Thursday, 1 November 2012

HAMNET Bulletin: November 2012



HAMNET conforms to and abides by the IARU discipline of engaging in emergency communication locally and worldwide during and after disasters as internationally Amateur Radio is regarded as a National Resource!

HAMNET, as a group of volunteers, supports Disaster Risk Management in South Africa and serves on the sub committee of the South African Search & Rescue Organisation – SASAR!

It is recommended that when becoming a member of HAMNET, you also become an SARL member to abide by and conform to the IARU International and HAMNET rules regarding emergency communication!

All HAMNET information is available on alternatively just follow the link! Weekly updates are supplied to Amateur Radio Today on Sunday’s and a monthly bulletin is supplied to members and available on the SARL website and as a podcast!

You can also follow us on Facebook and Twitter


A tornado is a violent rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of up to 300 mph.

They can destroy large buildings, uproot trees and hurl vehicles hundreds of yards. They can also drive straw into trees. Damage paths can be in excess of one mile wide to 50 miles long.

South Africa has not been prone to this sort of phenomenon on a regular basis, but recent events – over the past few years – there is an indication that this funnel type of wind storm is on the increase in our country!

Most tornadoes form from thunderstorms. You need warm, moist air and cool, dry air to meet. When these two air masses meet, they create instability in the atmosphere. A change in wind direction and an increase in wind speed with increasing height create an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the updraft tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.

This is just a brief description of the events leading up to and the development of a Tornado or “twister” as they are sometimes called in the USA.

They are almost impossible to predict, yet a lot of research is constantly being done in the USA which is prone, in any season, to over 1000 tornadoes in one year.

It is too early for us here in south Africa to get really concerned about a possible increase in tornadoes but maybe the time has come that consider keeping some form of record to evaluate if this really is a problem of the future.

The same applies to incoming Cyclones off the Indian Ocean. Normally they start around now but this year one already formed early in October and fortunately dissipated before it could make landfall, Madagascar of Mozambique.

SAWDOS is an excellent platform where we can collate information and possibly over a period of time, do some evaluations!


HAMNET is currently involved in a Search and Rescue operation. Although there is still a media embargo on this operation, we can briefly describe how it all came about.

A light aircraft, on a flight from Malawi on Sunday to Lanseria airport, failed to make regular radio contact after a certain position. This is a South African registered craft with result that Air Rescue Control was advised.

Hamnet received a call on Monday morning around 10am from ARCC and Chris Gryffenberg, ZS6COG immediately sent out a call for operators with valid passports and who are available to be deployed to Beira in Mozambique. Needless to say, we had enough respondents and two were selected, one with good knowledge of Mozambique and its terrain!

After getting all the equipment together, the team left for Beira on Tuesday morning and within an hour of their arrival, we had excellent radio contact with them. A JOC was set up outside ATNS at O R Tambo airport and so far although we have little success in locating the missing plane, communications from the JOC to Beira is running smoothly and radio conditions are really very good! The communications team in Beira are Judy, ZS6JDY and Francois, ZS6COI.

Our thanks at this stage to the team at the JOC for doing an excellent job and getting many good reports from ARCC!

Once we have clearance, more details will be discussed and I suggest debrief after the event to iron out issues that cropped up during the operation must be discussed as a sharpener for the next call-out!


With regards the occasional problem we may encounter with equipment in vehicles at roadblocks, HAMNET is currently in contact with senior SAPS Officials locally and in Pretoria to ‘educate’ Police members around the country that we are purely hobbyists and to educate them on Regulation 308 A and the ICASA Licence!

Once this has been finalised, further information will be published in the Hamnet Bulletin.

Comments suggestions and contributions please contact or send to: or or at 011 679-5260 or 083 585-3847. Fax 086-580.6110.

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