Patent Publication Number: US-7913232-B2

Title: Certifying software for safety-critical systems

Description:
FIELD OF THE INVENTION 
     The present invention relates to certifying software for safety-critical systems. 
     BACKGROUND 
     A safety-critical system is a computer, electronic, or electromechanical system that upon failure can cause injury or loss of human life, severe environmental damage, provide a large adverse financial impact, or other similar catastrophic event. A failure of a safety-critical system includes failure of the system to perform intended functions, failure to warn the operator(s) or customer(s) of an unsafe condition, or failure to display appropriate information. For example, an aircraft control system is considered a safety critical system since the failure of the system can result in the loss of passengers and aircraft crew. 
     To incorporate software into safety critical systems, standards, such as the Radio Technical Committee on Aeronautics (RTCA) guidance document DO-178B, entitled “Software Considerations in Airborne Systems and Equipment Certification”, were developed to focus on software dependence of safety-critical systems. By applying these standards during software development, safety hazards can be identified along with detecting conditions that can lead to the hazards. 
     SUMMARY 
     In an aspect, the invention features a method of collecting information including retrieving a first criterion for certifying software for use on a safety-critical system, receiving user input information associated to the first criterion, determining if the input information aids in satisfying the first criterion for certifying the software for use on the safety-critical system, and providing output information to the user, the output information identifying if the first criterion is satisfied. 
     Embodiments may include one or more of the following. The received user input information may be requested. The user input information may include user-entered text. The user input information may include a user-entered file identifier. The file identifier may identify a file containing a block diagram model. The file identifier may identify a file containing information satisfying the first criterion. The method of collecting information may include storing the received user input information. The method of collecting information may include storing the output information. The method of collecting information may include processing the user input information into processed information satisfying the first criterion. The method of collecting information may include storing the processed information. The first criterion may include an objective of a guidance document. The guidance document may be the Radio Technical Committee on Aeronautics guidance document DO-178B. Providing the output information may include displaying the output information to the user. Providing the output information may include producing an output document. The safety-critical system may include an aircraft. The method of collecting information may include assigning a software level to the software. The assigned software level may be based on the software failing on the safety-critical system. Receiving user input may include using a qualified software tool. The method of collecting information may include using a qualified software tool. The method of collecting information may include repeating retrieving, receiving, determining, and providing for a second criterion, different from the first criterion. 
     In another aspect, the invention features a method including in a computer system, retrieving a first criterion for certifying the software for use on a safety-critical system, receiving user input information associated to the first criterion, determining if the input information aids in satisfying the first criterion for certifying the software for use on the safety-critical system, and providing output information to the user, the output information identifying if the first criterion is satisfied. 
     In another aspect, the invention features an article including a storage medium having stored thereon instructions that when executed by a machine result in the following: retrieve a first criterion for certifying software for use on a safety-critical system, receive user input information associated to the first criterion, determine if the input information aids in satisfying the first criterion for certifying the software for use on the safety-critical system, and provide output information to the user, the output information identifying if the first criterion is satisfied. 
     Embodiments may include one or more of the following. The received user input information may be requested. The user input information may include user-entered text. The user input information may include a user-entered file identifier. The file identifier may identify a file containing a block diagram model. The file identifier may identify a file containing information satisfying the first criterion. The article may include instructions that when executed cause the machine to store the received user input information. The article may include instructions that when executed cause the machine to store the output information. The article may include instructions that when executed cause the machine to process the user input information into processed information satisfying the first criterion. The article may include instructions that when executed cause the machine to store the processed information. The first criterion may include an objective of a guidance document. The guidance document may be the Radio Technical Committee on Aeronautics guidance document DO-178B. The article may include instructions that when executed cause the machine to provide the output information that may include displaying the output information to the user. The article may include instructions that when executed cause the machine to provide the output information that may include producing an output document. The safety-critical system may include an aircraft. The article may include instructions that when executed cause the machine to assign a software level to the software. The assigned software level may be based on the software failing on the safety-critical system. The article may include instructions that when executed cause the machine to receive user input using a qualified software tool. The article may include qualified software tool instructions. The article may include instructions that when executed cause the machine to repeat retrieving, receiving, determining, and providing for a second criterion, different from the first criterion. 
     In another aspect, the invention features a graphical user interface (GUI) including a workspace, a set of graphical semantics for displaying a first criterion for certifying software for use on a safety-critical system, a set of graphical semantics for receiving user input information to aid in satisfying the first criterion, and a set of graphical semantics for displaying output information to the user, the output information identifying if the first criterion is satisfied. 
     Embodiments may include one or more of the following. The received user input information may be requested. The graphical user interface may include a qualified software tool. The graphical user interface may include a set of graphical semantics for displaying a second criterion for certifying the software for use on the safety-critical system. 
     The invention may include one or more of the following advantages. By guiding a developer through each pertinent objective associated in developing a particular piece of software, the developer can determine if the appropriate certification information needed for certification has been collected. By guiding the developer through the pertinent objectives, the developer can also efficiently determine what certification information, if any, still needs to be collected to satisfy the objectives. Additionally, by processing information supplied by the developer into a form and structure needed for certification, the developer is removed from participating in additional processing. 
     Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of software, a software wizard, and a safety-critical system. 
         FIG. 2  is a flow diagram of a software certification process. 
         FIG. 3   a - c  are flow diagrams of a portion of the software certification process of  FIG. 2 . 
     
