On 7 February 2006, a McDonnell Douglas DC8-70-71F (N748UP) being operated by United Parcel Service (UPS) on a scheduled cargo flight from Atlanta to Philadelphia as UPS 1307 and on a night visual approach at destination reported the illumination of a cargo smoke warning to TWR and the emergency services were alerted. Immediately after touchdown, rapidly thickening smoke entered the flight deck and the three crew evacuated the aircraft as soon as it came to a stop on the runway. It proved difficult to locate the source of the fire and impossible to prevent the eventual destruction of the aircraft by fire.
Damage the crown of the fuselage showing the locations of some of the main deck containers. [Reproduced from the Official Report]
An Investigation was carried out by the NTSB. The FDR and CVR were both recovered from the wreckage and most of their data were successfully downloaded.
The flight crew was established as having been led by a 59 year-old Captain with 25,000 hours total flying experience which included 16,000 hours in command on type. The 40 year-old First Officer, who had been PF for the accident flight, had 7,500 hours total flying experience which included 2,100 hours on type after earlier turboprop experience. The 61 year-old Flight Engineer, who had previously flown in the USAF and subsequently held a professional pilot licence, had 9,000 total flying hours including 2,000 as a flight engineer of which 430 were on type.
Since no evidence was found to indicate that the fire had been of electrical origin, the Investigation concentrated on the cargo as the likely source of ignition. It was noted that the aircraft main deck had been configured to accommodate 18 cargo containers and that there had been a further 4 cargo compartments on the lower deck - see the illustration below. A "smoke curtain" was installed between the forward crew galley and the main deck cargo area as a smoke barrier. A closable opening in this curtain provided access to the cargo area but with cargo containers loaded, it was not possible to walk aft into it.
The aircraft cargo configuration. [Reproduced from the Official Report]
It was established that 25 minutes prior to the eventual landing at Philadelphia when the flight was some 50 nm south west of Washington DC, the crew had first begun to detect an unusual odour. Both the First Officer and the Flight Engineer reported that the odour had "smelt like wood burning" and the latter went to the fire curtain and shone a flashlight into the main deck cargo area but could see no visible smoke although the same odour was slightly more obvious. On return to the flight deck, he reported this and opined that the odour "did not smell electrical in nature". All three flight crew stated that "unusual odours of non-threatening origin such as flying over forest fires or emanating from unusual cargo were a relatively routine occurrence".
Over the next few minutes, the Captain and the Flight Engineer reported having tried to identify the source of the odour "by conducting several emergency checklist steps, including increasing the bleed air flow and checking the bleed air switches" and as the aircraft descended through approximately 18,000 feet about 65 miles from destination, "the CVR recorded the Flight Engineer stating that he had set the air conditioning packs to maximum flow and turned off the recirculation fan".
The Captain stated that he had considered diverting to another airport soon after the odour was first detected but that he had decided to continue as planned "because there was no evidence of a problem such as the illumination of the cargo smoke warning lights".
The aircraft was cleared to descend to 6,000 feet and it was reported that the odour continued to be present although no stronger. A further flashlight-assisted check through the fire curtain access by the Flight Engineer did not find any change in odour intensity or any visible smoke or haze.
Then, as the aircraft descended through 3,600 feet, a main deck cargo smoke warning was annunciated on the flight deck followed about a minute later by a similar warning for the lower cargo compartment. The Captain instructed the First Officer and the Flight Engineer to don their oxygen masks "if they had not already done so" and almost immediately the flight was cleared for a visual approach to runway 27R and transferred to TWR. On initial contact, the Captain "reported that the cargo smoke indicator had illuminated and requested that emergency response equipment meet them upon landing". Less than a minute after the APP controller had cleared the aircraft for an approach to runway 27R, TWR issued a landing clearance for runway 27L without drawing attention to the change and the change was not noticed or read back by the Captain.
Meanwhile, the Flight Engineer was actioning the 'Lower and/or Main Cargo Compartment Smoke or Fire Checklist and had reached the item which required him to close the cargo air SOV which required him to go back onto the main deck. On his return, he advised that "when he opened the door of the access panel to the cargo air shutoff valve, black smoke billowed out of the access panel". The First Officer called for the landing checklist and, as it was being actioned, TWR queried the apparent approach to 27R and when it became clear the change had not been heard, re-cleared the aircraft to land on 27R and advised the attending RFFS of this.
