 If it's clear a long security line or any line will cause you to miss your flight, go to the head of that line. I've done it maybe a dozen times and often in countries where I didn't even speak the language. But any airline passenger recognizes the panic of someone about to miss a flight. I try to move gracefully while offering a nonstop stream of excuse me's and apologies. Only once have I ever encountered one cranky person in line who wanted to block me.