It is intended to be the minimum standard for making manned aircraft visible in U-Space, and it is also what is used by SafeSky. In the meantime however in Europe most IFR aircraft with a MTOM of 5700kg or more and/or a max TAS greater than 250kt are required to carry ADS-B equipment.

Moreover EASA has been promoting voluntary takeup of the equipment. Indeed many certified and uncertified GA aircraft now carry ADS-B equipment alongside their Mode-S transponders, adding so-called Extended Squitter (ES) to their transponder broadcasts.

Even the author’s two-seater gyroplane, for instance, is ADS-B In/Out equipped in combination with Flarm, enabling it to see other ADS-B equipped aircraft and gliders on screen as well as audible traffic warnings. EASA’s new ADS-L protocol comes in two variations: ADS-L 860 and ADS-L Mobile.

The technical specification for the latter mobile variety I believe has not been published yet. The former 860 variety however uses the same SRD860 frequency band as Flarm, but it is not the same protocol. Flarm intended to be used as an air-to-air anticollision protocol conducts sophisticated collision risk calculations, while ADS-L is solely intended as an air-to-ground protocol for use in U-space thus providing minimal position data only. More or less recent Flarm equipment may be upgraded to add ADSL alongside its own protocol, but native ADS-L equipment will not do Flarm.

The Europan e-conspicuity landscape is consequently becoming relatively complex, as shown in the following graphic taken from the Flarm website: Interoperability of all these protocols becomes an issue. Actually, air-to-air interoperability was never EASA’s concern, as its brief was only to develop a solution for safely operating manned aircraft in uncontrolled U space