- South African Airways 747 at Mauritius, Indian Ocean
- Accident Overview
- Accident Board Findings
- Accident Board Recommendations
- Relevant Regulations / Policy / Background
- Prevailing Cultural / Organizational Factors
- Key Safety Issue(s)
- Safety Assumptions
- Resulting Safety Initiatives
- Airworthiness Directives (ADs) Issued
- Common Themes
- Related Accidents / Incidents
- Lessons Learned
- South African Airways 747 at Mauritius, Indian Ocean
On November 28, 1987, South African Airways (SAA) Flight 295, a Boeing Model 747-200 airplane named "Helderberg" by SAA, crashed into the Indian Ocean en route from Taipai's Chiang Kai Shek Airport to Mauritius's Plaisance Airport at a location about 110 miles off the island of Mauritius. All 159 people on board were lost. The crash occurred about ten hours into the flight, less than twenty minutes after the flight crew reported the presence of smoke on the airplane to air traffic control at Mauritius. The crash was attributed to an uncontrolled fire that occurred in the airplane's main deck cargo compartment. The crash site was in about 15,000 feet of water, which complicated recovery and investigation efforts. The investigation was conducted by the Republic of South Africa. Assistance was provided by the Federal Aviation Administration (FAA), the National Transportation Safety Board (NTSB), and Boeing. (View South Africa Airways flight 295 flight path)
The SAA 747-200 was in a mixed passenger/freight configuration, known as a "combi" configuration. The main deck for 747 combi models is divided into a forward passenger compartment and a large aft cargo compartment. (View location of flight 295's Main Deck Cargo Area) Other airplane models that have combi configurations, such as the 727 and 737, have the main deck cargo compartment located forward of the passenger compartment rather than aft. In either case, the passenger and cargo compartments are separated by a rigid barrier, and this barrier has a door to allow crew members access to the cargo compartment during flight. On the 747-200 combi, the barrier between the passenger and cargo compartments cannot be easily repositioned or removed, resulting in a fixed passenger/cargo ratio. View Typical 747 combi floor plan. For other models, such as the 727 and 737, the partition can be readily moved to different locations or removed entirely within minutes to convert the airplane into all passenger, all freight, or various passenger/freight combi configurations to accommodate daily or seasonal operational needs. View Typical 737 combi floor plan.
Combi cargo compartment
Main deck cargo compartments on combi airplanes are generally certified by the FAA as "Class B" cargo compartments as defined by 14 CFR part 25 §25.857(b) design requirements. View Relevant Part 25 regulations. To meet FAA design requirements, a Class B cargo compartment must have a fire detection system to alert the flight crew of the presence of a cargo fire. It is not required to have a built-in fire suppression system. If a fire occurs in the compartment, the primary means to control it is via a crewmember entering the compartment and using hand-held fire extinguishers. Supporting airplane features, like seals, liners, and ventilation systems, are designed to ensure that if a main deck cargo fire occurs, it will be contained within the compartment until manual firefighting can be successfully accomplished, and to ensure that hazardous amounts of smoke, flames, and extinguishing agent do not enter areas of the airplane occupied by people, such as the cockpit and passenger cabin.
SAA Flight 295 departed Taipei's Chiang Kai Shek airport shortly after 2:23 pm with 140 passengers and 19 crew members on board. Calculated flight time to Mauritius' Plaisance Airport was 10 hours and 14 minutes. The airplane's main deck Class B cargo compartment was loaded with six large pallets of cargo, which consisted primarily of electrical items (including computers), hardware, paper articles, textiles, and sports equipment, packaged with materials that included cardboard and plastic. The height of the cargo loaded on each pallet was reported to be about seven feet.
