B737-800
Communication Breakdown; Situational Awareness
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Fuel Issue; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Diverted
Human Factors; Procedure; Weather
Flight was approaching MCI from the East as a line of weather was approaching MCI from the West. I sent an ACARS message to the crew alerting them that the weather was approaching the field but that they should get in before the weather hit. The weather arrived first. The flight was put into holding when the crew sent me an ACARS informing me that MCI was covered in storms and that they needed to divert. They were looking at FOE. I responded that FOE looked good but that they would have to fly through the weather to get there; but that ZZZ looked good and it was clear enroute. At that time I discovered that ZZZ was not authorized for the [aircraft make/model] so I recommended STL and gave them the burn to STL as well as the REMF [Remaining Fuel]. The crew responded that they were going to FOE and requested the burn. I responded that FOE was not authorized and that STL was the best option. The crew responded that they were then going to ZZZ. It was at this point that I told them that ZZZ was not authorized either and that STL was the best option. The crew responded that they did not have the fuel to make it to STL but then requested the burn to STL. I sent them the burn but while I was trying to calculate the numbers; they announced that they were going to ZZZ. I informed them again that ZZZ was not authorized and that ops could not handle us if we diverted. They responded that they were going to ZZZ. I informed him that they would be proceeding there under his emergency authority and changed the release to reflect a new destination of ZZZ. I then informed him two to three times that he would need to [advise ATC of emergency] in order to get into ZZZ and asked if he had. He finally responded that he had over ACARS as well as told me on the phone once he got on the ground. The flight landed safely in ZZZ.
Air Carrier Dispatcher reported confusion and miscommunication with the flight crew during a weather diversion.