UPS DC87 at Philadelphia on Feb 8th 2006, smoke in cargo hold, developed into full fire after landing
Last Update: August 29, 2021 / 13:59:38 GMT/Zulu time
The airplane is assumed a total loss.
NTSB has launched a full investigation.
The NTSB adopted their final report on Dec 4th 2007 concluding the probable cause of the accident was:
The National Transportation Safety Board determines that the probable cause of this accident was an in-flight cargo fire that initiated from an unknown source, which was most likely located within cargo container 12, 13, or 14. Contributing to the loss of the aircraft were the inadequate certification test requirements for smoke and fire detection systems and the lack of an on-board fire suppression system.
The NTSB summarized the sequence of events:
On February 7, 2006, about 2359 eastern standard time, United Parcel Service Company flight 1307, a McDonnell Douglas DC-8-71F, N748UP, landed at its destination airport, Philadelphia International Airport, Philadelphia, Pennsylvania, after a cargo smoke indication in the cockpit. The captain, first officer, and flight engineer evacuated the airplane after landing. The flight crewmembers sustained minor injuries, and the airplaneand most of the cargo were destroyed by fire after landing.
The NTSB summarized the sequence of events in more detail:
The accident flight crew reported that the flight was uneventful until just after beginning the descent to PHL. At 2334:39, while the airplane was descending through flight level 310 about 50 nautical miles southwest of Washington, D.C., the cockpit voice recorder (CVR) recorded the first officer asking the captain and the flight engineer if they detected an odor that smelled “like wood burning.” The flight engineer replied that he had “smelled it for a couple of seconds.” About 1 minute later, the first officer stated, “[it’s] pretty strong now.” Subsequently, the CVR recorded a sound similar to the cockpit door or seat operating and the flight engineer stating, “[it’s] more in the back.” About 3 1/2 minutes later, the first officer again stated that the odor smelled like wood, and the flight engineer agreed that the odor did smell like wood burning and stated that it did not smell electrical in nature.
During postaccident interviews, the captain stated that he considered diverting to another airport soon after the odor was first detected but that he chose to continue to PHL because there was no evidence of a problem, such as the illumination of the cargo smoke warning lights. The first officer stated that the odor did not appear to be a threat because the flight engineer did not see any visible smoke; therefore, the first officer did not believe that there was any need to divert. Further, the accident flight crew stated that unusual odors could be common from nonthreatening factors (such as flying over forest fires or unusual cargo).
Over the next 4 minutes, the captain and flight engineer tried to identify the source of the odor by conducting several emergency checklist steps, including increasing the bleed air flow and checking the bleed air switches. As the airplane was descending through about 18,000 feet and was about 65 miles from PHL, the CVR recorded the flight engineer stating that he set the air conditioning packs to maximum flow and turned off the recirculation fan. Shortly thereafter, the flight engineer and captain conducted the Approach checklist.
At 2344:59, the first officer contacted the PHL Terminal Radar Approach Control, and the approach controller instructed the flight to descend to 6,000 feet. The CVR then recorded the captain asking, “can you still smell it in the back there?” The flight engineer replied, “yeah . . . smells like it was more to the back there.” The first officer then asked, “smells like cardboard burning doesn’t it? you didn’t see smoke though something like that?” The flight engineer again went back to check the main cargo compartment with his flashlight, and he stated that the odor was “definitely stronger in the back” but that there was no smoke or haze. Over the next 10 minutes, the captain and flight engineer continued to troubleshoot the problem.
At 2354:42, as the airplane was descending through about 3,600 feet, the flight engineer stated, “we got cargo smoke.” The captain replied, “let’s do that checklist if you got time.” The first officer then stated that he would be turning toward the airport.
At 2355:01, the PHL approach controller cleared the visual approach to runway 27R and then instructed the flight crew to contact the air traffic control tower (ATCT). Ten seconds later, the captain made initial contact with the ATCT local controller, who cleared the flight to land on runway 27R. After acknowledging the clearance, the captain reported that the cargo smoke indicator had illuminated and requested that emergency response equipment meet them upon landing. The local controller immediately activated the crash phone and advised approach control of the emergency.
