Frank was played by Ralph Waite.
He worked wih Jesse in Cliffhanger as a helicopter pilot. He did put Jessie at the house high in the mountains and left her there at her request with the purpose of takng her back the next day. That´s how she was able to find Gabe and realise what was going on. The next day, when he got no call from Jessie, he went to find her and found on the way Evan that was nearly murdered by Qualen´s gang. Realising he was in a critical condition, he took him back to be treated medically. After that he resumed his search for Jesse and reported through radio his discovery of Evan giving his position to Eric Qualen´s gang.
He was later set up because of it and murdered by the gang of robbers lead by Eric Qualen with the purpose of robbing his helicopter so that they could later fly away with it from the Rocky Mountains once they would have their money. Before he died he gave Hal his knife so that he could save his life at the right time.