HF Aeronautical Communications

Aircraft on HF

Aircraft utilize HF communications when VHF (Line of Sight) communications is not sufficient. The primary usage of HF is for Trans-oceanic flights. Trans-oceanic flights communicate with ground stations via HF for position reports and other purposes. Another utilization of HF communications is for HFDL or High Frequency DataLink. Finally Military Aircraft (MILCRAFT) utilize HF for operational and training.

• MWARA frequencies - Aircraft use these stations to communicate over water when out of VHF radio range.
• MWARA Frequency map on HFunderground

VOLMET

VOLMET, or meteorological information for aircraft in flight, is the term applied to a worldwide network of radio stations that broadcast TAF, SIGMET and METAR reports on shortwave frequencies. Reports are sent using automated voice transmissions, in the upper sideband or J3E mode. As the name suggests, pilots on international air routes use these transmissions to determine what procedures to use for descent, approach, and landing, such as a visual approach or an instrument approach and the correct STAR. The actual term comes from the contraction of 2 French words, loosely translated as 'Flying Weather'.

The VOLMET network divides the world into specific regions, and individual VOLMET stations in each region broadcast weather reports for specific groups of air terminals in their region at specific times, coordinating their transmission schedules so as not to interfere with one another. Schedules are determined in intervals of five minutes, with one VOLMET station in each region broadcasting reports for a fixed list of cities in each interval. These schedules repeat every hour.

Use for Propagation

VOLMET Broadcasts are great for propagation measuring, since they have set schedules and frequencies all over the world and can give an clear indication of when propagation is strong or weak in areas.

VOLMET Station Frequencies and Times

ANCHORAGE
2863, 6679, 8828, 13282
H+25-30 & H+55-00 

ANDERSEN
18002 2200-0700Z
13201 2000-0900Z
11176 H24
8967 H24
6738 0700-2200Z
4721 0900-2000Z
H+15 & H+45

ASUNCION
5601 0905-2315Z
10067
H+05
H+15

AUCKLAND
6679 H24
8828 H24
13282 H24
H+20+H-25

BANGKOK
11387 2310-1145Z
6676 H24
H+10-15 & H+40-45

BANGKOK INTL
2965 1210-2245Z
H+10-15 & H+40-45

BEIJING
*13285 0000-1600Z
*8849
**5673
**3458
H+15 - H+20
H+45 - H+50
*Day
**Ngt

BEIRUT
3001 H24
5561 H24
H+15 & H+45

BRAZZAVILLE*
10057 0700-2000Z H+00 & H+25
10057 2000-0700Z H+30 & H+55
*English and French language

CALCUTTA
11387 H24
6676 (0300-1300Z)
2965 (1300-0300Z)
H+05-10 & H+35-40

COMODORO RIVADAVIA RADIO
4675 0900-2400Z
8938 0900-2400Z
H+30 & H+40

CORDOBA RADIO
5475 H24 H+25
8952 H24 H+25

DAMASCUS
2992 H24
5667 H24
8918 H24
13312 H24
H+30 & Special
H+00 & Special
H+00 & Special

EDMONTON MILITARY
6753 2300-1200Z EVEN HRS+20
15035 1200-2300Z, ODD HRS+20

EZEIZA RADIO
2881 H24
5601 H24
11369 H24
H+15 & H+01

GANDER
3485 H24 H+20-25
6604 H24
10051 H24 H+25-30
13270 H24 H+50-55 & H+55-60

HONG KONG
2863 H24 H+15-20
6679 H+45-50
8828
13282

HONOLULU
2863 H24 H+00-05
6679 H24 H+30-35
8828 H24
13282 H24 H+05-10 & H+35-40
H+25-30 & H+55-60

KARACHI
6680 H24
3432 1500-0130Z
10017 0130-1500Z
H+15 & H+45

LAJES
13244 1000-2100Z
8967 H24
6750 H24
H+00 & H+30
8070 1015-2315 H+15

MACDILL
18019 0900-2400Z
13244 0900-2400Z
11246 H24
8993 H24
6750 0001-0900Z
4746 0001-0900Z
H+15 & H+45

MONTEVIDEO
8873 1000-2100Z H+15 AFST CARRASCO INTL.
5451
11387 H24
6676 H24
2965
H+25-30 & H+55-00

NEW YORK
3485 H24
6604 H24
H+00-05
10051 H24
13270 H24 H+05-20 & H+30-50

OAKLAND
2863 H24 H+05-10
6679 H24 H+35-40
8828 H24
13282 H24

RESISTENCIA RADIO
4675 H24 H+20 & H+50
ROYAL AIR FORCE
5450 H24
11253 H24
Broadcast of airfields is twice an hour in slot times
allotted as follows: 00/30, 06/36, 12/42, 18/48, 24/54

