Trenny accompanied approximately 38 other students on a horticulture field trip on October 8, 1976. The bus left Bearden High in Knoxville Tennessee at about 9 am, the destination of the trip being the Great Smoky Mountains. To add some excitement, the teacher accompanying the students that day, had not told them of the destination until they had boarded the bus.
The bus stopped and parked at the parking lot in the Clingman's Dome area. The students were instructed to hike to Andrews Bald, and observe the trees and plants, but not to break any plants or collect anything. They were to return to the bus by the same trail no later than 3:30 pm. Wayne Dunlap, the supervising teacher told the students not to go any further than Andrews Bald or take any of the side trails. After a show of hands that instructions were understood, the students departed the bus.
The weather was overcast and chilly, but the students seemed to enjoy themselves and broke up into small groups according to their hiking pace. Trenny hiked to Andrews Bald with the same classmate that she had shared a seat with on the bus, Robert Simpson. At about 1:30 pm, Trenny left Robert's company and began the hike back to the bus alone.
Angela Beckner, Lisa Mikels and Bobbie Coghill were walking together when Trenny came up behind them. She was walking faster than the group was, so Bobbie started walking with her. They then caught up with Scott Troy and Anita Rounds. After about five minutes of walking with them, the group sat down to rest, but Trenny said that she wanted to keep going. At the time, the group was about half to three-quarters of a mile from the Clingman's Dome parking area and the bus.
After Trenny's departure from this group, the students were watching her, and she stopped, bent down and then turned right off the trail. David Eastham came up from behind and when the kids looked back down the trail, Trenny was not there. There were several groups both behind her group and in front of her group. There is no side trail at this point, the terrain is very rocky, ground is rough and overgrown with trees, thick underbrush and briars. A small stream makes the bank slick. The students assumed that she would be at the bus and continued on.