    
    
     DESCRIPTION OF TABLES 
     TABLE 1 is a table of failure condition categories, descriptions, and software levels from RTCA document DO-178B. 
     TABLE 2 is a table of an objective, objective applicability, objective output, and objective control categories. 
     TABLE 3-12 are certification tables from RTCA document DO-178B. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
             
            
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Software Planning Process 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 Software development 
                 4.1a 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Plan for Software Aspects of 
                 11.1 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 and Integral processes 
                 4.3 
                   
                   
                   
                   
                 Certification 
               
               
                   
                 activities are defined. 
                   
                   
                   
                   
                   
                 Software Development Plan 
                 11.2 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                   
                   
                   
                   
                   
                   
                 Software Verification Plan 
                 11.3 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                   
                   
                   
                   
                   
                   
                 SCM Plan 
                 11.4 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                   
                   
                   
                   
                   
                   
                 SQA Plan 
                 11.5 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 2 
                 Transition criteria, 
                 4.1b 
                 ◯ 
                 ◯ 
                 ◯ 
               
               
                   
                 inter-relationships 
                 4.3 
               
               
                   
                 and sequencing 
               
               
                   
                 among processes are 
               
               
                   
                 defined. 
               
               
                 3 
                 Software life cycle 
                 4.1c 
                 ◯ 
                 ◯ 
                 ◯ 
               
               
                   
                 environment is 
               
               
                   
                 defined. 
               
               
                 4 
                 Additional 
                 4.1d 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
               
               
                   
                 considerations 
               
               
                   
                 are addressed. 
               
               
                 5 
                 Software development 
                 4.1e 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 SW Requirements Standards 
                 11.6 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
               
               
                   
                 standards are defined. 
                   
                   
                   
                   
                   
                 SW Design Standards 
                 11.7 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
               
               
                   
                   
                   
                   
                   
                   
                   
                 SW Code Standards 
                 11.8 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
               
               
                 6 
                 Software plans comply 
                 4.1f 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 SQA Records 
                 11.19 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 with this document. 
                 4.6 
                   
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 7 
                 Software plans are 
                 4.1g 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 SQA Records 
                 11.19 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 coordinated. 
                 4.6 
                   
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with Independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Software Development Processes 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 High-level requirements 
                 5.1.1a 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Requirements Data 
                 11.9 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 are developed. 
               
               
                 2 
                 Derived high-level 
                 5.1.1b 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Requirements Data 
                 11.9 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 requirements are 
               
               
                   
                 defined. 
               
               
                 3 
                 Software architecture is 
                 5.2.1a 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Design Description 
                 11.10 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 developed. 
               
               
                 4 
                 Low-level requirements 
                 5.2.1a 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Design Description 
                 11.10 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are developed. 
               
               
                 5 
                 Derived low-level 
                 5.2.1b 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Design Description 
                 11.10 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 requirements are 
               
               
                   
                 defined. 
               
               
                 6 
                 Source Code is 
                 5.3.1a 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Source Code 
                 11.11 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 developed. 
               
               
                 7 
                 Executable Object Code 
                 5.4.1a 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Executable Object Code 
                 11.12 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 is produced and 
               
               
                   
                 integrated in the target 
               
               
                   
                 computer. 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisifed with Independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Verification Of Outputs of Software Requirements Process 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 Software high-level 
                 6.3.1a 
                 ● 
                 ● 
                 ◯ 
                 ◯ 
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 requirements comply 
               
               
                   
                 with system 
               
               
                   
                 requirements. 
               
               
                 2 
                 High-level requirements 
                 6.3.1b 
                 ● 
                 ● 
                 ◯ 
                 ◯ 
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are accurate and 
               
               
                   
                 consistent. 
               
               
                 3 
                 High-level requirements 
                 6.3.1c 
                 ◯ 
                 ◯ 
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are compatible with 
               
               
                   
                 target computer. 
               
               
                 4 
                 High-level requirements 
                 6.3.1d 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are verifiable. 
               
               
                 5 
                 High-level requirements 
                 6.3.1e 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 conform to standards. 
               
