) Loss of control and impact with Pacific Ocean, Alaska Airlines Flight 261, McDonnell Douglas MD-83, N963AS, about 2.7 miles north of Anacapa Island, California, January 31, 2000 (Aircraft Accident Report No. NTSB/AAR-02/01), National Transportation Safety Board. Washington, DC: National Transportation Safety Board [Accessed 28/02/17] Woltjer, R., & Hollnagel, E. (2007) The Alaska Airlines Flight 261 accident, A systemic analysis of functional resonance. Proceedings of the 2007 (14th) International Symposium on Aviation Psychology (ISAP), pp. 763-768. Available from https://www.diva-portal.org/smash/get/diva2:210824/fulltext01.pdf [Accessed 28/02/17]