Latest / Aviation Survival Stories / The EPR reading that fooled the autothrottle - did they land in time?

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The EPR reading that fooled the autothrottle - did they land in time? · Aviation Survival Stories

• 0:03
  Speaker 1: At 1.47 in the morning on the 24th of July, 2014,
• 0:06
  Speaker 1: a French military drone scanning the northern Mali desert found
• 0:11
  Speaker 1: a scar in the sand.
• 0:13
  Speaker 2: No fuselage. No tail section.
• 0:17
  Speaker 1: No structure recognizable as an aircraft. Just 116 people, reduced
• 0:23
  Speaker 1: to fragments across the scrubland near a place called Gossi.
• 0:26
  Speaker 1: The flight data recorder had stopped transmitting at that exact second. 1.47.
• 0:30
  Speaker 2: 1.47.
• 0:31
  Speaker 1: And it would take the world nearly two years to
• 0:33
  Speaker 1: understand what those final 32 minutes actually contained. The plane
• 0:38
  Speaker 1: had been in the air for 32 minutes.
• 0:40
  Speaker 2: There were no survivors.
• 0:42
  Speaker 1: French President Francois Hollande confirmed it himself the next day.
• 0:45
  Speaker 1: Not one person aboard Air Algerie flight AH5017 walked away
• 0:50
  Speaker 1: from that desert. Here's the detail that makes this story
• 0:53
  Speaker 1: impossible to set aside. The cockpit voice recorder, the device
• 0:57
  Speaker 1: built to capture every word, every alarm, every decision made
• 1:00
  Speaker 1: in those final moments. was effectively silent. The magnetic tape
• 1:03
  Speaker 1: had degraded past reading. What the crew said to each
• 1:06
  Speaker 1: other as the aircraft fell is gone, and it will
• 1:08
  Speaker 1: stay gone. What investigators did have was the flight data recorder,
• 1:12
  Speaker 1: and what it showed was not a bomb, not a collision,
• 1:16
  Speaker 1: not the kind of catastrophic mechanical failure that leaves wreckage
• 1:19
  Speaker 1: scattered by an explosion. It showed an aircraft that had
• 1:22
  Speaker 1: been quietly, systematically betrayed by the very systems built to
• 1:26
  Speaker 1: keep it flying, while the two pilots, working in darkness
• 1:29
  Speaker 1: over the Sahara, fought a problem they may never have
• 1:32
  Speaker 1: fully understood until it was already too late to fix.
• 1:36
  Speaker 1: Flight AH5017 lifted off before sunrise and never landed, a
• 1:41
  Speaker 1: chain of events stretching back more than a year before departure,
• 1:44
  Speaker 1: a legal reckoning that, 12 years later, still has not
• 1:47
  Speaker 1: produced a single verdict. The route between Ouagadougou and Algiers
• 1:51
  Speaker 1: was never glamorous. It was a functional corridor, a night departure,
• 1:55
  Speaker 1: a pre-dawn arrival, a connection between the capital of Burkina
• 1:58
  Speaker 1: Faso and the Algerian coast that most passengers treated as
• 2:02
  Speaker 1: a means to an end.
• 2:03
  Speaker 2: Not a destination.
• 2:05
  Speaker 1: Flight AH5017 departed at 1.15 in the morning, local time.
• 2:09
  Speaker 1: It flew under the Air Algeri name, but the aircraft
• 2:12
  Speaker 1: and its crew belonged to Swiftair, a Spanish charter airline
• 2:15
  Speaker 1: that had wet-leased the plane and its people to Air
• 2:17
  Speaker 1: Algeri for these routes. The aircraft was a McDonnell Douglas MD-80,
• 2:21
  Speaker 1: registration ECLTV.
• 2:23
  Speaker 2: It had first flown in June of 1996.
• 2:26
  Speaker 1: By that July night it was 18 years old, and
• 2:28
  Speaker 1: had completed 32,000 cycles, 32,000 takeoffs, 32,000 landings.
• 2:33
  Speaker 2: That number matters.
