Dengrove likely drew these sketches not long after February 20, 1981, when Aerolínas Argentinas Flight 342 nearly collided with the antenna on Tower One of the World Trade Center.

In the night’s dense fog and rain, the plane’s pilot had descended too early to 1,500 feet on approach to JFK Airport. Air Traffic Controller Donald Zimmerman heard an emergency alarm, contacted the pilot, and shouted at him, “Argentine 342. Climb. Climb immediately. Maintain 3,000.” The pilot did, and a disaster in which the mid-size, narrow-body Boeing 707 could have clipped Tower One was averted.

In these sketches, it appears that Dengrove was contemplating a hypothetical situation in which the plane collided with one of the towers.