From a legal point of view there is no argument, the pilot is under the control and direction of the airline. The airline provides the tools to carry out that job.
The case however is an example of the Inland Revenue taking a practical and commercial view of things. If the IR steps in and decides that a pilot must be a full time employee and not a contractor then Ryanair will employ them all. The result will be a loss of income to the IR. Ryanair as an Irish employer will deduct tax form the pilots salary and pay the tax in Ireland.
The IR looses out, The Irish tax office is in the same boat. If they go to Ryanair and decide that all the pilots have to be employees then ryaniar will make the pilots employees of brookfield. The Irish tax office looses out.
The Irish tax office at the highest level have made a policy decison to leave ryanair to continue employing contractors providing they ensure that each contractor is registered and paying tax.
The situation is as it is, there are tax planning opportunites available to any guy who is contracting to legally reduce his tax to a fraction of that which he would pay as an employee. he can do this without having to pay massive accountancy or tax adviser bills.