Ensuring Software Quality-Experiences of Testing Tejas Airdata Software

Kavitha Rajalakshrni; Y.V. Jeppu; K. Karunakar

doi:10.14429/dsj.56.1863

Kavitha Rajalakshrni Aeronautical Development Agency, Bangalore
Y.V. Jeppu Aeronautical Development Agency, Bangalore
K. Karunakar Aeronautical Development Agency, Bangalore

DOI: https://doi.org/10.14429/dsj.56.1863

Keywords: Software quality, software testing, best practices, software verification and validation, safetycritical code, Tejas, light combat aircraft, quality assurance, digital flight control computer software, airdata algorithm, non-real time test methodology

Abstract

Two major safety-critical elements of the onboard software for the Tejas digital flight control
computer software are the control laws and the airdata algorithm. The airdata algorithm computes
essential parameters like static and dynamic pressures, altitude, speed, angle of attack, etc from
the airdata sensor input. These parameters are used by the control laws to stabilise the aircraft
and to provide the required uniform handling qualities over the complete flight envelope. The
algorithm is provided by the Control Law Design Team and coded by the Software Design Group
of Software House, ADA, Bangalore, in Ada language. The Independent Verification and Validation
Group is responsible for ensuring that the software is bug-free and certifiable. A non-real time
(NRT) test methodology has been developed in-house to stress test the onboard software. This
paper gives an overview of the methodology used to carry out the NRT test of the airdata
algorithm and some of the testing experiences.

References

Jeppu, Y.V.; Harichoudary, C.H. & Misra, B.B.

Testing of real time control system: A cost

effective approach. In SAAT 2000, Advances

in Aerospace Technologies, Hyderabad, India.

Jeppu, Y.V.; Karunakar, K. & Subramanyam,

P.S. Flight clearance of safety-critical software

using non-real time testing. In ATIO, 2002.

AIAA Paper No. AIAA-2002-582 1.

P.S. Testing safety critical Ada code using nonreal

time testing. In Reliable software technologies,

ADA-Europe 2003, edited by Jean-Pierre Rosen

and A. Strohmeier. Lecture Notes in Computer

Science, 2655. pp. 382-93.

Giri, Sukant K.; Mishra, Atit; Jeppu Y.V. &

Karunakar, K. A randomised test approach to

testing safety critical Ada code. In Reliable

software technologies, Ada-Europe-2004, edited

by Albert Liamosi and Alfred Strohmeier. Lecture

Notes in Computer Science, 3063. pp. 190-99.

Collinson, R.P.G. Introduction to avionics.

Microwave Technology Series-1 1. Chapman &

Hall, 1996