The Department accepted that it cannot be certain the programme will not encounter further technical or safety issues, stating that it is usual for engineering development on this scale to encounter challenges as it goes through the development cycle. It acknowledged that it is still testing compliance with the specifications and had proven only 30% of technical requirements so far.44 In addition, in December 2021, the Department was tracking 136 ‘concerns’, only four of which related to noise and vibration, and had still to remove 27 limitations of use on Ajax vehicles, of which 11 were critical to achieving initial operating capability.45 The Department said it was planning a series of reliability trials to test whether the vehicles were working properly and do what they were designed to do.46 Delivering the programme