Ionograms reveal no return signal reflections and recorded transmission were only of local ground wave stations
Failure of propagation due to a 10MeV Proton event producing Polar Cap Absorption manifesting as major D-Layer signal attenuation for central Alaska and other areas north of 60 degrees north latitude as shown on the below chart.
D-Layer attenuation associated with reports by NOAA of Radio Blackout Activity
Radio blackouts reaching the R3 levels were observed over the past 24
hours. The largest was at Sep 10 2017 1606 UTC
Radio Blackout Forecast for Sep 11-Sep 13 2017
Sep 11 Sep 12 Sep 13
R1-R2 80% 10% 1%
R3 or greater 50% 1% 1%
Rationale: The potential for R1-R3 (Minor-Strong) radio blackouts exists
on day one (Sep 11) from Region 2673. Probabilities are expected to drop
rapidly as the region moves further around the far-side of the Sun on
days two and three (Sep 12-13).