Richard Louis Pratt, 39, who was critically injured Sunday when the biplane he was piloting crashed in a school athletic field in Baltimore, died of his injuries Monday at the University of Maryland Shock Trauma unit in Baltimore.

His nine-year-old daughter Jewell was killed in the crash.

Police said witnesses reported that Mr. Pratt was apparently trying to guide his aircraft to an emergency landing on the school athletic field, which was empty, after the plane's propeller flew off in flight. Instead, the plane crashed into trees at the end of the field.

Mr. Pratt lived in Laurel and was the president of Advance International Inc., an advertising agency he established there six years ago.

He was born in Troy, N.Y., and earned a bachelor's degree and a master's degree in music from American University. He played guitar, piano and violin. He taught music in D.C. public schools and was a professional musician in this area before starting his advertising business.

Mr. Pratt also was a chief warrant officer in the D.C. National Guard and conductor of the 257th Army Band.

Survivors include his wife, Jacqueline, and three sons, Richard, Joey and Andrew, all of Laurel; his parents, retired Navy Capt. Richard T. and Bette Pratt of Dublin, N.H.; a brother, J. Madigan, of New York City; three sisters, Mary Beth Sullivan of Greenfield, N.H., Maureen Smith of New Hartford, Conn., and June Clark of New Canaan, Conn., and a grandmother, Bessie Peterhans of West Palm Beach, Fla.