A Southwest 737-700 suffered an uncontained engine failure on Tuesday, requiring an emergency landing in Philadelphia. Flight 1380 was flying between New York and Dallas with 143 passengers and five crew members when the incident occurred.

While the plane landed safely, with most passengers unharmed, seven were treated for minor injuries, and the AP is reporting that one woman has perished, presumably the passenger sitting near the damaged window who was “partially pulled from the aircraft“.

Aviation accidents are fortunately uncommon (this is the first fatality onboard a US carrier since 2009), and both the 737 and these engines are incredibly reliable. Southwest had a previous incident with this configuration in 2016, and the pilot was able to land the plane safely with no significant injuries to passengers or crew.

The difference, in this situation, is that the shrapnel from the engine failure pierced a window of the aircraft, leading to cabin depressurization and the passenger injuries.

You can see the window that was broken in this image — it’s significantly aft of the engines, which is also unexpected. The design of the 737 allows for a missing window above the engine (by the front leg of the “h” in “Southwest”) as a protective measure should anything happen to the engine. (Edit: this is also the location of the HVAC ductwork, but I believe the placement choice of the latter is still informed by the desire to have improved structural integrity in this location).

While it’s too soon to speculate, a focus of the NTSB investigation will almost certainly involve why the debris scattered in such a way, along with the determining the cause of the engine failure itself.

Southwest CEO Gary Kelly has a statement here:

And you can find the initial National Transportation Safety Board briefing here:

LIVE: NTSB holds press conference on Southwest Airlines flight

This is a tragic accident, and I’m sure it was a terrifying experience for those onboard. It’s fortunate that the crew was able to react quickly, and that the plane was able to be landed quickly and safely. You can hear the audio of the very calm and collected pilot interacting with ATC here:

Similarly to when we see videos of passengers evacuating aircraft with their hand baggage in-tow, the images shared by some of the passengers serve as a reminder to always pay attention to the safety briefing, even if you’re a regular traveler. Seatbelts should always be worn when seated — the pilot may not have time to turn on the Fasten Seatbelt Sign in an emergency — and should oxygen be needed, the mask goes over your mouth and nose.

It can be difficult to remember all the procedures during an emergency, and quick execution is critical. Despite the incredibly safe nature of air travel, accidents can happen.

There will be more information in the coming days and months as the NTSB and other groups investigate the incident. In the meantime, our thoughts are with the passengers, crew members, and families involved.

(Featured image via David Maialetti /The Philadelphia Inquirer via AP)