By Humphrey Carter ALL the recent attempts to improve the Balearics' damaged overseas tourism image could suffer a serious set back if the country's three main unions carry out their threat of widespread strike action at Palma airport in March and April. Seven days of industrial action in Palma are part of nation wide industrial protests called yesterday in anger over the announcement by Spanish airport authority AENA that it intends to start sub-contracting more services. Union bosses said yesterday that “flash” strikes will be held on March 5, 7, 9 and 12 while all-out industrial action will be called on April 2, 7 and 11. The full intentions of the unions will be announced today during a mass rally organised at Madrid airport to coincide with the visit of Prime Minister Jose Maria Aznar to open the new terminal. The unions claim that AENA's plan to sub-contract nearly 90 percent of airport services will directly effect 70 percent of the AENA work force. The airport authority intends to put maintenance, cleaning, administration, environmental quality control, human resources and fire fighting contracts out to tender. AENA only plans to maintain control of infrastructure, commercial management, airport operations and air traffic control. Strike action is expected to involve all airport sectors and could cause utter chaos at some of the larger and busier airports, such as Palma which will be starting to handle the Spring trade. AENA plans to offer 806 full-time jobs this year, a figure which it claims is higher than in previous years, but the unions maintain that, considering 400 new staff are needed for the new terminal at Madrid airport alone, far too many people will be left on short-term contracts.