public void update() {
    // speed calculation
    if (this.speedHorizontalTarget != this.speedHorizontal) {
        if (this.speedHorizontalTarget > this.speedHorizontal) {
            this.speedHorizontal += this.accelerationHorizontal;
            if (this.speedHorizontal > speedHorizontalTarget)
                this.speedHorizontal = speedHorizontalTarget;
        } else {
            this.speedHorizontal -= this.accelerationHorizontal;
            if (this.speedHorizontal < this.speedHorizontalTarget)
                this.speedHorizontal = speedHorizontalTarget;
        }
    }

    // direction calculation
    if (this.headingTargetDirection = true) {
        if (this.heading < this.headingTarget) {
            this.heading += this.turnRate;
            this.headingDirection = true;
        }
    } else {
        if (this.heading > (this.headingTarget)) {
            this.heading -= this.turnRate;
            this.headingDirection = false;
        }
    }

    // position calculation
    this.x += Math.cos(Math.toRadians(this.heading)) * this.speedHorizontal; // x pos + (heading * speed)
    this.y += Math.sin(Math.toRadians(this.heading)) * this.speedHorizontal; // y pos + (heading * speed)
    this.z += speedVertical; // current z + speed of vertical ascent
}