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Military Supersonic Flight Rules

- question from Adnan

According to a Navy pilot friend of mine, American military aircraft are never allowed to fly supersonically over the US, under normal peacetime conditions, except in specially designated areas. One such area is the High Altitude Supersonic Corridor (HASSC) in southern California. This corridor extends from northwest of Los Angeles to the Colorado River near Las Vegas, Nevada. A portion of the HASSC passes through the R-2508 Special Use Airspace Complex that includes Edwards Air Force Base, the China Lake Naval Air Warfare Center, and the Army's Fort Irwin. The HASSC is one of several special supersonic zones in the region, and is used by the Air Force, Navy, and foreign militaries for training and flight testing. The aircraft operating in this restricted area are responsible for the many odd rumbling noises and mysterious sounds often reported as secret, exotic, cutting-edge new airplanes supposedly developed at the infamous "Area 51."

Supersonic Corridors near Edwards AFB

Other special supersonic corridors exist througout the United States. Unlike the HASSC, most of these are not part of any Restricted Area, Prohibited Area or MOA (Military Operating Area). An example is a corridor in northeastern New York state near Saranac Lake. While the military controls access to and grants permission to fly supersonically through the HASSC, these other corridors are instead controlled by the FAA.

However, you do raise an interesting question when you correctly point out that a sonic boom created by an aircraft operating at high enough altitude cannot be heard on the ground. Since "controlled airspace" only extends up to 60,000 ft (18,305 m), any pilot flying above that level could conceivably fly as fast as he wanted without risking noise pollution. But how many planes do we have that can reach 60,000+ feet? Not many. The SR-71, F-15, and F-22 are about the only publicly-acknowledged supersonic aircraft that could operate that high, and the SR-71 had to get special permission to fly across-country supersonically.

Nonetheless, there are special circumstances that do allow pilots to exceed Mach 1 over populated areas. US pilots are allowed to do so over South Korea due to the unique defense issues that nation faces. In addition, fighters performing combat air patrols over the US as part of Operation Noble Eagle in the wake of the September 11 terrorist attacks have broken the sound barrier on occassion to catch up to airliners during air-rage incidents. One such incident occurred over the suburbs of Chicago in October 2001 when two F-16 fighters intercepted an American Airlines flight from LA to Chicago after a passenger began threatening to crash the plane into the Sears Tower.
- answer by Jeff Scott, 6 January 2002

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