Abstract:
A method and system of measuring availability of an in-flight entertainment system (“IFE”) on an aircraft. The method comprises designating a subsystem weight factor to each subsystem of said IFE, with the sum of all subsystem weight factors being equal to a predetermined number, selecting at least one element of the subsystem to measure its availability, designating a zonal weight factor for the at least one element based on a predetermined class to be serviced by the at least one element, assigning an element loss factor based on a level of service for at least one element, collecting performance information regarding the at least one element during a predetermined period of time, and measure the element&#39;s availability based on the subsystem weight factor, the zonal weight factor, the element loss factor and the level of service.

Description:
RELATED FIELD 
     The present invention relates to in-flight entertainment systems for passenger aircrafts and more particularly relates to a method and system for measuring system availability. 
     ART BACKGROUND 
     Commercial passenger airlines continuously try to make air travel as enjoyable as possible. One of such efforts is directed at providing in-flight entertainment systems (“IFE”) for passengers on the aircraft. One of the earliest forms of IFE is probably the audio programs through the plastic ear jacks. Then there were the individual systems to offer both audio and video programming. Nowadays, in addition to audio and video programming, passengers begin to expect the airlines to offer a host of features such as video-on-demand, video games, shopping, access to the Internet, phone and facsimile, and landscape camera. 
     To remain competitive, airlines respond by installing more and more gadgets on-board and at the same time demanding the suppliers for such gadgets to guarantee certain level of performance and availability during flight. Not surprisingly, the more electronics that are crammed into the limited cabin space, the more likely something will malfunction, thus severely affecting the travel experience of the passengers. Airlines thus want to make sure that the suppliers are held accountable by some standards. Measuring system availability for IFEs allows the airlines to ensure that they get their money&#39;s worth either in the form of greater customer satisfaction, or in the form of retaining commercial leverage, forcing suppliers to compensate and rectify the system malfunction. 
     The suppliers, on the other hand, find it necessary to meet airlines&#39; demands for performance and availability. However, each airline has its unique way of measuring system availability based on perceived priorities with different product features, thus resulting in a different set of factors for measurement. In other words, a 98% system availability for one airline customer does not mean the availability is 98% for another airline customer. Despite the lack of uniformity from one customer&#39;s measurement to another customer&#39;s, a supplier&#39;s inability to pass certain negotiated availability criteria is always justification for the supplier to compensate that airline customer. Further, the process of customizing performance requirements for each customer and the process of evaluating and negotiating for compensation become quite cumbersome and labor-intensive for the supplier, not to mention the comparable resources needed by the airline customer on the other side. In a worst-case scenario, an IFE supplier may find itself facing requests for compensation from many of its customers, each one with its own set of availability criteria which the supplier&#39;s products did not pass, resulting in conflicting priorities in remedying the system. 
     Conventionally, an IFE supplier has to rely on large teams of people to analyze and number-crunch for each customer, each month. After the number crunching, a supplier and a customer will attempt to reconcile to see if both parties agree with the numbers that are derived, and the underlying data. For example, if one system was unavailable because a passenger was found tampering with the wiring, that record can be disregarded for the reason of passenger abuse. While each airline customer has its unique approach to measuring system availability, the analysis is essentially derived from the maintenance and service reports of the same IFE hardware of the IFE supplier. 
     One industry group, Aeronautical Radio Inc., has drafted a set of standards, known as the draft ARINC 628 standard, for measuring IFE system availability. However, the methodology is found to be non-specific in the practical implementation resulting in ambiguous interpretations and therefore different applications for each customer. The standard includes a level of guidance which precludes a level of customization desired by airlines. This approach is therefore subject to abuse by suppliers who interpret it in a manner advantageous to their purpose, and subject to abandonment by airlines who cannot represent their priorities within the guidelines. 
     Therefore, it is desirable to be able to standardize the way to measure system performance and availability for IFE systems. 
     It is also desirable to be able to tailor or customize the methodology for different airline customers without affecting the standardized approach. 
