Douglas DC-10

Inadequate consideration given to human factors limitations in the inspection and quality control procedures used by United Airlines' engine overhaul facility which resulted in the failure to detect a fatigue crack originating from a previously undetected metallurgical defect located in a critical area of the stage 1 fan disk that was manufactured by General Electric Aircraft Engines. The subsequent catastrophic disintegration of the disk resulted in the liberation of debris in a pattern of distribution and with energy levels that exceeded the level of protection provided by design features of the hydraulic systems that operate the DC-10's flight controls.

Occurrence #1: airframe/component/system failure/malfunction
Phase of operation: takeoff
Findings
1. (f) flt control syst, wing slat system - false indication
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Occurrence #2: airframe/component/system failure/malfunction
Phase of operation: takeoff - aborted
Findings
2. Aborted takeoff - attempted
3. Airspeed (v1) - exceeded
4. (c) landing gear, normal brake system - inadequate
5. (c) acft/equip, inadequate aircraft component - manufacturer
6. (c) inadequate substantiation process - manufacturer
7. (c) inadequate certification/approval, aircraft - faa (organization)
8. Landing gear, normal brake system - worn
9. (c) landing gear, normal brake system - failure, total
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Occurrence #3: overrun
Phase of operation: takeoff - aborted
Findings
10. Terrain condition - soft
11. Object - approach light/navaid
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Occurrence #4: nose gear collapsed
Phase of operation: takeoff - aborted

The probable cause of the accident is primarily the amount of runway consumed in effecting the landing coupled with the lack of knowledge, with certainty of the position of the throttle levers by both the instructor and the trainee pilot in a crucial moment of deciding either to continue the takeoff or abort. The breakdown of communication and coordination between the instructor, the trainee pilot and the trainee flight engineer led to the subsequent overrun.
The following contributing factors were reported:
- The absence of uniform flight standards especially on procedures, within the Nigeria Airways Ltd. in that simulator trainings are not a progressive and logical sequence to flying the live aircraft.
- The extent of the accident was aggravated by the repeated collisions with solidly constructed approach light supporting structures which caused the fire and the shoddy performance of the airport fire services.
- The visibility was too close to the minima for a training flight.

The failure of the pilot of Korean Air Lines Flight 084 to follow accepted procedures during taxi, which caused him to become disoriented while selecting the runway; the failure of the pilot to use the compass to confirm his position; and the decision of the pilot to take off when he was unsure that the aircraft was positioned on the correct runway. Contributing to the accident was the fog, which reduced visibility to a point that the pilot could not ascertain his position visually and the control tower personnel could not assist the pilot. Also contributing to the accident was a lack of legible taxiway and runway signs at several intersections passed by Flight 084 while it was taxiing.

The Commission determines the cause of the accident to be the fractional detachment of the retread of the right wheel of the nose gear, originating a strong vibration which could not be identified by the captain, leading him into the belief that the aircraft would become uncontrollable in flight, and thus deciding to abandon the take-off over VR. The decision of aborting the take-off, though not in accordance with the standard operation procedure, is in this case considered reasonable, on the base of the irregular circumstances that the crew had to face, the short period of time available to take the decision, the lack of training in case of wheel failure and the absence of take-off procedures when failure other than that of the engines occurs.

The minimal braking effectiveness on the ice-covered runway; the failure of the Boston-Logan International Airport management to exercise maximum efforts to assess the condition of the runway to assure continued safety of landing operations; the failure of air traffic control to transmit the most recent pilot reports of braking action to the pilot of Flight 30H; and the captain's decision to accept and maintain an excessive airspeed derived from the auto throttle speed control system during the landing approach which caused the aircraft to land about 2,800 feet beyond the runway's displaced threshold. Contributing to the accident were the inadequacy of the present system of reports to convey reliable braking effectiveness information and the absence of provisions in the Federal Aviation Regulations to require:
- Airport management to measure the slipperiness of the runways using standardized procedures and to use standardized criteria in evaluating and reporting braking effectiveness and in making decisions to close runways.
- Operators to provide flight crews and other personnel with information necessary to correlate braking effectiveness on contaminated runways with aircraft stopping distances, and
- Extended minimum runway lengths for landing on runways which adequately take into consideration the reduction of braking effectiveness due to ice and snow.

