21 ISMOR Norton Manor: 31st August - 3rd September 2004

2. 21 ISMORNorton Manor: 31st August - 3rd September 2004 The Need For And Value Of Simple OA Models In Industry

3. OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models Example Summary

4. OA at Westland Helicopters (WHL)

5. The industry is: AgustaWestland: Therefore: Aerospace Helicopters, WHL OA • Small OA team.

6. WHL OA Role of OA in WHL is: • Having a deeper understanding of operational needs.

7. WHL OA • Matching potential products and technology to these operational needs.

8. WHL OA • OA is often a ‘bridging’ activity, between: • the customer community • ‘core’ engineering activities.

9. WHL OA • Assessing strengths / weaknesses of competitor products.

10. WHL OA • OA at WHL is within the engineering organisation; this is because: • It is an objective analytical discipline • It requires sound knowledge of the product’s technology and performance • It needs to understand future technologies and their potential for capability enhancement • It retains its credibility.

11. WHL OA In practice: • We are often working within tight time constraints • And explaining the work and results to non OA specialists.

12. OA at Westland Helicopters (WHL) OA Modelling at WHL

13. There are very detailed and complex models of aircraft and systems within engineering and the rest of the company, WHL OA - Modelling • We use the results of these as data sources • OA modelling at aggregated level above these.

14. We’re interested in aircraft in operational settings. WHL OA - Modelling

15. WHL OA Modelling Customer Requirements Aircraft Data Scenario Data OA MODELS Complex Engineering Models Relatively Simple

16. Some of the things WHL OA models address: WHL OA Modelling • Support Helicopter Fleet lift & availability • Single or several helicopter types • Single or multiple tasks • Short or long operational periods • Amphibious or land-based • Sortie flying hours analysis for amphibious forces • Ship operations • Aircraft survivability • Capability assessment • Support helicopters • Light utility helicopters • Attack helicopters.

17. Why do we use simple models? What is a simple model? Conversely, what isn’t? WHL OA - Modelling

18. OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models

19. If not Simple, then a Complex model: Complex Models • Large (lines of code) • Lot of input data • Involves wide range of aspects.

20. Complex Models • Drawbacks: • Takes time to collect data • Takes time to set up • May not be easily understood; can be rather a “black box” • Requires a great deal of documentation • High development costs in time & effort before can use • High cost of further development, • Advantages: • Models details • Copes with interactions of many systems • Variety of output.

21. Simple models: Simple Models • Small (lines of code) - small enough to operate on a PC • Limited input data • Limited number of aspects • Simple enough to develop or tailor for a particular problem • Fast enough to provide a quick turnround of results • Transparent enough for ready understanding.

22. Simple Models • Drawbacks: • Model few details or is high level • Limited number systems • Limited output, • Advantages: • Relatively easy to collect data • Quick to set up • Easily understood; “transparent” - fairly easily assimilated • Requires limited documentation • Can be tailored relatively cheaply / easily.

23. Benefits for WHL OA of using simple models: WHL OA - Modelling: Simple Models • Easier to set up and run • Easier to explain • Easier to maintain • So we need simple models.

24. OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models

25. But there is potential for abuse: Abuse of Simple Models • Customers may think there’s more in a simple model than there really is: • They may think it does what it cannot • They may have too much faith in the results (nobody reads the caveats).

26. Abuse of Simple Models • Or customers may want to bend models to do what they cannot. Such as compare apples with pears ... & lemons, pineapples, bananas, strawberries, …......

27. Or introduce details that may add realism, but are not really necessary. Abuse of Simple Models

28. Customers may think they understand it enough to want to take it and use it themselves: It may be a simple model to a specialist But in the wrong hands, it may not be recognized for what it really is. Abuse of Simple Models • This is particularly true of soft OA tools.

29. OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models Example

30. Target Scores (Requirements) Example One example is an MCDA tool that we use:

31. Target Scores (Requirements) Aircraft Scores (Capabilities) Example One example is an MCDA tool that we use:

32. Target Scores (Requirements) Aircraft Scores (Capabilities) Comparison: Aircraft Scores minus Target Scores Example One example is an MCDA tool that we use:

33. Example • Each characteristic is represented by a 5 level scale • e.g. Troop Capacity: • (No. of troops carried in crashworthy seats) • Level 1 = <2 • Level 2 = 2-3 • Level 3 = 4-5 • Level 4 = 6-7 • Level 5 = Over 7.

34. Advantages: Example - Advantages • It allows one to address diverse problems, • One can use hard and/or soft data • It permits comparisons of different aircraft / system configurations or types.

35. Example - Drawbacks (1) Drawbacks: • The scoring process must be set up very carefully • Steps must have similar impact e.g. Troop Capacity: Level 1 = <2 <2 Level 2 = 2-3 2 Level 3 = 4-5 3-6 Level 4 = 6-7 7 Level 5 = Over 7 >7 , • The scoring scales must be representative of the problem being examined e.g. Troop Capacity scale shown may be unsuitable for large lift operations.

36. Example Example - Drawbacks (2) • The user must be aware of any potential interdependencies • e.g. Payload / Range could be separated, but interdependency makes it difficult. • Hence, combine them, supported by lower level modelling • The user must be aware of any potential conflict. • e.g. Payload / Range and Troop Capacity.

37. Example Example - Drawbacks (3) • Aggregation needs to be handled with care (if at all) • Could: Take worst of a set of results (sometimes useful) Accumulate negative scores (no credit for overachieving) • Must capture and record all: • Assumptions • Judgements • Reasoning.

38. This is a lot to expect of a “naïve” user - who may not appreciate these subtleties. Abuse of Simple Models

39. Some things are best left in the hands of specialists. Abuse of Simple Models

40. OA at Westland Helicopters (WHL) OA Modelling at WHL Complex and Simple Models Abuse - Potential for Misuse of Simple Models Example Summary

41. In Summary At WHL we use a range of modelling techniques in support of the company, underpinned by more complex models We need relatively simple models because they are: Easier to use Easier to explain Easier to maintain There is always potential for these models to be abused, and we need to guard against this. Summary