In an analysis of the accident, NTSB investigators note that Karkow, a commercial pilot, was performing a new employee familiarization flight with Sever, who had just joined the company.
While flying over Lake Berryessa near Vacaville, California, where the company is based, Karkow entered a cove, which was surrounded by rising terrain on either side. Realizing there was no outlet to this cove, he climbed the amphibious aircraft to about 100 feet above the water and “accelerated hard” in an attempt to climb out of the canyon, according to a witness.Shortly after the witness lost sight of the plane, he heard it crash.
NTSB investigators theorize that it is likely the pilot mistakenly thought the canyon he entered was a different canyon that led to the larger, open portion of the lake.
Additionally, it is likely that, once he realized there was no exit from the canyon, he attempted to perform a 180° left turn to exit in the direction from which he entered.
“Based upon performance information outlined in the Pilot’s Operating Handbook for the accident airplane, the airplane’s altitude above the water’s surface and its indicated airspeed, and the ridge line elevations in the area adjacent to the accident site, the airplane would have not been able to climb out of the rising terrain that surrounded the area, which led to his failure to maintain clearance from terrain,” the report reads.
The NTSB determined the probable cause of this accident to be the pilot’s failure to maintain clearance from terrain while maneuvering at a low altitude. Contributing to the accident was the pilot’s mistaken entry into a canyon surrounded by steep rising terrain while at a low altitude for reasons that could not be determined.
“I want to thank the NTSB for its professionalism and thoroughness in this process; this is an important step in reaching closure for the families of Jon and Cagri, as well as the ICON team after such a traumatic loss,” said ICON CEO and Founder Kirk Hawkins. “Jon and Cagri were both extraordinary individuals and are missed tremendously. Cagri had recently joined ICON as a star engineering leader from Ford Motor Company. Jon was a legendary aircraft designer, test pilot, and unsung hero in aviation. He was a founding member of the ICON team, the lead aero engineer on the A5, and a core part of ICON’s DNA. The A5 not only reflects his genius, it represents his love for flying in its purest form — it was his final gift to aviation. The ICON family is committed to carrying the flag forward in Jon and Cagri’s honor.”
Memorials for both Jon and Cagri were held in the weeks after the accident. ICON also created a page dedicated to Jon on its website.