Polar Air Cargo will stop using six of its older-model "Classic" 747 freighters by July 1, leaving it operating a fleet of more efficient 747-400s.

Alan Caminiti, spokesman for parent Atlas Air Worldwide Holdings that also owns the Atlas Air cargo airline, said Polar "will cease flying" its three 747-200s, a 747-300 and a 747-100, all of which are now used for charter business.

A fourth -200 model in the Polar fleet, he said, is to be sold.

In its April 13 earnings report and related comments, company officials said they were moving away from reliance on the -200s, saying market conditions were weakening for that type of plane amid lots of competition and its higher operating costs.

The company sold one of its 747-200s on April 7, and said it might also speed up the retirement of older aircraft this year.

Because they carry less fuel as well as cargo, the older planes require an extra fueling stop on long flights compared with a 747-400, and use three-person flight crews instead of two in the -400 model.

Polar currently operates 11 aircraft in all, he said, including five 747-400s. Caminiti said when Polar grounds the Classics it will also pick up one more -400 model from Atlas, leaving it with six -400s.

In all, Atlas Air Worldwide has 41 of the jumbo jet freighters and boasts of having the world's largest 747 freighter fleet. That total includes 20 of the -400s, 19 model -200s and one each of the -100 and -300 models.

The Polar unit operates the only scheduled cargo service for the company, mainly serving large freight forwarders. But Caminiti said the fleet changes "should have no impact on Polar scheduled service reliability."

The Classics that Polar is parking this summer have all been used in charters or for extra scheduled service, he said, and "all such flying can and will be covered with Atlas capacity."

John D. Boyd