Mike Anderson and Rob Pizem have made the first free ascent of the Thunderbird Wall route on the North Face of Timbertop Mesa in Zion National Park. The remote, 2,000-foot wall was first climbed in 1986 after numerous attempts, and it went free at 5.13a. The two climbers made three visits, along with Chris Altstrin and Eric Draper, to recon the route and prepare variations for free climbing. When Anderson reached the mesa top on May 29 via aid climbing, it was only the third known ascent of the route in two decades.Anderson and Pizem returned at the beginning of June, starting their free-climbing push at 10 a.m. They climbed through the 14th pitch before dark, then rapped to a ledge for the night. The next day, they topped out at 8:30 a.m., completing a 24-hour free climb. All but one of the 16 pitches on the free Thunderbird Wall were 5.10 or harder, with five 5.12 pitches and one 5.13a lead, taking the outside corner of a dihedral originally climbed by a knifeblade crack. The pair placed seven protection bolts on variations to the original aid line and fixed some pitons for free climbing, but the additional pro still left some dangerous leads, with Anderson and Pizem each leading a 5.12- R pitch and dangerous 5.11 pitches. The two led or followed every pitch free.