In February 1966, just prior to the release of "Eight Miles High", Gene Clark left the band. His departure was partly due to his fear of flying, which made it impossible for him to keep up with the Byrds' itinerary, and partly due to his increasing isolation within the band. Clark, who had witnessed a fatal airplane crash as a youth, had a panic attack on a plane bound for New York and as a result, he disembarked and refused to take the flight. In effect, Clark's exit from the plane represented his exit from the Byrds, with McGuinn telling him, "If you can't fly, you can't be a Byrd." However, it has become known in the years since the incident that there were other stress and anxiety-related factors at work, as well as resentment within the band that Gene's songwriting income had made him the wealthiest member of the group. Clark was subsequently signed by Columbia Records as a solo artist and went on to produce a critically acclaimed but commercially unsuccessful body of work. He died on May 24, 1991, at the age of 46, from heart failure brought on by a bleeding stomach ulcer, although years of alcohol abuse and a heavy cigarette habit were also contributing factors.