On Jun 8, 11:21*pm, Darryl Ramm wrote:

Seems to me like decimal minutes is the safest way to go unless you
find out for sure elsewhere.

I'm a bit surprised this didn't provoke more interest. If a
navigation system accepts a control point specified in deg mm ss
format and interprets it as deg mm.mmm format the worst case error
would appear to be when ss is 59. This would potentially be
interpreted as .590 min. The error is .590 vs .983 or 0.39 minutes.
That's easily enough error to miss the one mile radius of a control
point.

I'll try to do some experimenting but would welcome feedback from
users of Cambridge DAT files as to what format is required for their
system.

TP exchange appears to produce some end user files in deg mm.sss
format even when the Cambridge DAT files are deg mm ss so it's
probablly not a major change to have DAT files always use deg mm.mmm
format. No reason to ask for a change though if there really isn't a
problem.

Perhaps the only thing that matters is that the scoring software and
the pilot's nav system handle the format in the same way.

Andy