This episode's headline: Megamerger; Israel's Next Step; Math Wars; Safe to Fly?; Mother's Day. ANCHOR: JIM LEHRER; GUESTS: HOWARD ANDERSON, The Yankee Group; GENE KIMMELMAN, Consumers Union; PETER TEMIN, MIT; DORE GOLD, UN Ambassador, Israel; URI SAVIR, Former Israeli Diplomat; JANE GARVEY, FAA Administrator; CORRESPONDENTS: LEE HOCHBERG; PHIL PONCE; ELIZABETH FARNSWORTH; PHIL PONCE; KWAME HOLMAN; ANNE TAYLOR FLEMING