Search efforts aboard the capsized Costa Concordia resumed Wednesday, even as the official overseeing the operation acknowledged for the first time it would take a miracle to find any more survivors from the ship's Jan. 13 grounding.

Franco Gabrielli, head of Italy's national civil protection agency, told reporters that rescuers would keep searching the ship, which is half-submerged off the Tuscan island of Giglio, until every reachable area is inspected.

"Finding someone alive today belongs in the realm of miracles," Gabrielli said. "But since none of us, at least inside, wants to give up on that possibility, we will continue."

And operations did continue Wednesday as crews set off more explosions on the submerged third floor deck to allow easier access for divers. On Tuesday, the body of a woman was found on the deck.

Rescuers have found 16 bodies, with 17 people still unaccounted for. The last time anyone was found alive was on Jan. 15, when a senior crew member was discovered less than 36 hours after the grounding.

The Concordia ran aground and capsized off the Tuscan island of Giglio on Jan. 13 after the captain, Francesco Schettino, veered from his approved course and gashed the ship's hull on a reef, forcing the panicked evacuation of 4,200 passengers and crew.

On Wednesday, the chief executive of Costa Crociere SpA, Pier Luigi Foschi, insisted that Schettino didn't have approval to change the ship's routing and was going far too fast _ 16 knots _ to be so close to shore.

But he defended the practice of so-called "tourist navigation," whereby enormous cruise ships steer close to shore to give passengers a look at the sites. He said it was part of the "cruise product" that passengers demand and that cruise lines are forced to offer to stay competitive.

"It's something that enriches the cruise product," Foschi told a parliamentary committee. "There are many components of the cruise product, and we have to do them like everyone else because we are in a global competition."

Costa is owned by Miami-based Carnival Corp., the world's largest cruise company.

Foschi stressed that such deviations from charted routes are supposed to follow strict protocols that ensure safety: ports are informed, the company is informed, and certainly no ship of the Concordia's size would be charging 200-300 yards (meters) off shore at 16 knots.

"For anyone who knows that zone, that ship with those characteristics shouldn't have been there," he said.

Schettino is under house arrest, facing accusations of manslaughter, causing a shipwreck and abandoning a ship before all passengers were evacuated.

On Wednesday, his lawyer filed a motion challenging the house arrest, saying Schettino wasn't a flight risk and asserting that there was no risk that he would repeat the crime since no cruise line would hire him, the ANSA news agency reported.