You can expect 250 or so cosmic ray events per second in a 42 litre sodium iodide crystal pack at 100m above sea level.
Source: 10 years airbourne geophysics, radiometric calibrations.
Addendum:
In-flight upset 154 km west of Learmonth, WA 7 October 2008 VH-QPA Airbus A330-303 [1] was a probable (but uncertain) example of cosmic ray events causing multiple spikes in one of three air data inertial reference units (ADIRUs) that also went on to cause a failure mode of the "best of three" reporting system leading to a pitch down in which [2]
> 110 of the 303 passengers and nine of the 12 crew members were injured; 12 of the occupants were seriously injured and another 39 received hospital medical treatment.
HOWEVER .. despite 250 events per second in a 42 litre volume, it took 128 million hours of unit operation to see a failure mode.
It's a lot of billiard balls going through a lot of space and a high bar for "something bad" ( just the right bit flip ) to happen.
Source: 10 years airbourne geophysics, radiometric calibrations.
Addendum:
In-flight upset 154 km west of Learmonth, WA 7 October 2008 VH-QPA Airbus A330-303 [1] was a probable (but uncertain) example of cosmic ray events causing multiple spikes in one of three air data inertial reference units (ADIRUs) that also went on to cause a failure mode of the "best of three" reporting system leading to a pitch down in which [2]
> 110 of the 303 passengers and nine of the 12 crew members were injured; 12 of the occupants were seriously injured and another 39 received hospital medical treatment.
HOWEVER .. despite 250 events per second in a 42 litre volume, it took 128 million hours of unit operation to see a failure mode.
It's a lot of billiard balls going through a lot of space and a high bar for "something bad" ( just the right bit flip ) to happen.
[1] https://www.atsb.gov.au/sites/default/files/media/3532398/ao...
[2] https://www.atsb.gov.au/publications/investigation_reports/2...
( Final Report TAB )