The narrator is trying to grab at any opportunities to gain power over her captors. Tormenting Engel doesn’t do much in the long run—but for the narrator, it’s worth it to feel powerful for just a moment. At the end of this passage, the narrator highlights just how powerless she is when she notes how hungry she is (since she’s a prisoner, it’s her captors’ fault that she’s hungry). And writing the table of flights seems to be a way for the narrator to attempt to organize her scrambled thoughts—again, the pressure and exhaustion are getting to her.