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[[image]] COLONIAL REGULATIONS [[image]] COLONIAL Section 3045 DESCENT A. RATE OF DESCENT 1. The maximum rate of descent for passenger comfort varies with the altitude as follows: (Do not exceed these rates for passenger comfort.) [[2 Columned Table]] | Altimeter Reading (Pointers at Zero) | Maximum Descent (Ft. per min.) | | --- | --- | | Sea Level | 300 | | 3000 | 325 | | 6000 | 355 | | 9000 | 390 | | 12000 | 430 | 2. It is desirable to descend at a constant rate of 300 feet per minute; it is not intended that the above rates of descent be used in normal operation as they indicate the rates of descent necessary to pass through altitudes of equal pressure variation at regular intervals of time. B. STARTING POINT OF DESCENT 1. Under normal conditions start the descent at a point whose distance in miles from the destination corresponds to the altitude in feet divided by 100; i.e., at 10,000 feet start descent 100 miles out. Descend about 1000 feet for each ten miles advance, depending upon wind velocity and direction. In the above table of maximum allowable descents it is noted that the rates are greater at higher altitudes. The pilot cannot take full advantage of this because of the limitations in governing of the constant speed propellers at cruising RPM. At 12,000 feet with the engines developing 550 HP cruising in level flight the air density is so low that the propellers are very nearly in full high pitch and if the plane is nosed down for the descent from this altitude, the resultant increase in speed will cause the propellers to reach full high pitch, synchronism is accomplished either by throttling the fast engine or by advancing the propeller controls to a higher RPM so that the governors still control the engine speed. Throttling the engines will reduce the powerand may affect the flight plan to cause late arrival. Increasing the RPM will allow a 300 ft. per minute descent with propeller governing at 550 HP. At about 8000 ft. the RPM should be reduced to 1800 to reduce the noise in the cabin.