FLARM abuse in competitions

To prevent abuse of the received data in competitions (which is an IGC
requirement) FLARM has since 2004 included a "Privacy" mode where not
all the received information is forwarded to the serial dataport and
therefore is never available to external, graphical displays or PDA's.
The *internal* threat calculations always use the full dataset.

For the mandatory 2008 update, "Privacy" mode is further refined with
the following goals:
- Discourage temporary turning off of FLARM during competitions
- Discourage use of "Privacy" mode outside competitions

Modification for the mandatory, scheduled 2008 update:
The guiding principle is that the pilot will not receive more
information than what is visually available anyway.

1) Rename to "Stealth mode" as this better describes the purpose and
operation. Heavily promote its non-usage and explain it to key
users.

2) The status and any changes of the "Stealth mode" is recorded in the
IGC file as an L-record (LFLA STEALTH [ON / OFF]) and is therefore
protected by the G-record. Consequently a competition authority can
easily
enforce the use (or non use) if desired.

3) Changes to "Stealth mode" during flight are delayed by five
minutes.

4) Full reciprocity: A pilot that enables "Stealth mode" will get the
information
as if all other aircraft had enabled "Stealth mode", independent of
their actual setting.

5) If FLARM is power cycled during flight, other aircraft are treated
as if in
"Stealth mode" for the first five minutes, independent of their
actual setting.

6) Targets with enabled "Stealth Mode" are only displayed in NEAREST
and
are available on the Dataport as a PFLAA message if they meet at
least
ONE of the following requirements:
- Target is a threat
- Target is within 100m horizontal / 50m vertical
- Target is within 1000m horizontal / 200m vertical and within
+-45° of own flight direction

7) If a PFLAA message is issued according to the rules above, all
fields in Italic are empty:

PFLAA,AlarmLevel,RelativeNorth,RelativeEast, RelativeVertical,IDType,ID,Track,
TurnRate,GroundSpeed,ClimbRate,AcftType

8) RelativeVertical degraded with (distance / 50) white noise when
other aircraft is not a threat.

Please comment.

THE FINAL V4.0 VERSION MAY BEHAVE DIFFERENTLY (based on your
comments).
CHECK RELEASE NOTES AND MANUAL!

Urs - FLARM