+-----------+
                             | PREPARING |
                +----------> |           |
                |            |           |
                |            +-----------+
                |                  |
                |                  | Buffer next flight
                |                  |
                |                 \|/
                |            +-----------+
                |            |           |
                |            |  SENDING  |<------------------+
                |            |           |                   |
                |            +-----------+                   |
        Receive |                  |                         |
           next |                  | Send flight or partial  |
         flight |                  | flight                  |
                |                  |                         |
                |                  | Set retransmit timer    |
                |                 \|/                        |
                |            +-----------+                   |
                |            |           |                   |
                +------------|  WAITING  |-------------------+
                |     +----->|           |   Timer expires   |
                |     |      +-----------+                   |
                |     |          |  |   |                    |
                |     |          |  |   |                    |
                |     +----------+  |   +--------------------+
                |    Receive record |   Read retransmit or ACK
        Receive |  (Maybe Send ACK) |
           last |                   |
         flight |                   | Receive ACK
                |                   | for last flight
               \|/                  |
                                    |
            +-----------+           |
            |           | <---------+
            | FINISHED  |
            |           |
            +-----------+
                |  /|\
                |   |
                |   |
                +---+

          Server read retransmit
              Retransmit ACK