Having (re)installed (due to idiocy) Ubuntu on my shack machine, I fired up the build-gnuradio script and built gr-airmodes. Some time later, I noticed the following WTF.
(-48 0.0000000000) Type 20 TCAS report from 9d529e: threat ID: 13e71ba advised: DON'T DESCEND DON'T DESCEND >500FPM DON'T DESCEND >1000FPM DESCEND DON'T CLIMB DON'T CLIMB >2000FPM TURN RIGHT DON'T TURN LEFT DON'T TURN RIGHT complement: DON'T CLIMB DON'T TURN LEFT at 33725ft
I hope that this is some quirk in the message decoding. I wouldn't fancy trying to understand that if my life depended on it!