Is there a speed limit for airplane?

Answer 1

No, the aviation industry is always looking for faster, higher, cheaper, safer and more maneuverable.

Yes. When an aircraft descends below a certain altitude, usually 10,000 feet in controlled airspace, there is an airspeed limit. If NOT, then all these planes would approach an airport at 400 mph and crash into everything.

The Air Traffic Controller will give permisison to a pilot to descend to 10,000 ft. They will watch the pilot's speed and when he reaches 10,000 feet, the pilot must (a) level out at the specified altitude and (b) be flying less than 260 knots(I think). If not, then he could be reported for unsafe flying and the pilot could be grounded. You know they are watching you when as soon as you level out the ATC will immediately come on the radio and give additional instructions.

Yes under 10,000 ft. The maximum speed for non-military aircraft according to the FARs (Federal Air Regulations) is 250 knots indicated air speed (KIAS) unless otherwise authorized by ATC (air traffic control). Also military aircraft (AFAIK) do NOT have a maximum speed limit at any altitude.

Maximum speed below 10,000 feet is either 250 knots or "minimum safe speed." If a plane won't fly correctly at less than 300 knots, you're allowed to fly it at 300 knots.

Air traffic controllers know what planes this applies to, so no getting on the radio in your PC-12 and claiming you can't fly slower than 350 knots or you'll fall out of the sky. They know better.

Answer 2

Yes, depending on altitude and where you are flying. Above 10,000 MSL feet the only speed restriction is mach1, however under 10,000 feet above sea level, there are a few others depending on where you are either 200 or 250knots