And they are a complete waste of money, with a better than 90% failure rate in practice, in real world bingles as was demonstrated in studies that resulted in the current regulations allowing portable ELTs.
I would have to disagree completely here. Maybe 'studies' have been shown to have only a 10% success rate of activation of the ELT, but I know I would want that 10% as opposed to none if the worst was to happen.
In addition to this, about 5 years ago, the property I was a pilot on in north queensland was called by AusSAR saying there was a beacon going off nearby and to check our 2 aircraft. A little while later it just so happened that the ELT was in a chopper belong to the property owner's brother in law, and the owners sister had rung us saying he was overdue. AUSSAR then gave us the coordinates of the ELT as it was a 406mhz unit. Unfortunately it had just gone dark. We found the crash after 2 hours of air to ground search with a UHF and 3 4wds. This was 5 hours after the crash, as was displayed on the analogue clock when we returned to the crash site 2 days later. The victim ended up in hospital for a month afterwards, and I would hazard a guess at saying, if that elt hadnt sent out such specific and valid GPS coordinates that we confirmed days later were spot on, and that we didn't find the site, or if the elt was not installed, and since he was in a bad way I'm sure turning a portable one on himself, if it was even near where he lay would have been difficult, once again I would say there may be one less life on this earth.
Anyway enough story telling, is there any updates on the missing plane in question?