In episode 97 of Take to the Sky: the Air Disaster Podcast, we explore Loganair Flight 6780, which is struck by lightning while on approach to Sumburgh Airport in the Shetland Islands, Scotland on December 15, 2014. After the strike, the pilots struggle against the controls to get the plane to climb, and then it begins to dive toward the South Sea at a high rate of speed. At the very last minute, and with only 1,100 feet left before impact, the pilots regained control of the plane and land safely back at Aberdeen Airport, saving the lives of all 33 people onboard. The shocking AAIB investigation found that the lightning strike had not negatively effected the plane’s performance; instead, the captain had incorrectly assumed that the autopilot had disengaged once lightning struck the plane. But on the SAAB 2000, the autopilot did not disengage – and that was the reason why the controls were so difficult. The plane had been configured in a nose down trim while on autopilot and the pilots tried to make a nose up input. And the only thing that allowed the pilots to regain full control over the aircraft was that during the final seconds of the steep dive, a glitch in one of the plane’s main computer systems disconnected the autopilot, which allowed the pilots to have manual control over the plane and climb to a higher altitude. Following this near-fatal crash, the AAIB made many recommendations, including to 1) review the design of the Saab 2000 autopilot system and require modification to ensure that the autopilot does not create a potential hazard when the flight crew applies an override force to the flight controls, which did eventually lead to the redesign of this autopilot system, and 2) require that an aircraft certification can only be met if the autopilot automatically disengages when the flight crew applies a significant override force to the flight controls and the auto-trim system does not oppose the flight crew’s inputs. Saab 2000 pilots were also required to attend 8 hours of training to ensure they understood the differences between this model and others.
Loganair Flight 6780 Flies Over South Sea in Storm While on Approach to Sumburgh Airport
It’s about 7 PM local time on December 15, 2014, and Loganair Flight 6780 is once again in the air over the South Sea, completing its regular route between Aberdeen Airport and Sumburgh Airport in the Shetland Islands, in Scotland.
Piloting this Saab 2000 turbo prop aircraft is the 42-year-old captain who had been employed by Loganair since 2005. And just to note, we do not have the names of the crew for this story. For now, we will refer to the captain by his title and to the first officer by her title only. The captain had a total of 5,780 flight hours, including 4,640 hours on a different Saab series aircraft and 143 hours on this type of Saab. Joining the captain is the 35-year-old first officer who had been employed by Loganair since early 2014. She had a total of 1,054 flight hours, including 260 hours on the Saab 2000.
Not to begin our story with too much drama, but it was a dark and stormy night as Flight 6780 and its 30 passengers and 3 crew members cruised along at 24,000 feet altitude (or 7,315 meters). But the stormy weather was not a surprise. In fact, before taking off from Aberdeen Airport, the captain and first officer had briefed for their flying duties and discussed the weather conditions which they expected to encounter inflight.
The majority of tonight’s route is being flown over the South Sea. Now about halfway through their 65-minute flight to their destination in Sumburgh, they begin their descent toward 11,000 feet (or 3,352 meters). Because of the storm and what may lay ahead of them, the captain wants to prepare. He first tunes into ATIS, or the Automatic Terminal Information Service, to hear the latest weather at the airport, which said the wind at the airport was gusting to 47 knots (or 54 mph) and visibility was limited in heavy rain and snow.
Because of these stormy conditions in front of them, the captain then briefed the first officer on actions they may need to take to mitigate the risk associated with a possible lightning strike at night. Though very rare, according to the show Air Crash Investigations, an aircraft is likely to be struck by lightning one and a half times per year. During their preparations, the flight crew turned up the cockpit lighting, located all the torches (or lights) in the flight deck, and made note of where the elevator emergency trim switch was located.
As they get closer to the airport, air traffic control (or ATC) provides Flight 6780 with a heading to the airport and the latest weather report, which confirms bad weather is still ahead. Hoping to prepare the cabin for what will most definitely be a bumpy ride, the captain turns on the fasten seatbelt sign for all passengers.
