The plane was at 32,000 feet when the left engine of the Southwest Airlines 737 suddenly disintegrated. It was flying at nearly 500 miles per hour and what happened next occurred in almost milliseconds — shrapnel from the engine rocketed into the side of the plane and punctured a passenger window and almost sucked one woman passenger out of the plane through the hole in the window. She died. The hole caused a rapid decompression inside the cabin and oxygen masks dropped. Inside the cockpit, the pilots knew they had two problems — loss of an engine (thrust) and rapid decompression. They had to make split second decisions — drop the plane below 10,000 feet, regain stability and fly the plane on one engine, and declare an emergency — before flying to the nearest airport with the longest runway (Philadelphia).

 

And that’s exactly what they did.  Now, what happens next will tell investigators whether this was an isolated, rare incident or a system problem with Southwest engines or its planes. There’s a nearly 100% chance it will be the former.

 

The investigators will painstakingly begin to deconstruct the events and all the component parts and systems of the plane, look at the pilots’ history, the maintenance history of both the plane and the engines and other factors ranging from weather to metallurgy; from fuel to electrical.

 

And one by one, they will begin to rule out things that could not have happened before they can begin to rule in any sort of probable cause. For example, at that altitude, they can easily deduce it was not a bird strike. And at this point, that’s about all they know.  They will look at engine performance to see if there was any sign of a problem before the left engine blew apart. They will look at the engine’s fan blades to check for any signs of alignment failure or disintegration. They will analyze the engine itself, especially the compressor to see if it stalled (or failed) which might have led to that immediate incident.

 

They will also check the airframe of the 18 year old jet. They will study any and all maintenance records of the 737 dating back to when it rolled off the assembly line. And in the case of Southwest, which only flies the 737, the investigators will also take a hard look at the entire fleet to see if there might be a more serious systemwide problem.

 

And they will look at everything from the crew’s history to the condition of the runway at LaGuardia to check other possible contributing factors. In any airline accident, there is the catalytic reason for the incident and then there are the underlying reasons. No possibility at this point is overlooked.

 

Again, chances are this was hopefully an isolated incident on an airline that has a stellar safety record (and an excellent safety culture). The pilots performed very well under very challenging conditions. Other than the one fatality (the first passenger death in Southwest’s history), there were remarkably few injuries. 

 

But one thing is certain…we will learn from this tragedy. It will probably take a year for the National Transportation Safety Board to issue its final report on the probable cause. We will stay on top of this story throughout the investigation.