• 2:34
  Speaker 1: Every pressurization cycle stresses an airframe. Every cycle ages the
• 2:38
  Speaker 1: sensors and actuators a modern jet depends on to read
• 2:40
  Speaker 1: its own performance. The captain was Agustin Comaron Moggio, 47
• 2:45
  Speaker 1: years old, Spanish, with nearly 13,000 flight hours behind him,
• 2:49
  Speaker 1: more than 10,000 of them on the MD-80 specifically.
• 2:52
  Speaker 2: He had logged 45.
• 2:53
  Speaker 1: Flights on these West African routes in the five weeks
• 2:55
  Speaker 1: before the accident alone. He knew this corridor the way
• 2:57
  Speaker 1: a person knows a street they walk every day. Beside
• 3:00
  Speaker 1: him sat First Officer Isabel Gost-Kaimari, 42, with more than 7,000
• 3:05
  Speaker 1: flight hours, over 6,000 of them as co-pilot on this
• 3:08
  Speaker 1: exact aircraft type. She had flown 43 flights on these
• 3:12
  Speaker 1: same routes in that same compressed stretch of weeks. Both
• 3:15
  Speaker 1: pilots were current. Both were experienced on this aircraft, on
• 3:19
  Speaker 1: this corridor, on this kind of night. 110 passengers boarded
• 3:24
  Speaker 1: in Ouagadougou. At least 52 were French, among them more
• 3:28
  Speaker 1: than 33 French military personnel. At least 20 were Lebanese,
• 3:32
  Speaker 1: some holding dual nationality. 28 were citizens of Burkina Faso.
• 3:36
  Speaker 1: There was a Chilean French national among them. Families, soldiers,
• 3:41
  Speaker 1: people who had somewhere to be in the morning, all.
• 3:43
  Speaker 2: Of them expecting to land in Algiers at ten past five.
• 3:47
  Speaker 1: Years later, a lawyer representing 28 of those Burkina Bay
• 3:49
  Speaker 1: families would stand in front of a camera and say
• 3:52
  Speaker 1: the thing that no maintenance log or court filing ever
• 3:54
  Speaker 1: manages to say. Maitre Halidu Waidraogo, president of the association Afavik,
• 3:59
  Speaker 1: said that the families no longer wanted Africa to become
• 4:01
  Speaker 1: a dumping ground where planes in poor condition are sent
• 4:03
  Speaker 1: to fly. He said his clients did not even have
• 4:06
  Speaker 1: the resources to be represented in the courtroom where their
• 4:08
  Speaker 1: case would be decided.
• 4:09
  Speaker 2: Hold that sentence. It will matter again before this story
• 4:12
  Speaker 2: is finished.
• 4:13
  Speaker 1: The maintenance record of ECL TV tells a quieter, more
• 4:16
  Speaker 1: uncomfortable story than any crash summary usually admits. A full
• 4:20
  Speaker 1: year before the accident, in July of 2013, The aircraft
• 4:24
  Speaker 1: had experienced intermittent auto throttle failures and the number two
• 4:28
  Speaker 1: EPR transmitter was replaced. Three months later, the number one
• 4:31
  Speaker 1: EPR indicator malfunctioned and the display was swapped out. In
• 4:35
  Speaker 1: March of 2014, the auto throttle actuator was replaced again
• 4:39
  Speaker 1: after another EPR failure and the left EPR transmitter went
• 4:42
  Speaker 1: with it. Then, less than a month before the accident,
• 4:45
  Speaker 1: on the 27th of June, the aircraft suffered an engine
• 4:48
  Speaker 1: surge violent enough that the crew rejected a takeoff outright.
• 4:51
  Speaker 1: The number one engine was pulled and replaced. four separate
• 4:54
  Speaker 1: interventions on the same system in 13 months. The EPR,
• 4:59
  Speaker 1: the engine pressure ratio, is the instrument that tells the
• 5:02
  Speaker 1: autothrottle how much thrust each engine is actually producing. The
• 5:05
  Speaker 1: autothrottle trusts that reading completely and adjusts power to match
• 5:08
  Speaker 1: whatever the pilots have commanded. Patrick Gandel, director of the
• 5:12
  Speaker 1: French Civil Aviation Authority, stated publicly that the aircraft had
• 5:15
  Speaker 1: been inspected in France two or three days before the
• 5:17
  Speaker 1: accident and found to be in good condition. That inspection
• 5:20
  Speaker 1: is in the record. So is the maintenance pattern that
• 5:22
  Speaker 1: came before it. Both things are true at once, and
• 5:25
  Speaker 1: neither one cancels.