Now just 16 miles (or 26 km) from the airport and about 2,000 feet (or 609 meters) above the sea, Flight 6780 turns onto its final approach to the runway. As they do, the captain notices that on their weather radar display in the cockpit, severe weather is developing at the end of their assigned runway. Acknowledging that this level of convective activity may not be safe for landing, the captain lets ATC know that they will indeed discontinue this approach and circle back around, allowing enough time for the storm activity to move past the runway.
Loganair 6780 is Struck by Lightning While on Approach to Sumburgh Airport
But suddenly, as Flight 6780 circles above the ocean, an explosive sound pierces the plane, a sound that could be compared to that of a gunshot – it is sharp, sudden, and startling. Anyone onboard the aircraft would have heard this extremely loud crack of a sound followed by seeing a flash of light engulf the cabin. Unbelievably, Flight 6780 has just been struck by lightning.
The flight crew is momentarily blinded by the flash of light, but they soon recover and regain their bearings in the cockpit. The first thing the flight crew must do is examine the circuit breakers to see if any breakers have popped. Luckily, everything seems to be OK. The captain confirms that the autopilot has disengaged, and he takes control of the aircraft. But as he does, he immediately notices how unusually heavy the controls feel. Much to the captain’s surprise, he realizes with a shock that the controls are not responding to any of his inputs. The first officer also tries her controls, but the same thing happens – they feel heavy and do not respond to her inputs. In fact, it would later be determined that the amount of pull on the controls is equal to 80 pounds of force.
The first officer contacts ATC and declares “mayday”, requesting that ATC clear the airspace for them. With further discussion and without knowing how well the aircraft could in fact perform, the pilots decide to divert and land back at their origin point, at Aberdeen. Though this airport is 190 miles (or 305 km) away, much further than Sumburgh which is just minutes away, the aircraft has enough fuel to make the trek back to Aberdeen. The crew also feels it is unsafe to try and land at Sumburgh given the weather and the uncertainty facing them as they try to assess how the plane has been affected by the lightning strike. There is no indication in the final report that this decision to divert was anything but the right call.
To get back to the airport at Aberdeen, the plane must climb. The captain tries to initiate a climb up to 4,000 feet (or 1,219 meters), but the plane struggles to climb and does so at a sluggish rate. While this is concerning, this is nothing compared to what happens next.
Loganair Flight 67800 Enters Dangerous, High Speed Dive as Pilots Fight for Control
Suddenly, the plane begins nosediving – and fast. In just seconds, and with only being 4,000 feet high when they first began to fall at a speed of over 350 mph (or 560 kph), Flight 6780 falls through 1,800 feet (or 548 meters). The crew desperately wrestles for control of the plane, pulling back on the controls with all their might, tying to get the nose to pitch up.
Now they fall through 1100 feet (or 335 meters). As a last-ditch effort, the first officer calls out “speed! speed!” and the captain increases power to all engines. Having now been diving for almost 20 seconds, and with less than 1100 feet remaining between them and the sea, miraculously, the aircraft finally begins to climb. This is an incredible stroke of luck – the plane was only 7 seconds from smashing into the sea at a high rate of speed of almost 400 mph – they had been falling at a rate of 9500 feet (or 2,895 meters) per minute. No one would have survived that impact with the sea. But, they pulled up and made it!
Loganair Flight 6780 Lands Safely at Aberdeen Airport With all 33 People Onboard Alive
Taking no chances and wanting all the altitude they could get, the flight crew climbs back to 24,000 feet (or 7,315 meters). And now, the controls are working better and responding to the flight crew’s inputs. Soon thereafter, Flight 6780 is on its final approach to Aberdeen, the flight crew carefully configures the plane for landing. And then at 8 PM local time, and about an hour and forty minutes after they first took off, the plane touches down safely on the runway – a landing so smooth and routine no one would have ever known what had just happened.
