Solar flares occur as a result of built up magnetic energy suddenly released from the sun. A typical solar flare attains temperatures of 100 million degrees Kelvin and may release radiation equivalent to millions of 100-megaton hydrogen bombs all exploding simultaneously. These extremely powerful explosions only release an amount of energy equal to about one-tenth of the energy emitted from the sun every second. This solar flare radiation does make it to the Earth where most of it is filtered through the protective layers of the atmosphere.
The Earth's atmosphere serves as a shield from the immense amount of cosmic radiation these solar flares produce and filters most of it out before it reaches the surface. Aircraft flying at higher altitudes have less of this atmospheric protection and fliers risk higher exposure to this radiation. Even though some radiation may reach the Earth's atmosphere, the risk of radiation to fliers remains negligible. On a typical flight from New York to Tokyo, normal solar radiation exposure may amount to the natural background radiation most surface dwellers receive in a week. Solar flares raise that exposure level to about the same exposure received during a typical x-ray.
If pilots and air crews who normally frequent the limits of Earth's upper atmosphere had concerns about exposure to radiation, every aircraft would include a device to measure radiation exposure from solar flares. Only aircraft that operate above 49,000 feet are required to have equipment to measure cosmic radiation exposure. The Concorde, a supersonic passenger aircraft in service from 1969 to 2000, flew at an altitude of 60,000 feet, exposing air crew and passengers to radiation levels slightly higher than those experienced by other normal commercial aircraft. Because the Concorde flew at higher altitudes, an on-board indicator provided pilots with information regarding cosmic radiation exposure.
Predicting solar flares, geomagnetic storms, radio blackouts and solar radiation storms keep scientists and staff at the Space Weather Prediction Center (SWPC) very busy. A division of the National Oceanic and Atmospheric Administration (NOAA), the SWPC provides information for those frequenting the upper reaches of Earth's atmosphere. Even during large solar flares or unusually high solar flare activity, fliers will not receive enough radiation exposure to cause any health concerns. Concerned frequent fliers should consult the SWPC to allay any apprehension over solar flare and air travel concerns.
