Definitely very sad, the attached article from Daily Mail mentions that jumpers sometime rely on their AAD to inform them when it’s time to deploy their chute. That’s nonsense no jumper relies on their AAD they rely on their altimeter and their ability to pull at the correct altitude for their experience level. The AAD is a back up device which will activate at pre determined altitude in the event that the jumper passes that altitude still descending at a certain speed, for example if the jumper has been knocked unconscious and cannot deploy or in the in rare circumstances if they lose altitude awareness. Ive witnessed a few cypress saves ( one of the devices used ) and they are quite dramatic. Clearly its not known why the device failed to activate in this case. Tragic ....Blue skies.