Loganiar 6780 Passengers Share Frightening Account of Lightning Strike and Nosedive
Because all 30 passengers survived, here are a few published accounts of what it was like to be onboard Flight 6780. Shona Mason bought her ticker on the flight because she was returning from a holiday. She described the ordeal as “really, really bumpy” and said if you were already afraid of flying and had been on this flight, it would have been your worst nightmare. Shona recounts the moment that things went terribly wrong: “We were on descent and I said to my partner, we’re going back up again, and just as we started to go up again there was an almighty bang and a flash that went over the left wing. Then we were really ascending, and at that point there were a few folks looking around going ‘oh my God, what’s happening?’ The poor guy across the isle from me just had eyes like rabbits in headlights.” Shona said it was only after they landed in Aberdeen and the captain, looking a little shaken, came out of the cockpit to speak to passengers that she realized how potentially serious the incident could have been.
Another Flight 6780 passenger who was heading up to work in Shetland for a week, was so shaken that he decided he wasn’t getting back on the plane the next day and headed home instead.
Another passenger travelling home on the flight, Sanna Aitken, said the flight had gone smoothly until the lightning struck, which she actually thought was an engine bursting because she hadn’t seen any lightning out the window prior to the strike. Despite the terror of the dive, she decided to focus on the positive fact that there did not seem to be any onboard fire and the plane still had its two wings and engine power. During the rapid dive, Sanna noticed that a man sitting behind her was using up a pile of sick bags, and he eventually threw up. Sanna found herself hanging on to the arm of the woman sitting beside her. When they landed, she let out a big sigh and burst out crying.
AAIB Investigates Near-Fatal Accident of Loganair 6780
The Air Accident Investigative Branch (or AAIB) is on the scene in Aberdeen to begin its investigation into what nearly cost the lives of 30 passengers and 3 crew members. Because this accident was not fatal, investigators have the privilege of interviewing the crew.
One interesting account came from the flight attendant, who said that she observed a rare phenomenon in the cabin right before the lightning strike: she said she saw ball lightning, which is a glowing ball of light that will appear before lightning strikes. These balls can even float like an orb and move around.
Next, investigators interview the flight crew, who explained that the plane experienced a lighting strike while it circled back around near Sumburgh Airport, followed by the disengagement of the autopilot. Next, the crew recounted their difficulties with the flight controls, the terrifying steep dive, and then the last-minute recovery.
AAIB Finds Evidence of Lightning Strike on Loganair Plane, But It Had No Effect on Flight Performance
When investigators examine the aircraft, they do find evidence of a lightning strike, and based on the exterior burn marks on the aircraft, investigators can tell that the lightning first struck the nose of the aircraft, traveled through the plane and exited at the exhaust cone.
Even though investigators understand the sequence of events, the flight crew’s account does not explain why a lightning strike would have impacted the aircraft so severely. This is because the impact of the lightning strike on the plane’s systems are basically nonexistent – every system on the plane checks out – nothing is malfunctioning. There is no evidence to suggest why the crew lost control of the plane after the strike – it absolutely had nothing to do with the lightning.
Unfortunately, the cockpit voice recorder (or CVR) only captured the final 30 minutes of the flight, which recounted the landing at Aberdeen, but nothing of the ordeal following the lightning strike. Investigators must rely on the data from the flight data recorder (or FDR), focusing on the inputs the pilots made in their effort to recover the plane from the steep dive.
Analyzing the data, investigators see when the lightning strike happened as they were circling at 2,000 feet (or 609 meters), followed by the slow climb back up to 4,000 feet (or 1,219 meters), and then the steep nosedive.
AAIB Discovers that Autopilot Never Disengaged and Pilots Unknowingly Fought Against It for Control of Aircraft
When investigators look at the data from the flight crew’s control columns, they can see that the crew were trying to pull back on the controls in an effort to push the nose up. And this is where they first get some answers. They look at the pitch trim data and how the elevators performed during the flight. Let’s talk about how these components work together so we can understand how these components impacted our story.
The elevators are attached to the trailing edge of each wing and work together to either raise or lower the tail of the plane. The pitch trim moves the elevators up and down to maintain the pitch of the aircraft, which results in the nose pointing down or up, respectively, and enabling the aircraft to climb or descend. The pilot operates the elevators by moving the control column forwards or backward and the trim switches are also located on the control column.
When investigators look at the pitch trim data (the nose up or down control), they find that the aircraft’s elevators were trying to pitch the nose down and not up. They were doing this in spite of the fact that the pilots were actively trying to make a nose up pitch control by pulling their control column back towards them. This means the plane was actually trimmed nose down.
