Paragraph 19 (Figure 4): It is curious that April 1989 is the example given for solar eruptions. The April 1989 event was not especially high flux, nor was it very energetic as it did not even register as a ground level enhancement (GLE). Consequently the likelihood of this event causing high dose rates at aviation altitudes is very low. A far better example would be the events of September and October 1989. These are commonly used as examples of enhanced radiation environments in both the atmosphere and in space, and are much greater in intensity than the April 1989 event.
GLEs do not seem to be mentioned at all in this document. This is clearly an omission as GLEs are the best indicator of significant events that will significantly enhance dose rates at aviation altitudes.
Paragraph 20: The document dismisses the SPE contribution to lifetime dose as “marginal”. However, it should be noted that an extreme event could well expose crew members (and passengers) to dose levels that are beyond the 5-10 mSv range considered as an annual reference level that may trigger special attention (paragraphs 50 & 51). I do not think this fact is made at all clear by the document.
Paragraph 55: SPE-linked dose is essentially conceded as unavoidable due to the technical difficulty of implementing “information systems”. This seems a little defeatist – such systems could be developed given sufficient political will, i.e. if bodies like the ICRP lobbied for them. Would it not be sensible to mention the possibility of using in-flight monitoring systems (i.e. radiation detectors) to alert pilots to an event in real-time. This is perfectly feasible from a technical standpoint, though has only rarely been trialled. The increased development and deployment of such monitors was the principal conclusion of recent collaborative work between the US and UK.
Paragraph 65: The Commission recommends only “occasional” monitoring. This seems to be a missed opportunity given momentum elsewhere is generally to expand in situ monitoring as much as possible. Labelling the SPE contribution as “marginal” conflates the relative contribution to lifetime exposure with the potential contribution to annual exposure. If the 1 mSv limits for members of the public and pregnant air crew are to be taken seriously then I think a greater focus should be placed on the potential exposure from large SPEs, and the various reduction/avoidance strategies that could be developed to mitigate this exposure.