announcing an employee is leaving

A reader writes:

We are a medium size company with around 500 employees. I need your advice on how to handle and communicate the fact that the HR head is quitting without triggering any negativity. (The HR head is an average performer, joined as an Assistant Manager HR 5 years and is now Manager of HR.) What is the best way to communicate to all employees and how to soften the presumably moderate blow? (There is a period of notice of 6 weeks. The person has already served 2 weeks. There is no immediate replacement. Till the next person joins, the present Assistant Manager will take control.)

Is there any reason to fear negativity? After all, all employees move on eventually.

I would simply send an all-staff email (or issue an all-staff memo, depending on the culture and practices of your company). It should announce that after five years with the company, the HR head has decided to move on and her last day will be ___. The company thanks her for her years of service (name some of her successes and personal qualities here if you can) and wishes her all the best. And until a replacement is hired, the Assistant HR Manager will be running that department.

Employees know people move on. You're likely overestimating the fall-out from the news. However, do get it out there officially pretty soon -- otherwise it will start leaking out and you'll get rumors instead.