You can't say "whatever the cost". What if it were $1 trillion per passenger? Obviously it's not, but there's some point at which you would change your mind. You have to assign a cost to these decisions in order to have a well reasoned discussion. The EPA, CPSC, NRC, OSHA, and OMB for example all use varying costs of life to make decisions with the value of one human life ranging from $1-$8 million.