Answer to Question #8997 Submitted to "Ask the Experts"

Is it permitted to fly with a Geiger counter (Gamma-Scout) in the cabin of a commercial aircraft? I am flying the polar route to Scotland from Seattle this summer and want to see what the readings will be. I have not found any restrictions so far in the United States or on the German or Scottish websites, but want to be sure.

There are no restrictions on hand-carrying of electronic equipment such as video cameras, calculators, laptops, or Geiger counters, as far as I know. I have carried Geiger counters in my hand-carried luggage for over 20 years. The Transportation Security Administration often wants these items separated for x-ray screening inspection. I would normally recommend that a probe-type GM (Geiger-Mueller) detector be disconnected and batteries be removed from the case. Since the Gamma-Scout has no probe, this cannot be done. Also, the Gamma-Scout has no ON/OFF switch, so it cannot be turned off. However, I would want to be sure that the sound speaker is turned off. Clicking Geiger counters tend to make people nervous.

I would like to also offer a couple other caveats about the Gamma-Scout. It is calibrated for cobalt-60 high-energy gamma rays (average 1.25 MeV) and may not read accurately at any other energy, either higher or lower. Also, Geiger counters are best suited for measuring beta particles and typically are not very sensitive to gamma or cosmic radiation (especially since the Gamma-Scout has a very small GM tube). Because of energy differences and low detector sensitivity, I would not take readings for cosmic radiation too literally. The detector may be used to compare relative readings (such as from ground surface to high altitude), but the absolute readings may be quite different if measured with a detector better suited to such measurements.

Also, despite the manufacturer’s claims, the Gamma-Scout will not be able to measure radon at all, for many reasons.  

Since the Gamma-Scout will allow you to review exposure history, I would also suggest that you NOT take it out to observe readings in flight. Neither flight crews nor other passengers would likely understand that they are exposed to larger amounts of cosmic radiation with altitude. If anyone thinks you are measuring radiation on board the airplane, that could be grounds for a jet-fighter-escorted landing. I assume you may not have an interest in making news headlines.

The Gamma-Scout website also provides answers to a number of questions.

Ray Johnson, MS, PE, FHPS, CHP