In a single hour flying between Reno and Phoenix, the passengers on Phillips's flight were exposed to a whole day's worth of ground-level radiation--or about what a person would absorb from an X-ray at the dentist's office. That's not a big deal for an occasional flyer, but as NASA points out, frequent fliers of 100,000 miles or more can accumulate doses equal to 20 chest X-rays or about 100 dental X-rays. Lead aprons, anyone?
The radiation sensor is the same one that Earth to Sky Calculus routinely flies to the stratosphere to measure cosmic rays. It detects X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners. Indeed, when the sensor passed through TSA security at the airport, it began to buzz loudly, signaling a heavy dose of X-rays in the carry-on baggage scanner. TSA agents gathered around the instrument to investigate and they were quite interested when Phillips explained its function. Several wanted to know if they themselves were exposed to radiation in the vicinity of the scanner; a quick scan of the area revealed no leaks.
After boarding the plane, Phillips monitored radiation levels closely. Dose rates tripled within 10 minutes of take-off and remained high for the duration of the flight. This simple experiment shows that space weather can touch us even when the sun is quiet. Imagine what an actual solar storm could do....