               
                 6 
                 High-level requirements 
                 6.3.1f 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are traceable to system 
               
               
                   
                 requirements. 
               
               
                 7 
                 Algorithms are accurate. 
                 6.3.1g 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with independence. 
               
               
                 ◯ The objective should be a satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 Verification Of Outputs of Software Design Process 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Low-level requirements 
                 6.3.2a 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                   
               
               
                   
                 comply with high-level 
               
               
                   
                 requirements. 
               
               
                 2 
                 Low-level requirements 
                 6.3.2b 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are accurate and 
               
               
                   
                 consistent. 
               
               
                 3 
                 Low-level requirements 
                 6.3.2c 
                 ◯ 
                 ◯ 
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are compatible with 
               
               
                   
                 target computer. 
               
               
                 4 
                 Low-level requirements 
                 6.3.2d 
                 ◯ 
                 ◯ 
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are verifiable. 
               
               
                 5 
                 Low-level requirements 
                 6.3.2e 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 conform to standards. 
               
               
                 6 
                 Low-level requirements 
                 6.3.2f 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 are traceable to high- 
               
               
                   
                 level requirements. 
               
               
                 7 
                 Algorithms are accurate. 
                 6.3.2g 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 8 
                 Software architecture is 
                 6.3.3a 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 compatible with high- 
               
               
                   
                 level requirements. 
               
               
                 9 
                 Software architecture is 
                 6.3.2b 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 consistent. 
               
               
                 10 
                 Software architecture is 
                 6.3.3c 
                 ◯ 
                 ◯ 
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 compatible with target 
               
               
                   
                 computer. 
               
               
                 11 
                 Software architecture is 
                 6.3.3d 
                 ◯ 
                 ◯ 
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 verifiable. 
               
               
                 12 
                 Software architecture. 
                 6.3.3e 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 conforms to standards 
               
               
                 13 
                 Software partitioning 
                 6.3.3f 
                 ● 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 integrity is confirmed. 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                 Verification Of Outputs of Software Coding &amp; Integration Processes 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 Source Code complies 
                 6.3.4a 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                   
               
               
                   
                 with low-level 
               
               
                   
                 requirements. 
               
               
                 2 
                 Source Code complies 
                 6.3.4b 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 with software 
               
               
                   
                 architecture. 
               
               
                 3 
                 Source Code is 
                 6.3.4c 
                 ◯ 
                 ◯ 
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 Verifiable. 
               
               
                 4 
                 Source Code conforms to 
                 6.3.4d 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 standards. 
               
               
                 5 
                 Source Code is 
                 6.3.4e 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 traceable to low-level 
               
               
                   
                 requirements. 
               
               
                 6 
                 Source Code is accurate 
                 6.3.4f 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 and consistent. 
               
               
                 7 
                 Output of software 
                 6.3.5 
                 ◯ 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 integration process is 
               
               
                   
                 complete and correct. 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                 Testing of Outputs of Integration Process 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 Executable Object Code 
                 6.4.2.1 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Verification Cases 
                 11.13 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 complies with high-level 
                 6.4.3 
                   
                   
                   
                   
                 and Procedures 
               
               
                   
                 requirements. 
                   
                   
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 2 
                 Executable Object Code 
                 6.4.2.2 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Verification Cases 
                 11.13 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 is robust with high-level 
                 6.4.3 
                   
                   
                   
                   
                 and Procedures 
               
               
                   
                 requirements. 
                   
                   
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 3 
                 Executable Object Code 
                 6.4.2.1 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Cases 
                 11.13 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
               
               
                   
                 complies with low-level 
                 6.4.3 
                   
                   
                   
                   
                 and Procedures 
               
               
                   
                 requirements. 
                   
                   
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 4 
                 Executable Object Code 
                 6.4.2.2 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Cases 
                 11.13 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
               
               
                   
                 is robust with low-level 
                 6.4.3 
                   
                   
                   
                   
                 and Procedures 
               
               
                   
                 requirements. 
                   
                   
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 5 
                 Executable Object Code 
                 6.4.3a 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Verification Cases 
                 11.13 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 is compatible with target 
                   
                   
                   
                   
                   
                 and Procedures 
               
               
                   
                 computer. 
                   
                   
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 Verification Of Verification Process Results 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 Test procedures are 
                 6.3.6b 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Cases 
                 11.13 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                   
               
               
                   
                 correct. 
                   
                   
                   
                   
                   
                 and Procedures 
               
               
                 2 
                 Test results are correct 
                 6.3.6c 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 and discrepancies 
               
               
                   
                 explained. 
               
               
                 3 
                 Test coverage of high- 
                 6.4.4.1 
                 ● 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 level requirements is 
               
               
                   
                 achieved. 
               
