Prediction methods for MTBF

By Stalker, Edward, Capt AFLMA

Arrived in my Email with a garbled return address. From context, it looks like a British or Australian document.


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SHORT COMMUNICATIONS
RELIABILITY PREDICTION USING ALTERNATIVE METHODS*

1. INTRODUCTION

1.1 Alternative methods may be used for predicting reliability, when approved by the Project Manager. This section outlines these methods and the conditions under which they may be applied.

2. METHODS 2.1 The alternative methods covered by this section are:

(a) Crystal ball (b) Astrological (c) Wet finger (d) Miscellaneous techniques (Tarot cards, ouija boards, etc.) (e) Witchcraft These will be discussed, in turn.

2.2 Crystal ball Crystal balls may be used, if operated by qualified personnel. Qualified personnel include gypsies and other operators approved by NATO AQAP-1, and reliability engineers in AQAP- 1 approved companies. Crystal balls must be calibrated against master standards in accordance with AQAP-6.

2.3 Astrology Astrological prediction methods may be used, but only as applied by AQAP-1 approved astrological scientists. Use of astrological data from daily newspapers, etc., is not acceptable, as these do not necessarily meet approval criteria and are not traceable. For astrological predictions, the dates of birth of the following must be provided:

(a) Project managers (MOD and supplier) (b) Senior reliability engineer (c) Chief designer (d) Secretaries of above, if they are evaluated as likely to affect attitudes, motivation and performance. (e) All the people who will make any part of the system. ( These data are only required when prediction accuracy of better than 0.001 percent is required).

2.4 Wet finger This is a simple and popular method, particularly among project managers. Since little expertise is required, it is a low-cost method. It features some of the disadvantages of the witchcraft methods (see below), but the secondary effects are less unpredictable, particularly if the personnel making the predictions are replaced or forget what the prediction was.

2.5 Miscellaneous methods Other methods may be used, e.g. Tarot cards, ouija boards, tea leaves, etc., but only by qualified staff or consultants approved as above. In any case, appropriate data must be provided as required by the operator.

2.6 Witchcraft Witchcraft may be used. However, this method of prediction is a reliability forcing process, rather than a prediction. Great care must be exercised to ensure that only achievable, conservative MTBF values are forced in this way, since death, serious injury, or madness can result if personnel observe failures or running times which lead to MTBFs different to the set values. There are no defence or Military standards for witches, so operator selection is difficult. It is advisable to employ one or more witches on a project, preferably as part of the reliability team, if this method is to be used. However, care must be exercised to ensure that they confine their powers to the reliability requirement. Security clearance can sometimes present further difficulties, particularly for non- NATO practitioners such as witch doctors, obeah men voodoo priests, etc. Note: Secretaries should not be asked to perform these rites, even when appearance indicate likely competence.

3. PREDICTION ACCURACY 3.1 These alternative methods described generally provide much more accurate reliability predictions than the other techniques described in this standard, e.g. MIL-HDBK-217E. In most cases individual failure events, not merely MTBFs, can be predicted, if appropriate resources are applied.

* Editor's note; This document was found circulating in official corridors. It is reproduced for information, without comment.