A propellant-handling module for installation in a host aircraft, comprising: a motorised drum unit comprising a line and drogue for engagement with a propellant supply line of a propellant supply aircraft for drawing the propellant supply line from the propellant supply aircraft to the host aircraft when the propellant supply aircraft is located behind the host aircraft; a propellant inlet configured for connection with the propellant supply line; a propellant outlet in communication with the propellant inlet and configured for connection with a propellant system of the host aircraft; an electrical power unit for powering the propellant-handling module; and a communication and control system for receiving a deploy command signal and a return command signal from the supply aircraft and configured to: receive said deploy command signal and in response control the motorised drum unit to deploy the line and drogue for said engagement with the propellant supply line; and receive said return command signal and in response control the motorised drum unit to return the line and drogue to the host aircraft in said engagement with the propellant supply line for drawing the propellant supply line from the propellant supply aircraft to the host aircraft when the propellant supply aircraft is located behind the host aircraft, wherein the module further comprises a housing which contains the motorised drum unit, the propellant inlet, the propellant outlet, the electrical power unit, and the communication and control system, and wherein the main part of the housing has the size and shape of a standard aircraft unit load device. a motorised drum unit comprising a line and drogue for engagement with a propellant supply line of a propellant supply aircraft for drawing the propellant supply line from the propellant supply aircraft to the host aircraft when the propellant supply aircraft is located behind the host aircraft; a propellant inlet configured for connection with the propellant supply line; a propellant outlet in communication with the propellant inlet and configured for connection with a propellant system of the host aircraft; an electrical power unit for powering the propellant-handling module; and a communication and control system for receiving a deploy command signal and a return command signal from the supply aircraft and configured to: receive said deploy command signal and in response control the motorised drum unit to deploy the line and drogue for said engagement with the propellant supply line; and receive said return command signal and in response control the motorised drum unit to return the line and drogue to the host aircraft in said engagement with the propellant supply line for drawing the propellant supply line from the propellant supply aircraft to the host aircraft when the propellant supply aircraft is located behind the host aircraft, receive said deploy command signal and in response control the motorised drum unit to deploy the line and drogue for said engagement with the propellant supply line; and receive said return command signal and in response control the motorised drum unit to return the line and drogue to the host aircraft in said engagement with the propellant supply line for drawing the propellant supply line from the propellant supply aircraft to the host aircraft when the propellant supply aircraft is located behind the host aircraft,