               
                 4 
                 Test coverage of low- 
                 6.4.4.1 
                 ● 
                 ◯ 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 level requirements is 
               
               
                   
                 achieved. 
               
               
                 5 
                 Test coverage of 
                 6.4.4.2 
                 ● 
                   
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
               
               
                   
                 software structure 
               
               
                   
                 (modified 
               
               
                   
                 condition/decision) is 
               
               
                   
                 achieved. 
               
               
                 6 
                 Test coverage of 
                 6.4.4.2a 
                 ● 
                 ● 
                   
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 software structure 
                 6.4.4.2b 
               
               
                   
                 (decision coverage) is 
               
               
                   
                 achieved. 
               
               
                 7 
                 Test coverage of 
                 6.4.4.2a 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 software structure 
                 6.4.4.2b 
               
               
                   
                 (statement coverage) is 
               
               
                   
                 achieved. 
               
               
                 8 
                 Test coverage of 
                 6.4.4.2c 
                 ● 
                 ● 
                 ◯ 
                   
                 Software Verification Results 
                 11.14 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 software structure (data 
               
               
                   
                 coupling and control 
               
               
                   
                 coupling) is achieved. 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 10 
               
             
            
               
                   
               
               
                 Software Configuration Management Process 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 Configuration items are 
                 7.2.1 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 SCM Records 
                 11.18 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 identified. 
               
               
                 2 
                 Baselines and 
                 7.2.2 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Configuration 
                 11.16 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 traceability are 
                   
                   
                   
                   
                   
                 Index 
               
               
                   
                 established. 
                   
                   
                   
                   
                   
                 SCM Records 
                 11.18 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                 3 
                 Problem reporting, 
                 7.2.3 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Problem Reports 
                 11.17 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 change control, 
                 7.2.4 
                   
                   
                   
                   
                 SCM Records 
                 11.18 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 change review, and 
               
               
                   
                 configuration status 
                 7.2.5 
               
               
                   
                 accounting are 
                 7.2.6 
               
               
                   
                 established. 
               
               
                 4 
                 Archive, retrieval, and 
                 7.2.7 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 SCM Records 
                 11.18 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 release are established. 
               
               
                 5 
                 Software load control is 
                 7.2.8 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 SCM Records 
                 11.18 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 established. 
               
               
                 6 
                 Software life cycle 
                 7.2.9 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Life Cycle 
                 11.15 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (2)} 
               
               
                   
                 environment control is 
                   
                   
                   
                   
                   
                 Environment Configuration 
               
               
                   
                 established. 
                   
                   
                   
                   
                   
                 Index 
               
               
                   
                   
                   
                   
                   
                   
                   
                 SCM Records 
                 11.18 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 Software Quality Assurance Process 
               
            
           
           
               
               
               
               
            
               
                   
                 Applicability 
                   
                 Control 
               
               
                   
                 by 
                   
                 Category 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
               
                 1 
                 Assurance is obtained 
                 8.1a 
                 ● 
                 ● 
                 ● 
                 ● 
                 Software Quality Assurance 
                 11.19 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 that software 
                   
                   
                   
                   
                   
                 (SQA) Records 
               
               
                   
                 development and integral 
               
               
                   
                 integral processes comply 
               
               
                   
                 with approved software 
               
               
                   
                 plans and standards. 
               
               
                 2 
                 Assurance is obtained 
                 8.1b 
                 ● 
                 ● 
                   
                   
                 SQA Records 
                 11.19 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 that transition criteria for 
               
               
                   
                 the software life cycle 
               
               
                   
                 processes are satisfied. 
               
               
                 3 
                 Software conformity 
                 8.1c 
                 ● 
                 ● 
                 ● 
                 ● 
                 SQA Records 
                 11.19 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
                 {circle around (2)} 
               
               
                   
                 review is conducted. 
                 8.3 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 12 
               
             
            
               
                   
               
               
                 Certification Liaison Process 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 Applicability 
                   
                 Control 
               
               
                   
                   
                 by 
                   
                 Category 
               
               
                   
                 Objective 
                 SW Level 
                 Output 
                 by SW level 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
                 Description 
                 Ref. 
                 A 
                 B 
                 C 
                 D 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 1 
                 Communication and 
                 9.0 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Plan for Software Aspects of 
                 11.1 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 understanding between 
                   
                   
                   
                   
                   
                 Certification 
               
               
                   
                 the applicant and the 
               
               
                   
                 certification authority is 
               
               
                   
                 established. 
               
               
                 2 
                 The means of 
                 9.1 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Plan for Software Aspects of 
                 11.1 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 compliance is proposed 
                   
                   
                   
                   
                   
                 Certification 
               
               
                   
                 and agreement with the 
               
               
                   
                 Plan for Software 
               
               
                   
                 Aspects of Certification 
               
               
                   
                 is obtained. 
               