     It is also desirable, if not imperative, to be able to reduce the administrative burden required to assess availability guarantees from customer to customer for the term of the performance guarantee. By way of example only, the magnitude of assessment is in excess of 10,000 individual flights per month spread between a few airlines. This level of effort increases with each airline and each different formula definition. 
     SUMMARY OF THE INVENTION 
     A method and system of measuring availability of an in-flight entertainment system (“IFE”) on an aircraft is disclosed. The method comprises the steps of designating a subsystem weight factor to each subsystem of said IFE, with the sum of all subsystem weight factors being equal to a predetermined number, e.g. 100%, selecting at least one element of the subsystem to measure its availability, designating a zonal weight factor for at least one element based on a predetermined class to be serviced by at least one element, assigning an element loss factor based on a level of service for at least one element, collecting performance information regarding at least one element during a predetermined period of time, and measure the element&#39;s availability based on the subsystem weight factor, the zonal weight factor, the element loss factor and the level of service. 
     The method and system in accordance with the present invention uses configurable data tables, which allows customization of the calculations without revising the tool, as shown in the following. For example, the element loss factors (“ELF”) for the seat system may need to be unique for different IFE service levels to allow more accurate calculations when airlines deploy IFE functionality in phases. In addition, elements that do not apply to an airline&#39;s configuration, as indicated by the different service levels, will have a factor of zero. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS AND TABLES 
     FIG. 1 shows a simplified block diagram illustrating the method and system of SA measurement in accordance with the present invention. 
     FIG. 2 shows a simplified block diagram of the methodology of SA measurement in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A method and system for measuring system availability for in-flight entertainment systems is disclosed. In the description that follows, numerous specific details are set forth in detail to provide a more thorough understanding of the present invention. It will be apparent, however, to one ordinarily skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known features have not been described in detail so as not to obscure the present invention. 
     FIG. 1 shows a simplified block diagram illustrating the method and system of SA measurement in accordance with the present invention. To calculate the SA for the IFE systems, data can come from several sources. One of such sources is the aircraft data  110  from a flight, which may include the following data: 
     Aircraft Tail Number; 
     Flight Departure Airport; 
     Flight Arrival Airport; 
     Date of Flight Arrival; 
     Flight Number; 
     Cabin Log Record including: 
     Cabin Log record number; 
     Indication of Failure; 
     Specific Seats or line-replaceable units (“LRU”) impacted. 
     Another source of data is the on-board service data  115  from a flight, which may include the following: 
     Aircraft Tail Number; 
     Flight Departure Airport; 
     Flight Arrival Airport; 
     Date of Flight Arrival; 
     Flight Number; 
     Maintenance Event Record to contain the following: 
     On-Board Maintenance Record Number; 
     Action Code (removed, passenger misuse, no fault found, cable/wiring reseated, deferral, preventative maintenance, others.) 
     Specific Seats Impacted; 
     Indication of Failure; 
     Reason for Maintenance Event Record (Cabin log record number, Maintenance action, fault list); 
     LRU removal data including: LRU name, LRU part number, LRU serial number, LRU specific location system. 
     A further source of data is the bench and shop repair data  120  after an LRU is removed from the aircraft. Such data may include the following: 
     On-board Maintenance Record Number; 
     LRU type, part number, serial number, and failure/repair action; 
     Passenger misuse indication; 
     Aircraft tail number where an LRU is removed; 
     Date of an LRU&#39;s removal from aircraft. 
     Once the data is collected and properly formatted, the data is processed to determine the SA  100 . It should be noted that not all data from the sources are relevant to SA analysis. For example, a relevant failure may be defined as a loss that affects any flight attendant or passenger&#39;s entertainment system service including but not limited to the loss of: video, audio, passenger control unit functions, touch screen functions, telephone functions, interactive applications, entertainment system&#39;s mechanical failures, and degradation of video and audio quality at the seat. If the failures are defined as relevant, they will be represented as the elements used in the SA measurement in accordance with the present invention. 
     Other failures may be deemed irrelevant based on the reasons behind their occurrence and such irrelevant failures are excluded from the SA measurement. For example, failures may be deemed irrelevant if the reasons are: 
     Improper operation of the supplier&#39;s IFE equipment by airline customer&#39;s personnel; 
