A safe jump is a tactic used against a knocked-down opponent to pressure them with little to no risk. In most fighting games, characters who have special moves that are invincible for a few moments can perform them the first possible moment after being knocked down (with reversal timing - include link to Reversal definition) to counter any attacks. For example, in SF4, if you knock Sagat down and try to sweep him as he gets up, he can perform a reversal Tiger Uppercut, which will beat the sweep because Tiger Uppercut is invincible for a moment when it is first executed. Safe jumps take advantage of the fact that most moves of this type are immediately invincible, but cannot actually hit the opponent until a few moments later. Going back to the Sagat example, all versions of Tiger Uppercut have 5 frames of startup - that is, the attack does not hit the opponent for the first 5/60ths of a second of the move. If timed correctly, a character performing a jumping attack against a knocked-down Sagat can land during this 5-frame window and be blocking before the Tiger Uppercut hits. This is a very powerful technique, as when executed correctly, all possible outcomes are advantageous or neutral for the attacker:
1. Sagat tries to reversal and fails. In this situation, the jumping attack hits Sagat as he stands up, doing damage and often leading into a combo.
2. Sagat does not try to reversal, and forgets to block high or otherwise makes a dumb error. Again, the jumping attack hits as Sagat stands up, doing damage and often leading into a combo.
3. Sagat blocks high, blocking the attack. Most jumping attacks will typically leave the attacker at a neutral or advantageous situation when blocked. Make sure to pick the right jumping attack!
4. Sagat tries to reversal and succeeds. In this situation, the Tiger Uppercut's startup invincibility will allow Sagat to go right through the jumping attack, and he will not get hit. However, because Tiger Uppercut has 5 frames of startup, the attacker has time to land and block the Tiger Uppercut, and then punish with whatever they want.
In specific games, the knocked down opponent may have additional options. For example, in SF4, Sagat could Focus Attack on wakeup, absorbing the jumping attack, and then try to dash away to safety. However, in general, these additional options all still result in advantageous or at least neutral situations for the attacker, making the Safe Jump a very powerful technique.
The exact timing of Safe Jump attacks depends on the specific characters involved, and not all characters are vulnerable to them. For example, in SF4, Ryu's Shoryuken's (all strengths) have only 3 frames of Startup. Due to SF4's specific mechanics, characters who perform jumping attacks cannot block for 3 frames after landing. As a result, it is impossible to Safe Jump Ryu in SF4, as his Shoryuken will hit before the attacker can land and block. In order to get the most out of this advanced technique, learn your matchups!