Three minutes after the appearance of the cargo smoke warning, the aircraft landed on 27R. Immediately after touchdown, the Flight Engineer reported smoke entering the flight deck and once the aircraft had come to a stop, the First Officer called for an emergency evacuation and the Captain and First officer conducted the Emergency Evacuation checklist. All three flight crew successfully evacuated the aircraft in the presence of thick black smoke using the emergency slide at the L1 door. The TWR controller's late reversion to the originally-anticipated runway, 27R, did delay the arrival of the emergency services on the scene but they still arrived there as the flight crew were evacuating the aircraft. It was noted that the attempted change of landing runway to 27L contrary to the crew expectation on account of their approach clearance had occurred because 27L was "the runway designated for emergencies".
The Captain and the First Officer both reported attempting to retrieve the NOTOC (Notification to Captain) from its usual location before leaving the flight deck but were unable to find it and could only advise RFFS personnel that the cargo included Hazardous Goods. Thirty five minutes later, the NOTOC was located by a member of the RFFS team where it had been stowed by the Flight Engineer after it had fallen to the floor from its usual position.
The RFFS reported that as the aircraft was evacuated, there was no sign of fire, just thick black smoke coming from the open L1 door and from the air conditioning outflow valve in the tail. On boarding the aircraft, RFFS personnel pulled back the smoke curtain and were able to see smoke - but no fire - on the main deck. All of the lower cargo compartments were opened but no smoke or fire was observed in any of them. The L4 and R4 doors were also opened and these accesses were used to off-load some cargo and commence water extinguishing action. Use of a thermal imaging camera did not locate any hot spots. Attempts to open the main cargo door were not successful but about 40 minutes after the aircraft had been evacuated, RFFS personnel opened the right forward over wing hatch and saw flames for the first time just aft of the hatch opening between the tops of the cargo containers and the cabin ceiling. Concerted attempts to locate and contain the fire followed but were not successful and two hours after the evacuation, the first fuselage burn-through occurred in the fuselage crown aft of the wings. The fire was not brought under control for a further two hours by which time the aircraft had been destroyed.
Examination of the debris found the remains of some declared hazardous materials but these were intact, undamaged and in their original outer packaging - authorized and properly labelled fibreboard boxes. A number of other hazardous materials were also found in the debris but none of these had been declared as such and thereby manifested. It was not possible to attribute the fire origin to any particular cargo item although it was possible to conclude that the fire "most likely originated in (main deck) container 12, 13 or 14" and that it had originated as a smouldering fire which had only breached the container where it started shortly before the cargo smoke warning had appeared on the flight deck.
It was concluded that the performance of the flight crew in response to the emergency had not contributed in any way to the accident outcome. In particular, the decision to continue on track to destination after the initial detection of a smell of smoke was "not inappropriate" given the absence of any other abnormalities and the absence of any flight deck alert annunciations.
A series of 'Safety Issues' based on relevant 'inadequacies' which were identified during the Investigation included the following:
Guidance and Checklists relating to in-flight fire and smoke
The Investigation found that UPS guidance and checklists covering smoke, fire, or fumes in the absence of a flight deck warning were not adequate because neither UPS nor Boeing provided information which was specific to this circumstance. The UPS DC8 OM contained four checklists covering fire, smoke or fumes but three of them were predicated on visible evidence of smoke or fire or an alert activation in the flight deck and there was no guidance on when to apply the fourth, the 'Fumes Evacuation Checklist', especially in the absence of any environmental effects which could have compromised the ability of a flight crew to continue their tasks normally. It was also noted that increasing both air conditioning packs to maximum flow as required in the 'Fumes Evacuation Checklist' would have increased the airflow through the cabin and evacuated any smoke more quickly thus reducing the contamination and both inhibiting the ability of the flight crew to identify the source of the odour and reducing the chances of smoke detectors detecting the presence of smoke. This same action would have also supplied additional oxygen to the smouldering fire. Although Boeing was understood to be updating the fire, smoke and fumes Checklists for most of its aircraft types to cover the observed deficiency, it was noted that there was no intention to do this for older types like the DC-8.