     Improper operation of other equipment not supplied by the supplier, but required for proper operation of the supplier&#39;s IFE equipment; 
     Improper alteration or repair by others than the Supplier; 
     Mismatch between each aircraft configuration database and the aircraft&#39;s actual configuration; 
     Failure due to any factors defined as Force Majeure between the supplier and the airline customer. 
     After the SA analysis, an availability report  130  can be generated for the IFE supplier and the airline customer. Such report, as previously discussed, may be used by the parties to determine whether the supplier&#39;s IFE systems have met the guaranteed availability requirements. Such report may also be used by IFE suppliers to forecast the performance of IFE equipment for preventative maintenance purposes. 
     With reference to FIG. 2, the SA methodology in accordance with the present invention is now described in more detail. Box  20  shows, generally, the process of designating loss factors and zonal weights corresponding to the products and services offered to a customer. Box  21  shows, generally, the intermediate process of mapping subsystem service records to faults/failures. Box  23  shows, generally, the process of calculating subsystem availability and the overall SA for the flight based on the faults/failures and loss factors/zonal weights. 
     Referring to FIG. 2, in Box  20 , the services and products which are offered to a customer are identified ( 200 ). Any applicable loss factors and subsystems/zonal weights are also specified ( 205 ). To finalize such factors, weights, products and service guarantees for a customer, it typically involves negotiation between the customer and its supplier ( 210 ). However, as can be appreciated by those skilled in the art, as more customers sign on to the methodology, it is possible that a more standardized range of products, services, loss factors and weights can be developed for the supplier&#39;s IFE systems. 
     In Box  21 , for each flight, on-board service records, including those from a built-in test unit if installed, are mapped to the faults and failures ( 220 ). The factors and weights for that customer can be used to map the overhead subsystem LRU faults to overhead display availability per zone ( 225 ,  230 ), if overhead availability is measured. The factors and weights can also be used to map the faults and failures of the cabin file server and passenger access terminal to cabin management subsystem elements ( 225 ,  240 ), if cabin management availability is measured. The factors and weights for that customer can also be used to map the faults and failures of seat LRUs to the seat subsystem ( 270 ), after mapping the IFE source faults and failures to IFE source elements ( 250 ). 
     In Box  23 , the subsystem availability for the overhead subsystem can be calculated ( 230 ,  235 ). The subsystem availability for the cabin management subsystem can also be calculated ( 240 ,  245 ). The seat subsystem availability can further be calculated ( 255 ,  260 ,  275 ). And finally, an overall SA for the flight can be calculated by summing all the subsystem availability measures ( 280 ). 
     The methodology of SA tool measures the availability of a supplier&#39;s IFE system on board of an aircraft at a point in time, e.g. at departure, in-flight or between departure and arrival. The SA tool processes on-board service, or maintenance log, information along with aircraft configuration data to calculate system availability. Preferably, such information is automatically offloaded from a built-in self-test unit which can detect system failures or isolate faulty LRUs on the aircraft. One example of such built-in tester is the Built-in Test/Built-in Test Equipment system (“BIT/BITE”) available from Rockwell Collins, Inc, the Assignee of the present invention. 
     As can be appreciated by those skilled in the art, measuring an IFE system availability can be done by measuring at least one of the following subsystems: cabin management subsystem availability, overhead subsystem availability, and seat subsystem availability, which may include IFE sources availability. The number for each subsystem is thus available as intermediate calculation result. However, those skilled in the art can readily determine that their availability measurement may be based on one or more subsystems combined. Further, the SA tool is preferably in compliance, as is the SA tool in accordance with the present invention, with the draft ARINC 628 standard for calculating IFE system availability. 
     The SA tool in accordance with the present invention uses configurable data tables, which allows customization of the calculations without revising the tool, as shown in the following. For example, the element loss factors (“ELF”) for the seat system may need to be unique for different IFE service levels to allow more accurate calculations when airlines deploy IFE functionality in phases. In addition, elements that do not apply to an airline&#39;s configuration, as indicated by the different IFE system service levels, will have a factor of zero. An example of four levels of IFE service are described in Table 1. It should be appreciated by those skilled in the art that different levels of IFE service can be configured based on their particular applications. 
     
