A system for voice announcing air traffic controller to pilot data link communication messages of a type which are in conformance with predetermined industry standard message formats, the system and method including a voice annunciation to the flight crew of such messages with the aid of a database of predetermined speech files which correspond to predetermined controller pilot data link communication messages. The flight crew is able to select a language, gender, dialect, accent, etc. of the announced voice message so as to provide for enhanced communication of air traffic control messages to the flight crew.

A terrain advisory system utilizes stored data representative of terrain and other obstacles in predetermined geographical areas of interest to provide advisory warnings of the proximity of terrain, obstacles and restricted areas as they are approached. When used in a vehicle such as an aircraft, the system monitors the position, altitude, ground speed, ground track and the vertical speed of the vehicle and provides advisory indications of the position and path of travel of the vehicle with respect to obstacles and terrain. Such advisory indications may take the form of voice warnings describing the nature and position of any obstacles, or a visual display showing the position of the obstacles and terrain with respect to the vehicle.

Unattended measurements of horizontal and vertical visibility are broadcast, along with the results of time trend analysis so as to provide for short-term prediction of visibility. A calibration mechanism is provided along with sensors to determine mis-alignment of the apparatus. Broadcast information is particularly useful to pilots approaching unattended airports for landing.

A system for communicating data between an aircraft and ground unit over conventional amplitude modulated (AM) voice radio channels employs a data collection unit for collecting data desired to be transmitted, such as global positioning system (GPS) data, altitude, or aircraft identification information which is encoded by a data encoder. A gating means senses when the microphone of the AM transmitter is keyed, and passes the encoded data and the voice signals to the existing AM modulator of the AM voice transceiver. This results in a transmitted signal received by a receiving unit, such as a ground unit, which separates the received signal into an AM modulated voice signal and a AM data signal. The AM voice signal is demodulated by normal means into an audible signal, with the AM data signal being decoded by a data decoder into data. This data may be used to identify the aircraft symbol on a radar screen, identify the voice signal with a aircraft identification number, or flight number thereby reducing the amount of identification required. In alternative embodiments, avionics equipment may be added to the aircraft responsive to the data being sent from the ground unit, allowing collision avoidance capabilities.