On several occasions I have down loaded the charts in the AIP. When planning the trip they are in the memory. After shutting down the iPad and restarting for the trip the AIP charts have disappeared. Have I some incorrect settings?

Thanks Tim,

since the index can  get lost or corrupted - maybe caused by a previous Skydemon crash (happens !),
why not store a backup copy of the index so that the original file can be automatically restored in case it gets corrupted or lost.
More a workaround than a real fix but that would help in the meantime. I consider this as a P1 bug, really a loss of the most basic functionality. Additionally, you could add trace/debug code in next SD revision so that users experiencing a problem can upload traces for your analysis.