       
         
               
             
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Example of IFE Service Levels 
               
             
          
           
               
                 IFE Service Level 
                 Description 
               
               
                   
               
               
                 Distributed Video Only 
                 Distributed video and audio with in-seat 
               
               
                   
                 channel selection 
               
               
                 Basic Interactive 
                 Interactive menu capability to select movies, 
               
               
                   
                 games, and audio at the seat 
               
               
                 Full Interactive 
                 Basic Interactive service plus revenue-based 
               
               
                   
                 services like duty-free and shopping 
               
               
                 Digital Audio/Video 
                 Full Interactive service plus broadcast digital 
               
               
                   
                 audio/video or on-demand video and audio 
               
               
                   
                 control by passenger 
               
               
                   
               
             
          
         
       
     
     In accordance with the present invention, the SA tool can be tailored for an airline&#39;s configuration using the factors and weights defined during contract negotiation between the supplier and the customer. Preferably, there can be a common user interface that allows specific built-in test unit records to be excluded from the availability calculation, e.g. irrelevant failures, or to supplement the availability calculation using an on-board maintenance record that records a removal not reported by the built-in test unit. This feature serves to allow human detectable faults to be included in the availability computation. 
     Equations. The following equations are used to calculate system availability. The point at which availability is calculated may be based on how the IFE supplier and the airline customer would like to monitor availability. The weight of each subsystem&#39;s availability to the overall system availability calculation can be customized using data tables defined in the airline&#39;s contract with the IFE supplier.                    System Availability     =       (       OSW   H     *   Overhead                 Availability     )     +       (       CSW   H     *   Cabin                 Mgmt                 Availability     )                     (       SSW   H     *     Seat                     Availability       )                
          where        :                       
              OSW         =     overhead system weight (configurable)               H         =       highest IFE service level (from aircraft database,
 see Table 1 for Service Levels)                            CSW         =     cabin management system weight (configurable)               SSW         =     seat system weight (configurable)                  
              and                                OSW     +   CSW   +   SSW     =     100      %                            Equation  1                                              Overhead Availability     =                100   *                      (       ∑       k   =   1     ,   3            (       OZ   k     *                ZS   k     *                  (       TD   k     -                DL   k       )     /                TD   k         )       )     /                                  (       ∑       k   =   1     ,   3            (       OZ   k     *                ZS   k       )       )          
          where:                     
                OZ   =                overhead zone weight factor (configurable)                 ZS   =                number of actual seats in zone (from aircraft database)                 TD   =                total number of displays in zone (from aircraft database)                 DL   =                count of displays unavailable in zone
 (see Notes to Eq. 2)                 k              =                zone index from 1 to 3                                   Equation  2                                 
     For Equation 2, it should be noted that for each display (overhead/bulkhead monitor/LCD or projector) in zone, the display can be marked as unavailable if the display or the tapping unit/VDU for display is declared faulty.                  Cabin Mgmt Availability     =     100   -     100   *     min        (     1   ,       ∑     lost                 elements            CMLF   H         )                  
          where:                     
                             CMLF   =                element loss factor for 
unavailable      cabin management      
elements (see Table 2)                     H              =                highest service level (from aircraft database, 
see Table 1)                     Equation  3                                
     Reference is to Equation 1, where the percentage of system availability is the sum of all three (expandable) subsystem availability measures. As Equation 1 shows, three subsystems are currently evaluated for the system availability calculation. It should be apparent to those skilled in the art that any IFE supplier and airline customer may readily modify the equation to only use the availability sum of one or more subsystems, or to add more subsystems as they become available. However, for the purpose of illustration, the total system availability from the currently implemented three subsystems are described. 
     Referring to Equations 1, 2, 3 and 6, an airline customer may customize the availability equations by allowing unique weighting factors for each seat and overhead zone. The zone-specific weight factors may be unique between the overhead subsystem and the seat subsystem. If an overhead or seat subsystem is not installed within a zone, then the applicable weight factor for that zone should be set to zero. For example, if there are no overhead units in the first class cabin, then the applicable weight factor is set to zero for the overhead units in the first class zone. 
     Referring to Equation 2, the equation for Overhead Availability supports an airline customer&#39;s need to assess overhead subsystem loss based on the zone weight and number of seats affected in the zone. 
     Reference is now turned to Table 2. Note that for each cabin management availability element, a configurable loss factor for service level is specified. Whether such element is a loss can be derived from the on-board service data or any built-in test unit such as the aforementioned BIT/BITE. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Cabin Management Elements 
               
