Formal safety analysis of mode transitions in aircraft flight control system

Abstract

Various well-established techniques exist for functional safety analysis of safety-critical avionics systems. Most of these techniques are based on informal models and due to this, analysis is often subjective and success is dependent on the skill of the practitioner. Various standards like DO-178B, IEC 61508 etc. that provide guidelines to perform safety analysis also propose formal verification methods as one of the techniques for functional safety analysis. This technique is based on formal models of the system under development and can be applied on requirements, design and code to get assurance of the respective artifact satisfying a wide variety of functional requirements.In this paper, we present a case study of applying formal verification methods for doing safety analysis of requirements of a generic aircraft flight control system. Flight control system is broadly specified in two parts: mode transition logic part specifies which mode the system is in and represents the function performed by the flight control system. In each mode, certain control laws are executed to implement the various flight control functions. We used a particular technique in formal verification namely that of model checking for analysis. The mode transition logic of a generic auto pilot was modeled and verified using three different open source model checking tools---SPIN, NuSMV and SAL.2.C.1-3

Analyze the Mode Transition Logic of Automatic Flight Control System using Semi-Formal Approach

“…The computerized system having the same structure and functions as we expected and it satisfied the requirements according the standard guidelines [5,6].…”

“…A formal verification technique is a mathematically based languages tools and techniques to formally model the design based on the project requirements. These formal methods technique is used to analyze the system behavior for all the possibilities and converge of the system [5,6].…”

Hazards in advising autonomy: A structured approach seeking novelty in developing the requirements for an exemplar

“…The divergent view arises when these importance values are reversed and both tiers of analysis reprocessed. In this analysis the requirements to incorporate formal methods [11] and redundant V&V techniques [12] prove to be only weakly supported. Due to space constraints the set of unreduced QFD charts cannot be shown here.…”

A Verification Method for Software Safety Requirement by Combining Model Checking and FTA

“…However, the conventional requirements verification methods such as manual review, analysis and testing for safety analysis of software requirements have problems in terms of correctness and efficiency. Formal method [2] has been proved to be an effective method to reduce errors and an important way to improve the software dependability. Moreover it has been gradually applied into safety-critical software systems in some aerospace research institutions.…”