Jan. 30, 2006 — This period is supposed to be the peaceful nadir of the sun’s 11-year cycle of activity, but 2005 was anything but calm.

Last year saw record-breaking mega-flares, and commercial airliners continue to put themselves in the path of the resulting bouts of radiation-clogged space weather.

Twice in 2005 airlines had to cut and run from polar routes in the Arctic, when the sun let loose flares that launched some of the fastest space weather ever recorded.

The tempests contained super-hot protons that bulleted toward Earth, crossing the 93 million miles between the sun and our planet in an astonishing 20 minutes.

Once here, the proton blast hit Earth's magnetic field and followed the field lines to the poles, where it rained down into the atmosphere.

"It basically shut down the polar (airline) routes," said space weather forecaster Joe Kunches of the NOAA Space Environment Center, speaking about the first storm of January 2005.

That radiation storm caused a complete high-latitude, high-frequency radio blackout, along with fluctuations in Earth's ionosphere that are known to cause errors in GPS navigation systems.

Because airliners are required to be in radio range at all times, it was illegal to fly over the North Pole while the storm raged.

The second big solar flare of 2005 exploded on Sept. 7 and was no less troubling. It sent protons flying at 5.8 million miles per minute — the speediest seen in 20 years of observations by the National Center for Atmospheric Research's High Altitude Observatory in Hawaii.

Kunches reviewed both "proton events," their effects on airline operations and the growing importance of space weather forecasting in a presentation at the meeting of the American Meteorological Society (AMS) underway this week in Atlanta.

The health effects of flying through such storms are uncertain, said Kunches. There are a lot of concerns about pregnant women and other especially vulnerable passengers, he said.