Which figure of speech is used in this text?
Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped . . . I trust you are not in too much distress.
—Captain Eric Moody, after his Boeing 747's engines failed

 - assonance
 - understatement
The text uses understatement, which involves deliberately representing something as less serious or important than it really is.
We have a small problem is an understatement, since the plane was likely to crash.