40:1
OIS elevation at equivalent obstacle 8,173.6'
c.
When the departure joins an en route airway, normally the departure area ends at the point where the departure course and the en route intersect. At that point continue the OIS evaluation as necessary to the point where the height of the OIS equals the lowest MEA for the direction of flight minus ROC.
d.
Where an MEA or MCA is at the departure/airway intersect point, and where the aircraft has not reached the MEA or MCA or the OIS has not reached MEA/MCA minus ROC, then:
(1)
Provide a CIH evaluation, see paragraph 13, at the airway intersect point and/or a climb gradient to the MCA altitude.
(2)
If during a CIH evaluation an OIS penetration occurs, establish a climb gradient to raise the OIS at holding end of the segment line so that the CIH OIS evaluation clears the offending obstacle.
e.
The OIS height where the departure course and en route segment intersect is determined by measuring the shortest distance within the primary area to a line drawn perpendicular to the course through the point of intersection defined by a WP/fix/NAVAID.
f.
Apply a level surface evaluation for the entire departure in a similar manner as stated in paragraph 274 and 277, TERPS.
12. Climb Gradients.
a. For the initial climb area, calculate a climb gradient to the first WP, as necessary, using the following formula:
Where: G = climb gradient (ft/NM)
DI = distance (NM) from DER measured along the route centerline
HC = height (ft) to climb above DER (allow for elevation differential between airport elevation and DER elevation)
Example: The first WP is located 1.6 NM beyond the DER:
b. For any segment, including the initial climb area, avoid obstacles (including equivalent obstacles
400
G == 250'/NM
from paragraph 10b) which penetrate the OIS, by specifying a climb gradient that provides 48 ft/NM
1.6
ROC not to exceed the maximum required obstacle clearance specified in paragraph 10 applied over distance (D). Apply the minimum climb gradient required for obstacle clearance. The minimum climb gradient for an obstacle is determined from the formula:
(48D ) + HO
G =
D
Where: G = Climb Gradient (ft/NM)
HO= Height (ft) of obstacle above DER (ft) or HE as appropriate D = Distance (NM) from DER measured along the shortest distance within the primary area
Example: Determine minimum climb gradient (G): EE 9,615' DER elevation -7,640' Height (HE) of equivalent obstruction above DER 1,975'
48D + HEG =
(round to next higher 5-foot increment)
D
48 3.513)+1975
(
= 610.2 = 615/NM
3.513
c. Specify the climb gradient to an altitude where a gradient greater than 200 ft/NM is no longer required. The climb gradient termination altitude(AT) may be determined by the formula: AT = 48D + EO (round to the next higher 100-foot increment) Where: EO = Obstacle Elevation (MSL) D = (as defined in paragraph 11b)
Example: Minimum climb gradient termination altitude (AT):
AT = 48D + EE (round to the next higher 100-foot increment)
[3.513 x 48] + 9615 = 9783.6 = 9800' MSL
d.
Multiple Climb Gradients. Where multiple climb gradients exist within a segment (e.g., due to multiple obstacle clearances, and/or as well as air traffic control requirements, or to meet en route MCA requirements), publish the highest computed climb gradient for that segment.
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