Here is why. Despite the flight crew’s account that the autopilot system had disconnected, it had in fact not disconnected after the lighting strike. And not only did it remain engaged, but it was set to keep the plane flying level at 2,000 feet – their approach altitude.
So, when the pilots tried to climb to 4,000 feet, they were unknowingly fighting with the autopilot system settings during this time – this explains why the controls were so heavy and the plane was trimmed nose down instead of nose up as they wanted it to be.
AAIB Investigation into Loganair Flight 6780 Accident Uncovers Design Flaws Within Saab 2000 Autopilot System
This steers the investigation toward the discovery of several problems that eventually lead to recommendations following this accident.
One problem is with how the autopilot system indicator shows the system is on or off. The green letters ‘AP’ are presented on the display panel when the autopilot is engaged. And when it switches off, the letters “AP” remain lit but only change colors from green to white. Investigators felt that during high stress situations like Flight 6780, it would be easy for pilots to miss this indicator change. Another problem was found in the captain’s training. The Saab 2000 series, the plane that was Flight 6780, was completely different than the other model which the captain had more experience flying. In his training for the other model, the Saab 340, his training taught him that during a lightning strike, autopilot would automatically disconnect. He assumed that would happen on the Saab 2000 aircraft, too, but it did not.
Another problem uncovered by the investigation was within the design of the autopilot system. Unlike almost every other aircraft, the autopilot on the Saab 2000 will not automatically disengage if a pilot applies great force on the control column or on the trim switches (which is exactly what the captain and first officer of Flight 6780 were doing). What troubles investigators about this design feature is that it means the autopilot system essentially has greater authority than the human pilots flying the plane.
Instead of the autopilot shutting off when a pilot applies force to the control column, in the design of the Saab 2000, the pilot is expected to press the autopilot disengage button on the control wheel before moving the controls, and the designers of the system probably expected that pilots would almost always do this. If the pilot forgot to disengage the autopilot first or was under the impression that the autopilot was already disengaged, it was probably expected that the additional force on the controls would be a cue to the pilot that the autopilot was still engaged. But of course, in most other aircraft, this was not read as a cue that it was ON but as a method pilots would use to actually turn OFF the autopilot.
Lastly, there would have been an audible chime that sounded that would have told the pilots that the autopilot was still engaged, and the plane was trimmed to be nose down. But, investigators believe that the flight crew were understandably too distracted by what was going on to hear the chimes and to notice the color change on the autopilot system indicator on the display panel. This is what investigators call cognitive tunneling, when you focus on fewer and fewer things under stress.
AAIB Finds Sheer Luck Saved Loganair Flight 6780 Flight from Complete Disaster
But as we know, the plane did pull up at the last minute when the captain applied full power to the engines. If all these things were happening with the autopilot and trim, how was this recovery even possible? The chilling truth is this: the 33 souls onboard Flight 6780 were saved only by a sheer stroke of luck.
The autopilot did eventually disengage, but only due to a random glitch – a momentary loss of data to the air data computer, where the autopilot system lives. The plane was trimmed nose down while the autopilot remained on, and it began to descend. The aircraft continued to descend and then accelerate as the engine output was gradually reduced and moved to flight idle. Then, the autopilot disconnects due to that random glitch. From there, the plane was able to climb when the captain applied full power. Had it disconnected 7 seconds later, all would have been lost. This is an astonishing finding on the part of investigators. Too much of a close call.
Following the near-fatal accident of Flight 6780, the AAIB issued five safety recommendations, including for agencies to 1) review the design of the Saab 2000 autopilot system and require modification to ensure that the autopilot does not create a potential hazard when the flight crew applies an override force to the flight controls, which did eventually lead to the redesign of this autopilot system, and 2) require that an aircraft certification can only be met if the autopilot automatically disengages when the flight crew applies a significant override force to the flight controls and the auto-trim system does not oppose the flight crew’s inputs. Saab 2000 pilots were also required to attend 8 hours of training to ensure they understood the differences between this model and others.
And THAT is the story of the very near miss of Loganair Flight 6780.