How do I know which flight or rental we're talking about?

Every conversation recaps its booking at the top of the thread. There you'll find the route or the aircraft, the date and the amount, along with the name and role of the person you're talking to.

What's shown

For a flight: the route (departure to arrival), the date, the number of seats and the price. For a rental: the aircraft's model and registration, the dates of the period and the price.

Who you're talking to

The thread also shows who you're exchanging with, their name and their role: pilot or passenger, owner or renter. You'll never mix up two bookings, even if you have several on the go.