A voice warning system is a system designed to alert the crew of an aircraft to imminent safety hazards. It is often known as a Bitchin' Betty, a slang term used by some pilots and aircrew and submariners (mainly North American). The enunciating voice, in at least some aircraft systems, may be either male or female. In some cases, this may be selected according to pilot preference. If the voice is female, it may be referred to as Bitching Betty; if the voice is male, it may be referred to as Barking Bob. A female voice is heard on military aircraft such as the F-16 Fighting Falcon, the Eurofighter Typhoon and the Mikoyan MiG-29. A male voice is heard on Boeing commercial airliners and is also used in the BAE Hawk. In the United Kingdom, the term Nagging Nora is sometimes used. In New Zealand, the term used for Boeing aircraft is Hank the Yank. The voice warning system used on London Underground trains, which also uses a female voice, is known to some staff as Sonya, as it "gets on ya nerves". Notable examples There are two notable systems, which employ voice warnings, and which are found in most commercial and military aircraft: TCAS (traffic collision avoidance system) and TAWS/EGPWS (terrain avoidance warning system / enhanced ground proximity warning system). Both systems provide warnings and verbal instructions. The auditory warnings produced by these systems usually include a separate attention-getting sound, followed by one or more verbal commands to the pilot/crew. Perhaps the most widely known example, encountered in many video games and movies, is the "Pull up! Pull up!" command. Other common spoken warnings are "Terrain, terrain", "Windshear! Windshear!", or "Traffic! Traffic!". These may be followed by short directions to the pilot, advising how the situation may be resolved. TCAS and TAWS/EGPWS are usually integrated to prevent conflicting advice, such as an instruction to "Descend! Descend!" to avoid another aircraft when the aircraft is already close to the ground. Modern Boeing and Airbus airliners both feature a male voice, which calls out height above terrain on approach to landing, and other related warnings. Airbus aircraft feature a distinctive British RP accent (heard on recent builds of the A320 and all Airbus aircraft since the A330 and A340), or a French accent (heard on ECAM-equipped A300s, A310s and early A320s). A female voice was incorporated into McDonnell Douglas DC-9, MD-80/90,