It would be good to avoid pointing LSST at aircraft, or in their wake (to avoid contrails).
Modern aviation is moving to ping-respond systems that broadcast GPS coordinates. One such system, mandated by FAA for adoption by 2020, is the ADS-B protocol.
here is an overview article about iPad versions:
http://ipadpilotnews.com/2012/08/understanding-ads-b-traffic/
http://ipadpilotnews.com/2014/05/ads-b-receiver-buy/
Vendors that sell stand-alone ADS-B receivers include:
Kinetics avionics SBS-3, about $750.
http://www.4cellular.com/product_info.php?cPath=73_84&products_id=174
Linux decoding of 1090 transmissions:
http://penturalabs.wordpress.com/2013/09/25/sdr-ads-b-decoding-dump1090-linuxosx/
http://landoflinux.com/linux_sdr_adsb_gqrx_radio.html
Raspberry pi implementation
http://www.satsignal.eu/raspberry-pi/dump1090.html
Ham radio SDR implementation
http://www.hamradioscience.com/the-rtl-2832u-sdr-and-ads-b/
QST article
http://www.arrl.org/files/file/QST/This%20Month%20in%20QST/January%202014/VirtualRadarJan2013QST.pdf
ADS-B antenna hacks
http://www.rtl-sdr.com/adsb-aircraft-radar-with-rtl-sdr/
Cute antenna and 1090 preamp combination available at
http://www.wimo.com/gp1090-1090mhz-antenna_e.html
apple OSX implementation of RTL-SDR dongle readout
http://www.hfunderground.com/wiki/RTL-SDR
OSX 10.8 1090 decoder
http://www.blackcatsystems.com/download/Cocoa1090.zip
Stuff purchased for testing:
1090 MHz bandpass RF filters
SDR radio dongle
misc connectors