Pilots: A Tragic Aircraft Accident and a Reminder

The current issue of Flying writes up a tragic weather-related aviation accident over the skies of Kentucky. A Piper aircraft, flying at night, encountered a severe thunderstorm near Whitesville which led to the plane breaking up in-flight. There is an important lesson here for all pilots regarding the use of ground-based radars. 

The wreckage of the doomed flight. 

The article links to the National Transportation Safety Board's report and probable cause finding. Knowing we have a number of pilots among our readers, I thought a few comments would be helpful in avoiding this type of accident in the future. The article about the accident is here. 

The plane departed Bowling Green enroute to Owensboro. The pilot posted the screen capture below to his social media account. The radar was from 11:15pm, 34 minutes before the crash. 

The airplane symbol was the then-current position of the aircraft. At the end of the purple line was the planned destination, the Owensboro Airport (KOWB). The radar shows intense (red) thunderstorms with tops of 45,000 feet. At the very top, the pilot-in-command comments the storms look like "hornets." In my opinion, you never want to tangle with hornets, real or figurative. More important is the FAA forbids pilots of all types of aircraft to fly into thunderstorms. 

The above image is from ground-based radars, specifically the National Weather Service's WSR-88D. More on that in a moment. 

I suspected these might be severe thunderstorms so I checked Iowa State University's database and, sure enough:

The storms strengthened after the ground- based radar image (above) was seen by the pilots. Quarter-sized hail was forecast to occur. Remember: National Weather Service thunderstorm-related warnings (tornado, flash flood, severe thunderstorm) are not provided to pilots. We have discussed many times (example from 2011) on this blog that the Federal Aviation Administration intentionally does not provide tornado and severe thunderstorm warnings to pilots. They use less specific SIGMETS to convey thunderstorm hazards. 

Below is an image from the NTSB's report that shows the path of the aircraft with the circle in the vicinity of in-flight breakup. The thunderstorm had been moving rapidly toward the northeast as it intensified. 

Here's the problem: There is a lag of 1 to 2 minutes between the radar measuring the storm and it appearing on an in-cockpit displays. In this case, the lag issue was magnified by the fact the radar was being operated (inappropriately, in my opinion) in six-minute mode. In a severe thunderstorm situation, the radar should be operated to collect images 80-second intervals; the evening of September 27th -- with severe thunderstorms in progress -- it was operated 360-second intervals. So, by the time the pilots saw an updated image, it was nearly eight minutes old.

It is unclear to me why so many National Weather Service offices run their radars at six minute intervals during tornadoes and severe thunderstorms. Regardless, it is vital pilots be aware that the ground-based radar images they see are never "live." The FAA recommends pilots keep at least a 20-mile interval between them and thunderstorms. I agree. 

Radar should be used defensively...keep a wide berth between your plane and thunderstorms.