REA4 is a station of the  Long-Range Aviation Command [ru] of the Russian Air Force. It broadcasts weather reports and "Monolith" messages using Morse code.

Frequencies

European Russia

Asiatic Russia

Weather reports

Every hour at H+40, REA4 broadcasts a SYNOP report from one of the Long-Range Aviation airfields. These broadcasts consist of a series of 5-digit groups preceded by REA4 REA4 = and followed by = REA4 K. The following is an example message with a translation:

REA4 REA4 = 20100 99900 19150 27627 81997 21702 10014 21015 70300 82031 912// = REA4 K

• 20100 - 20th of the month at 10:00
• 99900 - Standard weather broadcast type
• 19150 - Beginning of the observation period; here: 19th of the month at 15:00
• 27627 - Airfield identifier
• 81997 - Manned weather station, weather group included, cloudbase above 2500 m, visibility 10 km
• 21702 - 2/8ths total cloud cover, 170° wind direction, 2 m/s windspeed
• 10014 - +1.4°C temperature
• 21015 - -1.5°C dewpoint
• 70300 - Clouds developing from previously clear skies
• 82031 - Mid-level altocumulus translucidous and high-level cirrus fibratus
• 912// - Observation made during the 12th hour, minutes omitted

The airfield identifiers used are as follows:

• 20069 - Engels-2
• 22212 - Belaya
• 23672 - Dyagilevo
• 23746
• 23767
• 27627 - Soltsy-2
• 62596 - Ukrainka
• 73842 - Shaykovka

It is commonplace for a single weather report to be rebroadcast for hours, with only the first group changing.

"Monolith" messages

REA4 also broadcasts standard "Monolith" messages. A2CA is the most common callsign, corresponding to all recipients. Others seen include 7XMF, HA57, JUE4, JZLB, L9XC, MJUR, MSK7, PABA, QMCK, OM9V, 2WQX, HEDT, P79N, QMCK, 4DPL, QVMY, NUHL, 93JT and REA4. Also, it is worth noting that after The Buzzer messages, the next day, REA4 transmits about 20-25 repeated messages that will not be logged.