The changing faces of “c”

15.12.2007

Submission:

(I. W.
Previously "c" was a standard value added to the fix tolerance to determine the Latest Turning Point. This value was divided into 3 seconds “bank establishment time” and 3 seconds “pilot reaction time”.

Now it seems that planes have got bigger and pilots slower (Refer: Pans-Ops, Table I-2-3-1). So for an approach (IAF, IF and FAF) the “bank establishment time” is 5 seconds and the “pilot reaction time” is 6 seconds. However on the missed approach planes are supposedly lighter and pilots are really awake so the "c" value is back to 6 seconds total.

In a departure we add 10% to the speed, so that is probably why the “bank establishment time” is back to 3 seconds and because it is the beginning of the flight I suppose we can bring the “pilot reaction time” back to 3 seconds as well.

Now when we come to the RNAV section (Pans-Ops Part III-Section 2, Chapter 1, paragraph 1.3) the "c" value loses the “pilot reaction time” and is now just the “bank establishment time”. As far as I read the section, "c" is 10 seconds for a flyover waypoint and 5 seconds for a flyby waypoint.

1.) So what happens if I have a turn in the approach at a DME distance that is also defined as a flyover waypoint? Do I use 10 or 11 seconds ?

2.) Same with a departure 6 or 10 seconds flyover ?

3.) What happens if this is basic GPS and the FMS may not be coupled with the autopilot? Do I add on to the RNAV "c" value the “pilot reaction time”? If I do that I have:
Flyover: departure/missed approach "c"=13, approach "c"=16 (seconds)
Flyby: departure/missed approach "c"=8, approach "c"=10 (seconds)

So far I have possible "c" values of 5, 6, 8, 10, 11, 13 and 16 and then come the enroute values...

Any thoughts from all of you?)