What’s the difference between 978 & 1090 MHz systems and which will I need?
In the United States, the ADS-B requirements can be satisfied by two different frequencies for various reasons determined by the FAA. The short answer is that the 978 MHz frequency can receive both the ADS-B In (traffic and weather) while also accomplishing the ADS-B Out requirement for most GA aircraft. The exception is aircraft flying above 18,000’ and/or outside the United States. These aircraft would need to be equipped with a 1090 MHz In/Out to guarantee compliance and continued access to free traffic and weather. The Lynx NGT-9000 models are dual-band 978 and 1090 MHz system that operate on both frequencies, removing the restrictions of flying outside or above the above mentioned thresholds.