Official Best Practices for June 30 Leap Second Published

A leap second is scheduled to occur on June 30, and most affected industries are taking steps to prepare. Now the DHS National Coordinating Center for Communications has issued guidance with a paper titled “Best Practices for Leap Second Event Occurring on 30 June 2015.”

The paper is sponsored by the National Cybersecurity and Communications Integration Center (NCCIC) in coordination with the United States Naval Observatory, National Institute of Standards and Technology (NIST), the USCG Navigation Center, and the National Coordination Office for Space-Based Positioning, Navigation and Timing (PNT).  

The paper is intended to assist federal, state and local governments and private-sector organizations prepare for the June 30 leap second event. Entities using precision time should be mindful that no leap second adjustment has occurred on a non-holiday weekday in the past decade. Of the three leap seconds implemented since 2000, two have been scheduled on December 31 and the most recent was on July 1, 2012.

The U.S. Coast Guard Navigation Center (NAVCEN) asks anyone who experiences any operational challenges relating to the leap second insertion to report it via the NAVCEN website under “Report a GPS Problem”.

In theory, on June 30, all UTC clocks should insert a second labeled 23h 59m 60s (the leap second) following one labeled 23h 59m 59s UTC. This is equivalent to having all of the clocks in the world stop for one second at that time, as explained in May’s Expert Advice column.