• 5:26
  Speaker 2: The other out.
• 5:27
  Speaker 1: Now picture ECLTV climbing through the dark north of Ouagadougou,
• 5:31
  Speaker 1: heading for 31,000 feet, carrying a system with four documented
• 5:35
  Speaker 1: failures behind it, and 116 people who had no way
• 5:39
  Speaker 1: of knowing any of this. Thirteen minutes after takeoff, the
• 5:43
  Speaker 1: crew made the first of two decisions the flight data
• 5:46
  Speaker 1: recorder would capture with total precision. A storm system was
• 5:49
  Speaker 1: building ahead of them. Captain Komoron Mogyo turned the aircraft
• 5:53
  Speaker 1: left to avoid it, Standard.
• 5:55
  Speaker 2: Prudent, even.
• 5:56
  Speaker 1: The kind of call a captain makes a hundred times
• 5:58
  Speaker 1: in a career without anyone downstream ever knowing it happened.
• 6:01
  Speaker 1: It is the second decision, the one they never got
• 6:04
  Speaker 1: the chance to make on purpose, that investigators would spend
• 6:06
  Speaker 1: nearly two years trying to reconstruct. At 1.47 in the morning,
• 6:11
  Speaker 1: ECL TV leveled at 31,000 feet. Cruise speed, 280 knots.
• 6:17
  Speaker 1: The autopilot and autothrottle were both engaged. Every instrument in
• 6:20
  Speaker 1: that cockpit said the flight was normal. Then the numbers
• 6:24
  Speaker 1: started lying. Two small probes on the outside of the engines,
• 6:28
  Speaker 1: the PT2 pressure sensors, measure incoming air and feed the
• 6:31
  Speaker 1: reading the autothrottle uses to calculate thrust. Investigators with the
• 6:35
  Speaker 1: French Bureau, the BEE, concluded that ice crystals had clogged
• 6:38
  Speaker 1: those probes. The anti-ice system that should have kept them
• 6:41
  Speaker 1: clear had not been switched on. Within two or three
• 6:44
  Speaker 1: minutes of reaching crew's altitude, the autothrottle began reading engine
• 6:47
  Speaker 1: pressure numbers that did not reflect reality. And because the
• 6:51
  Speaker 1: autothrottle believed exactly what its sensors told it, it did
• 6:54
  Speaker 1: the only logical thing a machine can do with false data.
• 6:58
  Speaker 2: It reduced thrust.
• 7:00
  Speaker 1: Speed dropped from 280 knots through 240 through 200. The
• 7:05
  Speaker 1: aircraft needed power it was no longer getting. The autopilot, meanwhile,
• 7:09
  Speaker 1: was still doing its job, holding 31,000 feet exactly as programmed.
• 7:14
  Speaker 1: But as speed bled away and lift went with it,
• 7:16
  Speaker 1: holding that altitude took more and more nose-up pitch. The
• 7:18
  Speaker 1: autopilot commanded it, The nose kept rising. The angle of
• 7:22
  Speaker 1: attack climbed past 11 degrees, past 15, past 20, and
• 7:25
  Speaker 1: 11 degrees is roughly where the MD-80 stalls. At 24 degrees,
• 7:29
  Speaker 1: the aircraft was not flying anymore, in any sense that matters.
• 7:33
  Speaker 1: The stick shaker triggered. A mechanical jolt through the control column,
• 7:36
  Speaker 1: built to be impossible to ignore. Three seconds later, a
• 7:40
  Speaker 1: synthesized voice spoke on the captain's speaker.
• 7:42
  Speaker 2: One word.
• 7:44
  Speaker 1: Stall. 25 seconds after the stick shaker first fired... The
• 7:49
  Speaker 1: autopilot disconnected. What the crew did inside those 25 seconds
• 7:53
  Speaker 1: is the one question the cockpit voice recorder can never answer.
• 7:57
  Speaker 2: The tape was later found in a degraded magnetic state.
• 7:59
  Speaker 1: Its recordings fragmented and scattered across hours of unrelated archived audio.
