The sequence in question is in chapter 2. The pilot of the plane has had a heart and has died. Brian is in control of the aircraft and had been able to make brief radio contact with somebody. After losing radio contact, Brian tries every ten minutes to raise somebody on the radio. Throughout that time, Brian debates whether or not to take the plane down to the first clearing that he sees or stay in the air until the plane runs out of fuel. Brian opts for the latter choice. His plan is to put the plane into a shallow dive once the fuel runs out. That will keep his airspeed up and air moving over the control surfaces. That will give him some lift and rudder control. While, in the shallow dive, Brian will direct the plane toward the nearest lake. His plan is to crash the plane into a lake and soften the crash by pulling up at the last second. That will trade air speed for increased lift, slow him a bit, and hopefully soften the crash landing.
When the plane ran out of gas he should hold the nose down and head for the nearest lake and try to fly the plane kind of onto the water. That's how he thought of it. Kind of fly the plane onto the water. And just before it hit he should pull back on the wheel and slow the plane down to reduce the impact.