fail-safe

And because airplanes are packed with fail-safes, there are times when a flight with a malfunctioning system can safely proceed simply by relying on one or more backups instead.

This is a fail-safe scenario but the converse "wrong side" failures -- when the signal goes from red to green -- are much more hazardous.

However, discussions of fall-backs and fail-safes have not been welcome in the Wales camp while the possibility of automatic qualification remains.

"These memory immune cells with latent suppressive properties act as a fail-safe mechanism in addition to the protection from traditional memory suppressive T cells."

He made his money through Green Hill Software, a company he founded in 1982 that develops fail-safe operating systems and programming tools for commercial customers.