• 8:04
  Speaker 1: Investigators recovered only broken pieces of radio traffic.
• 8:07
  Speaker 2: No voices from that cockpit survive. No commands. No call-outs.
• 8:11
  Speaker 2: No reactions.
• 8:13
  Speaker 1: What the flight data recorder shows is only what the
• 8:15
  Speaker 1: aircraft did. The left wing dropped. The nose pitched down.
• 8:19
  Speaker 1: The control surfaces moved. Pitch up, right bank. Proof that
• 8:22
  Speaker 1: hands were on the controls, that inputs were being made.
• 8:25
  Speaker 1: But the descent was never arrested. At 1.47 in the morning,
• 8:29
  Speaker 1: ECLTV struck the.
• 8:30
  Speaker 2: Ground near Gossi.
• 8:32
  Speaker 1: Altitude at impact, 1,600 feet above sea level.
• 8:36
  Speaker 2: Speed, 380 knots.
• 8:38
  Speaker 1: The recorder stopped transmitting at that instant, and the mystery
• 8:41
  Speaker 1: it left behind sealed itself shut.
• 8:43
  Speaker 2: Here is where the story could simply end. Machine failure. Physics. Silence.
• 8:49
  Speaker 1: But there is a detail in the record that refuses
• 8:51
  Speaker 1: to let it end that easily. In those final minutes,
• 8:54
  Speaker 1: the crew requested a return to Burkina Faso. That communication
• 8:57
  Speaker 1: was recovered. They knew something was wrong. They were trying
• 9:01
  Speaker 1: to get back, not frozen, not asleep, not overwhelmed into stillness.
• 9:05
  Speaker 1: Two people who had flown this corridor a combined 88
• 9:08
  Speaker 1: times in five weeks were doing exactly what pilots are
• 9:10
  Speaker 1: trained to do, work the problem, turn for home, buy time.
• 9:15
  Speaker 2: They were fighting, and they.
• 9:17
  Speaker 1: Were losing to a chain of failures Nobody had trained
• 9:19
  Speaker 1: them to recognize in the specific, quiet, deceptive form it
• 9:23
  Speaker 1: took that night. That is worth sitting with for a moment,
• 9:27
  Speaker 1: because everything that follows in this story is really an
• 9:29
  Speaker 1: attempt to answer one question.
• 9:31
  Speaker 2: What, exactly, were they fighting?
• 9:34
  Speaker 1: The interval between the stick shaker and the autopilot disconnecting,
• 9:37
  Speaker 1: 25 seconds, is not a gap in the story. It
• 9:41
  Speaker 1: is the window the entire case has been fought over.
• 9:44
  Speaker 1: Two experienced pilots were in that cockpit while a stall
• 9:46
  Speaker 1: warning sounded.
• 9:48
  Speaker 2: They were not asleep.
• 9:49
  Speaker 1: They were not incapacitated. They had just deviated cleanly around
• 9:52
  Speaker 1: a storm. They were flying, actively, competently, right up until
• 9:57
  Speaker 1: they were not. The BEA's reconstruction lays out a sequence
• 10:00
  Speaker 1: that is almost architectural in its cruelty. The autothrottle was
• 10:04
  Speaker 1: reading corrupted EPR values, and so was the crew, because
• 10:07
  Speaker 1: the EPR gauge, their primary instrument for understanding engine thrust,
• 10:11
  Speaker 1: was showing them whatever the corrupted sensors reported.
• 10:14
  Speaker 2: If those false numbers.
• 10:15
  Speaker 1: Looked plausible, even slightly low but not alarming, the crew
• 10:18
  Speaker 1: may never have identified a sensor failure at all. They
• 10:21
  Speaker 1: may have believed their engines were producing something close to
• 10:23
  Speaker 1: commanded thrust. That belief, if it existed, would have been catastrophic.
• 10:30
  Speaker 1: The correct response to a stall is immediate and specific.
• 10:33
  Speaker 1: Push the nose down, add full thrust, recover. But if
• 10:36
  Speaker 1: your instruments are telling you the engines are already producing
• 10:38
  Speaker 1: near-normal power, the instinct to slam the throttles forward gets blunted.
