Sen. Conrad Burns, R-Mont., a co-sponsor of legislation to arm pilots, asked Magaw to reconsider his opposition.
"Those who want to be armed will put themselves through the same training the air marshals go through," Burns said.
Magaw said a formal announcement of the decision will be made later in the week.
Airline pilots have been pushing for guns, saying it would allow them to confront a hijacker who breaks into the cockpit. Hijackers took over four commercial airlines on Sept. 11, crashing two of them into the World Trade Center and a third into the Pentagon (news - web sites). The fourth crashed in a field in Pennsylvania.
Flight attendants, meanwhile, have advocated nonlethal weapons, such as stun guns, that they could use in emergencies.
Sen. Ernest Hollings, D-S.C., who chairs the Commerce Committee, said guns would not be needed as long as pilots kept cockpit doors locked while in flight.