This episode's headline: EgyptAir Crash; NewsMaker; China at 50; Supreme Court Watch; Dialogue. ANCHOR: JIM LEHRER; GUESTS: CAPT. SAM DE BOW, NOAA; GEORGE ROBERTSON, NATO Secretary-General; JAN CRAWFORD GREENBURG, Chicago Tribune; NICHOLAS LEMANN, Author, ""The Big Test""; CORRESPONDENTS: SUSAN DENTZER; RAY SUAREZ; TERENCE SMITH; GWEN IFILL; KWAME HOLMAN; FRED DE SAM LAZARO; BETTY ANN BOWSER; ELIZABETH FARNSWORTH; MARGARET WARNER; DAVID GERGEN