             
          
           
               
                   
                 Factor For 
                   
               
               
                 Cabin Management 
                 Service 
                 Source(s) of Loss 
               
               
                 Availability Element 
                 Level 
                 Indication 
               
               
                   
               
               
                 PAT (see * below) 
                 configurable 
                 BB Data 
               
               
                 Keyboard &amp; Touchscreen 
                 config 
                 Service Data 
               
               
                 Credit Card Reader 
                 config 
                 Service Data 
               
               
                 Audio Jack 
                 config 
                 Service Data 
               
               
                 Modem 
                 config 
                 Service Data 
               
               
                 Phone 
                 config 
                 BB Data 
               
               
                 Manual Reset (one reset) 
                 config 
                 BB Data 
               
               
                 Manual Reset (two resets) 
                 config 
                 BB Data 
               
               
                 Manual Reset (3 or more) 
                 config 
                 BB Data 
               
               
                 PAT &lt;-&gt; VCC/AVU 
                 config 
                 BB Data 
               
               
                 PAT &lt;-&gt; CFS 
                 config 
                 BB Data 
               
               
                 PAT &lt;-&gt; PESC-V 
                 config 
                 BB Data 
               
               
                 CFS 
               
               
                 CFS &lt;-&gt; Printer Comm. 
                 config 
                 BB Data 
               
               
                 CFS &lt;-&gt; PESC-A1 (PAXLAN) 
                 config 
                 BB Data 
               
               
                 CFS &lt;-&gt; IFE Sources Comm.* 
                 config 
                 BB Data 
               
               
                 Printer (excl. out of paper) 
                 config 
                 BB/Service 
               
               
                 CD ROM 
                 config 
                 Service Data 
               
               
                   
               
               
                 *If there is more than one PAT or more than one IFE source communication path, then factor is adjusted per Equation 4  
               
               
                 Acronyms for Table 2:  
               
               
                 PAT Primary Access Terminal  
               
               
                 VCC Video Control Center  
               
               
                 AVU Audio Video Unit  
               
               
                 CFS Cabin File Server  
               
               
                 PESC-V Passenger Entertainment System Controller  
               
               
                 COMM Communication  
               
               
                 PESC-A Passenger Entertainment System Controller  
               
               
                 PAXLAN Passenger Local Area Network  
               
               
                 BB Data Data from Built-in Test Unit such as BIT/BITE  
               
             
          
         
       