               
                 3 
                 Compliance 
                 9.2 
                 ◯ 
                 ◯ 
                 ◯ 
                 ◯ 
                 Software Accomplishment 
                 11.20 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                 substantiation is 
                   
                   
                   
                   
                   
                 Summary 
               
               
                   
                 provided. 
                   
                   
                   
                   
                   
                 Software Configuration 
                 11.16 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
                 {circle around (1)} 
               
               
                   
                   
                   
                   
                   
                   
                   
                 Index 
               
               
                   
               
               
                 LEGEND: 
               
               
                 ● The objective should be satisfied with Independence. 
               
               
                 ◯ The objective should be satisfied. 
               
               
                 Blank Satisfaction of objective is at applicant&#39;s discretion. 
               
               
                 {circle around (1)} Data satisfies the objectives of Control Category 1 (CC1). 
               
               
                 {circle around (2)} Data satisfies the objectives of Control Category 2 (CC2). 
               
            
           
         
       
     
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an exemplary system  10  includes software  12  that is developed to, for example, control a jet engine on an airliner  18  that is considered safety-critical system. Once the jet engine control software  12  is developed, a certification process  16  is used to assure that certification information needed to certify the software is collected. In some arrangements a “software wizard”  14  provides a user interface (UI) such that a user is guided through the certification process  14  and prompted to enter the needed certification information. After the certification information is collected, the certification process  16  processes and formats the certification information such that the user can provide the appropriate certification information to the Federal Aviation Administration (FAA) to obtain certification for the jet engine control software  12 . Once the FAA certification is attained, the jet engine control software  12  can be integrated into the airliner  18  for use on the safety-critical system. 
     The certification process  16  is used to assure that the jet engine control software  12  is safe and airworthy. By using the certification process  16  through the software wizard  14 , the user (e.g., software developer) is guided through the objectives of the “Software Considerations in Airborne Systems and Equipment Certification,” guidance document (RTCA document Do-178B), incorporated by reference herein, so that certification information needed to satisfy the particular objectives associated with the jet engine control software  12  are collected. By prompting the user to provide information, the certification information needed for each appropriate objective is collected and processed into an appropriate form required for certification. 
     Guidance document DO-178B is typically used by civil aviation manufactures in the approval of software developed for airborne platforms. The purpose of the guidance document is to provide detailed guidelines for the production of software so that associated functions are performed at a level of confidence in safety to comply with airworthiness requirements. By complying with these requirements software products are produced by the appropriate state-of-the-practice methods. 
     To associate the objectives provided by the DO-178B guidance document to the safety-critical software, a system safety assessment is applied to the software development effort. A system safety assessment is a process that identifies hazards, failure conditions that lead to the hazards, and the effects of mitigating the hazards and failure conditions. Typically these assessments are performed by or in association with the FAA. As a result of the system safety assessment, the software development effort is assigned a software level. The system safety assessment task determines this software level based on a contribution of the software to the potential failure conditions and the severity of the potential failure conditions. 
     Referring to Table 1, five possible software levels A-E are shown in column  20  that can individually be assigned to a software development, such as the jet engine control software  12  (shown in  FIG. 1 ). Table 1 also provides a relationship between the respective software levels and respective failure condition categories in column  22  and a summarized description of the failure condition in column  24 . The range of the failure conditions and respective software levels include catastrophic conditions (software level A) that would prevent the continued safe flight or landing of the airliner  18  (shown in  FIG. 1 ) to conditions that do not affect the operation capability of the airliner or crew (software level E). 
     These software levels A-E in column  20  are used to define differing degrees of rigor that the FAA applies to certify software for a safety-critical system. To apply the different degrees of rigor for each particular software level, guidance document DO-178B lists objectives that must be met to certify safety-critical software. Referring to Table 2, one exemplary objective  26  is shown that illustrates a layout and structure of each objective provided by DO-178B. The objective  26  includes an objective number  28 , a description of the objective  30 , and a reference  32  to the particular paragraph in DO-178B where the objective is further detailed. Following the objective  26  portion, four columns  34 - 40  provide the applicability of the objective to the software levels A-D (shown in Table 1). Since software level E covers non-effective software in regards to safety-critical functions, no objectives are required. Included in each respective column  34 - 40  is a symbol, or blank space, that corresponds to a legend  42  shown with the table. For example, this particular objective  26  is applicable for software classified under software levels A, B, and C. However, for software classified under software level D this objective does not need to be satisfied. Also, since software classified under software level E has no effect on operation of the aircraft, the objective also does not have to be satisfied. As shown for this particular objective, level A and B software requires that the objective be satisfied with independence while level C software does not require independence. As defined in the guidance document DO-178B, independence is achieved when the verification activity is performed by a person(s) other than the developer of the item being verified. For software quality assurance, independence also includes the authority to ensure corrective action. 
     The next two columns  44 ,  46  following the applicability columns  34 - 40 , moving left to right, describe the output required to satisfy the objective. The description column  44  provides the document which reports whether the objective is satisfied or not, based on the information provided by the user, and the reference column  46  identifies the paragraph within Chapter 11 of DO-178B that details the attributes of document listed in column  44 . In some objectives the description column  44  provides the particular type for code (e.g., source code, object code, executable code, etc.) that needs to be collected to satisfy the particular objective and the reference column  46  identifies the paragraph in DO-178B that details the needed code. 
     The last four columns  48 - 54  of Table 2 associate the four software levels to control category  1  (CC 1 ) and control category  2  (CC 2 ) listed in the legend  42 . The control categories define management activities, which are defined in the guidance document DO-178B, and are addressed in producing the outputs. Typically control category  1  (CC 1 ) requires more management activities than control category  2  (CC 2 ). For example, CC 1  requires problem reporting and change control, however, CC 2  requires only change control. 
     Although Table 2 provides the relationship between the four software levels and the objective  26 , the guidance document DO-178B includes numerous other objectives associated with safety-critical software development that are dependent upon the software level of the software development. In general the more risk of failure associated to a particular software level, the more objectives have to be satisfied. For example, the number of objectives associated to each particular software level is listed below as provided from the guidance document DO-178B:
         Software Level A: 66 objectives   Software Level B: 65 objectives   Software Level C: 58 objectives   Software Level D: 28 objectives   Software Level E: 0 objectives       