SALTA RADIO
5475 H24 H+15 & H+45

SHANNON
3413 SS-SR H+00
8957 H24
5505 H24
13264 SR-SS
H+05, H+10, H+15, H+20, H+30, H+35, H+40, H+45, H+50

SINGAPORE
6676 1230-2230Z
11387 2230-1230Z
H+20 & H+50

SYDNEY
6676 H24
11387 H24
H+00 & H+30

TAIWAN
2880 H24
5010 H+07
12400

TRENTON (MILITARY)
15034 1000-0000Z
6754 2300-1100Z
H+10-15, H+15-20, H+20-25, H+25-30

TOKYO
2863 H24
6679 H+10-15 & H+40-45
8828
13282

YOKOTA
18002 0001-0800Z
13201 2100-1000Z
11236 H24
8967 H24
6738 0800-2400Z
4747 1000-2100Z
H+00 & H+30

What is HFDL?

HFDL is a HF data link protocol, defined in ARINC spec 635-3. The HFDL service is operated by ARINC as GLOBALink service through a worldwide network of HF stations.

The name is somewhat misleading, as HFDL actually describes a class of data signals; it is also referred to as HF ACARS.

• Transmissions on HF are in USB on a sub carrier of 1440 Hz with a symbol speed of 1800 baud.
• Modulation is 2-PSK, 4-PSK or 8-PSK with effective bit rates of 300, 600, 1200 or 1800 bits/sec.

PC-HFDL

PC-HFDL is a Windows software to decode HFDL data traffic and has been written by Charles Brain. Just feed the HF receiver speaker's output into the soundcard of a Windows PC. It can be downloaded from the HFDL Yahoo group listed below.

PC-HFDL screen

The best monitoring results will be achieved with the following PC-HFDL settings:

• PREAM ON - to control the audio offset of the receiver
• SPDU OFF - only needed temporarily ON to see the squitters of a new unknown ground station
• MPDU ON - see the MPDU packets
• LPDU ON - see the LPDUs within the MPDUs
• BDU ON - see the BDUs
• VERB ON - see more details
• HFNPDU ON - see the routine position reports
• HEX OFF - only needed for debugging purposes

So in short, with all options ON except SPDU and HEX, the complete session can be seen: LOG-ON of the aircraft to the ground station giving its 24bit ICAO-ID, the assignment of the 1byte sequence ID number to the given ICAO-ID by the ground station referenced in all subsequent traffic, clear distinction of MPDU packets containing more than just one LPDU, and full traffic details.

The HFDL Yahoo group can be found here. Version 2.042 (which is Vista compatible) can be downloaded from this stub page

Other Packages known to support HFDL

• Hoka Code30/A
• Hoka Code 300/A
• Hoka 300-32
• Monteria Centurion
• Skysweeper
• Wavecom W61PC
• Wavecom W61LAN

Frequencies in Use

Thanks to MT Utility World which had the text link. New entries are in bold
ARINC System Table 34

Node ID	Xmtr Name	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
01	San Francisco CA	21934	17919	13276	11327	10081	8927	6559	5508	4672	2947
02	Molokai, HI	21937	21928	17934	17919	13324	13312	13276	11348	11312	10081	8936	8912	6565	6559	5514	5463	4687	3434	3019	2947
03	Reykjavik, ISL	17985	15025	11184	8977	6712	5720	3900	3116
04	Riverhead, NY	21934	21931	17952	17934	17919	13276	11387	11354	11315	10027	8912	8885	8831	6661	6652	6646	5652	5523	3428	3410
05	Auckland, NZL	21949	17916	13351	11327	10084	8921	6535	5583	3404	3016
06	Hat Yai, THA	21949	17928	13270	10066	8825	6535	5655	4687	3470
07	Shannon, IRL	11384	10081	8942	8843	6532	5547	3455	2998
08	Johannesburg, AFS	21949	13321	8834	4681	3016
09	Barrow, AK	21937	21928	17934	17919	11354	10093	10027	8936	8927	6646	5544	5538	5529	4687	4654	3497	3007	2992	2944
11	Albrook PAN	21940	17901	10063	6589	5589	2902
13	Santa Cruz, BOL	21997	21988	21973	21946	17916	13315	11318	8957	6628	4660	3467	2983
14	Krasnoyarsk, RUS	21990	17912	13321	10087	8886	6596	5622	4679	2905	2878
15	Al Muharraq, BHR	21982	17967	13354	11312	10075	8885	5544	2986
16	Agana, GUM	17919	13312	11306	11288	8927	6652	5451
17	Telde, Gran Canaria, CNR	21955	17928	13303	11348	8948	6529	5589	2905