  The geographic structure of radiation dose rates at aircraft altitudes in
Earth's atmosphere during the irradiation of Earth by proton spectra from
incoming solar particle events is examined using the recently developed MAIRE+
software. Conditions are examined under two incoming proton spectra, a low/hard
spectral index and a high/soft spectral index spectra, which are representative
of some of the solar particle events that have caused reasonably sized
Ground-Level Enhancements/Events (GLEs) over the past 70 years. It is found
through the use of `cut-throughs' of the atmosphere, that the atmosphere can be
divided into three volumes; a high dose rate polar region, a low dose rate
equatorial region, and a transition region between the two. The location of
these regions as a function of latitude, longitude and altitude is
characterised. It is also found that the location of the transition region
changes for different magnetospheric disturbance levels, implying that the
total radiation dose rate an aircraft will experience if it passes through the
transition region will be subject to large systematic uncertainties,
particularly during the currently unknown levels of magnetospheric disturbance
that a major solar event could cause. The impact that various magnetospheric
conditions might have on dose rates that specific flight routes might
experience is also discussed.