• 10:43
  Speaker 1: The instruments were arguing against exactly what the pilots' bodies
• 10:45
  Speaker 1: must have been screaming at them to do. The official
• 10:48
  Speaker 1: cause was confirmed on the 22nd of April, 2016, by
• 10:52
  Speaker 1: the Malian Commission of Inquiry. Ice crystals obstructed the PT2
• 10:55
  Speaker 1: pressure sensors. Corrupted data reached the autothrottle.
• 10:59
  Speaker 2: Thrust fell.
• 11:00
  Speaker 1: Speed bled away. The autopilot held the nose up until
• 11:02
  Speaker 1: the aircraft could no longer fly. 116 people died in
• 11:06
  Speaker 1: a stall that began with sensors that had no protection
• 11:09
  Speaker 1: against ice, because the switch that would have protected them
• 11:11
  Speaker 1: was off. That cause reads as mechanical.
• 11:15
  Speaker 2: Impersonal.
• 11:16
  Speaker 1: The kind of conclusion that makes an accident feel inevitable,
• 11:19
  Speaker 1: as though no human hand was ever really involved.
• 11:22
  Speaker 2: But hold that version against everything already laid out here.
• 11:24
  Speaker 1: The year of documented EPR failures, the aborted takeoff less
• 11:28
  Speaker 1: than a month earlier, the fifth and final intervention that
• 11:30
  Speaker 1: nobody logged because it was the crash itself, and the
• 11:32
  Speaker 1: story stops being purely mechanical. It becomes organizational. On a
• 11:36
  Speaker 1: wet lease arrangement between a Spanish operator and an Algerian airline,
• 11:40
  Speaker 1: flying across West Africa at one in the morning into
• 11:42
  Speaker 1: known storm weather, The question of who was responsible for
• 11:45
  Speaker 1: making sure that anti-ice switch got flipped is not a
• 11:48
  Speaker 1: technical question. It is a question about a chain of command.
• 11:52
  Speaker 1: French investigating magistrates eventually reached a similar conclusion, that the
• 11:56
  Speaker 1: crew's failure to recognize deteriorating engine parameters pointed not to
• 12:00
  Speaker 1: pilot error sitting alone, but to the conditions under which
• 12:03
  Speaker 1: that crew had been trained, briefed, and sent out to fly.
• 12:07
  Speaker 1: A more cautious reading exists, too, that the anti-ice omission
• 12:10
  Speaker 1: may have been a single lapse in an otherwise ordinary flight.
• 12:13
  Speaker 1: and that the sensors failed faster than any crew could
• 12:15
  Speaker 1: reasonably have diagnosed in time. Both readings sit in the
• 12:18
  Speaker 1: same case file. Neither one fully clears the system that
• 12:21
  Speaker 1: put six crew members and 110 passengers on that aircraft
• 12:25
  Speaker 1: on that night with that maintenance history behind the instrument panel.
• 12:29
  Speaker 1: What the evidence does not support is the idea that
• 12:31
  Speaker 1: any of this was unavoidable. The anti-ice system was there.
• 12:35
  Speaker 2: It had a switch. That switch was never turned on.
• 12:38
  Speaker 2: The legal reckoning has taken longer than anyone expected.
• 12:41
  Speaker 1: In May of 2021, Paris judicial authorities ordered Swiftair to
• 12:45
  Speaker 1: stand trial for involuntary manslaughter and negligence. No individual crew
• 12:49
  Speaker 1: member was charged, only the company. What followed was nearly
• 12:53
  Speaker 1: five years of postponements, a referral to the European Court
• 12:55
  Speaker 1: of Justice, and a second referral that was rejected in turn.
• 12:59
  Speaker 1: The trial finally opened on the 9th of March, 2026,
• 13:02
  Speaker 1: nearly 12 years after the crash, and closed the following
• 13:05
  Speaker 1: month without a verdict. Fernando Llorens, Swiftair's vice-president, offered condolences
• 13:11
  Speaker 1: to the families and said a lack of respect for
• 13:13
  Speaker 1: regulations could not be attributed to his company. Suzanne Ayo,
• 13:16
  Speaker 1: who leads the French Families Association, said she hoped the
• 13:19
  Speaker 1: truth would emerge to identify what each party was responsible for.
