Zulu,
Looks like ICOM ight have surrendered on this one. Their website seems to stipulates the handhelds for ground use only..
Aviation/Airband Radio : Icom UK - radio transceivers, receivers and navigation products
Having said that, I'm pretty sure that an A24 was fitted to a microlight I had a ride in recently and it seemed to work fine with both sets of headsets. I'm sure the microlight boys can post some answers here for you (as well as austerwobbler).