The probable cause of this accident was the decision of the captain to continue the flight at low level toward an area of poor surface and horizon definition when the crew was not certain of their position and the subsequent inability to detect the rising terrain which intercepted the aircraft’s flight path. The following findings were reported:
- The flight planned route entered in the company’s base computer was varied after the crew’s briefing in that the position for McMurdo on the computer printout used at the briefing was incorrect by over 2 degrees of longitude and was subsequently corrected prior to this flight.
- The system of checking the detailed flight plan entries into the base computer was inadequate in that an error of 2° of longitude persisted in a flight plan for some 14 months,
- Some diagrams and maps issued at the route qualification briefing could have been misleading in that they depicted a track which passed to the true west of Ross Island over a sea level ice shelf, whereas the flight planned track passed to the east over high ground reaching to 12,450 feet AMSL,
- The briefing conducted by Air New Zealand Limited contained omissions and inaccuracies which had not been detected by either earlier participating aircrews or the supervising Airline Inspectors,
- The crew were not aware of the VHF R/T callsigns in use in the area and these are not published in the briefing notes, the NZAIP, or the US Department of Defence documents which were available to the crew. They were however specified in US Navy instruction CNSFA INST 3722.1, a copy of which was held by Operation Deep Freeze Headquarters,
- The question of making a landing near McMurdo on either the ice runway or the skiways at Williams Field and the type of emergencies which might require such a diversion was not discussed at the company’s briefing,
- The Civil Aviation Division Airline Inspectors had formally approved the audio visual stage of the route qualification briefing for the flight and one had witnessed a typical audio visual segment of the briefing for an Antarctic flight, twice, without requiring any amendments or detecting the errors contained in the briefing. They had also confirmed that it was no longer necessary for captains to carry out a supervised flight as required in the Operations Specifications in view of these briefings and the flight simulator detail,
- Civil Aviation Regulation 77 1(a) had not been complied with,
- The operator departed from the stated undertaking to carry two captains on each flight and substituted an additional first officer in lieu of the second captain,
- Of the flight deck crew only one engineer had flown to the Antarctic previously,
- The crew were not monitoring their actual position in relation to the topography adequately even though a continuous readout of the aircraft’s latitude and longitude and distance to run to the next waypoint was continuously available to them from the AINS,
-The crew did not observe the transition level in use in the McMurdo air traffic control area for resetting this aircraft’s altimeters and this procedure was not published in either the briefing notes or the US Department of Defence documents which were made available to the crew. The procedure used was that prescribed in US Federal Aviation Regulation 91.81 which required the QNH to be set basically at FL 180 during descent but this was modified in low pressure areas,
- The captain’s altimeter was not set to the correct QNH until the aircraft reached 3,500 feet,
- The captain initiated a descent to an altitude below both the IMC (16000 feet) and VMC (6000 feet) minima for the area in a cloud free area but in contravention of the operator’s briefing and outside the sector approved for the descent to 6000 feet by the DCA and the Company,
- The co-pilot was devoting a significant proportion of his time in an endeavour to establish VHF contact with the McMurdo ground stations and did not monitor the decisions of the pilot in command adequately in that he did not offer any criticism of the intention to descend below MSA in contravention of company restrictions and basic good airmanship,
- The descent was intentionally continued below the VMC limit specified by CAD and Air New Zealand Limited, of 6000 feet to an indicated 1500 feet,
- The crew were distracted but not preoccupied by their failure to raise the Ice Tower or any local ground station on VHF, the failure of the DME to lock on to the TACAN and the lack of any identification of the aircraft on radar,
- The company deleted an earlier requirement for VMC descents to be monitored by radar and substituted the alternative procedure of contacting the radar controller for co-ordination of the descent,
- The failure of the aircraft’s systems to establish satisfactory VHF contactor to “lock on” to the McMurdo TACAN was probably due to the aircraft’s low altitude in conjunction with significant high ground between the aircraft and the ground equipment,
- The flight engineers endeavoured to monitor the progress of the flight and expressed their dissatisfaction with the descent toward a cloud covered area,
- Although the route selected by Air New Zealand for the approach to McMurdo crossed almost directly over a 12450 ft active volcano just 20 miles from destination in preference to the normal approach path of military aircraft which was across the sea level ice shelf the Air New Zealand route was safe provided the crew observed the minimum altitudes stipulated for the flight and no extraordinary activity occurred in the volcano,
- Despite the shortcomings of some aspects of the route qualification briefing, this flight and Antarctic flights in general were not unacceptably hazardous, if they had been conducted strictly in accordance with the route qualification briefing as presented,
- The CAD procedure of reapproving Antarctic flights each season on the condition that they complied with the constraints of the previous season’s flights led to some items being discontinued without formal notification or agreement, e.g. the carriage of 2 captains on each flight, and the requirement for a briefing by ODF Headquarters,
- The on board navigation and flight guidance system operated normally during the latter stages of the flight,
- The aircraft’s GPWS operated in accordance with its design specifications,
- CAD had not implemented effectively the section of the ICAO standard detailed in Annex 6 of the convention which requires appropriate life-sustaining equipment to be carried on flights across land areas which have been designated by the State concerned as areas in which search and rescue would be especially difficult. Although the Commander of the USN Antarctic Support Force stated that “limited SAR capability existed over land and very little over water”, this may not constitute “designation of the area” as being especially difficult for search and rescue activities by the State concerned,
- Although some notes on Antarctic survival were given to the Chief Purser immediately before this flight no additional life-sustaining equipment was carried or training given to the crew members to facilitate survival following an emergency landing on the ice or in the polar waters of Antarctica,
- Neither the passengers nor the crew were expecting the collision and all received fatal injuries on impact with the ice,
- The search and rescue organisation was mobilised and co-ordinated in a competent manner despite the difficult environment and the aircraft was located as soon as practicable, (11 hours) after the collision occurred,
- The aircraft was not fitted with a self activated ELT but such equipment is not at present required,
- The aircraft’s CVR and DFDR operated as intended and provided an excellent record for the investigators of this accident. The CVR system however could be significantly improved as discussed in recommendation 8.
- The aircraft’s radar would have depicted the mountainous terrain ahead.

