Saturday practice at Hobbs NM

On 6/21/2011 11:49 PM, Eric Greenwell wrote:
On 6/21/2011 8:20 PM, Mike Schumann wrote:
On 6/21/2011 7:15 PM, Eric Greenwell wrote:
On 6/21/2011 1:56 PM, Mike Schumann wrote:


The reality is that FLARM, ADS-B, or any other GPS based technology is
useless in collision avoidance at close quarters. At the very best, the
position accuracy is only 50 ft and is only updated once a second.
Flying at 50 knots, you are traveling ~70 ft / second, so a lot can
happen between updates.

These systems are great in warning you about aircraft in your area that
you might otherwise not be aware of, and to give you an overview of how
many aircraft are in a particular gaggle and their relative altitudes,
but you absolutely can't rely on them for collision avoidance in a
thermal.

Is this conclusion based, at least in part, on your personal use of
FLARM in several contests?


I have not flown with FLARM, nor do I fly in contests. I did not mean to
imply that FLARM is not helpful in alerting you to targets that you
might not have otherwise seen. My point is that you can not rely on
FLARM at close quarters in lieu of keeping a good lookout and making
sure that you always keep in visual contact with any other gliders that
are close to you.

I don't recall anyone suggesting you use only FLARM in that situation.
You said originally that it was useless in that situation, which seems
like too strong a statement if you don't have experience with FLARM. So,
have you modified your assertion, or am I missing some nuance?


Useless was probably not the right word. This technology is obviously
very useful for identifying and warning a pilot about all equipped
aircraft that are potentially a threat. However, this technology does
not have the accuracy or update frequency to function as a reliable
collision avoidance system for aircraft that are operating at close
quarters.

--
Mike Schumann