reception coupling unit of a hose and drogue device of a tanker aircraft with the probe of a receiver aircraft for in - flight refueling , including , respectively , first and second cooperating latching devices that can be positioned in one or more latching states in a refueling operation , in which the reception coupling unit includes at least a detector of the latching states and at least a first indication device and / or a second indication device for providing , respectively , to the pilot of the receiver aircraft and / or to the crew of the tanker aircraft indications that the cooperating latching devices are positioned in one or more of the latching states , the detector being operatively connected , respectively , to a first indication device and / or to a second indication device .