Smoke and fire detection system test certification requirements
Because the first flight deck warning of smoke did not occur until around 20 minutes after the fire is likely to have started, the detection system did not perform in accordance with the performance standards established by the FAA which require "smoke detector system activation within 5 minutes of fire initiation". The Investigation found that the certification of the DC8 smoke detection system did not take any account of the effect of a loaded cargo area on smoke detection within it, nor was it required to. It was considered that with cargo containers loaded, the incoming airflow would be primarily directed outward and downward towards the floor and that the containers would also create a barrier which any smoke would have to pass before entering an open space in which it could be sensed by the smoke detection system.
Fire suppression system requirements
It was noted that the accident aircraft was not required to be equipped with a fire suppression system and as a direct result, it was possible for a smouldering fire in one of the cargo containers to develop into a substantial fire that burned through the container and ceiling liner while the aircraft was airborne. Whilst it was recognised that there was a realistic prospect of such systems soon being required, it was noted that FAA flammability tests on primary lithium batteries i.e. lithium-metal (non rechargeable) batteries have shown that Halon is not an effective means of suppressing fires involving these batteries. Therefore, although requiring fire suppression systems on all-cargo aircraft would reduce the risk of fire involving most cargo items, including secondary (rechargeable) lithium batteries, it would have no effect on the risk of a primary lithium battery fire so that additional and specific mitigation of this risk would be needed.
Cargo aircraft emergency exit requirements
- ARFF personnel did not properly deploy their "High-Reach Extendable Turret with Skin-Penetrating Nozzle (HRET/SPN) which prevented them gaining access to the seat of the fire using the main cargo door as access and as a way to remove containers for access"'. Partly as a result of this, the fire continued until the aircraft had become a hull loss. This problem had been observed in a previous similar accident and it was considered that it could be attributed to insufficient attention to personnel training.
- When investigating the fact that emergency services personnel were not familiar with the operation of the accident aircraft's main cargo door even though the airport has substantial cargo operations, it was found that they had not been provided with any familiarisation training on cargo aircraft. Although it was noted that this has since been introduced at Philadelphia, it was considered that a similar deficiency may still exist at other airports where it would be relevant.
- A review of the DC-8 Emergency Response diagrams that UPS provided to the Philadelphia emergency services after the accident found that they were neither accurate nor complete.
- Noting that all the flight crew had used the L1 door and slide to evacuate the aircraft in preference to the flight deck window rope exits, that a forward floor level emergency exit was not required on cargo aircraft and that, although the accident aircraft was only certificated to carry up to a maximum of 7 occupants, some wide body all-cargo aircraft were certificated to carry up to 27 occupants, it was considered that emergency exit designation for at least one forward door on all-cargo aircraft would be appropriate.
Procedures for the dissemination of Hazardous Materials information
Following the occurrence of the accident, there was a delay in retrieving the only copy of the NOTOC from the aircraft and the attending emergency services personnel were not provided with equivalent information by UPS. Although this procedural failure has since been resolved in respect of UPS operations, it was considered that since the same problem has previously occurred after other accidents, it is likely that it may still persist in the case of other aircraft operators. It was noted that the prevailing US regulations only required aircraft operators to provide NOTOC-equivalent information to emergency responders "on request" and that UPS had not provided the information they held at their Flight Control Unit "because they did not receive a request for it, therefore, they were not obligated to volunteer it, as stipulated by the Regulations".
Transport of lithium batteries on board aircraft
Although the Investigation was unable to establish whether lithium batteries played a role in fire, it was noted that such occurrences on commercial aircraft were continuing to occur and that many incidents involving lithium batteries due to be loaded onto aircraft, on board aircraft or during and after unloading were exempt from reporting requirements. It was likely that their true extent was not being recorded and thereby relevant fire prevention lessons were not being learned. It was considered that only with full awareness and proportionate investigation of all incidents, could appropriate regulations be applied to lithium battery carriage on transport aircraft and that current requirements did not fully achieve this.
The Probable Cause of the Accident was determined as "an in-flight cargo fire that initiated from an unknown source, which was most likely located within cargo container 12, 13, or 14".
Two Contributory Factors to the loss of the aircraft were also identified as:
- the inadequate certification test requirements for smoke and fire detection systems.
- the lack of an on-board fire suppression system.
