Lufthansa German Airlines and Emery Worldwide chose to develop computer software that enabled them to communicate with the U.S. Customs Service in- house, rather than go to outside suppliers as many of their competitors have done.

Fear of disrupting an already established system was Lufthansa's main motivation for creating its software in-house, said Pat Hanbury, application manager for cargo."We've had a cargo system for years now, and it's done everything except interface with Customs," Mr. Hanbury said.

Customs processes trade documents and data through its Automated Commercial System. Air carriers, consolidators and container stations send information to Customs through the Air-Automated Manifest System. A manifest is a list of the cargo contained in a given shipment.

Lufthansa On-Line Cargo Tracing and Entry System has been on-line for almost two decades, Mr. Hanbury said. "Cuslink" is the name for the software the carrier developed to communicate with the agency.

Developing the Cuslink package took more than a year, Mr. Hanbury said. Lufthansa works with International Business Machines Corp. computers. Benefits

from the software should come almost immediately, he said, with 90 percent of the cargo cleared before the planes arrive.

Besides handling information about Lufthansa's cargo, the German airline's system also will handle data on goods moved by Qantas, Kuwaiti Airlines and Air Moroc.

Emery also developed its software in-house, said Anthony Patrizio, director, international service support. The company's IBM-based Econ system contains most of the data required by customs. The main job was putting the information in the formats the agency required, he said.

Emery also spent three months developing its software package and another six months testing it with Customs. Eventually, all of Emery's paperwork with Customs will move electronically.

Both companies have to go through a strict certification process with Customs before their data is officially accepted.

Initially, they will work with both paper and electronic message-moving. After Customs has granted its approval, only the electronic messages will move.

Gaining certifications in the early days of Air-AMS took months. In a sign of both Customs' and the airline's increasing comfort with the systems, Lufthansa finished its tests in just five weeks.