I thank you very much, yet it's not yet completely clear.
Imagine a world where certification rules do not exist, and where it's cheap and easy to have CAS, EAS, TAS indicator without any error, in that world, you built your aircraft.
What need could you possibly have of a CAS indicator?
My understanding is that a CAS ASI is useless, as long as I have an EAS indicator which is better fit for purpose.
Am I right?
As nowadays, with ADCs, it seems to me that it's easy to design an ASI that can provide an indication within 3%/5kt of EAS, why still bothering with CAS in the certification process?
Why did the regulator chose to use the calibrated airspeed instead of the equivalent airspeed in the IAS requirement?
(b) Each airspeed system must be calibrated in flight to determine the system error. The system error, including position error, but excluding the airspeed indicator instrument calibration error, may not exceed 3% of the calibrated airspeed or 9.3 km/h (5 knots), whichever is greater, throughout the following speed ranges:
(1) 1·3 VS1 to VMO/MMO or VNE, whichever is appropriate with flaps retracted.
(2) 1·3 VS1 to VFE with flaps extended.
Last edited by 172510; 1st Jun 2015 at 16:29.