     The guidance document distributes these objectives across various development processes that are used in producing software products for safety-critical systems. These development processes are the software requirements process, the software design process, the software coding process, and the integration process. Guidance document DO-178B also describes the integral processes that ensure correctness, control, and confidence of the software life cycles and their outputs. The integral processes are the software verification process, the software configuration management process, the software quality assurance process, and the certification liaison process. Each of these processes are described in detail in the guidance document DO-178B that also includes a description of the software planning processes that define and coordinate the activities of the software development and integral processes for the software being developed for the safety-critical system. 
     Each of the processes are associated with one or more objectives that are listed in Annex A of DO-178B and are organized by the development processes and integral processes mentioned above. Referring to Tables 3-12, the objectives, which are similar in structure and form to the objective shown in Table 2, are listed under the respective ten processes listed below. 
     Table 3: Software Planning Process 
     Table 4: Software Development Processes 
     Table 5: Verification of Outputs of Software Requirements Process 
     Table 6: Verification of Outputs of Software Design Process 
     Table 7: Verification of Outputs of Software Coding &amp; Integration Processes 
     Table 8: Testing of Outputs of Integration Process 
     Table 9: Verification of Verification Process Results 
     Table 10: Software Configuration Management Process 
     Table 11: Software Quality Assurance Process 
     Table 12: Certification Liaison Process 
     By using the certification process  16  (shown in  FIG. 1 ) through the software wizard  14  (also shown in  FIG. 1 ) interactive environment, the user is presented each objective associated to the software being developed and prompted to provide certification information to satisfy the objective. In general, the process  16  and wizard  14  are executed by one or more computers and appropriate objectives are displayed to the user in a series of screens. The user views the series of objectives and may be prompted to enter certification information to assist the certification process  16  in collecting and processing information to satisfy the appropriate objectives that are required to certify the software for incorporation on safety-critical systems. 
     Referring to  FIG. 2  a certification process  60  is shown that provides a user with the objectives that are associated to the particular software being developed for use on a safety-critical system such as the airliner  18  shown in  FIG. 1 . For example, if the user is developing software to control the jet engine on the airliner  18 , the certification process  60  guides the user through all the objectives associated with developing the jet engine control software  12 , which typically is assigned software level “A” by the FAA since failure of the software can prevent safe flight. In another example, a user may be developing software to control the “occupied” light on the restroom door of the airliner  18 . This software maybe assigned software level “D” or “E” by the FAA since failure of the software will not reduce aircraft safety. However, similar to the jet engine control software  12 , the certification process  60  can guide the user through each objective associated with the “occupied” light software assigned software level “D” or “E”. 
     Along with guiding the user through the appropriate objectives, the certification process  60  also can produce, or assist the user in producing, outputs needed to satisfy the objectives associated to the particular software being developed. For example, the output to satisfy a particular objective may be a planning document, a design description, source code, executable code, or other type of output described in the guidance document DO-178B. Once the particular outputs have been collected that satisfy the objectives associated to the developed software, the outputs can be provided to the FAA, or other governing entity, for assessing conformance with DO-178B. Typically this conformance is determined through on-site reviews and/or desktop (data) reviews by regulatory authorities or appropriately designated industry representatives. By collecting the required outputs, each pertinent objective can be efficiently assessed to determine if the objective has been satisfied. 
     In some arrangements the certification process  60  uses an interactive tool, such as the software wizard  14  environment, to guide the user through the pertinent objectives associated to the safety-critical software under development. A series of dialog boxes associated with the software wizard  14  are used to enable the user to complete the certification process  60 . Besides providing the appropriate objectives to the user, the wizard  14  can also provide an interactive tool to collect responses from the user to aid in satisfying the one or more displayed objectives. 
