I am seeking advice on how corporations deal with the temporary delegation of the CEO’s authority.

When our CEO plans to be unavailable (eg – going on vacation), we put in place a written delegation letter, advising who is “Acting CEO” for the specific anticipated time period.  That document is available should there be an issue about the authority of the person acting.

Do others follow this type of practice and for planned absences? 

What about unanticipated absences (eg – CEO becomes incommunicado, vacation extended, illness, etc.)? 

What other alternatives are being used (eg – a  “chain-of-command” policy, an ongoing blanket letter delegating authority when necessary)?  How do you word the documents so that it is clear when someone has to step in (eg – someone doesn’t become Acting CEO if CEO takes longer than expected lunch!)?

Thanks for your help!