One Safety Recommendation was issued on 25 September 2006 whilst the Investigation was in progress:
- that the Federal Aviation Administration should amend Federal Aviation Administration Order 7110.65, 'Air Traffic Control', to require that, when amending a runway assignment, controllers provide a specific instruction to the pilot advising of the runway change. For example, “UPS 1307, change to runway 25L, cleared to land.” [A-06-65]
Upon completion of the Investigation, the FAA Response to this initial Safety Recommendation was classified as "Open - Unacceptable Response" since action to implement the proposed change had yet to be taken.
On completion of the Investigation, a further 14 Safety Recommendations were made as follows:
- that the Federal Aviation Administration should provide clear guidance to operators of passenger and cargo aircraft operating under 14 Code of Federal Regulations Parts 121, 135, and 91K on flight crew procedures for responding to evidence of a fire in the absence of a cockpit alert based on the guidance developed by the 2004 smoke, fire and fumes industry initiative. [A-07-97]
- that the Federal Aviation Administration should ensure that the performance requirements for smoke and fire detection systems on cargo airplanes account for the effects of cargo containers on airflow around the detection sensors and on the containment of smoke from a fire inside a container, and establish standardized methods of demonstrating compliance with those requirements. [A-07-98]
- that the Federal Aviation Administration should require that fire suppression systems be installed in the cargo compartments of all cargo airplanes operating under 14 Code of Federal Regulations Part 121. [A-07-99]
- that the Federal Aviation Administration should provide guidance to aircraft rescue and fire fighting personnel on the best training methods to obtain and maintain proficiency with the high-reach extendable turret with skin-penetrating nozzle. [A-07-100]
- that the Federal Aviation Administration should require airport inspectors to ensure that Part 139 airports with cargo operations include cargo aircraft in their aircraft rescue and fire fighting aircraft familiarisation training programs. [A-07-101]
- that the Federal Aviation Administration should require cargo operators to designate at least one floor level door as a required emergency exit and equip the door with an evacuation slide, when appropriate. [A-07-102]
- that the Federal Aviation Administration should require all emergency exits on cargo aircraft that are operable from the outside to have a 2-inch contrasting coloured band outlining the exit. [A-07-103]
- that the Pipeline and Hazardous Materials Safety Administration should require aircraft operators to implement measures to reduce the risk of primary lithium batteries becoming involved in fires on cargo-only aircraft, such as transporting such batteries in fire resistant containers and/or in restricted quantities at any single location on the aircraft. [A-07-104]
- that the Pipeline and Hazardous Materials Safety Administration should, until fire suppression systems are required on cargo-only aircraft as asked for in Safety Recommendation A-07-99, require that cargo shipments of secondary lithium batteries, including those contained in or packed with equipment, be transported in crew-accessible locations where portable fire suppression systems can be used. [A-07-105]
- that the Pipeline and Hazardous Materials Safety Administration should require those aircraft operators that transport hazardous materials to immediately provide consolidated and specific information about hazardous materials on board an aircraft, including proper shipping name, hazard class, quantity, number of packages, and location, to on-scene emergency responders upon notification of an accident or incident. [A-07-106]
- that the Pipeline and Hazardous Materials Safety Administration should require commercial cargo and passenger operators to report to the Pipeline and Hazardous Materials Safety Administration all incidents involving primary and secondary lithium batteries, including those contained in or packed with equipment, that occur either on board or during loading or unloading operations and retain the failed items for evaluation purposes. [A-07-107]
- that the Pipeline and Hazardous Materials Safety Administration should analyse the causes of all thermal failures and fires involving secondary and primary lithium batteries and, based on this analysis, take appropriate action to mitigate any risks determined to be posed by transporting lithium batteries, including those contained in or packed with equipment, on board cargo and passenger aircraft as cargo; checked baggage; or carry-on items. [A-07-108]
- that the Pipeline and Hazardous Materials Safety Administration' should eliminate regulatory exemptions for the packaging, marking, and labelling of cargo shipments of small secondary lithium batteries (no more than 8 grams equivalent lithium content) until the analysis of the failures and the implementation of risk-based requirements asked for in Safety Recommendation A-07-108 are completed. [A-07-109]
- that the Cargo Airline Association should work with its member airlines and other groups, such as the Air Transport Association, major aircraft manufacturers, and the Aircraft Rescue and Fire Fighting (ARFF) Working Group, to develop and disseminate accurate and complete airplane Emergency Response diagrams for ARFF personnel at airports with cargo operations. [A-07-110]
The Final Report of the Investigation was adopted by the NTSB on 4 December 2007.