At what point can you not recover from Falco's dair?

[Captain Phobos]

My favorite finishing move with Falco is his dair to spike my opponent. It's not hard to set up, and it kills pretty early, but I want to know if there's ever a time a character can recover from it. Normally, I have my opponent at about 70% before I spike them, and I can't remember a time when they haven't died instantly, but at what percentage does it become and instakill? If I were to spike someone at zero, would they die?

 

[BlueNinja]

On Final Destination, Falco's Dair killed Mario after a full jump at 85%. Spiking that high up is unlikely, but offstage, 70% will kill some characters.