 | Stew Biff A common speed limit encountered by all aeroplanes is the restriction to fly at 250 knots (288mph) or less when under an altitude of 10,000 feet, which falls into the Class B airspace level. In some cases the Class B level can extend a little higher. For example, in Atlanta the ceiling of the Class B airspace is up to 12,500 feet. Most commercial flights, however, fly at 38,000 feet above the Class B maximum height and there is not a specific speed limit imposed. BA Captain Dave Thomas stated why they fly at this height: 'This sort of altitude is a good compromise between engine efficiency and aerodynamic efficiency for jet aircraft. 'Of course, the more efficiently we fly the more fuel we save, which is good for the environment and allows us to keep fares low for our customers.' Although there is not a specific speed limit for commercial planes above 10,000 feet, pilots have to abide by the aircraft manufacturer's maximum safe speed for the aircraft to fly. When you dip down below 2,500 feet within four nautical miles 'or the primary airport of a Class C or Class D airspace area' another speed limit band applies. |
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