UPS - B744F - UAE final report
Date: Wednesday, August 14, 2013
UPS Flight 6, Uncontained Cargo Fire
A few days ago, the General Civil Aviation Authority of the United Arab
Emirates has released its final report on the Boeing 744 which crashed on the
3rd of September in 2010 after an uncontained cargo fire.
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Uncontained
Cargo Fire Leading to Loss of Control Inflight and Uncontrolled Descent Into
Terrain
The 326-page accident report is excellently written and deals with all
the issues involved with this tragic flight and an analysis of the situation.
Here’s a summary of the main points.
11:35 UPS Airlines Boeing 747-400AF, a two-crew four-engine wide-body
aircraft, arrives from Hong Kong on a scheduled cargo service.
The Flight Crew reported a failure with the PACK 1 air conditioner
during the flight. The ground engineer could not replicate the fault.
The PACKs provide preconditioned air to the pressurized fuselage. The
Boeing 747 has three PACKs.
14:51 The Boeing 747 departs as UPS Airlines Flight 6 as a scheduled
cargo flight to Cologne Bonn Airport. The First Officer is the Pilot Flying and
the Captain is the Pilot Not Flying. They depart on Runway 30R and fly north
west over the southern Arabian Gulf.
The First Officer flew the aircraft manually to an altitude of 11,300
feet and then engaged the autopilot after receiving another PACK 1 fault. The
flight crew reset PACK 1 which cleared the fault.
The aircraft continued to climb. Shortly before they reached their
cruising altitude of 32,000 feet, a fire warning bell sounded and the master
warning light illuminated. They had a fire on the forward main deck. The
Captain took control of the aircraft.
15:12:57 CAPT in cockpit: Fire, main deck forward. Alright, I’ll fly the
aircraft
15:13:07 CAPT in cockpit: I got the radio, go ahead and run [the
checklist]
15:13:14 CAPT to ATC: Just got a fire indication on the main deck I need
to land ASAP
15:13:19 BAE-C: Doha at your ten o’clock and one hundred miles is that close
enough?
15:13:23 CAPT: how about we turn around and go back to Dubai, I’d like
to declare an emergency
15:13:27 BAE-C: UPS six make a right turn heading zero nine zero descend
to flight level two eight zero.
Doha was closer, they were about 180 miles from Dubai. However, it is
unlikely that the crew understood the extent of the fire.
The crew put on oxygen masks and worked their way through the Fire/Smoke/Fumes
checklist.
The fire suppression system automatically shut down PACK 2 and 3. The
flight crew manually turned the switches to OFF, in accordance with their check
list. In fire suppression mode, PACK 1 should have continued to supply
preconditioned air to the upper deck. This provides positive air pressure to
the cockpit to prevent smoke and fumes from entering the cockpit area. However,
at 15:15:21, PACK 1 stopped operating. This meant that no packs were operating
and there was no ventilation to the upper deck and flight deck. Smoke began to
enter the cockpit.
15:15:23 CAPT to ATC: I need a descent down to ten thousand right away
sir.
It’s unclear why the Captain requested the descent, although it seems to
me he was probably reacting to the smoke and concerned about available oxygen.
However, this was not on his checklist, which stated he should fly at 25,000 feet,
the optimum altitude to prevent combustion. His action did not support the fire
suppression system which was based on depressurisation and oxygen deprivation.
The uncontained cargo fire severely damaged the control cables, the
truss frame supporting the cables and the cable tension.
15:15:37 CAPT: alright. I’ve barely got control
15:15:38 F.O: I can’t hear you
15:15:41 CAPT: Alright
15:15:47 F.O: alright… find out what the hell’s goin on, I’ve barely got
control of the aircraft.
15:16:41 CAPT: I have no control of the aircraft.
15:15:43 F.O: okay… what?
15:16:47 CAPT: I have no pitch control of the aircraft
15:15:53 F.O: you don’t have control at all?
15:16:42 CAPT: I have no control of the aircraft.
15:16:47 CAPT: I have no pitch control of the aircraft.
They regained control of the elevator control system through the autopilot.
Meanwhile, the cockpit was filling with smoke. Within two minutes, neither crew
member could see the control panels or look out of the cockpit.
15:16:57 CAPT: Pull the smoke handle.
Pulling the smoke handle might have caused a pressure differential,
drawing more smoke into the cockpit. The Captain contacted ATC to report the
situation and then spoke to the First Officer.
15:17:39 CAPT: Can you see anything?
15:17:40 F.O: No, I can’t see anything.
The flight crew attempted to input the Dubai Runway 12 left data into
the flight management computer, so that they could configure the aircraft for
an auto-flight/auto-land approach, but they couldn’t see the FMC display for
all the smoke. At that point, the Captain’s oxygen supply failed.
15:19:56 CAPT: I’ve got no oxygen.
15:19:58 F.O: Okay
15:20:00 F.O: Keep working at it, you got it.
