Table 11. Number of Failures for All Vehicles (1186 Flights)
           Flight              Failure-Res oonse Mode                   3&4
           Phase        1     2        3        4       5      'NA'    Tumble
           0             0    0        0        3       0        0       1
           0-1         13     4        3-      68      15       11      19
           0-2         13     4        3      129      27       29      33
           0-3         13     4        3      161      28       38      40
           0-4         13     4        3      165      28       45      42
           0-5         13     4        3      165      28       53      42

                          Table 12. Date of Most Recent Failure
           Response                            Vehicle
            Mode           Atlas         Delta          Titan           Thor*
               1         03/02/65         none       12/12/59          04/19/58
               2         12/18/81         none       05/01/63          12/30/58
               3        .04/25/61         none          none           07/21/59
               4         08/22/92      05/03/86      10/05/93         03/24//64
               5         12/08/80      08/27/69      11/30/65         01/24/62
          *Last Thor launch was 02/23/65
For the reasons advanced previously, an exponential filter has been used to estimate
relative probabilities of occurrence for Modes 1 through 5 and the fraction of Mode-3
and Mode-4 failures that tumble while the vehicle is thrusting. The percentage
weightings for various data samples are shown in Table 13 for values of F from 0.980 to
0.999. Because of the large size of the composite sample (1186), the filter-control
constant of 0.98 used previously to estimate absolute failure probabilities for individual
vehicles does not seem suitable for estimating relative probabilities for the individual
response modes. Use of 0.98 would effectively place 98.2% of the total weight on the
most recent 200 tests thus, in effect, eliminating the earliest 986 tests from the solution.
These are the very tests needed to provide an adequate sample of failures from which
to estimate relative frequencies of occurrence of the individual response modes.




9/10/96                                     26                                          RTI