Er....where did you get the ".../17" or ".../38" bit fro6m???
I've run 27 or 30 or 35 nm (ie near-as-dammit 30 nm) & find I'm 4 nm off track. That equates to 8 deg TE (ie x 2). If I double that I'll be back on track in the same time & distance. I'll also know how much to alter heading in order to maintain track once there. Do you really think that's difficult?
I'll repeat the table:
approx Dist run or to go..........multiply dist off x to get Tr. Error or Closing angle
60...........................1 eg 4 nm off then TE=4 deg
30...........................2 eg 3 nm off, TE = 6 deg
20...........................3 eg 3 nm off, CA= 9 deg
15...........................4 need I continue???
45...........................add half the dist off to itself. eg 6 nm off, TE=9 deg
If I need/want to regain track at a specific point (eg in the desert where fixes are few) or even parallel track without closing then I can do that too. How is that done using SCA?
ETIs require a groundspeed check anyway. Adding a minute IAW SCA doesn't seem to allow for altered GS for the remainder of the on track route. Have I missed something?