The accident was the consequence of the combination of the following factors:
- Non-compliance with the meteorological minima for the approach procedure, as cleared,
- Failure to comply with the aircraft's operating procedures during the approach phase,
- Landing on a runway closed to traffic,
- During the final approach to the runway assigned and having reached a height of 800 feet above the ground, the aircraft flew into a fog bank which concealed it from the control tower operator,
- The aircraft's crew did not comply with the procedural minima for the approach for which it had been cleared, in that the crew descended below the minima without reporting the runway in sight or initiating a go-around procedure,
- The crew never reported to the control tower operator that the runway was in sight and no landing clearance was therefore given,
- The data obtained from the cockpit voice recorder revealed that the crew did not comply with the operational procedures laid down in the relevant manuals, in particular the requirement to call out the altimeter readings during the final approach phase.

The asymmetrical stall and the ensuing roll of the aircraft because of the uncommanded retraction of the left wing outboard leading edge slats and the loss of stall warning and slat disagreement indication systems resulting from maintenance-induced damage leading to the separation of the no.1 engine and pylon assembly procedures which led to failure of the pylon structure. Contributing to the cause of the accident were the vulnerability of the design of the pylon attach points to maintenance damage; the vulnerability of the design of the leading edge slat system to the damage which produced asymmetry; deficiencies in FAA surveillance and reporting systems which failed to detect and prevent the use of improper maintenance procedures; deficiencies in the practices and communications among the operators, the manufacturer, and the FAA which failed to determine and disseminate the particulars regarding previous maintenance damage incidents; and the intolerance of prescribed operational procedures to this unique emergency.