Planning the high-speed descent phase of a flight requires some judgment, especially during summer months when we like to cruise in cool comfort above the build-ups and the haze layer. That's usually 10,000 feet or higher in summer, at least where I do most of my flying on the eastern half of the country (mountain flying 'Out West' is a whole 'nuther ball game). In a section of his book Weather Flying, Robert Buck labels one section 'It's rougher than you think' with good reason. He discusses the let-down phase of a flight and some potential hazards to passengers' comfort at best; and the aircraft structural integrity at worst. Buck lays out the scenario of the pilot pushing the nose down "until the airspeed needle is tickling the red line." Or worse. The smooth air up high and the impressive groundspeed readout is tempting, but there's a serious gotcha here. Buck continues: "He slips down through the inversion into the convective layer and suddenly he is hitting really solid bumps. The combination of very high speed and the strong bumps is certainly putting a heavy load on the structure." Buck advises pilots to reduce airspeed before reaching the tops of the haze layer, which should be easily visible. After feeling the bumps and gauging their intensity, you can then make an educated decision on what speed will work well for the remainder of the descent phase.