This holiday season seemed to be filled with commercial aviation incidents. Spirit Airlines filed for chapter 11 bankruptcy. A 737-400 crashed near a house, killing one person and injuring three more. Azerbaijan Airlines 8243 was shot down on December 25, resulting in the death of 38 out of 67 passengers. And most recently, Jeju Air Flight 2216 performed a belly landing and overran the runway, killing 179 out of 181 occupants. The only survivors were the two flight attendants located at the back of the plane.
Still, research shows the airline industry is still highly reliable. A recent MIT study1 found that the risk of a fatality from commercial air travel is 1 in 13.7 million. Incidents like Jeju Air 2216 are highly unusual. In fact, this disaster set several grim milestones in aviation history:
The media is buzzing with speculation, and debates over the root cause are in full swing. Let’s step back and examine the knowns and unknowns as we begin to make sense of this exceptional event.
On December 29, the aircraft took off from Suvarnabhumi airport at 2:28 local time en route to Muan International Airport (MWX) in South Korea. The aircraft was cleared to land at Muan on a routine approach for Runway 01. This was the LOESS6 approach, directly from the south (see diagram below).
Muan International ILS Approach Runway 01 (Korean Office of Civil Aviation)
However, at 8:57 AM local time, MWX air traffic control (ATC) broadcast a warning of bird activity in the area. MWX is in a wetlands area on the southern side of South Korea. The airport has a chart for pilots warning them of the bird concentration around the runway.
MWX Bird Concentration Chart (Korean Office of Civil Aviation)
The above diagram shows not only where birds tend to feed and roost, but also the typical travel pattern of the birds and their elevation. You’ll see that on both sides of the runway, between 0 and 163 feet above ground level (AGL), it’s common to see birds going between the feeding and roosting areas. The normal approach to runway 01 intersects the travel path of the birds.
On approach, the pilot of Jeju Air 2216 has the plane configured for landing to the north, with the gear down, and flaps deployed. At 8:59 AM the pilot reported a bird strike, declared an emergency, and announced a go-around. At this time, the pilot retracted the flaps and landing gear to perform the go-around.
One minute later, at 9:00 AM, the pilot requested authorization to land on Runway 19 to the south, which is the same runway as 01, but in the opposite direction. Air Traffic Control (ATC) then cleared the aircraft to land. The pilot performed a teardrop turn7 (steep descent) to land on Runway 19. At 9:02 AM, the plane touched down on the runway approximately 1,200 meters past threshold (the front end of the runway) and performed a belly landing (gear up).
At 9:03 AM, unable to slow down, the 737-800 skidded past the runway, crashing into an embankment located south of Runway 19.
Immediately after the incident, mainstream media and social media commentators started to debate the root cause. It’s a typical reaction to complex events with many factors at play. Let’s look at what the common conversations are and explore them in a Cause Map™ diagram.
We start the analysis—yes, even catastrophic events—with a simple 5-Why. It’s an easy way to start, the first phase, but only part of a thorough explanation.
Jeju Air 2216 5-Why Analysis
This partial analysis explains why we’re seeing a lot of people blaming the berm. The logic applied here is: “If there wasn’t a berm at the end of the runway, this incident wouldn’t have happened.” That is certainly true, but we can see how people end up arguing over it. Because another group might counter:
All these views make sense, but the disagreement comes from the partial explanation.
As we start to expand our analysis, we can move beyond opinions to objective, evidence-based discussions. We know the physics requires both the plane and the berm to be in the same location at the same time. This is an example of one of our Fundamental Relationships: contact.
The berm was located at the end of Runway 19 to provide support to the Instrument Landing System (ILS) antenna array.
Berm Location (Image by Google Maps, Annotated by ThinkReliability)
Imagery ©2025 Airbus, Imagery ©2025 Airbus, CNES / Airbus, Maxar Technologies, Map data ©2025 TMap Mobility 500 ft
It is currently unclear whether providing support for the ILS antenna was the only purpose for the berm. In the USA, ILS antenna arrays are supported with frangible supports so that if an aircraft overruns the runway, the plane will not be catastrophically destroyed. The other theory I’ve read is that this berm was there to protect the public. Indeed, there is a public area to the south of the Runway 19, but it is approximately 400 – 700 meters from the berm.
