Dozens of airline employees were arrested yesterday on drug smuggling charges in a series of predawn raids at their homes by federal agents. The arrests ended a two-year government sting operation at Miami International Airport targeting ramp workers who would smuggle anything from cocaine to hand grenades from Latin America to cities in the northeastern United States.

The sting, dubbed "Operation Ramp Rat" by the government, focused on ramp workers at American Airlines -- who service airplanes on the ground, pumping gas and loading baggage -- and food handlers employed by Lufthansa Service Sky Chefs. Also arrested were an employee of the U.S. Immigration and Naturalization Service, one from the Agriculture Department and a part-time deputy from the Broward County Sheriff's Office.

American is the largest U.S. airline serving Latin America. Officials in Colombia said that it was the airline used by 10 Colombians arrested in Cali last weekend and charged with smuggling more than half a ton of cocaine and heroin to Miami.

The sting operation was launched in April 1997, after informants told the Drug Enforcement Administration that airline employees were involved in smuggling. In April 1998, law enforcement officials began a second sting operation, dubbed "Operation Sky Chef," when they discovered that drugs were being shipped into the Miami airport through the Lufthansa Service Sky Chef, food caterer for American.

Investigators became interested in Sky Chefs after seizing 15 pounds of heroin that was smuggled from Colombia in coffee packets. The packets were inadvertently used to make coffee that was served to the plane's pilot, who complained that it tasted weak.

The operation resulted in the indictment of 58 individuals; by late yesterday, 48 of them had been arrested in raids that began at 4 a.m. At least six of those arrested were picked up on indictments handed up in New York in a separate case.

Brett Eaton, spokesman for the DEA in Miami, said there were so many arrests that at one point the agency had to borrow a bus from the Marshals Service to hold prisoners as they waited to be booked and fingerprinted.

Over the course of the sting, federal agents posing as drug dealers or gun smugglers hid 660 pounds of fake cocaine and an unknown number of guns on planes and in baggage from Colombia, Bolivia and Ecuador to Miami. The sting involved 37 smuggling transactions in all.

Once the drugs or guns were inside the country, the airline employees would use their security clearances to gain access to the contraband on the aircraft and to circumvent customs and other airport security. They then would either deliver the contraband to waiting undercover agents in Miami, or carry it to a departure terminal and use their free flight benefits to transport it to northeastern cities including the District, Baltimore and Philadelphia.

In one case, DEA officials said an American employee showed up at work on his day off in his uniform and used his security clearance to retrieve a pistol and three hand grenades from an incoming flight. He then walked the contraband across the tarmac to a domestic terminal, changed into civilian clothes and used his free flight benefits to fly the weapons to Philadelphia.

DEA officials said the employees would charge from $1,500 to $3,500 per kilo to smuggle the drugs and up to $7,000 per weapon to smuggle guns and ammunition.

"We were convinced we could basically get anything on the planes," U.S. Attorney Tom Scott told a news conference in Miami after the arrests.

Scott said existing security measures at the Miami airport were routinely breached, warning that the breaches were "extremely serious" and in the "age of domestic terrorism the current situation at [the airport] is intolerable."

American Airlines said it had cooperated fully with law enforcement agencies throughout the two-year operation.

"While we are disturbed that a small group of employees were part of this smuggling ring, their activities have been under federal government and company surveillance for quite some time," American said in a statement released from its Fort Worth headquarters. Calls to Onex Corp., the parent corporation of Sky Chefs, were not returned.

Eaton called the sting "an important operation," but said "we understand [smuggling] goes on elsewhere" at the airport. He did not say where.

This is not the first time airline employees have been involved in drug smuggling at Miami International Airport. In July 1997, six American Airlines mechanics were arrested in Miami on suspicion of smuggling a half-ton of cocaine and heroin into the United States.