Typical loading for 747 Class B cargo compartment
More than nine hours into the flight and only about 45 minutes before expected arrival in Mauritius, the flight crew reported smoke to Mauritius Approach Control (MRU) and proceeded to declare an emergency. The airplane's fire detection system had detected smoke in the Class B cargo compartment, and an audible alarm was provided in the cockpit. This alarm could be heard on the airplane's cockpit voice recorder (CVR) tape, which was reviewed after the accident. The alarm likely occurred shortly before Flight 295 contacted MRU to report the smoke. Unfortunately, the CVR and the wiring to it were located in the vicinity of the Class B cargo compartment, and damage from the fire rendered the CVR inoperable within eighty seconds after the audible alarm can be heard on the tape. As such, determining precisely how much time elapsed between the alarm and when contact with MRU was made was not possible because the contact with MRU was made after the CVR failed. The time was probably a matter of minutes, during which the flight crew was likely involved in emergency procedures associated with detection of a cargo fire (Emergency checklist for main deck fire smoke) and control of smoke. (Emergency checklist for main deck smoke evacuation)
Flight 295's initial report of smoke to MRU was made at about 11:49pm. Communications between Flight 295 and MRU continued for about fifteen minutes before contact was lost. These fifteen minutes of communications between Flight 295 and MRU that were recorded by MRU, along with the limited recording from the damaged CVR, provide information about crew activities in the last minutes of the flight. The flight data recorder (FDR) was not recovered from the crash site, but like the CVR was located in the vicinity of the Class B cargo compartment and would have been susceptible to the same kind of fire damage as the CVR.
Review of the CVR tape and the communications recorded by MRU indicate that the emergency on board developed quickly. Within four seconds of the audible smoke detection warning in the cockpit, an intercom chime can be heard on the CVR tape, possibly indicating that the flight attendants in the passenger cabin had become aware of the fire nearly simultaneously. Another intercom chime occurred about one minute later, possibly a further attempt by the flight attendants to contact the flight crew. Many of the communications with Flight 295 recorded by MRU were related to plans for an emergency landing at Plaisance Airport, but the recording also picked up some of the communications within the cockpit between crewmembers. About two minutes after the first communication with MRU regarding smoke, the pilot reported, "we've lost a lot of electrics, we haven't got anything on the aircraft now," an indication that the fire was likely affecting airplane systems. (Transcript of CVR and MRU recordings)
Flight 295's last communication with MRU occurred at about 12:04am. The airplane crashed into the Indian Ocean off the coast of Mauritius in 15,000 feet of water at about 12:07am (4:07am local time). The Republic of South Africa Accident Inquiry Board (SAAIB) conducted the crash investigation, with support from the FAA, NTSB, and Boeing. The remote location and depth of the water at the crash site, along with poor weather conditions, complicated recovery and investigation efforts. Some limited floating wreckage was recovered, consisting mostly of light cargo, cabin paneling and furnishings, and escape slides/rafts. Most of the wreckage was submerged in two large debris fields. Few items were actually recovered from the sea floor. Examination of most of the wreckage was limited to use of underwater photographic and video equipment.
Underwater photos of Flight 295 wreckage
The SAAIB concluded that an intense fire had developed in the Class B cargo compartment at the forward right hand pallet position, just aft of the barrier between the passenger and cargo compartments and the cargo net, and that the fire had spread to the middle left and aft right cargo pallet positions, causing extensive heat damage to wiring and liners inside the cargo compartment and the adjacent fuselage structure. (View South African Airways Class B Cargo Fire Animation.) The SAAIB also concluded that substances involved in the fire included plastic and cardboard packing materials, and that smoke, carbon monoxide, and carbon dioxide from the fire had entered the passenger cabin. The SAAIB published its findings in their "Report of the Board of Inquiry into the Helderberg Air Disaster," dated May 14, 1990. (SAAIB report)
The ignition source for the fire could not be determined, nor could the precise event that precipitated the crash of the airplane following detection of the fire. The flight crew's last communication with MRU sounded relatively calm and related to plans for the emergency landing. The SAAIB concluded that the airplane was not under control when it crashed into the sea at high speed about three minutes later. Evidence showed that the airplane's wing struck the water in a perpendicular position and that the engines were not turning. Specific events identified by the SAAIB that could have precipitated the crash included 1) crew incapacitation, 2) crew distraction, 3) heat-related weakening of the structure causing in-flight break-up, 4) heat-related damage to flight control cables, and 5) heat-related deformation of the fuselage.
Regardless of the cause of the fire and the specific event that precipitated the crash, the SAAIB, NTSB, and FAA all concluded that the existing Class B cargo compartment fire protection features on the SAA airplane were inadequate, particularly the reliance on manual firefighting as the primary means to control a fire in the cargo compartment. This determination was documented in the SAAIB report, an NTSB Safety Recommendation, dated May 16, 1988, and a report developed by a team led by the FAA (FAA report). Each organization recognized the need for additional research and recommended interim actions that included use of fire resistant containers for all cargo.