     
     Referring to Equation 3, the equation looks at objective faults/failures and assesses impact to flight attendant functionality loss. Note that the sum of total element loss factors has a maximum of 1, by using the “min” function. This has the benefit of placing a floor, instead of a negative number, on the cabin management subsystem availability when there is a total loss of functionality. 
     The Control IFE System function group includes functions such as “start and end IFE system,” “enter flight data,” “control of video announcements,” “printing,” and “monitor of seat video and audio.” The Control IFE Sources function group includes functions to control the audio and video players, movie cycles, cameras, and Airshow. The Control In-Seat Video System function group allows control of seat video channels and reset of seats. The Control Overhead Video System function group controls overhead video. 
     With aircraft configurations possibly having multiple LRUs of the same type (e.g., tape players, media file servers) that offer redundant capability, a single loss factor is assigned representing the total loss of that capability. When one of these LRUs is declared faulty, a percentage of the loss factor is utilized in the availability calculation. 
     Likewise, for single LRUs that support multi-channel output (e.g., triple tape deck), a single loss factor is assigned representing total loss of all outputs. When one of these outputs fails, a percentage of the loss factor is utilized in the availability calculation. Equation 4 defines the standard equation that is used and Table 3 identifies the elements and components considered for these types of calculations in the IFE Sources Loss and Seat Availability equations. 
     
       
         
               
             
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Element Components Definitions 
               
             
          
           
               
                 Element Type 
                 Component Definition 
               
               
                   
               
               
                 Analog Video Sources 
                 Total number of tape slots for all tape decks 
               
               
                 MFS (Media File Server) 
                 Total number of MFSs 
               
               
                 Audio Sources 
                 Total number of audio sources 
               
               
                 Landscape Camera 
                 Total number of landscape cameras 
               
               
                 Audio Jack 
                 Number of audio jacks at seat 
               
               
                 IFE Sources Comm. 
                 Total number of 485 comm. ports on CFS 
               
               
                   
               
             
          
         
       
     
     
       
         
           
             
               
                 
                   
                     
                       %  of Element Unavailable 
                     
                     = 
                     
                       LF 
                       * 
                       
                         ( 
                         
                           FE 
                           / 
                           TE 
                         
                         ) 
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     where: 
                   
                    
                   
                       
                   
                    
                   
                     
 
                   
                    
                   
                     
                       
                         
                           
                               
                           
                            
                           
                             LF 
                             = 
                             
                                 
                             
                              
                             
                               loss factor (configurable) 
                             
                           
                         
                       
                     
                     
                       
                         
                           FE 
                           = 
                           
                               
                           
                            
                           
                             number of element components
unavailable (see Table 3) 
                           
                         
                       
                     
                     
                       
                         
                           TE 
                           = 
                           
                               
                           
                            
                           
                             total number of  element components 
(aircraft database) 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Equation  4 
                 
               
             
           
         
                 
         
             
         
      
     
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 IFE Sources Element Table 
               
             
          
           
               
                   
                   
                   
                 Source of 
               
               
                   
                 # Seats 
                   
                 Loss 
               
               
                 Element Type 
                 Affected 
                 Factor [HSL] 
                 Indication 
               
               
                   
               
               
                 Analog Video Sources 
                 all 
                 configurable 
                 BB &amp; Service 
               
               
                   
                   
                 (see Equation 4) 
                 Data 
               
               
                 MFS 
                 all 
                 configurable 
                 BB &amp; Service 
               
               
                   
                   
                 (see Equation 4) 
                 Data 
               
               
                 Ethernet Hub 
                 all 
                 configurable 
                 BB &amp; Service 
               
               
                   
                   
                   
                 Data 
               
               
                 Audio Sources 
                 all 
                 configurable 
                 Service Data 
               
               
                   
                   
                 (see Equation 4) 
               
               
                 Passenger Video Info 
                 all 
                 configurable 
                 Service Data 
               
               
                 System 
               
               
                 Landscape Camera 
                 all 
                 configurable 
                 Service Data 
               
               
                   
                   
                 (see Equation 4) 
               
               
                   
               
             
          
         
       
     
     Referring to Equation 5 below, the loss associated with IFE sources supplied and serviced by the IFE supplier is calculated separately in accordance with the ARINC 628 draft standard for IFE system availability numbers. Note that the IFE Sources Loss of Equation 5 is inverse to ARINC 628 IFE Source Availability. This equation calculates the cumulative effect of all IFE source losses. This result is used in the Seat subsystem availability calculation and is applied to all seats in the aircraft.                  IFE Sources Loss     =       ∑     IFE                 elements            ISE   H              
          where:                     
                             ISE   =                loss factors for unavailable IFE Sources (see Table 4)                   H              =                highest IFE service level (aircraft database, see Table 1)                     Equation  5                                
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Seat System Elements 
               
