Ross M
I was holding short at KDAL many moons ago doing a runup at 13L. The approaching Hawker was close in and had no landing gear extended! I keyed the mike and announced "Hawker on final, you have no gear!" An immediate go around was performed. He was within 6 ft of runway when he attained positive rate. It was at this time the tower had heard me and commanded a go around, but it was academic at that point. I departed for my mission of the day and never heard anything but the tower controller say thanks.