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Ofcom Issues Revised Guidance on EMF Compliance, Prepared in Conjunction With LAA


Communications regulator Ofcom has issued revised guidance on electromagnetic field (EMF) license conditions that will apply to radio equipment in light aircraft.


Following receipt of communications from Ofcom in April, the LAA made representations that the proposed requirements, while well intentioned, were overly onerous and hard to interpret. As a result LAA engineers Jon Viner and Joe Hadley worked with the regulator to better define the risks from aircraft equipage. Their work, carried out on behalf of other member organisations within the GA Alliance, has resulted in the revised guidance.


The simplified guidance for aeronautical radio users can be downloaded from https://www.ofcom.org.uk/__data/assets/pdf_file/0027/220797/emf-licence-condition-what-you-need-to-know-aeronautical-radio.pdf


In summary:
If you only use handheld radio equipment, you do not need to comply and do not need to take any further action in relation to your VHF radio.


If you use fixed equipment with an external antenna and a radiated power of 25 Watts, and you transmit for less than 25% of the time in any six minute period (i.e. less than 1 minute and 30 seconds), you do not need to comply and do not need to take any further action in relation to your VHF radio. (There should be very few situations where operators would need to transmit for more than 25% of the time).


Aircraft transponders generally have a nominal output power of up to 260 Watts, with a typical antenna gain of 3dB. However, they transmit very short pulsed signals for 0.55% of the time. This means that the average radiated power of this equipment is in the region of 4-5 Watts.


Ofcom has calculated that, in the absence of a ground plane, the compliance distance for this equipment would be in the region of 26cm. However, the presence of an antenna ground plane will mean that compliance distances will be very small (typically much less than 10 cm).


In most cases therefore, no further action will be required, unless an antenna ground plane is not installed AND the transponder antenna is located less than 26cm from a passenger who is a member of the general public. In such cases a compliance check will be required as outlined in the Ofcom advice.




Light Aircraft Association

17th June 2021
























Photography (mostly) Neil Wilson

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