No matter where you fly, there are plenty of speed restrictions you need to know...

Flights Below 10,000 Feet MSL

According to FAR 91.117(a), unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 mph).

If you're flying a piston aircraft, this might not mean a lot to you. However, it's an important factor for turbine aircraft. Jets don't slow down quickly, and turbine pilots often need to level off at 10,000 feet to bleed off airspeed before continuing their descent. This is extremely common at 10,000 feet, and generally, pilots don't have to notify ATC that they're leveling to slow down.

Flights Above 10,000 Feet MSL

With limited exceptions, aircraft are not allowed to exceed Mach 1 over the United States (FAR 91.817). According to NASA, during the 1950s and into the 1960s, sonic booms were echoing across the nation as the Air Force developed more and more Mach-1-busting jets.

Between 1956 and 1968, there were 38,831 claims against the Air Force (14,006 were approved) to cover losses from sonic booms. The claims ranged from broken glass and cracked plaster, to assertions of pets dying. Lucky for you, unless you own a fighter jet, you probably don't need to worry about breaking this FAR.

Speed Restrictions In/Around Class B Airspace

There isn't a specific speed restriction for operating in Class B airspace. If you're below 10,000 feet, you need to meet the standard speed restriction of 250 knots. However, if you're in Class B at 10,000' MSL or higher, you can fly faster than 250 knots (though ATC usually restricts aircraft speed for traffic flow and separation).

Most Class B airspace ends at 10,000' MSL, so this isn't much of a factor. However, some Class B airspace extends higher, like Denver's Class B, which extends up to 12,000' MSL.

According to 91.117(c), no person may operate an aircraft beneath Class B airspace, or in a VFR corridor through Class B, at an indicated airspeed of more than 200 knots (230 mph). This is done to help separate aircraft operating within Class B from those operating outside of Class B. Some aircraft flying below Class B may not be in contact with ATC, and the speed restriction of 200 knots provides ATC an added buffer to get traffic out of the way, should an airspace deviation occur.

Speed Restrictions In Class C/D Airspace

Unlike Class B, airports with Class C/D airspace have lower maximum speeds around the immediate vicinity of the airport. No person may operate an aircraft at an indicated airspeed of more than 200 knots (230 mph) at or below 2,500 feet above the surface, within 4 nautical miles of the primary Class C or Class D airport.

Other Recommendations

The last rule is simple. If the minimum safe airspeed for any particular operation is greater than the maximum speed, the aircraft may be operated at that minimum speed (FAR 91.117(d)). It gives you a clear fallback as a pilot to ensure you're not being forced to exceed your operational limitations.

There are airspeed limits for different altitudes, classes of airspace, and aircraft limitations. Know the requirements, and you'll never exceed a speed limit, no matter what aircraft you're flying.

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