Understanding that fly by's at 140kts are different than fly by's a 300kts or more. We were doing a fly by in Houston as part of the NHRA Championship one year. The AF NG unit sent their ground guy with a PRC (wasn't even a 112, older than that, he did have a nice Hawaiian shirt with flip flops for the full professional look). Fortunately our guy had a civilian radio we coughed up the $200 dollars for. So we tried to help out and act for the relay for the Vipers. I passed the TOT. The Viper guy got hung up on the TOT time. Somehow he confused the TOT time with his start run time (maybe TOT means something different to the TX NG). So we come up on our start point at our preset time (I had timed the speeds vs the leg start point) and notify the Vipers. As we are making our run, I am a little busy as lead trying to get the formation right and adjusting our speeds so that we cross the Christmas tree on the mark. Like 30 seconds out I hear, "Hey I am still reading the time of ###". I was a little busy and not sure what I even said back but since we were just off of the mark, I was sure they would not make it. We hit the mark +- 5 seconds and circle for our landing (one of the really cool things about doing flybys in Helicopters). As we were setting down, zoom come the Vipers. Pissed to say the least. Forgetting that I was still on the coordination Freq, I go "Hey what the hell happened to those guys". My questions was followed by a push freq on their part. They had excuse after excuse but they were still 2 mikes late. Fly buys are hard. Especially if the event coordinator does not understand how to time his singer, use GPS time and won’t set a hard time. Another time we were sitting at Ellington Field for a rain delay. Our guy called as told us they were going to start in 15 minutes. No chance in hell of making but Fvk it, let’s go anyway. We made the fastest red con one and blasted out (well blasted for helicopters). Forget the marks and the planning, we put the Christmas Tree in the nav and pulled all the TQ we could get. As we are flying in, they is supposed to be a jumper, I am trying to talk to our ground guy (with the same radio I gave him last year and probably with the same batteries) and all we can hear is static. I kept expecting to vegamatic a skydiver at any moment but we managed to cross the line at the sec (although140kts at 150 AGL makes for a very short surprising fly by). At fly bys you are a hero or a chump. I have been both. But nothing adds the pressure like knowing you’re going to be walking around with the crowd afterwards