To ensure the safest and most efficient flow of air traffic, aircraft are bound by certain speed restrictions depending on altitude and terminal structure.
Aircraft Speed Limits Under General Operating & Flight Rules
According to FAR 91.117, which covers general operating and flight rules:
– You may not operate an aircraft below 10,000 feet MSL at an airspeed greater than 250 knots (288 mph) – unless otherwise authorized by the Administrator
– You may not operate an aircraft at or below 2,500 feet within 4 nautical miles from an airport in class C and D airspace at an airspeed greater than 200 knots (230 mph) – unless otherwise authorized or required by ATC
– For VFR flights below class B airspace and in transit corridors through class B airspace, you may not operate an aircraft at an airspeed greater than 200 knots (230 mph)
– Exceptions apply if the minimum safe airspeed for any particular operation is greater than the maximum speed stated above. There is no need to notify ATC when the speed limit is exceeded for this reason
Airspace Speed Limits
There are no speed restrictions in Class A airspace other than to maintain sub-sonic flight
– When above 10,000 ft, there is no speed restriction inside Class B airspace
– When below 10,000 ft the speed limit is 250 knots
– There is a speed limit of 200 knots below the airspace or in a corridor
– Unless otherwise authorized, there is a speed limit of 200 knots (230 mph) within 4 nautical miles and 2,500 ft of the primary airport of a Class C airspace area
– Unless otherwise authorized or required by ATC, there is a speed limit of 200 knots (230 mph) at or below 2,500 ft AGL within 4 nautical miles of the primary airport of a Class D airspace area
– There is a speed limit of 250 knots below 10,000 ft MSL when operating in Class E airspace
– There is a speed limit of 250 knots below 10,000 ft MSL when operating in Class G airspace
Aircraft Holding Speed Limits
– There is a maximum speed limit of 200 knots at 6,000 feet MSL and below
– There is a maximum speed limit of 230 knots at 6,001-14,000 feet MSL
– There is a maximum speed limit of 265 knots at 14,001 feet MSL and above
Why is There a Speed Limit Below 10,000 ft?
The FAA imposes a 250-knot speed limit below 10,000 ft for two reasons: traffic avoidance and bird strike risk.
It can be challenging to observe aircraft at more congested altitudes. Flying at high speeds also leaves less time to take evasive action, even once visual contact is made.
While it may not always be possible to completely avoid bird strikes, flying at a lower speed means less impact and thus a lower likelihood of incurring severe damage. Additionally, far fewer birds fly above 10,000 feet, so there is not as much of a risk of strikes at higher altitudes.