Halo could killed Massa, deflecting the spring to his chest.
A canopy is dangerous on fire or a flipped over car, and could not save Wheldon.
Aeroscreen couldn't save Surtess, and Wilson hit on top of head, not even halo could save them.
Open wheel racing is dangerous, so Motorsport is. F1 was over confident on his safety in '94, and we know what happen. Maybe is more safety knowing the risk than think you are complete safe.
Indycar still dangerous after Wilson's death, but this weekend on Dixon's and Bourdairs' crashes the nosecone stay attached to the car.
To avoid those kinds of accident, Motorsport what caused they, avoid a flying wheel, a flying nosecone, etc.