unplanned

unintentional; not intended

Juno MacGuff is the kind of teenager we all wish we could have been: quick-witted, frighteningly intelligent beyond her years and comfortable enough in her own skin to resist those incessant high-school pressures to conform, even as her body expands with an unplanned pregnancy.

spontaneous and not thought through in advance

All of these factors increase the probability of stranding and the severity of the consequences. Since 2011, there have been several strandings that resulted in unplanned evacuations, because the passengers became desperate from personal discomfort or lack of confidence of being rescued.

not having any structure or organization