At 2355:57, the flight engineer stated, “[it’s] showing that we have a lower aft cargo fire section C.”
Subsequently, the captain told the first officer and flight engineer
to don their oxygen masks if they had not done so already. The captain then asked the flight engineer to accomplish the Lower and/or Main Cargo Compartment Smoke or Fire checklist by himself, and the flight engineer proceeded to execute the checklist.
According to air traffic control (ATC) transcripts, the Philadelphia approach controller asked the PHL ATCT local controller whether the flight was going to land on the left side, referring to runway 27L, which is the runway at PHL designated for use in emergency situations. At 2356:12, the local controller cleared the flight to land on runway 27L, and the captain acknowledged the landing clearance but not the change in landing runway.
The flight engineer continued the Lower and/or Main Cargo Compartment Smoke or Fire checklist items. When he reached the step to close the cargo air shutoff valve, he stated that he had to “go in the back and do that.”10 During postaccident interviews, the flight engineer stated that, when he opened the door of the access panel to the cargo air shutoff valve, black smoke billowed out of the access panel.
At 2357:47, the first officer called for the Landing checklist. About 21 seconds later, the ATCT local controller stated, “just confirmed you are lined up for the left side it appears that you are lined up for the right.” The first officer replied, “I thought we were cleared for the right . . . are we cleared to land on the right?” At 2358:16, the local controller replied, “you are cleared to land on the right we will just tell fire.” The airplane landed on runway 27R about 2359. Immediately after touchdown, the flight engineer reported smoke in the cockpit.
After the airplane came to a stop, the first officer called for an emergency evacuation, and the captain and first officer conducted the Emergency Evacuation checklist. All of the flight crewmembers successfully evacuated the airplane using the emergency slide located at the left forward (L1) door.
The NTSB stated: "The airplane was destroyed by fire after landing. Most of the cargo on board the airplane was destroyed or damaged by fire."
The NTSB analysed:
Investigators considered whether the flight crew should have executed a diversion to another airport when the odor was first detected. The flight crewmembers stated during postaccident interviews that they decided to continue to PHL because no smoke detector warning lights illuminated in the cockpit and no smoke was visually evident, which minimized their belief that an actual hazard existed. Further, the crewmembers also noted that unusual odors could be common from nonthreatening factors, such as flying over forest fires or from unusual cargo. Without supporting evidence, such as visible smoke and aural alerts, odor is an elusive and highly subjective factor for determining the presence of a hazard.
Safety Board calculations indicated that, if the flight crew had begun a diversion at the first indication of an odor and performed a standard or emergency descent into Washington Dulles International Airport, Andrews Air Force Base, or Baltimore Washington International Airport, it would have taken about 17 to 18 minutes to land, compared to the 24 minutes it took to land at PHL. Because the flight was already established on the descent to PHL, a diversion would have added cockpit workload that might have affected the crew’s ability to focus its attention on the potential smoke or fire hazard. The Safety Board concludes that the flight crew’s continued descent to PHL was not inappropriate given that there was no evidence of abnormalities other than the odor and that no cockpit alerts had activated.
During the review of the flight crew’s actions and decision-making, investigators found that company guidance and checklists regarding smoke, fire, or fumes in the absence of a cockpit warning were not adequate because neither UPS nor Boeing provided specific flight crew procedures for responding to such a situation. Instead, the UPS DC-8 AOM provided four checklists that could have been applied to such a situation, three of which were predicated on visible evidence of smoke or fire or an alert activation in the cockpit.
As noted, during this period, no smoke or fire warning lights illuminated in the cockpit, no visible evidence of smoke or fire existed, the CVR recorded no comments by the flight crew about burning eyes or headaches, and no evidence of abnormalities other than odor existed. Although one of the checklists, the Fumes Evacuation checklist, did apply specifically to fumes, the AOM did not provide guidance on when to use the checklist.
Increasing both air conditioning packs to maximum flow (as part of the Fumes Evacuation checklist) would have increased the airflow through the cabin. This would have evacuated the smoke more quickly, diluting the air and inhibiting the flight crew’s ability to identify the source of the odor and the smoke detectors’ ability to detect the smoke. Further, additional oxygen would have been provided to the smoldering fire.
