Re: "Flying boxes/arrays" may be the culprit??
Weight and balance are issues with anything in the air. Properly engineered and assembled structures can deal with these, but it's up to the operator to know those limits and enforce them when clients think you're being too picky.
We fly lots of VerTec 4889 with 4880 subs and use both bungee cords and ratchet straps. As has been pointed out in other posts here and at PSW, both ridged attachment and pendulum swinging are bad. Ridged transfers 100% of the wind load laterally to the towers; swinging creates a dynamic load of unknown energy loading the structure in ways the engineer cannot account for on an individual basis. We let a small bit of swing happen as it reduces the wind load (hence the bungees) but if it gets to the point where the ratchet straps take tension it's time to have a talk with the promoter about the weather.
Ground stacks blow over, too, even when strapped down. I've had pSeudo-4 speakers blown off scaffolding (2" ratchet straps holding them down) in storms. That said, you can't ground stack a line array and get the results the act/client require or that the audience deserves. And think about it: if the winds are that high there are other issues that related to the safety of the artists, crew and audience that need to be addressed. I'd rather pick up pieces of gear at an evacuated site than clean the blood off equipment (and my hands, so to speak).
So yes, flying speakers can and is done safely on a routine basis and groundstacking is not the panacea one might think.
Have fun, good luck.
Tim Mc
