Australian Submarine Corporation was made responsible for the delivery of the Rockwell combat system, but had little ability to enforce this. Rockwell was contracted to deliver the combat system by 9 September 1993, but was unlikely to do so. ASC's management board voted to issue a default notice to Rockwell as the American company had defaulted on the contract, but was ordered by the Department of Defence to retract the default notice and accept gradual delivery of partially completed versions of the combat system—referred to as 'releases' and 'drops'—until the complete system had been delivered. Sea trials of "Collins" were unable to commence until Release 1.5 of the combat system software was delivered; because of ongoing delays in the provision of the software, the early phases of the trials were completed using stand-alone equipment By March 1994, the combat system had become the major area of concern for the submarine project: assembly of the system was almost nine months behind schedule, and at least 20% of the software had not been compiled. The combat system continued to be a problem during the next few years, with progressive drops offering little improvements in performance over the previous version, and the completion date of Release 2—the designation for the full contractual realisation of the combat system software—was continually postponed.