By the time a student pilot is ready for a first
                solo flight, he knows, intellectually, that the plane's nature is to fly rather than plummet to the
                ground. He knows that he is himself capable of bringing the plane in for a landing. By this point the
                student will have carried out dozens of landings with the instructor sitting next to him, providing
                reassurance through his presence but doing none of the actual work. Similarly, by the time the
                instructor lets the student go for his first solo flight, the instructor also knows that the student can
                land the plane safely. The percentage of mishaps on first solos is very low.

                    But the moment when the instructor gets out of the plane and the student sits preparing for his
                first unaccompanied takeoff begins a several-minute portion of life no one who has been through it
                ever forgets. As a student preparing for a solo, you know that once you push in the throttle and get
                far enough down the runway that you can't just cut the power and stop the plane, there is absolutely
                no way out of the situation other than accomplishing a landing by yourself. It highlights the tension
                between the supposedly logical left side of the brain, which knows you can do this because you have
                done it dozens of times with the instructor watching, and the right side, which is thinking: My God,
                we're going to die! The first solo flight I took is currently the most vivid of the many "firsts" in my
                life. No doubt that's mainly because it's the most recent, but it is also because pushing in the
                throttle and thinking, "Let's go," is such an act of will.
 

-- From the First Chapter of `Free Flight' by James Fallows.