The following tables from FAA AC 90-48C will allow glider pilots to realize the importance of a transponder and or portable collision avoidance system as part of their aircraft. Note that the PCAS system is battery operated, so your glider will not suffer battery drain from it.

The first table shows that the typical reaction time from a pilot (probably a young healthy one...) may be as long as 12.5 seconds...

The second table calculates the seconds to impact from a jet at cruise speed, or at 360mph, which in fact is the speed the Hawker had at the time of impact over the Pine Nuts. Had the glider pilot seen the Hawker when it was 1 mile away it would have been too late!

 
Recognition & Reaction Time

00:00 See object 0.1
00:00 Recognize aircraft 1.0
00:01 Become aware of collision course 5.0
00:06 Decision to turn left or right 4.0
00:10 Muscular reaction 0.4
00:10 Aircraft lag time 2.0
00:12 TOTAL TIME 12.5

Seconds to Impact
Range 600 MPH   360 MPH
10 miles 60 secs.  100 secs.
 6 miles 36 secs.    60 secs.
 5 miles 30 secs.    50 secs.
 4 miles 24 secs.    40 secs.
 3 miles 18 secs.    30 secs.
 2 miles 12 secs.    20 secs.
 1 mile 6 secs.       10 secs.
 0.5 mile 3 secs.      5 secs.

Becker transponder

MRX Portable Collision Avoidance System (PCAS)