     The certification process  60  starts ( 62 ) when the software level assigned to the software under development for the safety-critical system is received ( 64 ). Typically the software level is determined by the FAA based on the nature of the software under development, however in some arrangements the user of the certification process  60  can enter the assigned level into the process. As mentioned above, the software levels are shown in Table 1 and range over software associated with catastrophic effects (software level A) to no effect on airliner operations (software level E). After the software level is received ( 64 ), the certification process  60  retrieves ( 66 ) the first objective that must be satisfied based on received software level. Referring briefly to Tables 3-12, each of the objectives that may be applicable to the received software level are shown. For example, objective 1 of table 3 is applicable to software levels A-D and the description of the objective, along with other appropriate associated information, would be retrieved by the certification process  60 . 
     After the first objective has been retrieved ( 66 ), the certification process  60  displays ( 68 ) the objective to the user. In some arrangements the description of the objective is displayed to the user along with a response field for the user to input information that is used to satisfy the objective. After the objective has been the displayed ( 68 ), the certification process  60  waits to receive ( 70 ) input from the user to satisfy the objective that is currently displayed. 
     Referring to  FIG. 3   a,  receiving ( 70 ) input from the user may, in some arrangements for certain objectives, include the certification process  60  receiving ( 86 ) a filename from the user. After the filename is received ( 86 ), the certification process  60  uses ( 88 ) the filename to retrieve data from a respective file for use as input from the user to satisfy the particular objective displayed. For example, a filename can be entered by the user to provide a system block diagram model to the certification process  60 . The block diagram model, or other data structure may have been produced by the Simulink®, Stateflow®, or the Stateflow Coder® software package from Mathworks, Inc. of Natick, Mass., incorporated by reference herein. After retrieving ( 88 ) the system block diagram model or other data structure, the certification process  60  continues in  FIG. 2 . 
     Referring to  FIG. 3   b,  in some arrangements, receiving ( 70 ) input from the user may include receiving ( 90 ) a filename and processing data from the corresponding file to produce the information needed to satisfy the currently displayed objective. For example, after receiving ( 90 ) the filename, the certification process  60  uses the filename to retrieve ( 92 ) a block diagram model from the respective file. Once the block diagram model is retrieved ( 92 ), the certification process  60 , for example, produces ( 94 ) source code by passing the block diagram model to an automatic code generation software package such as Real-Time Workshop®, Real-Time Embedded Coder Workshop®, Stateflow Coder®, etc. from Mathworks of Natick, Mass., incorporated by reference herein. Once the source code is produced ( 94 ) from the block diagram model, the certification process  60  can use ( 96 ) the source code as user input and continue the certification process  60  shown in  FIG. 2  to satisfy the currently displayed objective. 
     Referring to  FIG. 3   c,  in some arrangements, receiving ( 70 ) input from the user may include retrieving ( 98 ) a qualified software tool that is associated with the currently displayed objective and using the qualified software tool to produce the information needed to satisfy the currently displayed objective. By using a qualified software tool, such as a software development tool or a software verification tool as described in section 12.2 of the DO-178B guidance document, the output of the qualified software tool does not have to be verified as described by section 6 of the DO-178B guidance document. Thus, by using a qualified software tool, processes described in the DO-178B guidance document can be eliminated, reduced or automated. After retrieving ( 98 ) the qualified software tool, the certification process  60  uses ( 100 ) the qualified software tool to produce verified source code. After the verified source code is produced ( 100 ), the certification process  60  can use ( 102 ) the source code as user input and continue the certification process  60  shown in  FIG. 2  to satisfy the currently displayed objective. 
     Returning again to  FIG. 2 , after receiving ( 70 ) input from the user, the certification process  60  collects and processes ( 72 ) the input to satisfy the currently displayed objective. For example, the format or structure of the user input can be altered to satisfy the displayed objective. Also, the processed user input can be stored for assessing at a later time. Once the input is collected and processed ( 72 ) the certification process  60  produces ( 74 ) the one or more outputs, as described in the DO-178B guidance document, which are needed to satisfy the current objective. This output, as detailed in DO-178B, may be a document, a file containing a document, a file containing a block diagram model, a file containing source code, or a file containing some other similar information needed to satisfy an objective of the DO-178B guidance document. In some arrangements the output may include a Boolean variable that reports whether the objective has been met or not. 
     After producing ( 74 ) the output, the certification process  60  stores ( 76 ) the output for later accessing by the user, or another party, to determine if the objectives have be met or not. After storing ( 76 ) the output, the certification process  60  determines ( 78 ) if all the appropriate objectives have been displayed to the user based on the particular software level assigned to the developed software. Referring briefly to Tables 3-12, the applicability for each of software level is provided and as mentioned may currently include up to  66  individual objectives. 