Although these would be appropriate steps to take in a situation involving fumes that might, for example, cause irritation or otherwise prevent the flight crew’s ability to operate the airplane, they are not appropriate in a situation in which a fire is suspected.
Therefore, the Safety Board concludes that the increased airflow that resulted from the Fumes Evacuation checklist actions diluted the smoke and inhibited its detection by either the smoke detection system or flight crewmembers and provided the fire with additional oxygen.
The NTSB analysed the fire development:
The first indication of the fire was the first officer’s query to the other crewmembers about the smell of burning wood, which occurred about 20 minutes before the main cargo compartment Cargo Smoke warning light activated, indicating that the fire had been burning for at least that long. However, the flight engineer saw no smoke either of the two times that he visually checked the main cargo compartment. This evidence indicates that the fire initially did not generate a significant amount of smoke and was most likely initiated as a smoldering fire inside a cargo container. The construction of the cargo containers, which results in restricted airflow in or out of the container, likely inhibited the growth and detection of the fire in its initial stages. On the basis of this evidence, the Safety Board concludes that the fire on board the accident airplane initiated as a smoldering fire.
Once the fire breached the cargo container in which it initiated, it would have begun to spread to adjacent containers. Detection of the fire by the main cargo compartment smoke detectors most likely occurred around the time of the first container burnthrough.
The smoke detector in lower cargo compartment 33 alerted about 1 minute after the main cargo compartment alert, and some of the captain’s displays then began to falter, indicating the continued progression of the fire.
The flight engineer first saw smoke when he exited the cockpit to close the main cargo air shutoff valve and black smoke emanated from the valve’s access panel. About 2 minutes later, almost immediately after touchdown, the flight engineer reported that smoke had begun entering the cockpit. The smoke continued to worsen after the airplane came to a stop, and the smoke in the cockpit became so thick that the two pilots could not see each other before evacuating the airplane.
ARFF personnel who entered the airplane through the L1 door observed smoke but no fire in the main cargo compartment. Flames were first observed about 40 minutes after the airplane landed when ARFF personnel opened the right-forward overwing hatch and noticed flames above the containers just aft of the opening. The continued growth of the fire after the airplane landed was probably affected by the introduction of fresh air through the openings in the airplane, both through its open doors and eventually through holes created in the fuselage as the fire ultimately burned through the fuselage crown.
The growth of the fire was also affected by the combustible nature of the packages and packing materials in the cargo containers, which provided a readily ignitable fuel source for the growing fire. The fuselage burned through aft of the wings (near containers 12, 13, and 14) about 2 hours after landing.
On the basis of this evidence, the Safety Board concludes that the fire was detected by the airplane’s smoke and fire detection system after the fire breached a cargo container, at which time, it proceeded to spread and that the growth of the fire after landing was fed by air entering through open doors and burnthrough holes.
With respect to the origin of the fire the NTSB analysed:
Because the fire most likely originated in cargo container 12, 13, or 14, investigators attempted to determine the contents of the packages that were not accounted for on scene by contacting the shippers of the packages in these containers. This effort was unable to determine the contents of all of the packages in these containers; however, the effort did reveal that several electronic devices likely containing secondary lithium batteries were shipped in these containers. Unfortunately, the lack of information about the devices or the batteries prevented any determination of whether these batteries were associated with previously known recalls. The Safety Board concludes that the exact origin and cause of the in-flight fire on board the airplane could not be determined due to the destruction of potentially helpful evidence; however, the available evidence suggests that the fire most likely originated in container 12, 13, or 14.
Following further cargo fires causing crashes in 2010 (see Crash: UPS B744 at Dubai on Sep 3rd 2010, cargo fire and 2011 (see Crash: Asiana B744 near Jeju on Jul 28th 2011, fire in cargo hold) the NTSB released safety recommendations for cargo container fire detection, see News: NTSB releases safety recommendations for cargo container fire detection, which specifically also included this accident.
(Editorial note: this report originally was a private report in 2006 well before The Aviation Herald opened doors on May 12th 2008, and has been upgraded on Aug 29th 2021 upon reader request/comment by "The Legacy", see below).
This article is published under license from Avherald.com. © of text by Avherald.com.
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