In aviation, "Bravo" refers to Class B Airspace, which is the most restrictive and busy type of controlled airspace in the United States. Depicted on aeronautical charts as an "upside-down wedding cake," Class B airspace surrounds the nation's busiest airports (like LAX, ATL, or JFK). To enter this airspace, a pilot must receive an explicit "clearance" from Air Traffic Control; simply being in radio contact is not enough. The term "Bravo" is used in the phonetic alphabet to clearly identify the airspace class over the radio. Operating in Bravo requires specific equipment, including a transponder with altitude reporting (Mode C) and specialized pilot certification. It is designed to funnel high volumes of commercial jet traffic safely into major metropolitan areas while separating them from smaller, slower general aviation aircraft.