• 13:23
  Speaker 1: Remember the sentence to hold on to. Maître Halidou Ouedraogo,
• 13:27
  Speaker 1: representing 28 Burkina Bay families who could not afford to
• 13:30
  Speaker 1: sit in that Paris courtroom, said the families no longer
• 13:32
  Speaker 1: wanted Africa to become a dumping ground where planes in
• 13:35
  Speaker 1: poor condition are sent to fly. Put that sentence next
• 13:37
  Speaker 1: to the switch that was never turned on. put it
• 13:40
  Speaker 1: next to an 18-year-old airframe with four documented failures in
• 13:43
  Speaker 1: the exact system that killed everyone aboard. Said that way,
• 13:46
  Speaker 1: it stops sounding like grief. It starts sounding like an
• 13:48
  Speaker 1: accusation with a paper trail behind it. Some of the
• 13:51
  Speaker 1: victims have never been identified. Their remains are to be
• 13:54
  Speaker 1: buried in Bamako. In Paris, in the Parc de Bercy,
• 13:59
  Speaker 1: there is a path named in 2019. The Allée des
• 14:02
  Speaker 1: Sansez Victimes du Vol AH5017 du 24 juillet 2014. 116 names.
• 14:08
  Speaker 1: in a place where people walk in the afternoons without
• 14:10
  Speaker 1: knowing what they are walking past. In Ouagadougou, a memorial
• 14:15
  Speaker 1: was inaugurated on the 24th of July, 2018, in front
• 14:18
  Speaker 1: of the country's president. It marks the place most of
• 14:20
  Speaker 1: those people left from and never came back to. At 1.47
• 14:24
  Speaker 1: in the morning, on the 24th of July, 2014, a
• 14:28
  Speaker 1: flight data recorder stopped transmitting. That was the number this
• 14:31
  Speaker 1: story opened with. What it could not tell you then
• 14:33
  Speaker 1: was everything that came before it. An 18-year-old aircraft with 32,000
• 14:37
  Speaker 1: cycles lobbed, Four documented failures in the one system that
• 14:41
  Speaker 1: failed that night. A crew that had flown this exact
• 14:43
  Speaker 1: route a combined 88 times in five weeks. A storm
• 14:46
  Speaker 1: they saw coming and turned to avoid. Sensors with no
• 14:49
  Speaker 1: protection at all against the ice hiding at that storm's edge.
• 14:53
  Speaker 1: The autothrottle did exactly what it was built to do
• 14:55
  Speaker 1: with the data it was given.
• 14:56
  Speaker 2: It reduced thrust.
• 14:58
  Speaker 1: The autopilot did exactly what it was built to do.
• 15:00
  Speaker 1: It held altitude. Both systems obeyed their instructions perfectly. Right
• 15:04
  Speaker 1: up until the laws of physics made obedience impossible. 147
• 15:08
  Speaker 1: was never the start of a chain of bad luck.
• 15:10
  Speaker 1: It was the end of a chain that can be traced,
• 15:12
  Speaker 1: link by link, back through maintenance logs and cost decisions,
• 15:16
  Speaker 1: and the particular economics of a wet lease agreement crossing
• 15:18
  Speaker 1: three countries. The stall warning said one word on the
• 15:22
  Speaker 1: captain's speaker. Just the one word. What the cockpit voice
• 15:25
  Speaker 1: recorder can never tell us is whether that word arrived
• 15:28
  Speaker 1: with enough time behind it to mean anything at all.
• 15:31
  Speaker 2: That silence.
• 15:32
  Speaker 1: Not the crash, but the silence left in the recorder afterward.
• 15:36
  Speaker 1: is what the families of 116 people have been living
• 15:39
  Speaker 1: beside for over a decade. They know exactly what the
• 15:42
  Speaker 1: data says. They will never know what was actually said.
• 15:46
  Speaker 1: A path in a Paris park carries 116 names. Some
• 15:50
  Speaker 1: of them still cannot be attached to remains. Somewhere in
• 15:52
  Speaker 1: a courtroom that has already spent five years reaching no conclusion,
• 15:56
  Speaker 1: the file remains open. The anti-ice switch was there. It
• 16:00
  Speaker 1: was designed to prevent exactly this.
• 16:02
  Speaker 2: It never moved. This show is made by Oba Media.