Ukrainian efforts to improve air transport oversight are making only gradual progress, largely because an action plan is being held up by the country's legislative system.
Four of the country's airlines are banned from European operations and the country's overall safety oversight remains a concern to the European Commission.
While Ukraine's state aviation administration has been trying to implement a 12-point action plan submitted last year but a team of European specialists, during a visit at the end of May this year, found that the authority had "made limited progress".
All actions aimed at enhancing oversight "remain open" says the Commission, detailing recent revisions to the blacklist.
"The implementation of the action plan is directly linked to the complexity of the legal system of Ukraine," it says.
Ukraine is planning to adopt a new aviation law next year, but this means related rules on aircraft operations, crew licensing and airworthiness are only likely to be introduced over the period from 2011 to 2015.
The Commission says the Ukrainian system does not identify clearly the standards used for approval of aircraft and operators, and their compliance with ICAO, and adds that the country's authorities "do not have sufficient qualified personnel" to carry out oversight of the 74 holders of air operator's certificates.
Review of the AOC system used by Ukraine, adds the Commission, shows that it does not clearly identify regulations and standards applied for certification, or provide certainty over the precise fleet authorised for operations.
The Commission says it will continue to co-operate with Ukrainian authorities to enhance oversight.
While some of the carriers causing most concern - among them Ukrainian Mediterranean Airlines and Motor-Sich - are taking corrective steps, the Commission says they have yet to make sufficient progress to be removed from the blacklist.