I have been watching NFL football for many years on TV, and have yet to hear a full explanation of the “on-side kick.” The announcers only give half of the story, namely, “The ball, on a kick-off must go at least 10 yards before the kicking team can recover it.” It does not seem to matter if the receiving team touches the ball during an on-side kick, just that the ball goes ten yards. Now, the untold part of the story, there must be an upper yardage limit on the on-side free ball, or teams would recover, and not just “down” the ball near the end zone. Is there an upper limit on on-side kicks? Or, like deep kicks, must someone on the receiving team touch a 10 yard kick before the kickers can get it?
Good question
This is how punts differ from kick-offs. On a punt, the kicking team cannot recover the ball untouched. When the kicking team touches the ball it is downed. However, if the recieving team touches the ball first, the kicking team may then recover the football.
On a kick-off, the ball is live. There is no upper yardage limit. After the ball goes 10 yards on a kick-off the kicking team may gain possetion of the ball, regardless of whether or not the recieving team has touched the ball.
Are you sure? On kick-offs, the kicking team is always trying to down the ball deep in the other team’s end of the field. This sometimes leads to acrobatics, as members of the kicking team try to stop the ball from going into the endzone, and thus coming out to the 20. Other times, often when the receiver calls a Fair Catch, but doesn’t catch or touch it, you will see several members of the kicking team watching the ball, waiting for it to stop, so they can down it. If the ball were live, wouldn’t they pick it up and beat feet to the endzone?
I have never seen a kicking team try to down a ball, or the reciever call for a fair catch, on a kick-off. These things only happen on punts. I am very certain of this.
Once the kickoff goest 10 yards, it’s fair game for anyone who grabs it. The kicking team can’t usually get to the ball before the recieving team in a regular kickoff, so concentrate on stopping the returner. But if the receiving team doesn’t touch the ball, and it doesn’t go into the end zone (touchback) or out of bounds (penalty), then the kicking team can take it.
BTW, technically every kickoff is onside as long as it goes ten yards. You might want to win a few bar bets by saying, just before the kickoff, “I’ll bet the next kick is onside.” If you don’t mind getting beat up later for being a wise guy. 
OK. I guess I’ll have to watch more closely on kick offs. You’ve convinced me (almost) that my sig is correct …
Fair catches are allowed on kickoffs as well as punts (at least they are in college football). I don’t remember an NFL fair catch on a kickoff however. I suppose some team might want to call one to attempt one of those freaky fair-catch field goal tries.
In the NFL, a free kick (a kickoff or a kick after a safety) is live for both teams once it has gone 10 yards. If it goes in the end zone and the kicking team recovers, it’s six points.
HOWEVER, in college football, if the receiving team doesn’t bother to try to make an attempt at returning a free kick in the end zone, it’s a touchback. A college player would have to knock the ball into the end zone deliberately for the other team to get a touchdown.
Everything **** said is true. Once the ball goes ten yards, anyone can get it. (On a kickoff not on a punt) You never see the kicking team trying to down a kickoff because they generally don’t get near the ball. On a punt the gunners get to take off down the field fifteen yards and a second or two ahead of the ball. On a kickoff the player and the ball leave at the same time. A good kickoff goes about 70 yards in under 5 seconds. People don’t run that fast.
On a side note, I have seen a kickoff fair caught. This was done as a method of clock control. Apparently the clock doesn’t start running on a kickoff until someone touches the ball after the kicker. (and possibly when the ball hits the ground. I’m not sure.) The situation was as follows. Team A scores to take the lead with about 5 seconds to go in the game. Team B (who were probably the Bears) apparently thought they had a better chance at Hail Mary than a kick return. They also realised that any attempt at any return or an attempt to get out of bounds would take too long. Team A does one of those dumbass pooch kicks that I don’t fully understand. Team B upback fair catchs the ball on the 40 and either zero or one second goes off the clock. The clock stops on a change of possesion so the Bears get to run a play. (Which resulted in an interception if memory serves.)