If I may say ... those that cheerfully suggest to Been hacked and others, to take a flight in a light aircraft, appear to have ZERO idea of how fear of flying (or of anything) manifests itself. I urge anyone that is nervous to NOT go in a light aircraft - or even a turbo-prop, until they feel they have a better understanding of their fear and what sparks it off.
Firstly, the difference between a light aircraft and a passenger liner are so astronomical as to not need explanation. BUT if the person thinks that any little 'blip' and 'shimmy' of a A320 or B767 airframe worries them - then a light aircraft will have them hysterical within a minute of rotation!
The smaller the machine, the greater you feel each and every bump. They will be fixated on the fact that there is only one engine and one pilot. They will be in a new environment that appears far riskier than anything they have been in before. The list of fears they will find is almost endless and with no real way of 'mapping' it onto their experience as a pax in a commercial liner.
If they can attend a course where they are shown footage of what is happening on the flight deck and played the sounds, whilst a pilot explains them all and shows them external pictures of the aircraft to show what is happening (flaps retracting, raising the gear) then they can map what they hear and feel with what is supposed to be happening and that it is OK.
Secondly, I have a phobia about a particular event (nothing to do with flying itself, although the two can sometimes be linked) and I know that the unreasonable nature of a phobia is that it springs up at you at any moment and you cannot control it. I know that it is just a phobia but, when it launches itself, I can be left sweating and shaking - even when nothing has actually happened.
So, please, do not suggest that a nervous pax takes a flight in a light a/c until they understand what they would be letting themselves in for. There are a number of well documented courses, DVDs and books, FWOF has spoken of their help, that is the place to start.