From almost Day One of our pilot training, we’re told to stay out of and 20 miles from a thunderstorm. We’re also told not to fly into instrument conditions without an appropriate rating and clearance. Yet, the accident record shows many pilots regularly ignore those admonitions. The accident record, however, doesn’t reflect the number of pilots who bend or break them and live to do it again. We’d guess that number is substantial.
Why that is so remains puzzling. No, the instrument rating isn’t free; earning it requires a commitment of time and resources. Maintaining currency is almost as time- and resource-consuming as the rating. But the benefits of having and using the instrument rating to someone who uses a personal airplane for transportation far outweigh these costs.
Meanwhile, having the rating doesn’t mean we’re bulletproof. Airlines regularly cancel or delay flights for weather-related reasons, including thunderstorms. Flying into or near thunderstorms, of course, is an ill-advised practice regardless of the airplane’s capabilities or how it’s equipped. We shouldn’t have to tell you why.
Put together these two factors—lack of an instrument rating and flying into thunderstorms—and the chances of a favorable outcome are close to zero. Here’s an example of what can happen.
Background
On August 11, 2010, at about 0855 Pacific time, an Aero Commander 500-B impacted terrain about 80 miles south of Burns, Ore. The non-instrument-rated, 1350-hour private pilot and his passenger were killed; the airplane sustained substantial damage. The VFR cross-country flight departed Redding, Calif., about 0725, en route to Butte, Mon. Visual conditions were present from the surface up to about 4000 feet above the terrain. Overcast clouds, occasional thunderstorms, lightning and rain were reported on the ground both before and after the accident.
At 2014 the day before and 0625 the morning of the accident, the pilot obtained computer-generated weather briefings. At 0701 on the day of the accident, he contacted Flight Service for a telephonic weather briefing, which lasted about 10 minutes.
He departed and at 0753 contacted the Seattle ARTCC to request flight following, direct to his destination. After he initiated two en route climbs to 15,500 feet, ATC advised the pilot his flight following services were terminated for lack of radar coverage. The pilot also was advised of a band of moderate to heavy precipitation 60 miles ahead, and that it was a “…weather band that extends about 60 miles.” The pilot acknowledged the controller, which was the last known transmission from the pilot prior to the accident.
Investigation
Between 0845 and 0850, individuals on the ground began to hear the airplane’s engines. The initial sound was described as normal, but then developed into what a 3500-hour pilot/witness described as “…full-power settings, frequent attitude changes, and high angles of attack, typical of what you would hear during an aerobatic demonstration at an airshow.” The airplane was obscured from the witness by the overcast.
The airplane broke out of the bottom of the clouds, performing what witnesses described as either barrel rolls or snap rolls as it descended nearly straight down to the ground. Somewhere between 20 and 40 seconds later, one or two pieces of the airplane’s structure floated down out of the sky.
When the pilot called Flight Service on the morning of the flight, he was advised that a direct route would take him through an area where there were broken clouds at 10,000 feet, with tops to 22,000 feet, along with rain showers. Thunderstorms were expected. In addition, a direct route would take him through an area for which an Airmet had been issued, indicating widespread mountain obscuration by clouds. The pilot and the briefer discussed an alternate route that would take the flight “…east of all the precipitation and keep the last half of your route at least out of most of the cloud cover.” To which the pilot responded, “Yeah, alright.”
A post-accident weather study performed by the NTSB determined the accident site was north of the frontal boundary in an area of low to mid-altitude clouds, with tops in the range of 19,000 feet. The accident site also was within an area where the National Weather Service depicted an 80-percent probability of icing conditions at 15,000 feet, including supercooled large droplets.
Except for the portion of the left wing outboard of the center aileron pivot hinge and the outboard portions of the horizontal stabilizers/elevators—the latter of which were located within 250 feet of the primary wreckage—the majority of the airplane’s structure was located at the point of initial impact. The terrain into which the airplane crashed was very hard; there was no impact crater and the airframe basically telescoped into itself, precluding any flight control continuity checks. None of the cockpit instrumentation survived the crash intact.
The outboard left wing section that separated in flight came to rest about two-tenths of a mile from the primary wreckage. That component exhibited numerous fractures and deformations; a section of upper wing skin had been bent upward at nearly a 90-degree angle. After various inspections and metallurgical examinations, the NTSB concluded there was no evidence of any corrosion, fatigue crack propagation, loose rivets or unusual wear in or around the area of the fractures. All metallurgical indications were consistent with an overload failure of the wing structure.
Probable Cause
The National Transportation Safety Board determined the probable cause(s) of this accident to be: “The non-instrument rated pilot’s improper decision to continue flight into an area of known instrument meteorological conditions and his failure to maintain control of the airplane after entering those conditions.” If you’ve read this far, none of that should come as a shock.
Instead, what should be of concern is how and why a relatively experienced pilot—especially one lacking an instrument rating—would intentionally fly into an area of heavy precipitation and forecast icing. We’ll never know this pilot’s thought process and what led him to conclude flying into a thunderstorm was a good idea. We’ll also never know if the pilot had done this sort of thing before and somehow gotten away with it.
But we do know the outcome in this instance, and we know it has been and will continue to be repeated, even though the chances of success are close to zero.
