Initial Results from RC2100 In Service Evaluation

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A modified version of the Rockwell Collins 2100 VDR which contains a fix for the VDR deafness problem has been undergoing an in service evaluation (ISE) by Airbus since early September 2012. The ISE has recently completed (mid December 2012). Airbus are analysing the information gathered from the onboard recordings and intend to create a final report in January. However a statistical analysis of data from MUAC and DFS shows that the number of provider aborts (PAs) experienced by the two modified aircraft when compared against a control group of similar aircraft over the same period has been significantly reduced. The size of the sample is such that statistically speaking we can be 95% certain of the result i.e. there is a 5% chance that this change could have occured purely by chance.

MUAC Results

Based on data from Maastricht UAC over the evaluation period the first aircraft under the ISE conducted 34 CPDLC sessions and experienced 2 PAs and the second ISE aircraft conducted 28 CPDLC sessions and experienced 1 PA. Combining the two sets together this equates to a PA rate of 4.8% for the modified radio. The PAs that did occur have been analysed and are not related to VDR deafness.

A control group of eight similar aircraft (all retrofitted with FANSB+ software around the same time as the two ISE aircraft) conducted 172 CPDLC sessions over the same period and experienced 25 PAs, corresponding to a PA rate of 14.5%. Analysis has also shown the average duration of each flight was longer in the control group than for the two ISE aircraft. This is important since we know that the risk of a PA increases with flight duration so the reduction in PAs experienced is not simply because the flights were shorter.

So the modified aircraft experienced a reduction in PAs of 67% compared to the control group.

DFS Results

The two aircraft fitted with the modified radio conducted a total of 19 flights and experienced 1 PA, giving a PA rate of 5.3%. The control group conducted 69 flights over the same period and experienced 20 PAs giving a PA rate of 29%. The PA that did occur on the modified aircraft was not caused by the VDR deafness issue.

So the modified aircraft show a reduction in PAs of 81.7% compared to the control group.

Summary

The modified Rockwell Collins 2100 VDR has been shown to result in a 70-80% reduction in the rate of Provider Aborts and so its widespread introduction into service would result in a signficiant improvement in the overall rate of PAs.