IFR Departure Surface (40:1) and Climb GradientUse Airspace OMS to calculate FAA Order 8260.3B
Airspace OMS now calculates the provisions of FAA Order 8260.3B for Runway Departure (40:1 Surface) screening criteria. The results of various airport runway departures are calculated and placed into the Airspace Summary Report . Any airport with an instrument approach will have all runways classified as instrument departure and the 40:1 departure slope applies. The 40:1 surface is calculated out to 22.09 nautical miles from the runway end within an arc of 180° centered along the runway centerline extended. These requirements are part of FAR Part 77.23(a)(3). This is TERPS criteria.
The standard aircraft departure climb gradient (CG) is 200 feet per nautical mile. This value is designed to provide 48 feet of clearance at one nautical mile from the departure end of the runway (DER). The Departure Report generated during an Airspace® study will identify the airport, runway, runway elevation, distance, 40:1 maximum height and the climb gradient. If the calculated climb gradient is greater than 200 feet per nautical mile the airport departure minimums must be reviewed to determine if a climb gradient greater than 200 feet is published.
Exceeding the 40:1 departure slope and or 200 feet per nautical mile climb gradient will likely result in a determination of presumed hazard (DPH) from the FAA for your study. If there is a published climb gradient greater than 200 feet per nautical mile and that value exceeds the calculated value determined by Airspace® you should request an extended study by the FAA be initiated. This will be the only way to clear the DPH letter. However, if the calculated climb gradient is greater than the published value an extended study is not likely to achieve the desired results.
Using TERPS Professional to see the whole picture
Airspace® calculations are screening only. To calculate the correct 40:1 surface beyond the Initial Climb Area (ICA) please use your TERPS® software.