Flying a Piper Archer on Saturday, he traced the route of the Kennedy flight from Essex County Airport in West Caldwell, N.J., following a path toward Cape Cod and proceeding as far as Bridgeport, where authorities asked that planes stop because of the tragedy unfolding in Massachusetts. Buck has flown into the Martha's Vineyard airport frequently. Just after sunset, when cool, high-altitude air rushes down to fill a temperature vacuum formed by a cooling Earth, a sudden Stygian fog condenses upward. The phenomenon is called air inversion.
Inversion is especially intense over water and can instantly degrade visibility to zero.
The entire East Coast of the United States had sat under a sweltering low-pressure system for most of the week, and that was creating hazardous weather conditions for pilots, especially toward the end of each day. Exceptionally competent, instrument-trained pilots can fly into such conditions by relying on their artificial horizon and other instruments, but the better they are, the more they know to avoid those conditions on the Cape. Indeed, the briefers at Islip that night were reporting the strong possibility of isolated thundershowers, possible fog over water and the high likelihood of obscured coastlines. That's why experienced pilots approach summer night flights over water very cautiously. He had his four-seat Cessna Skyhawk loaded Friday when he decided to make a last check of the weather.