             
          
           
               
                   
                 # Seats 
                   
                 Sources of 
               
               
                 Element Type 
                 Affected 
                 Factor [HSL] 
                 Loss Indication 
               
               
                   
               
               
                 PVP/PVP Power 
                 1 
                 configurable 
                 BB &amp; Service Data 
               
               
                 Supply 
               
               
                 Audio Jack 
                 1 
                 configurable 
                 Service Data 
               
               
                   
                   
                 (see Equation 4) 
               
               
                 PCU 
                 1 
                 configurable 
                 BB &amp; Service Data 
               
               
                 SDU 
                 1 
                 configurable 
                 BB &amp; Service Data 
               
               
                 AVU 
                 aircraft db 
                 configurable 
                 BB &amp; Service Data 
               
               
                 SCC Only 
                 1 
                 configurable 
                 BB &amp; Service Data 
               
               
                 Phone Only 
                 aircraft db 
                 configurable 
                 BB &amp; Service Data 
               
               
                 Manual Reset (one 
                 1 
                 configurable 
                 BIT/BITE Data 
               
               
                 reset) 
               
               
                 Manual Reset (two 
                 1 
                 configurable 
                 BIT/BITE Data 
               
               
                 resets) 
               
               
                 Manual Reset (three 
                 1 
                 configurable 
                 BIT/BITE Data 
               
               
                 or more) 
               
               
                 ADB 
                 aircraft db 
                 configurable 
                 BB &amp; Service Data 
               
               
                 Column Only 
                 aircraft db 
                 configurable 
                 BB &amp; Service Data 
               
               
                 Phone Col. Only 
                 aircraft db 
                 configurable 
                 BB &amp; Service Data 
               
               
                 Manual Col. Reset 
                 aircraft db 
                 configurable 
                 BIT/BITE Data 
               
               
                 (one reset) 
               
               
                 Manual Col. Reset 
                 aircraft db 
                 configurable 
                 BIT/BITE Data 
               
               
                 (two resets) 
               
               
                 Manual Col. Reset 
                 aircraft db 
                 configurable 
                 BIT/BITE Data 
               
               
                 (three or more) 
               
               
                 CFS/TES CFS 
                 all 
                 configurable 
                 BB &amp; Service Data 
               
               
                 Manual Reset (one 
                 all 
                 configurable 
                 BIT/BITE Data 
               
               
                 reset) 
               
               
                 Manual Reset (two 
                 all 
                 configurable 
                 BIT/BITE Data 
               
               
                 resets) 
               
               
                 Manual Reset (three 
                 all 
                 configurable 
                 BIT/BITE Data 
               
               
                 or more) 
               
               
                 VMOD 
                 all 
                 configurable 
                 BB &amp; Service Data 
               
               
                 PESC-V 
                 all 
                 configurable 
                 BB &amp; Service Data 
               
               
                 PESC-A1 
                 all 
                 configurable 
                 BB &amp; Service Data 
               
               
                 PESC-A2 
                 all 
                 configurable 
                 BB &amp; Service Data 
               
               
                 RF Distribution Box 
                 all 
                 configurable 
                 Service Data 
               
               
                   
               
               
                 Acronyms for Table 5  
               
               
                 PVP Passenger Video Player  
               
               
                 PCU Passenger Control Unit  
               
               
                 SDU Seat Display Unit  
               
               
                 AVU Audio Video Unit  
               
               
                 SCC Seat Controller Card  
               
               
                 ADB Area Distribution Box  
               
               
                 CFS Cabin File Server  
               
               
                 TES Total Entertainment System  
               
               
                 VMOD Video Modulator  
               
               
                 PESC Passenger Entertainment System Controller  
               
               
                 RF Radio Frequency  
               
             
          
