PILOT OPERATING INSTRUCTIONS (Page 15 of 16 pages)
(5) The airplane and engine Operating values listed below "Operating Data" in any column except are calculated to give constant miles per gallon at any altitude listed. Therefore, the airplane may be operated at any altitude and at the corresponding set of values given so long as they are in the same column listing the range desired.
Ranges listed in column 1 under "mas. Cont. Power" are correct only at sea level and 12,000 feet.
(6) The flight plan may be readily changed at any time enroute, and the chart will show the balance of range at various cruising powers by following the "Instructions for Using Chart" printed on each page.
(7) In using the FLIGHT OPERATION INSTRUCTION CHARTS set the propeller control to give the desired rpm and open the throttle to give the desired indicated air speed. Use the manifold pressure only as an approximately value for reference.
(b) If the original flight plan calls for a mission requiring changes in power, speed, or gross load, in accordance with "GR.WT," increments shown in the series of "FLIGHT OPERATION INSTRUCTION CHARTS" provided, the total flight should be broken down into a series of individual short flights, each computed as outlined in paragraph a, in its entirety and then added together to make up the total flight and its requirements.
This material is courtesy of Stan Wood WW2 P-38 Pilot in the Pacific.
More about Stan Wood and his P-38 experiances: Click Here