I can remember three situations where I had to intervene to stop disaster, once from the ground, twice from the tree.
Mid 80's, from the ground watching a fellow climber cutting the wrong leader of an intertwined crossover, unaware he was cutting the leader he was tied into. Had to bean him pretty hard with a rock to stop him.
Mid 90's, while training and tutoring my older brother to prune big eucs with no gaffs, on Torrey Pines Golf Course. I had just tied into the top of a big euc when I looked over to see how my brother was doing pruning the tree next to mine. To my horror, he was making his way out to the end of a lateral the same height as his TIP, which leaned out in the same direction as the lateral, unaware that his TIP was inching upward and outward following him and about to slip off the top of the leader altogether. Fortunately he heard me screaming at him to look at his TIP about to follow him to his death!
Early 2000's, again from the top of a big euc, I looked down and saw a rookie temp groundie, disobeying my orders to only drag brush to the whole tree chipper and stage it, and let only the lead groundie feed it into the chipper. It was a macho thing cuz he was a burly muscle bound 240 lb dude, while the lead groundie was a little 160 lb munchkin like me.
So I look down and watched as big boy grabbed a big leader and fed it into the chipper, and stand there as it flipped over violently, knocking him off his feet, and dragging him by the knee towards the feed table, in increments due to the autofeed of the 1800 chipper.
So I whistle at the lead groundie and point towards the chipper, whereupon he made a heroic sprint to engage the safety bar, just as the feedwheels grabbed his knee. Off to urgent care for a dozen or so stitches. An extremely close call narrowly avoided by good teamwork n signaling between the lead groundie n I.
Stay in this biz long enough and you'll experience lotsa high adrenaline fueled moments of sheer terror!
Jomoco