Article 3
1. A Member State wishing to return a third-country national by air shall examine whether it is possible to use a direct flight to the country of destination. 2. If a Member State wishing to return a third-country national cannot for reasonable practical circumstances use a direct flight to the country of destination, it can request transit by air via another Member State. An application for transit by air shall in principle not be made if the removal measure requires a change of airport on the territory of the requested Member State. 3. Without prejudice to the obligations of Article 8, the requested Member State may refuse transit by air if: (a) the third-country national under national legislation in the requested Member State is charged with criminal offences or is wanted for the carrying out of a sentence; (b) transit through other States or admission by the country of destination is not feasible; (c) the removal measure requires a change of airport on the territory of the requested Member State; (d) the requested assistance is impossible at a particular moment for practical reasons, or (e) the third-country national will be a threat to public policy, public security, public health or to the international relations of the requested Member State. 4. In the case of paragraph 3(d), the requested Member State shall as quickly as possible inform the requesting Member State of a date as close as possible to the originally requested date on which transit by air may be assisted, in so far as the other conditions are complied with. 5. Authorisations for transit by air which have already been issued may be revoked by the requested Member State if circumstances within the meaning of paragraph 3 subsequently come to light, justifying a refusal of the transit. 6. The requested Member State shall inform the requesting Member State forthwith of the refusal or revocation of a transit by air authorisation under paragraph 3 or 5 or of any other reason why the transit is not possible, and shall provide an explanation of the reasons.