15:20:02 CAPT: I got no oxygen I can’t breathe.
15:20:04 F.O: okay okay.
15:20:06 F.O: what do you want me to get you?
15:20:08 CAPT: Oxygen.
15:20:11 F.O: Okay
15:20:12 CAPT: Get me oxygen.
15:20:12 F.O: hold on okay.
15:20:16 F.O: Are you okay?
15:20:17 CAPT: (I’m out of) oxygen.
15:20:19 F.O: I don’t know where to get it.
15:20:20 CAPT:(I’m out of) oxygen.
15:20:21 F.O: Okay
15:20:21 CAPT:You fly (the aircraft)
A portable oxygen bottle was behind the Captain’s seat, next to the
left-hand observer’s seat, but neither crew member retrieved the bottle. The
Captain moved aft of the cockpit area, presumably to try to find the
supplementary oxygen. He removed his oxygen mask and smoke goggles and said, “I
cannot see.” That was the last recording which included the Captain; he died as
a result of carbon monoxide inhalation.
Seven minutes had elapsed since the fire alarm had first sounded. The
First Officer was now Pilot Flying, with no support nor monitoring. A nearby
aircraft contacted him to relay information to Bahrain. The First Officer
established communication and attempted to cope with a swiftly escalating task
load, which left him no time to enquire after the Captain.
15:25:42 PF: I would like immediate vectors to the nearest airport I’m
gonna need radar guidance I cannot see.
Based on his comments, the investigators believe that the pilot was able
to see heading, speed and altitude select windows. He could not see the primary
flight displays. He could not read the navigation display. Thus he could set up
flight configurations but he couldn’t see the response. He also made numerous comments
about not being able to see outside and that the heat was increasing and his
oxygen was getting low.
He couldn’t see the radio either, so he couldn’t change frequency
although he was now out of range of the controller at BAE-C. The controller
asked aircraft to relay information to and from the Boeing. Dubai ATC also
transmitted several advisory messages to the flight on local frequencies in hopes
of getting a message to the Boeing, including “any runway is available.” They
turned on the lights for Runway 30L.
A relay aircraft contacted the Pilot Flying and attempted to pass his
information on to Bahrain. The relay aircraft (identified as 751) struggled to
relay the information and get answers from Bahrain. The relay system was of
little use to the Pilot Flying who didn’t know his own altitude or speed and
needed immediate data.
15:29:59 PF: Okay Bahrain give me what is my current airspeed?
[groundspeed]
15:30:07 PF: Current airspeed immediately immediately.
15:30:14 PF: What is my distance from Dubai International UPS er six
what is my distance we are on fire. it is getting very hot and we cannot see.
15:30:22 RELAY AIRCRAFT: Okay I ask Bahrain understood and UPS six
request the distance from Dubai from now?
15:30:28 PF: Sir I need to speak directly to you I cannot be passed
along I need to speak directly to you. I am flying blind.
15:30:36 RELAY AIRCRAFT: Understood UPS six we are just changes to
another aircraft to be with Dubai to relay with you I ask again to Bahrain
Bahrain distance UPS six to Dubai?
The workload of the Pilot Flying was immense. He was communicating
through aircraft relays while he controlled the flight and attempted to
navigate to Dubai International, with no access to navigation equipment and no
possibility of looking out the window. He repeatedly asked the relays for
information on height, speed and direction to plan his blind flight. There was
no opportunity to finish the checklist nor check on the Captain.
The options available to the pilot were limited. The aircraft was seriously
compromised but without primary instruments, so the First Officer couldn’t see
what was and wasn’t working. He couldn’t even ditch the aircraft in the Arabian
Gulf as he didn’t know his own altitude and couldn’t see out the window.
The Boeing 747 approached Dubai travelling 350 knots at an altitude of
9,000 feet and descending.
The computed airspeed was 350 knots, at an altitude of 9,000 feet and
descending on a heading of 105° which was an interception heading for the ILS
at RWY12L. The FMC was tuned for RWY12L, the PF selected the ‘Approach’ push
button on the Mode Control Panel [MCP] the aircraft captures the Glide Slope
(G/S). The AP did not transition into the Localizer Mode while the Localizer
was armed.
ATC at Dubai asked a relay aircraft to advise the Pilot Flying, “You’re
too fast and too high. Can you make a 360? Perform a 360 if able.”
The First Officer responded simply with, “Negative, negative, negative.”
The Pilot Flying set the landing gear lever to down. This caused an
aural warning alarm: Landing Gear Disagree Caution.
15:38:20 PF: “I have no gear.”
The aircraft passed north of the aerodrome on a heading of 89° at a
speed of 320 knots, altitude 4200 feet and descending.
He had no landing gear. He was fast and high. The fire was still burning
and the cockpit was thick with smoke. He couldn’t see a thing. And now he’d
overflown the airport.
There was another airfield, Sharjah Airport, which was 10 nautical miles
to the left of the aircraft. The relay pilot asked if the Pilot Flying could turn
left onto a 10 mile final approach for Sharjah’s runway 30.
