Wednesday, 20th of December, 1972

– United States of America – “1972 O’Hare Collision”

North Central Airlines Flight 575, a domestic scheduled passenger flight from Chicago-O’Hare International Airport, IL (ORD/KORD), to Madison Regional Airport, WI (MSN/KMSN), operated with a McDonnell Douglas DC-9-31, registered N954N, was taking off when it collided with a Delta Air Lines Flight 954, a Convair CV-880-22-2 (N8807E) operating a domestic scheduled passenger flight from Tampa International Airport, FL, to Chicago-O’Hare International Airport, Illinois.

The DC-9 was unable to climb and it subsequently crash landed on the runway. The airplane was destroyed by the immediate post crash fire and ten passengers from the 41 onboard sustained fatal injures. (10 fatalities, 35 survivors)

The Convair lost substantial portions of the left wing and vertical stabilizer and caused three major compressions in the aft portion of its fuselage. There were no fatalities among the 88 occupants.

– Details:

Delta Air Lines Flight 954 was a regularly scheduled flight from Tampa, Florida, to O’Hare International Airport, Chicago, Illinois. Operating Convair CV-880 N8807E, it departed Tampa at 3:41 p.m. EST on December 20, 1972, and made a routine flight to Chicago, where it landed on Runway 14L at O’Hare International Airport at 5:55 or 5:56 p.m. CST. During their approach, the flight crew was informed that Runways 14L and 14R were being used for departures, but were never told that Runway 27L also was being used for departures.

Conditions at the airport were foggy, with a visibility of about one-quarter mile (0.4 km). Upon clearing Runway 14L, Flight 954 began taxiing southwest and south toward the terminal, leaving Runway 14L by way of the Bridge Route taxiway. It had already crossed the north–south bridge that carries the taxiway from Runway 14L to the terminal by the time the first officer contacted O’Hare ground control and reported that the aircraft was “inside [i.e., south of] the bridge”, had not yet received a gate assignment, and needed to wait in a holding area until receiving an assignment.

The ground controller did not hear the words “inside the bridge,” and, assuming Flight 954 had just left the end of Runway 14L and was still well north of the bridge, ambiguously instructed it to hold in the “thirty-two box”, meaning in the controller’s mind the 32R run-up pad at the southeast end of Runway 14L, where he assumed the plane to be. To reach the 32R run-up pad, Flight 954 would have had to turn around and return to the end of Runway 14L, where it had just landed, taxiing against the flow of traffic; instead, Flight 954’s captain and first officer both assumed that the ground controller understood that they were “inside the bridge” and was referring to the 32L run-up pad, which was located at the southeast end of Runway 14R, on the other side of the terminal from the 32R run-up pad. Assuming that they were cleared to taxi to the 32L pad, they proceeded toward it using the Bridge, Outer Circular, and North–South taxiways, via a route that intersected with Runway 27L.

There was no further communication between Flight 954 and the ground controller. This left the ground controller with the assumption that Flight 954 was holding at the 32R run-up pad and in no danger of conflicting with other traffic and the flight crew with the assumption that they were cleared to taxi to the 32L run-up pad and could cross Runway 27L without danger of a collision with aircraft using that runway. Moreover, Flight 954’s flight crew had never received word that Runway 27L was an active runway, and had no reason to anticipate encountering other aircraft while taxiing across it.

North Central Airlines Flight 575 was a regularly scheduled flight originating at O’Hare International Airport and stopping at Madison, Wisconsin, before terminating at Duluth, Minnesota. Operating McDonnell Douglas DC-9-31 N954N, the flight received clearance from O’Hare ground control at 5:50 p.m. CST to taxi to Runway 27L for departure. At 5:58:52.3 p.m. CST the O’Hare local controller cleared Flight 575 into takeoff position on the runway and at 5:59:18 p.m. CST cleared it for takeoff. At 5:59:24.3 p.m. CST, the captain reported that he was beginning his takeoff roll.

As the North Central DC-9 rolled down the runway, visibility was about 1⁄4 mile (400 m). It had reached a speed of about 140 knots (160 mph; 260 km/h) when its captain, peering ahead into the fog just after 6:00:03 p.m. CST, spotted Delta Flight 954 on the runway about 1,600 feet (500 m) ahead. At 6:00:07.2 p.m. CST, Flight 575’s captain gave the order “Pull ‘er up!” and he and the first officer pulled back on their control columns in an attempt to lift their DC-9 over the Delta CV-880. Although the DC-9 lifted into the air, it was too late to avoid contact with the CV-880, and the two aircraft collided at 6:00:08.3 p.m. CST.

The DC-9 tore off substantial portions of the CV-880’s left wing and vertical stabilizer and caused three major compressions in the aft portion of its fuselage. The DC-9’s right main landing gear detached during the collision, as did a flap from its right wing.

After the collision, the captain of Flight 575 determined that his DC-9 could not remain airborne, and attempted to land back on the runway. When he did, the plane’s two remaining landing gear collapsed rearward, and the DC-9 skidded on its belly off Runway 27L, across a grassy area, and onto Runway 32L, where it came to rest. It immediately burst into flames.

The crew of Flight 954 apparently were unaware of the approaching DC-9 until hearing it strike their CV-880, and did not see the DC-9 until the first officer observed it crashing on the runway beyond them.

– Cause:

“The failure of the air traffic control system to ensure separation of aircraft during a period of restricted visibility. This failure included the following: (1) the controller omitted a critical word which made his transmission to the flight crew of the Delta CV-880 ambiguous; (2) the controller did not use all the available information to determine the location of the CV-880; and (3) the CV-880 flight crew did not request clarification of the controller’s communications”

– Report:…/def…/files/2018-12/N954N.pdf