For several years following the accident, the FAA conducted research and evaluated potential design and operational changes to improve the safety of Class B cargo compartments. Considerable testing was conducted by the FAA Technical Center, including evaluations related to manual firefighting with hand-held fire extinguishers and the use of fire resistant covers and containers for cargo carriage. (FAA Technical Center reports: Cargo Compartment Fire Protection in Large commercial Transport Aircraft, Effectiveness of Flight Attendants Attempting to Extinguish Fires in an Accessible Cargo Compartment, Effectiveness of Hand-Held Fire Extinguishers on Cargo Container Fires, Evaluation of Large Class B Cargo Compartment's Fire Protection) During this time, the FAA issued a series of Airworthiness Directives (ADs) applicable to large transport category airplanes, such as the 737 and 747, which were considered to be at the highest risk if a cargo fire occurred. The first AD, AD89-18-12 (Notice of Proposed Rulemaking 88-NM-80-AD) was issued shortly after the accident and required airplane design and operational changes directly related to some of the findings and recommendations related to the SAA accident. The AD required operators of combi airplanes with Class B cargo compartments to accomplish some short-term operational and equipment changes, and within three years to either:
- Convert the existing Class B cargo compartment to Class C, which would include developing and installing a built-in fire suppression system and improved cargo compartment liners, or
- Carry all cargo in the Class B cargo compartment in containers that meet Class C requirements. Such containers would have to be developed and would be required to incorporate fire protection features, including built-in fire detection and suppression capability.
AD 89-18-12R1 was issued shortly after the release of AD 89-18-12 in response to industry requests for a third option to be added to the AD. This third option once again relied heavily on manual firefighting, but with significant improvements such as more comprehensive firefighter training, additional firefighting equipment, improved cargo compartment liners, and installation of a fifteen-minute-duration fire suppression system to "knock down" the fire prior to entry of the trained firefighter in the cargo compartment for manual firefighting.
Following issuance of AD 89-18-12R1, industry reported significant design, cost, and operational difficulties in complying with any of the three options within the timeframe prescribed by the AD. Designing and implementing Class C features on an existing airplane per the first option of the AD was considered prohibitively expensive and would require significant changes to existing airplane systems. Designing specialized containers that have Class C features and integrating these containers into airline operations per the second option of the AD was considered costly and logistically unmanageable. Implementing highly trained firefighters on every flight per the third option of the AD was also considered logistically unmanageable. In addition, the FAA had increasing concerns that even trained firefighters could not effectively control in-flight fires, in part due to some tests that indicated that even trained firefighters could not effectively combat fires in large cargo compartments due to factors such as size of the pallets and containers of cargo, limited access provisions, anticipated fire and smoke conditions in the compartment during firefighting, and kind of firefighting equipment available. (Video of FAA Technical Center testing)
The FAA continued to review Class B cargo compartment fire protection deficiencies, challenges, and potential solutions. The FAA recognized the need to provide operators with short-term relief from some of the requirements of AD 89-18-12R1 due to the impending deadlines for compliance with the AD, the actual time needed to develop and implement the options provided in the AD, and concerns about the effectiveness of some of these options. In response to these concerns, the FAA superseded AD 89-18-12R1 with AD 91-10-02, (NPRM 91-NM-34-AD) to provide relief from some of the immediate requirements of AD 89-18-12R1, and more significantly, solicit additional public comments regarding Class B cargo compartment fire protection approaches.
The FAA reviewed the public comments submitted in conjunction with issuance of AD 91-10-02, along with data from testing conducted by the FAA Technical Center. As the result, the FAA developed and issued a final directive, AD 93-07-15, (P-2 - NPRM 92-NM-67-AD) which superseded the three earlier ADs. AD 93-07-15 retained the first two options of the previous ADs, but eliminated entirely the third option related to use of highly trained firefighters as the primary means to control cargo fires. This AD also offered two new options. In summary, the four options provided by the AD 93-07-15 were:
- Convert the Class B cargo compartment to Class C,
- Use containers that meet the requirements of Class C for all cargo carried in the Class B cargo compartment,
- Use fire-resistant covers or containers for all cargo, along with other design, equipment, and operational modifications, or
- Incorporate a long-duration fire suppression system, along with other design, equipment, and operational modifications.
Because of the costs of implementing AD 93-07-15 and earlier versions of the AD, some operators chose to eliminate main deck Class B cargo compartments entirely from their airplanes, converting them to all-passenger or all-freight configurations. Most 747 combi operators that chose to retain their Class B cargo compartments selected the fourth option. Operators of smaller combis, such as the 727 and 737 combis, generally chose the third option.