Personal Black Box

I assume you are all aware of the existence of aeroplane black boxes that record flight data (FDRs) and cockpit voices (CVRs). These devices can be very useful in determining the cause of an air crash.

In modern black boxes, data is recorded on solid state memory boards, protected by a brightly coloured crash-resistant shell. These recorders cost around $10-15,000, and can record about 30 mins of sound (along with data).

To ensure that a recorder will survive a crash intact, it must be insulated by three layers - a thin alumunium housing, an inch-thick dry-silica heat proof layer, and a 0.25 inch stainless steel or titanium shell.

It should be possible to market scaled-down personal versions, for the paranoid passenger who couldn't stand the idea of missing the chance to say a final farewell to their loved ones.

At a little over three inches thick, this walkman sized recorder should be able to carry at least a few minutes of sound. This should be more than enough to record that final goodbye, revised will - or perhaps the realisation of your impending death may spur you to confess where you hid the body.

Basically an MP3 recorder with a crash-proof shell, mass production should mean that these recorders could market around the $100-200 range. For an additional charge you could go for the version that transmits a signal to help find it among the debris.

*Edit - alternatively, the memory capacity of the Cockpit Voice Recorder on all flights could be increased, and a small microphone be embedded in each armrest on the 'plane. In the event of an impending crash the pilot could activate these microphones and allow each passenger to record their final message.