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Inmarsat Monitoring And Aviation Anecdotes
You may be aware that each year around October, I travel to Atlanta in the United States to attend a radio communications monitoring convention. It is one of the ways I can keep up to date with technology and the latest ideas. Last October, after jetting my way with Qantas to the States, I met John Wilson, amateur radio operator W4UVV, who is very much into InMarSat monitoring. Already, I had found more than enough justification for my trip!
InMarSat is the medium which international oceanic flying aircraft are moving to from HF voice reporting. The satellite equipped aircraft (steadily building in numbers) are transmitting a combination of ACARS data, cabin telephony, and flight deck telephony. Some of the messages, such as a proportion of the ACARS transmissions, are generated automatically. If an airliner is satellite equipped, and within range of a VHF ground station, the ACARS will route through the VHF (131.55, 130.025, 129.025 MHz) ground station. If it is out of range with a land based VHF station, the equipment will redirect the message to the satellite.
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In Atlanta last October, Ed Flynn from San Rafael in California was demonstrating his prowess in pulling in ACARS messages on VHF. Combine the two disciplines, Ed Flynn’s ACARS with John Wilson’s InMarSat knowledge, and we’re literally “back in business.” Monitoring oceanic airliners via InMarSat—digitally and otherwise! I will tell you more next month. But basically, what is needed is a satellite dish of at least 1.8 metres, a waveguide feedhorn, a microwave RF amplifier, an IF (intermediate frequency) line amplifier, 12 volt DC power supply, RF connectors, coax cable, insulated wire, a weatherproof cover, and a receiver or scanner capable of FM reception from 1530.000 to 1545.000 MHz. InMarSat reception is possible! It is being done now. I saw it with my own eyes in Atlanta, and the system really should only cost you about $300 plus the dish. I am setting up my system right now. Anyway, more next month on InMarSat reception. I’ll finish off here with a frequency table to put you in the picture.
Wunala Dreaming At Hobart
Scene: Hobart Airport, Tasmania. Contributor: Anonymous aviation industry employee.
A Qantas Boeing 747-438, VH-OJB, “Wunala Dreaming,” resplendent in its red ochre livery of Australian Aboriginal murals and symbols, is sitting on the tarmac, about to be invaded by hordes of visitors to the airport. It’s open day, and the 747 is one of the key exhibits of the day.
Enter, Stage Left: two RPT aircraft into the circuit pattern, and they commence a three-way exchange of views with the tower.
RPT Jet No 1: “Oh yuk, what’s that down there?” Hobart Tower: “I think they’re having a corroboree.” RPT Jet No 2: “I suppose that’s what happens when you park your plane in the open overnight!”
Geographically Embarrassed
Lew Kettle from Bundaberg in Queensland was monitoring Yankee Yankee Yankee (registration changed for the story) with this geographically embarrassed pilot situation.
Aircraft: “I’m over a power house, or a factory… or something. Err… there’s a large town ahead, and it has a railway line through the centre!” Brisbane FIS: “Yankee Yankee Yankee, I think you’re over Gympie. Please orbit, I’ll ring Gympie Police to confirm.”
(About 5 minutes later…)
Brisbane FIS: “Yankee Yankee Yankee, Gympie Police confirm you are over Gympie, please state intentions.” Aircraft: “I will track direct Maroochydore!” Brisbane FIS: “I think you better follow the railway line my friend!”
Lew Kettle felt sorry for the pilot, and has begged me to change the registration details, which I have done. The actual registration was much different to VH-YYY.
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