Guilty verdict in Grand Prismatic Spring unmanned aircraft case

    800px-Grand_prismatic_spring[1]YELLOWSTONE NATIONAL PARK — A man from the Netherlands has been sentenced in connection with an unmanned aircraft incident earlier this year in Yellowstone National Park.

    World-wide attention was drawn to the incident where an unmanned aircraft crashed into Grand Prismatic Spring the afternoon of August 2.

    The spring in is the largest in the United States and the third largest in the world and was noted by geologists working in the park in 1871 who named by it for its amazing colors. Its colors match the rainbow dispersion of white light by an optical prism.

    Last month, Theodorus Van Vliet entered a guilty plea to violating the park ban against operating an unmanned aircraft. He was fined $1,000 and ordered to pay over $2,200 in restitution. The park has been unable to confirm the location of the unmanned aircraft, which remains somewhere on the floor of the iconic hot spring.

    This is the second successful prosecution arising from a violation of the ban on use of unmanned aircraft in Yellowstone, an activity which is prohibited nationwide on all lands and waters administered by the National Park System.

    In September, Andreas Meissner of Germany was sentenced to a one year ban from the park, was placed on one year of unsupervised probation, and was ordered to pay more than $1,600 in fines and restitution in return for a guilty plea in connection with operating an unmanned aircraft which crashed into Yellowstone Lake near the West Thumb Marina back on July 18.

    A third case is pending. Donald Criswell of Molalla, Oregon, has been charged with violating the ban after he flew his unmanned aircraft over the crowded Midway Geyser Basin and close to bison on August 19. His case is scheduled to be heard in federal court in Mammoth Hot Springs later this month.


    The prohibition on operation of unmanned aircraft in Yellowstone National Park was included in the 2014 update to the Superintendent’s Compendium, which can be found online at It is also highlighted on the front page and inside the fall edition of the Official Park Newspaper which is distributed to visitors at park entrance stations and is also posted to the web at

    This ban is being enforced at Yellowstone. Violators will be contacted, investigated and may be subject to confiscation of their unmanned aircraft, a mandatory court appearance and fines.

    Yellowstone Public Affairs