Safety statistics usually compare death/injury rates per passenger kilometre, but this is a bit misleading, because pax wouldn't make the type of long journeys they make by plane if they had to travel by any other mode of transport.
For example, you can't compare safety for a holiday flight from the UK to Florida with the same journey by car. People travelling by car on holiday would go to nearby countries. So although the pax risk of death/injury per kilometre is much lower by air, total risk of death/injury may not be so different.