A navigation system comprising: a communications system in a first vehicle configured to exchange position information with a second vehicle, wherein the first vehicle is an aircraft; a first inertial measurement unit enabled global positioning system device in the first vehicle, having a first global positioning system unit and a first inertial measurement unit with a first level of accuracy, wherein the first inertial measurement unit enabled global positioning system device is configured to provide first information that identifies a position of the first vehicle relative to the second vehicle using current position information received from the second vehicle; a first radio device configured to receive current position information from the second vehicle and provide it to the first inertial measurement unit enabled global positioning system device for identifying the position of the first vehicle relative to the second vehicle; a second inertial measurement unit enabled global positioning system device in the first vehicle having a second global positioning system unit and a second inertial measurement unit with a second level of accuracy that is greater than the first level of accuracy, wherein the second inertial measurement unit enabled global positioning system device is configured to provide second information that identifies the position of the first vehicle relative to the second vehicle; a second radio device configured to receive current position information from the second vehicle and provide it to the second inertial measurement unit enabled global positioning system device for identifying the position of the first vehicle relative to the second vehicle; a controller configured to identify a difference in the position of the first vehicle between the first information and the second information and to determine whether the difference in the position of the first vehicle meets a desired level of accuracy for the first information, wherein the desired level of accuracy varies depending on the flight situation; to identify the position of the first vehicle relative to the second vehicle using the first information and to perform an action if the desired level of accuracy of the first information has not been met wherein the action comprises identifying the position of the first vehicle relative to the second vehicle using prior position information received from the second vehicle and position information generated by at least one of a global positioning system unit and the second inertial measurement unit in the second inertial measurement unit enabled global positioning system device. a communications system in a first vehicle configured to exchange position information with a second vehicle, wherein the first vehicle is an aircraft; a first inertial measurement unit enabled global positioning system device in the first vehicle, having a first global positioning system unit and a first inertial measurement unit with a first level of accuracy, wherein the first inertial measurement unit enabled global positioning system device is configured to provide first information that identifies a position of the first vehicle relative to the second vehicle using current position information received from the second vehicle; a first radio device configured to receive current position information from the second vehicle and provide it to the first inertial measurement unit enabled global positioning system device for identifying the position of the first vehicle relative to the second vehicle; a second inertial measurement unit enabled global positioning system device in the first vehicle having a second global positioning system unit and a second inertial measurement unit with a second level of accuracy that is greater than the first level of accuracy, wherein the second inertial measurement unit enabled global positioning system device is configured to provide second information that identifies the position of the first vehicle relative to the second vehicle; a second radio device configured to receive current position information from the second vehicle and provide it to the second inertial measurement unit enabled global positioning system device for identifying the position of the first vehicle relative to the second vehicle; a controller configured to identify a difference in the position of the first vehicle between the first information and the second information and to determine whether the difference in the position of the first vehicle meets a desired level of accuracy for the first information, wherein the desired level of accuracy varies depending on the flight situation; to identify the position of the first vehicle relative to the second vehicle using the first information and to perform an action if the desired level of accuracy of the first information has not been met wherein the action comprises identifying the position of the first vehicle relative to the second vehicle using prior position information received from the second vehicle and position information generated by at least one of a global positioning system unit and the second inertial measurement unit in the second inertial measurement unit enabled global positioning system device.