learned that telling anecdotes involving engine failures from failed loops in vintage aeroplanes in her hearing is unwise
I've decided that on balance telling the truth about "interesting" occurrences works out better. It probably helps that I've got across the general safety culture, and she is aware that for most eventualities there are several levels of backup plan available, and that most people walk away from a forced landing.
Now that she's actually seen a real life in flight emergency for herself (we sorted the problem and completed the trip as planned, but it was real while it lasted) I can't actually tell whether she's more worried or less worried than she used to be ...