19:38:37 PF: Sir, where are we? Where are we located?
19:38:39 RELAY AIRCRAFT: Are you able to do a left turn now, to Sharjah?
It’s ten miles away.
19:38:43 PF: Gimme a left turn, what heading?
The relay aircraft advised that SHJ was at 095° from the current
position at 10nm. The PF acknowledged the heading change to 095° for SHJ.
However, the Pilot Flying selected 195°. The aircraft banked to the
right as the Flight Management Computer captured the heading change. The
aircraft entered a descending right-hand turn at an altitude of 4,000 feet.
Then there were a number of pitch oscillations commanded by the Pilot Flying as
the elevator effectiveness decreased.
The aircraft was heading straight for Dubai Silicone Oasis, a large
urban community. I suppose the one good thing in this fiasco is that it never
made it that far.
15:40:15 RELAY AIRCRAFT: Okay Dubai field is three o’clock it’s at your
three o’clock and five miles
15:40:20 PF: What is my altitude, and my heading?
15:40:25 PF: My airspeed? [groundspeed]
The pitch control was ineffective. The control column was fully aft but
there was no corresponding elevator movement. The aircraft was out of control.
15:41:33 The Ground Proximity Warning System sounds an alert: PULL UP
15:41:35 [data ends]
The Boeing crashed into a service road in the Nad Al Sheba military base
nine miles south of Dubai.
So what caused the fire to go so quickly out of control?
The cargo loaded in Hong Kong included a large amount of lithium
batteries distributed throughout the cargo decks. However, packing slips and
package details, showing that the cargo contained lithium batteries and
electronic devices packed with lithium batteries, were not inspected until after
the accident. At least three of the shipments contained lithium ion batteries
which are specified as a hazard class 9 and should have been declared as
hazardous cargo.
Lithium batteries have a history of thermal runaway and fire, are
unstable when damaged and can short circuit if exposed to overcharging, the
application of reverse polarity or exposure to high temperature are all potential
failure scenarios which can lead to thermal runaway. Once a battery is in
thermal runaway, it cannot be extinguished with the types of extinguishing
agent used on board aircraft and the potential for ignition of adjacent
combustible material exists.
The investigators believe that a lithium battery or batteries went into
an “energetic failure characterised by thermal runaway” – in other words a battery
auto-ignited. This started a chain reaction, igniting all the combustible
material on the deck. The resulting fast-burning blaze then ignited the
adjacent cargo, which also included lithium batteries. The remaining cargo then
ignited and continued in a sustained state of combustion, that is the
conflagration continued burning until the crash.
The single point of failure in this accident was the inability of the
cargo compartment liner to prevent the fire and smoke penetration of the area
above pallet locations in main deck fire zone 3.
This resulted in severe damage to the aircraft control and crew
survivability systems, resulting in numerous cascading failures.
As the cargo compartment liner failed, the thermal energy available was
immediately affecting the systems above the fire location: this included the
control assembly trusses, the oxygen system, the ECS ducting and the habitable
area above the fire in the supernumerary compartment and in the cockpit.
The probable causes start with the fire developing in the palletized
cargo, which escalated rapidly into a catastrophic uncontained fire. The cargo
compartment liners failed. The heat from the fire caused the malfunctions in
the truss assemblies and control cables, disabling the cable tension and elevator
function. The heat also affected the supplementary oxygen system, cutting off
the Captain’s oxygen supply.
The volume of toxic smoke obscured the view of the primary flight
displays and the view outside the cockpit, exacerbated by the shutdown of PACK
1. And finally, the fire detection itself did not give enough time for the
flight crew or the smoke suppression systems to react before the fire was a
conflagration.
A key consideration that the investigation puts forward is the useful
response time in the case of an onboard fire.
A study conducted by the Transportation Safety Board of Canada, in which
15 in-flight fires between 1967 and 1998 were investigated, revealed that the
average elapsed time between the discovery of an in-flight fire and the
aircraft ditched, conducted a forced landing, or crashed ranged between 5 and
35 minutes, average landing of the aircraft is 17 minutes.
Two other B747 Freighter accidents caused by main deck cargo fires have
similar time of detection to time of loss of the aircraft time frames, South
African Airways Flight 295 was 19 minutes before loss of contact and Asiana
Airlines Flight 991 was eight minutes. Both aircraft had cargo that ignited in
the aft of the main deck cargo compartment.
The accident aircraft in this case, was 28 minutes from the time of
detection until loss of control in flight. The cargo that ignited was in the
forward section of the main deck cargo compartment. The average time is
seventeen minutes. This should be factored into the fire checklist that an
immediate landing should be announced, planned, organised and executed without
delay.
These findings indicate that crews may have a limited time to complete
various checklist actions before an emergency landing needs to be completed and
the checklist guidance to initiate such a diversion should be provided and
should appear early in a checklist sequence.
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