FLARM has both traffic warnings (but onlly against other FLARM equipped aircraft*) and obstacle warnings. The obstacle warning facility was developed for mountain flying gliders to warn agains the cables in the Alps that are often umnmarked, but potentially deadly.
The only problem is developing and updating the database.
The systems can be 'portable' and escape some of the installation costs of approved devices. I understand that EASA approval of PowerFLARM (se below) is contemplated but ther's still the minor mod paperwork issues to contend with.
* PowerFLARM from the same development team also warns against Transponder equipped traffic that is repsonding to outside interrogations.
Last edited by Fitter2; 22nd Jan 2013 at 09:36.