As cruise ships rethink their marking campaigns in the wake of the Costa Concordia cruise ship sinking, two announced this week that they would offer vacationers free flights.

Royal Caribbean Cruises is offering 10,000 free flights if holidays are booked by the end of February. Celebrity Cruises, meanwhile, is giving away a slightly smaller number of free flights available for European cruises, and flying from more restricted number of regional airports.

The two operators had suspended marketing during a crucial sales period for cruising as a mark of respect for those killed in the Costa Concordia cruise ship sinking off the Italian coast on Jan. 13.

Now, they believe the time is right to resume.

It's up to us to work with our trade partners and get the message to the consumers that this was an awful, very rare but terrible accident and we as an industry are doing everything we can to make sure it never happens again, Jo Rzymowska, UK general manager of Royal Caribbean Cruises, told Travel Weekly. We needed to be sensitive about what happened and the immediate decision to stop all activity was not a difficult one. It was crystal clear to us in the light of the tragedy that was the right thing to do.

From then on we have monitored things day by day by getting sentiment from the market, and a lot of that we did by talking to our trade partners, Rzymowska added. We feel that Feb. 1 is the right time to go out with our own activity.

The campaign will last through February and offer 10,000 free flights for summer 2012 sailing across Royal Caribbean's European program.

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On Monday, Carnival Corp. estimated that the Costa Concordia cruise ship sinking off Italy's coast would lower net income by $155 million to $175 million in fiscal 2012.

Passenger bookings have dropped for Carnival, the world's largest cruise ship company, since Costa Concordia ran aground off the Tuscan island of Giglio on Friday, Jan. 13, triggering an evacuation of over 4,000 passengers and crew members. However, industry insiders remain positive.

Costa's booking activity is difficult to interpret because of the significant rebooking activity stemming from the loss of the ship's use and related re-deployments, the company said. However, we believe it to be down significantly. Despite these recent trends, we believe the incident will not have a significant long-term impact on our business.

Fleet-wide booking volumes, excluding Costa, declined in the mid teens'' following the disaster through Jan. 25, bottoming out Jan. 16, Carnival revealed Monday.

At least 17 people died after the ship ran aground, with another 16 still missing. The ship remains partially submerged off the Italian coast and, on Monday, all rescue efforts officially ended.

Since the disaster, Carnival announced a review of safety and emergency response procedures across its entire fleet. The Miami-based company owns nine cruise ship brands including the Cunard Line, Holland America, and Princess. Costa Concordia represents 1.5% of Carnival's overall feet capacity.

Cruise watchers have been looking to see what, if any, impact the Costa Concordia cruise ship sinking would have on cruise booking. Though it's too early to determine any long-term effects, indicators show that sales remain strong.

Statistically, cruising remains one of the safest vacation options, which may account for why few travelers canceled existing trips in the wake of the Costa Concordia disaster.

It is very sad, one writer noted in an open forum on cruise site CruiseMates. But it isn't changing any of my cruise plans., Britain's largest online cruise agent, reported 150,000 searches in the week following the disaster - just 7,000 fewer than the previous week.

Another European site, Cruise118, boasted a 10 percent increase on 2011 numbers while North American sites CruiseOne and posted gains of six percent.

Vicky Mary, president of Cincinnati-based Victoria Travel, said she hasn't booked Costa in several years but agreed cruise sales for both Europe and elsewhere remained normal.

I booked a cruise today and I'll book another tomorrow, Mary said.

She was adamant people shouldn't be worried about safety.

When you listen to the people who built these new ships, I mean, they're built incredibly well. I think that people understand that this is an anomaly. People see that the big ships are incredible. They're like living in a fantasy. I mean they replicate cities - how cool is that?