Fall from Ladder

Worker was installing a triplex service to a new home. The Powerline Journeyman (PLJ) set up the ladder on the gable end of the house, next to the mast, because the roof was snow packed and slippery at the eaves trough. He climbed the ladder onto the roof without incident and then tied in with his pole strap to the service mast and completed making the connections without incident.
After completing connections, PLJ disconnected his pole strap from the mast and stepped onto the ladder, from the side of the ladder closest to the eaves trough. Both his hands and feet were in contact with ladder rungs. At this point, the ladder footings slipped out and the ladder slid towards the ground. He instinctively reached for the mast but could not hold on to it once he grabbed it. He then fell approximately 11 ft to the ground with the ladder. Ensure that when your setting up a ladder that it is on even ground and that you don’t set up the ladder outside the 4:1 ratio.