The airport is running a series of tests today to see if makeshift check-in facilities are good enough to restart some flights and that repair work and new security measures are adequate after the deadly March 22 attacks.
Feist told L'Echo in an interview published today that everything depends on the outcome of the tests at Zaventem, with some 800 airport staff going through the temporary facilities.
"I must stress, however, that that is just hypothetical."
Brussels is a major European hub and has flights to destinations worldwide.
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Even if some services are possible, they would amount to about only 20 per cent of normal, that is handling about 800-1,000 passengers an hour, Feist said.
For a full return to normal, "we will have to wait for months," Feist added.
Two suicide bombers blew themselves up in the departure hall last today, wrecking the concourse, and shortly afterwards another bomber hit the Brussels metro, leaving 35 people dead in Belgium's worst-ever terror attack.