     Returning to  FIG. 2 , if the certification process  60  determines ( 78 ) that at least one more objective is to be assessed, the certification process  60  retrieves ( 80 ) the next pertinent objective and returns to display ( 68 ) the next objective and repeat the process for this objective. If determined ( 78 ) that no more objectives are applicable to the software being assessed, based on the received software level, the certification process  60  produces ( 82 ) an output report for the user that reports whether each pertinent objective is satisfied and the particular certification information that satisfied each objective. Once the output report has been produced ( 82 ), the certification process  60  exits ( 84 ). 
     The invention can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The invention can be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network. 
     Method steps of the invention can be performed by one or more programmable processors executing a computer program to perform functions of the invention by operating on input data and generating output. Method steps can also be performed by, and apparatus of the invention can be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). 
     Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in special purpose logic circuitry. 
     The invention can be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the invention, or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet. 
     The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. 
     In conjunction with  FIG. 1-3  the guidance document DO-178B is used to determine if the developed software meets the appropriate objectives and can be incorporated into the safety-critical system (i.e., the airliner  18 ). However, in some arrangements other guidance documents can be used by the certification process  60  (shown in  FIG. 2 ) to certify software for other safety-critical systems. For example, the United States of America Department of Defense Military Standard for Software Development and Documentation (MIL-STD-498) can be used by the certification process  60  for certifying software for weapons systems and automated information systems. In some arrangements the certification process  60  can use the International Electrotechnical Commission (IEC) standard 61508 that covers safety-related systems that are electrotechnical in nature (e.g., electromechanical systems, solid-state electronic systems and computer-based systems). For example, the IEC 61508 standard can be used to certify safety-critical industrial control systems. In still another example, the certification process  60  can use the United Kingdom (UK) Ministry of Defense guidance documents MoD-00-55, MoD-00-56, and MoD-00-58 for certifying safety-critical military systems in the UK. In still another example, the certification process  60  can use the Food and Drug Administration guidance document FDA-247 to certify software for safety-critical medical equipment. Also, the certification process  60  can use the U.S. Nuclear Regulatory Commission guidance document 1.173 for certifying software associated with safety-critical nuclear power systems. 
     Also in conjunction with  FIG. 1-3 , user input is provided by information entered into a field or a user-entered filename. User input is also provided by processing a block diagram model into source code. However, the user input may also be provided by MATLAB®, Simulink®, Stateflow®, Real-Time Workshop®, Real-Time Workshop Embedded Coder®, Stateflow Coder®, Simulink Performance Tools®, model based test tools, Simulink Report Generator®, or source control interfaces (e.g., the Requirements Management Interface®, the Requirements Management Interface®, etc.) from the Mathworks, Inc. of Natick, Mass., incorporated by reference herein. 
     Also, in conjunction with  FIG. 1-3  a qualified software tool is used to produce verified source code to satisfy an objective. However, in some arrangements a qualified software tool can be used by the certification process  60  to satisfy more than one objective, or to satisfy one or more processes described in the DO-178B guidance document, or to satisfy one or more of the tables described in the DO-178B guidance document. Additionally, the certification process  60  can be qualified to be a qualified software tool such that verified output, as described in the DO-178B guidance document, is provided by the certification process  60 . 
     Also, in conjunction with  FIG. 1-3  certification process  60  output is a report to the user that detailed whether each pertinent DO-178B objective was satisfied or not. However in some arrangements the certification process output includes documents, software code (e.g., source code, object code, executable code, etc.) that can be compiled or interpretive, block diagram model outputs, or other information in a structure or form that is assessable by the MATLAB®, Simulink®, Stateflow®, Real-Time Workshop®, Real-Time Workshop Embedded Coder®, Stateflow Coder®, Simulink Performance Tools®, model based test tools, Simulink Report Generator®, or a source control interface (e.g., Requirements Management Interface®, Configurations Management Interface®, etc.) individually or in combination. 
     Other embodiments are within the scope of the following claims.