         
       
     
     
       
         
           
             
               
                 
                   
                     
                       Seat Availability 
                     
                     = 
                     
                       100 
                       * 
                       
                         
                           ( 
                           
                             
                               ∑ 
                               
                                 
                                   k 
                                   = 
                                   1 
                                 
                                 , 
                                 3 
                               
                             
                              
                             
                               ( 
                               
                                 
                                   SZ 
                                   k 
                                 
                                 * 
                                 
                                   ( 
                                   
                                     
                                       ZS 
                                       k 
                                     
                                     - 
                                     
                                       SL 
                                       k 
                                     
                                   
                                   ) 
                                 
                               
                               ) 
                             
                           
                           ) 
                         
                         / 
                         
                           ( 
                           
                             
                               ∑ 
                               
                                 
                                   k 
                                   = 
                                   1 
                                 
                                 , 
                                 3 
                               
                             
                              
                             
                               ( 
                               
                                 
                                   SZ 
                                   k 
                                 
                                 * 
                                 
                                   ZS 
                                   k 
                                 
                               
                               ) 
                             
                           
                           ) 
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     where 
                      
                     
                       : 
                     
                   
                    
                   
                       
                   
                    
                   
                     
 
                   
                    
                   
                     
                       
                         
                           
                               
                           
                            
                           
                             SZ 
                             = 
                             
                                 
                             
                              
                             
                               seat zone weight factor (configurable) 
                             
                           
                         
                       
                     
                     
                       
                         
                           ZS 
                           = 
                           
                               
                           
                            
                           
                             number of actual seats in zone
(aircraft database) 
                           
                         
                       
                     
                     
                       
                         
                           k 
                           = 
                           
                               
                           
                            
                           
                             zone index from one to three 
                           
                         
                       
                     
                   
                    
                   
                     
 
                   
                    
                   
                     
                       and 
                        
                       
                           
                       
                        
                       SL 
                     
                     = 
                     
                       
                         ∑ 
                         
                           
                             s 
                             = 
                             1 
                           
                           , 
                           ZS 
                         
                       
                        
                       
                         min 
                          
                         
                           ( 
                           
                             1 
                             , 
                             
                               ISL 
                               + 
                               
                                 
                                   ∑ 
                                   
                                     lost 
                                      
                                     
                                         
                                     
                                      
                                     elements 
                                   
                                 
                                  
                                 
                                   ELF 
                                   Hs 
                                 
                               
                             
                           
                           ) 
                         
                       
                     
                   
                    
                   
                       
                   
                    
                   
                     
 
                   
                    
                   where 
                    
                   
                       
                   
                    
                   
                      
                   
                    
                   
                     
                       
                         
                           
                               
                           
                            
                           
                             ISL 
                              
                             
                                 
                             
                             = 
                             
                                 
                             
                              
                             
                               IFE Sources Loss (see Equation 5) 
                             
                           
                         
                       
                     
                     
                       
                         
                           ELF 
                           = 
                           
                               
                           
                            
                           
                             element loss factor for unavailable 
seat elements (see Table 5) 
                           
                         
                       
                     
                     
                       
                         
                           H 
                            
                           
                               
                           
                           = 
                           
                               
                           
                            
                           
                             highest IFE service level 
(aircraft database, see Table 1) 
                           
                         
                       
                     
                     
                       
                         
                           s 
                            
                           
                               
                           
                           = 
                           
                               
                           
                            
                           
                             seat index from one to  
                             ZS 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Equation  6 
                 
               
             
           
         
                 
         
             
         
      
     
     The system availability tool in accordance with the present invention can provide more accurate measurement of passenger impact, flight attendant impact and overhead impact separately as subsystems, or as a total system. The tool also provides differentiation between multiple levels of functionality and different zonal weighting. The tool with customizable data tables thus leads to a standardized methodology for measuring system availability without having to revise the tool from airline to airline, or for revised subsystem installations. 
     In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.