| Level | Effect | Physical measure | Average Frequency (1 cycle = 11 years) |
|
|---|---|---|---|---|
| R 1 | Minor |
HF Radio: Weak or minor
degradation of HF radio communication on sunlit side, occasional loss
of radio contact. Navigation: Low-frequency navigation signals degraded for brief intervals. |
M1 (10-5) |
2000 per cycle (950 days per cycle) |
| R 2 | Moderate |
HF Radio: Limited blackout
of HF radio communication on sunlit side, loss of radio contact for tens
of minutes. Navigation: Degradation of low-frequency navigation signals for tens of minutes. |
M5 (5 x 10-5) |
350 per cycle (300 days per cycle) |
| R 3 | Strong |
HF Radio: Wide area blackout
of HF radio communication, loss of radio contact for about an hour on
sunlit side of Earth. Navigation: Low-frequency navigation signals degraded for about an hour. |
X1 (10-4) |
175 per cycle (140 days per cycle) |
| R 4 | Severe |
HF Radio: : HF radio communication
blackout on most of the sunlit side of Earth for one to two hours. HF
radio contact lost during this time. Navigation: Outages of low-frequency navigation signals cause increased error in positioning for one to two hours. Minor disruptions of satellite navigation possible on the sunlit side of Earth. |
X10 (10-3) |
8 per cycle (8 days per cycle) |
| R 5 | Extreme |
HF Radio:Complete HF (high
frequency**) radio blackout on the entire sunlit side of the Earth lasting
for a number of hours. This results in no HF radio contact with mariners
and en route aviators in this sector. Navigation: Low-frequency navigation signals used by maritime and general aviation systems experience outages on the sunlit side of the Earth for many hours, causing loss in positioning. Increased satellite navigation errors in positioning for several hours on the sunlit side of Earth, which may spread into the night side. |
X20 (2 x 10-3) |
Less than 1 per cycle |