Context: As the movie opens, we see a guy climbing along the underside of an outcropping from a tall mountain peak. He turns out to be Gabe Walker, a ranger with Rocky Mountain Rescue. (Yes, that makes him "Ranger Walker," and he is addressed as such several times during the course of the movie.) He is in communication with his co-worker and girlfriend, Jessie, who is on a chopper piloted by an older co-worker, Frank. The three are mounting a rescue of yet another co-worker, Hal Tucker, and his girlfriend Sarah, who is on her first climb. Hal and Sarah made it to the top of the mountain, but Hal has aggravated an old knee injury and can't make it back down.Gabe makes it to the top of the peak where Hal and Sarah are. The chopper drops Gabe a cable, which he secures, while the chopper lands on a nearby peak. All is set for the three to shuttle across the cable to where the chopper is. There is a lot of light-hearted banter as this is a routine operation that they all (except Sarah) do all the time. Hal goes first, and as he is crossing, Gabe asks Sarah how Hal persuaded her to accompany him on this escapade. She replies laconically, "He told me it's better than sex."Hal makes it across and now it's Sarah's turn. She is a little frightened at the thought of hanging from a cable 4,000 feet above the ground, but the fact that Hal crossed without incident is reassuring. Halfway across her equipment fails and suddenly she is hanging by a strap and unable to reach and grab onto the cable. Gabe quickly crosses to her and grabs her arm just as the strap breaks free. But they are unable to keep their grip on each other, and Sarah falls 4,000 feet to her death. This is by far the most dramatic and gripping scene in the movie and some viewers will be haunted by it for weeks afterwards. But really, except for providing some background for the interpersonal dynamics among the remaining characters, it has nothing to do with the plot of the rest of the movie.Fast forward eight months, and we pick up two different plot lines that will converge later. At the U.S. Treasury office in Denver, Treasury Agent Travers is preparing to leave on a flight with several large containers of printed currency totaling $100,000,000. His boss introduces FBI Agent Matheson, who is being transferred and is bumming a ride on the flight. Gabe, meanwhile, drives up to Jessie's (and formerly his) house. He had left after Sarah's funeral because he felt he had to get away, and has been working in Denver. He wants Jessie to come to Denver with him, but she won't. She leaves for work, leaving Gabe to get his stuff from the house and load it into his vehicle.On the plane, Matheson looks out his window and sees another plane flying next to them. He quickly and correctly sizes up the situation, informs the other two Treasury agents that Travers intends to hijack the plane, and pulls his gun on Travers. The other two agents dutifully pull their guns on Matheson, as does Travers. Travers shoots the other two agents, then shoots Matheson. In the cockpit, the co-pilot comments about the gunfire, and the pilot shoots him. The two planes move into position and run a cable between them. Travers transfers over, then the pilot sends the containers.But Matheson isn't dead. He manages to shoot the pilot, shoot the cable in enough places that it detaches from both planes and the containers fall to the ground, and shoot the other plane enough times that it crashes in the mountains, before his own plane explodes from explosives previously set by Travers. Kristel, the pilot of the other plane, radios for help, reaches Jessie, Hal, and Frank, tells them they are hikers who got lost in a snowstorm, and asks them to send a chopper. But they can't send a chopper because of the storm, so Hal sets off to 
 Question: Who is Frank?
Output: older co-worker