MIAMI — Norwegian Cruise Line Holdings CEO Frank Del Rio says that NCLH’s original target of mid-July for sailings out of U.S. ports is in jeopardy in the wake of new guidance from the CDC.

According to media reports, during NCLH’s Q1 earnings call this week Del Rio said: “Our team is working through the guidance, but at first glance, however, it appears the path forward is a bit rockier and a bit steeper than originally expected.”

Del Rio’s cautionary words came as the CDC gave ship operators including cruise lines final technical guidelines for trial runs, allowing cruise lines to begin test voyages in U.S. waters with volunteer passengers to see whether the ships can sail safely during a pandemic.

In NCLH’s earnings call, Del Rio called the test cruise requirements “preposterous, impractical and onerous.”

While passenger traffic on U.S. airlines has soared in recent weeks, and travel is beginning to boom again in the wake of the country’s strong vaccination rollout, the cruise industry is still at a standstill, at least from U.S. ports as per restrictions from the CDC. Many U.S.-based cruise lines have announced sailings from non-U.S. ports starting this summer, with a long list requiring all passengers to be fully vaccinated before sailing.

Last month the CDC indicated that cruising from U.S. ports could potentially start by mid-July.

With the CDC’s latest guidance, each practice cruise, with a duration between two and seven days, must have enough passengers to meet at least 10% of the ship’s capacity. Volunteers must be 18 or older and either fully vaccinated or free of medical conditions that would put them at high risk for severe COVID-19.

The cruise line must tell passengers that they are simulating untested safety measures “and that sailing during a pandemic is an inherently risky activity,” according to the CDC guidelines.

Passengers must be examined for COVID-19 symptoms before and after the trip, and at least 75% must be tested at the end. Restrictions on board will include face masks and social distancing. The CDC will allow guided shore excursions if tour operators follow certain standards.

Ships must make at least one practice run before resuming regular cruises in U.S. waters. However cruise companies can avoid the requirement if they can show that 98% of the crew and 95% of passengers are vaccinated.

Asked about how he felt about the CDC’s approach to the cruise industry compared to other modes of travel, Del Rio said: “Perplexed, flabbergasted and outraged.”

With file from The Associated Press