When it comes to qualifications and experience to be a DO or Chief Pilot, the FAA in the USA, and in the countries which use these rules as their standards, a DO is required to have 3 years as PIC on a transport category airplane of 5,700 kg AUW or more, with an air carrier. If you look at a Chief Pilot position, same 3 years requirement, but must be PIC qualified on one of the types of aircraft operated by that airline.
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The FAA rule is FAR 119.67...
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As to the JAA standards, I really don't know. I assume that there are standards and rules applicable to such positions. In Belgium, as usual, I would suspect that being a friend of a Flemish or Walloon minister for 3 years is one of the standards, and most important, demonstrate your ability to receive money under the table. Aeronautical experience as PIC on ultralights may be required occasionally, but is waivable.
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Happy contrails