Probably about 20:1 clean which is typical for jet transport aircraft. The glide ratio is only dependent on the wing's angle of attack which then determines the L/D ratio (lift over drag) and is NOT dependent on the weight of the aircraft. The only affect weight has on the glide ratio is that at higher weights the angle of attack for max L/D results in higher airspeed which varies as the square root of the differences in weight, e.g. an airplane that weighs four times as much must fly at a speed of twice that of the same plane at the lighter weight. The plane was 900 feet above the GW bridge meaning it could glide about 18,000 feet. Teterboro was 30,000 feet away and could not be reached.
Basic aerodynamics. I have been an ATP and flight instructor for 35 years. If you need a source search for "Aerodynamics for Naval Aviators" which I think is available online.