Because we don’t currently know whether the berm was situated in its exact location only for the ILS antennas or for other reasons, we’ll place question marks on the related causes to indicate missing evidence in our Cause Map diagram.
Jeju Air 2216 9-Why Analysis
Now, let’s focus on why the plane skidded off the runway by examining the speed of the plane and the landing location.
The plane skidded off the end of the runway because it was unable to stop by the end of Runway 19. It was unable to stop because it continued moving forward, landing approximately 1200 meters past the threshold at a high speed. In the video8, you can see that the flaps are not extended, and the landing gear is up.
For a 737-800 in clean configuration, the minimum stall speed is 128 knots (147mph). Based on estimates of the video and the wind at the time of the event, most experts are estimating a ground speed of approximately 160 knots (184 mph). The plane did appear to have the reverse thruster engaged on its #2 engine, but that alone wasn’t able to slow the plane down in time. We’ll add the speed of the plane into our Cause Map diagram below.
Jeju Air 2216 12-Why Analysis
Now let’s examine the landing location far down on Runway 19. On its final approach to Runway 01, Jeju Air 2216 experienced a bird strike. Shortly after the bird strike, the pilot and co-pilot retracted the landing gear and flaps and requested to land on Runway 19. On their final approach to Runway 19, they performed a teardrop turn—a difficult maneuver with little margin for error.
Bird Strike and Teardrop Turn (Image by Google Maps, Annotated by ThinkReliability)
Imagery ©2025 Airbus, Imagery ©2025 Airbus, CNES / Airbus, Maxar Technologies, Map data ©2025 TMap Mobility 500 ft
When the pilot landed on Runway 19, he landed approximately 1200 meters past the threshold.
Jeju Air 2216 Landing Location (Image by Google Maps, Annotated by ThinkReliability)
Imagery ©2025 Airbus, Imagery ©2025 Airbus, CNES / Airbus, Maxar Technologies, Map data ©2025 TMap Mobility 500 ft
This shows that the landing location of the aircraft also contributed to its inability to stop at the end of the runway. We’ll incorporate this information into our Cause Map diagram.
Air 2216 16-Why Analysis
As a bit of an armchair flight simulator pilot myself, I have a lot of questions about this incident. Based on my research and conversations with multiple pilots, I’ve found that the typical response after the bird strike would have been to complete the landing. When the strike occurred, the plane had the flaps deployed and gear down. So, it would have made the most sense to just land.
We don’t know the condition of the aircraft, or what the pilots were dealing with when all of this happened. In hindsight, the decisions to retract the flaps and gear, and the teardrop turn to land the other direction with the wind seem puzzling. The Quick Reference Handbooks (QRHs) regarding engine-out procedures and non-functional flaps for the 737-800 do not advise to perform a belly landing. All the QRHs that would apply in this incident tell the pilot to manually deploy the landing gear. The hydraulic system on the 737-800 is complicated, but it’s built with redundancy. Even if both engines were out, the pilots can manually drop the landing gear with a pull cord behind the pilots seats.
The brakes provide the most stopping ability for planes when landing. Removing this ability was a highly unusual choice—one we hope to explore further when the black box data is recovered.
For a more comprehensive analysis of what we know thus far, download our interim Cause Mapping® investigation file. I look forward to your thoughts and theories. Stay tuned for an update when more information becomes available.
Click on image to view the full intermediate investigation report1 - MIT study: https://www.sciencedirect.com/science/article/abs/pii/S0969699724001066?dgcid=author#appsec2
2 - Korean Air Flight 801: https://en.wikipedia.org/wiki/Korean_Air_Flight_801
3 - Aviation accident: https://en.wikipedia.org/wiki/Aviation_accident
4 - Boeing 737 Next Generation: https://en.wikipedia.org/wiki/Boeing_737_Next_Generation
5 - Lion Air Flight 610: https://en.wikipedia.org/wiki/Lion_Air_Flight_610
6 - LOESS is not an acronym, it is the name of the waypoint to assist in landing.
7 - Teardrop Turn: Youtube Video Example
8 - Video of the incident (Warning: Graphic Content)