Say Goodbye to the Leap Second

Few things in amateur radio are as taken for granted as a reliable time signal — but the system behind that precision is about to change, and it's been a long time coming.

The International Bureau of Weights and Measures has declared that the leap second is running out of time — literally. It could be phased out as early as 2027. For decades, this small periodic adjustment has kept clocks synchronised with the Earth's slightly irregular rotation, occurring roughly every couple of years. Highly precise atomic clocks have relied on it, and its presence underpins UTC, the time standard used throughout amateur radio, science, satellite operations, financial systems, and countless other fields worldwide.

Why It's Being Retired

Bureau official Noël Dimarcq announced that reconciling these small adjustments with the planet's unpredictable rotational changes has become too irregular a process to manage reliably — to the point of raising the once-unthinkable prospect of a negative leap second as early as 2029.

The idea of phasing out leap seconds isn't new. It came up for discussion three years ago at the ITU's World Radiocommunications Conference in Dubai, where Judah Levine of the National Institute of Standards and Technology proposed an alternative: introducing "leap minutes" roughly every 50 years instead.

Where Things Stand Now

In a vote taken on 15th October, officials instead favoured a different solution: the leap hour. Dimarcq explained the reasoning — the committee on time and frequency believes it's wiser to let a full extra hour's worth of adjustment accumulate, and then make that larger correction all at once, rather than fiddling with smaller adjustments on a regular basis.

Of course, accumulating a full hour's discrepancy could take years. It could even take centuries. However long it ends up taking, one thing's for certain — it will, quite literally, take time.