Thanks guys, really appreciate that!!
here is what I was looking for:
Adding to the plane's troubles was the pilots' decision to maneuver closely behind a DC-9 that was taxiing just ahead of their aircraft prior to takeoff, due to their mistaken belief that the warmth from the DC-9's engines would melt the snow and ice that had accumulated on Flight 90's wings. This action — which went specifically against flight manual recommendations for an icing situation — actually contributed to additional icing on the 737. By sitting behind the preceding aircraft, the exhaust gases melted the snow on the wings. During takeoff, instead of falling off the plane, this slush mixture then froze on the wings' leading edges and the engine inlet nose cone.