Some express delivery companies scrambled to alter their operations Wednesday, as drivers sporting pagers knocked out by a satellite that suddenly became incommunicado.

''I haven't gotten a page all morning,'' said Bryan McKie, a driver for Airborne Express in Washington. At 10 a.m., Mr. McKie said that on a normal day he would have already received five or six pages telling him where to pick up his next package. Instead, ''I've just been delivering this morning.''A $250 million communications satellite known as Galaxy 4 suddenly lost track of Earth Tuesday evening and stopped relaying pager messages to roughly 90 percent of the Americans who carry beepers. The satellite, owned by Greenwich, Conn.-based PanAmSat, also transmits signals for television feeds and other communications operations. The outage could last as long as a couple of days, said PanAmSat executives. Transportation and express delivery companies often use satellites for their tracking networks. But as of Wednesday morning, most reported their package locating systems intact. Communicating with drivers on the road, however, appeared more problematic.

United Parcel Service drivers were set to call dispatch centers through the day to get pick up information.

''They advised us that our pagers were not going to receive any vibrations and that we'd have to call and check in periodically,'' said Tola Adeleke, a UPS driver who was delivering packages at the Willard Hotel in Washington.

An Airborne spokesman said potentially half of his company's drivers, mostly concentrated on the East Coast, could be out of reach. Airborne has 13,300 delivery vehicles, and slightly less than half of them are company owned and operated. The majority are run by independent contractors who could use drivers like Mr. McKie who rely on beepers.

''If they are on pagers then they could be affected,'' said Airborne spokesman Tom Branigan. The company's tracking system was unaffected.

UPS also reported no problems with its tracking system. ''In the U.S. and in many countries abroad we do immediate tracking through cellular and other wireless data mechanisms and that doesn't use a satellite,'' said UPS technology spokeswoman Joan Schnorbus. ''We do use satellite for some communications but it is not the PanAm satellite.''

Ms. Schnorbus added that most UPS drivers have information systems in their trucks, and that Mr. Adeleke may rely on a beeper because he often operates in ''dead spots'' where the signals don't transmit.

Federal Express was unaffected, both on the road and off. FedEx trucks are equipped with computers that automatically tell a driver where to go for his next pick-up. FedEx driver Michael Hines sat in his truck on a break and said he was having no trouble.

''Everything comes off the computer,'' he said, pointing to the box next to the driver's seat.