Analysis Techniques For Man-Machine Systems Design

NATO UNCLASS.IFIED-AC/243(Panel 8)TR/7 -6-Volume 2Example of Mission AnalysisA mission analysis starts with the identification of mission phases, for example. the phases for a close air supportmission. Each phase is then expanded by a narrative description, as shown below.CLOSE AIR SUPPORT - MISSION PHASES 5.0 OUTBOUND CRUISE: At dawn the ground featurecheckpoint is detected and confirmed electro-optically by1.0 PRE-FLIGHT the LLTV (Low Light Level Television). Flight leaderraises Forward Air Controller (FAC) Alpha on the2.0 LAUNCH preassigned secure communication channel and receives his A.3.0 CLIMB TO ALTITUDE specific mission assignment and a more complete briefing.4.0 RENDEZVOUS FAC(A) informs Flight that an advance enemy force has5.0 OUTBOUND CRUISE moved up during the night and will soon be within striking6.0 DESCENDdistance of a strategic friendly position.6.0 DESCEND: FAC(A) provides an updated vector from70 LOITTER lthe coastal checkpoint and assigns Flight loiter position.80 PRE-ATTACK \Flight leader provides an estimated time of arrwal, and as9.0 ATTACK he crosses the coastline, he performs a navigation update,10.0 ESCAPE reduces power, and drops to a terrain-following altitude.I 1.0 CLIMB TO ALTITUDEThe pcnetration route has been chosen to minimize12.0 INBOUND CRUISE detection. No known enemy radar sites are along the route.No missiles are indicated by the threat detection and13.0 RENDEZVOUS wrigstwarning set.14.0 RECOVER \ 7.0 LOITER: Flight leader reviews his ordnance load via a15.0 POST FLIGHT tabular display on one of his multi-purpose CRT's (CathodeRay Tube). (after Linton et al., 1977)Figure 1.1:Example of decomposition of a narrative mission analysisAdvantagesUsers report the technique to be highly cost-effective. Itis comparatively easy to use, and is generally a lowcost activity. It requires few resources, and serves as avery useful means of reaching consensus on what andhow the system is to fulfil its objectives,DisadvantagesUsers report that the analyses can be too subjective, if alimited amount of data is available. Analysts and potentialoperators can become too enthusiastic about detail,prolonging the analysis time at the outset of thedevelopment process. Some users report difficulties incoordinating their analyses with other systems engineeringanalyses. For example, the human engineering analyseswill highlight operations which are manpower critical,whereas avionics specialists will focus on analyses whichload the avionics, not the human operators.The typical sequential description of system activities andevents is not suited to systems which control a process,such as C 3 1 or a machinery control monitoring system. Insuch cases it is better to analyse "events" which causechanges in the system state and require operatorintervention (see Kincade & Anderson, 1984).'NATO UNCLASSIFIED-6 -