Re AIM para 5-2-8, Instrument Departure Procedures
I read it a few times. I have a simple question for the case when there is a SID gradient required for obstacle clearance that is above 200 feet per nm (fpnm). Will there be a 48 fpnm obstacle clearance or is it perhaps greater?
For example, the AIM tells me that for a diverse departure obstacle assessment, if the 40:1 surface is clear of obstacles, then the climb gradient of 200 fpnm will assure at least 48 fpnm obstacle clearance. So I’m assuming that in the case where an obstacle is just a hair under the 40:1 surface, the obstacle clearance will be almost exactly 48 fpnm. The aircraft may be laterally some distance from the obstacle though. Does that all seem correct?
Now lets consider a location where a SID is specified in the clearance, and it is required for obstacle clearance, and is 500 fpnm.
Do we still have the same 48 fpnm obstacle clearance?
I realize the assessment starts at departure end of the runway, so an aircraft has that extra buffer.
Can anyone help?
Stan
I read it a few times. I have a simple question for the case when there is a SID gradient required for obstacle clearance that is above 200 feet per nm (fpnm). Will there be a 48 fpnm obstacle clearance or is it perhaps greater?
For example, the AIM tells me that for a diverse departure obstacle assessment, if the 40:1 surface is clear of obstacles, then the climb gradient of 200 fpnm will assure at least 48 fpnm obstacle clearance. So I’m assuming that in the case where an obstacle is just a hair under the 40:1 surface, the obstacle clearance will be almost exactly 48 fpnm. The aircraft may be laterally some distance from the obstacle though. Does that all seem correct?
Now lets consider a location where a SID is specified in the clearance, and it is required for obstacle clearance, and is 500 fpnm.
Do we still have the same 48 fpnm obstacle clearance?
I realize the assessment starts at departure end of the runway, so an aircraft has that extra buffer.
Can anyone help?
Stan