1972 — Dec 20, fog, North Central Air / Delta 954 runway collision, O’Hare AP, Chicago IL– 10

–10 Kimura. World Commercial Aircraft Accidents 3rd Ed., 1946-1993, V.1. 4-11-1994, p. 2-13.
–10 NTSB. AAR. North Central…and Delta… O’Hare Int. Airport, Chicago, IL, 1972. 1973.

Narrative Information

National Transportation Safety Board: “Synopsis

“A North Central Airlines DC-9-31 and a Delta Air Lines CV-880 [flight 954] collided at the intersection of Runway 27L and the North-South taxiway on the O’Hare International Airport, Chicago, Illinois, on December 20, at 1800 central standard time. The DC-9 was taking off on Runway 27L, and the CV-880 was taxiing across the runway when the collision occurred. Neither flightcrew saw the other aircraft in time to avoid the collision.

“Forty-one passengers and four crewmembers were aboard the DC-9. Ten passengers received fatal injuries; 13 passengers and 2 crewmembers were injured. The DC-9 was destroyed by impact and fire.

“Eighty-six passengers and seven crewmembers were aboard the CV-880. Two passengers received minor injuries; the aircraft was damaged sub¬stantially by impact.

“The weather at O’Hare International Airport at the time of the acci¬dent was reported, in part, as: ceiling indefinite 200 feet, sky obscured, with visibility mile in fog.

“The National Transportation Safety Board determines that the probable cause of this accident was the failure of the traffic control system to insure 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 flightcrew 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 flightcrew did not request clarification of the controller’s communications.” (NTSB 1973, 1)
….

“1.1 History of the Flights
Delta Air Lines Flight 954

“Flight 954, a CV-880, N8807E, was a regularly scheduled passenger flight from Tampa, Florida, to O’Hare International Airport, Chicago, Illinois. On December 20, 1972, the flight departed from Tampa at 1541 eastern standard time with 86 passengers and 7 crewmembers aboard. The en route portion of the flight was completed without re¬ported incident.

“Flight 954 established radio communication with Chicago Approach Control (CAC) at 1723:10. The flight had heard Automatic Terminal In¬formation Service (ATIS) “Golf” announce that Runway 14R was being used for landings and Runways 14R and 14L for departures. The local weather was reported, in part, to be: ceiling indefinite 200 feet, sky obscured, visibility 4 mile in fog.

“At 1739:10, the CAC controller informed all flights under his con¬ roll that parallel Instrument Landing System approaches would be con¬ducted to Runways 14L and 14R, and that all aircraft under his control would be vectored for the ILS approach to Runway 14L. The Runway Visual Range (RVR) for 14L was 3,000 feet.

“After receiving a clearance for the approach, Flight 954 contacted the O’Hare tower local controller at 1746:10. At 1752:30, the local controller cleared the flight to land on Runway 14L and advised the flightcrew that the RVR was 1,800 feet.

“At 1755:05, the O’Hare local controller requested Flight 954 to report when clear of Runway 141. The flightcrew reported clear of the runway at 1756:18; 2 seconds later, the local controller cleared the flight to the ground control frequency. Simultaneously, the ground controller attempted to contact the flight, without success.

“At 1757:29, the first officer of Flight 954 established radio com¬munications with the O’Hare ground controller with the transmission, “Delta nine fifty four is with you inside the Bridge and we gotta go to the box. The controller replied, “… OK if you can just pull
over to (the) thirty two pad.” The first officer replied, “Okay we’ll do it.” There were no further communications between the ground con¬troller and Flight 954. The controller made an entry on a scratch sheet which he later stated was to remind him that he had sent the CV-880 to the 32R pad to hold awaiting a gate assignment.

“The captain of Flight 954 taxied the aircraft via the Bridge, the Outer Circular, and the North-South taxiways A en route to the Runway 32L runup pad.

“The ground controller later stated that he did not hear the words “inside the bridge” in the first officer’s initial transmission. The ground controller also stated that he thought that the flight was taxi¬ing clear of the runway when he was contacted and in replying, it was his intention to determine whether the flight could hold on the Run¬way 32R runup pad.

“The captain and first officer both stated that they thought the con¬troller wanted them to hold on the Runway 32L runup pad and cleared them to do so. The collision occurred as Flight 954 was crossing Runway 27L en route to the 32L runup pad.

b. North Central Airlines Flight 575

“Flight 575, a DC-9, N954N, was a regularly scheduled passenger flight between Chicago, Illinois, and Duluth, Minnesota, with an inter¬mediate stop at Madison, Wisconsin. Forty-one passengers and four crew- members were aboard. At 1750, the O’Hare ground controller cleared the flight to taxi to Runway 27L for departure.

“At 1758:52.3, the O’Hare local controller cleared Flight 575 into the takeoff position on Runway 27L and advised the crew the visibility was one-fourth mile. Twenty-six seconds later, the local controller cleared the flight for takeoff; at 1759:24.3, the captain reported that he was beginning his takeoff roll.

“The first officer made the takeoff. The captain stated that the takeoff roll was normal until he called. “Rotate.” At that moment, the captain saw another aircraft ahead on the run¬way, and he immediately assisted the first officer in applying additional control pressure to gain altitude in an attempt to clear the other air¬craft. The attempt was unsuccessful. After the collision, the captain decided that his aircraft could not maintain flight, at which time he took control, and flew the aircraft back onto the runway.

The collision occurred at 1800:08.7, December 20, 1972. The geo¬graphic coordinates of the accident site are 41°58’9” N. and 87°54’4” W.” (NTSB 1973, 2-3)
….
“The DC-9 [North Central] was destroyed. The CV-880 [Delta] was substantially damaged.” (NTSB 1973, 4)

“CV-880

“The captain of the CV-880 stopped the aircraft, shut off the en¬gines, and ordered the evacuation of the passengers. All four main exits were opened and the slides were deployed and inflated. All passengers and crewmembers deplaned via the exits. Two passengers had received minor injuries in the crash. The cabin emergency lighting system functioned normally. The captain estimated that the evacuation was com¬pleted in approximately 5 minutes.

“Because of the restricted visibility, control tower and crash and rescue personnel were unaware of the CV-880 involvement in the accident until fire department personnel, responding to the DC-9 fire, came upon the CV-880. This occurred about 1828.” (NTSB 1973, 10)

“DC-9

“When the airplane touched down, the remaining landing gear col¬lapsed and the aircraft skidded to a stop on Runway 32L. Fire was seen around the aft section of the aircraft as it came to a stop. After pulling the engine fire extinguisher handles, the captain ordered evacu¬ation of the aircraft.
The first stewardess was seated on a folding seat attached to the forward cabin wall, facing aft. The second stewardess was seated in pas¬senger seat 15B rather than on the folding seat attached to the aft cabin bulkhead.

“As the airplane came to a stop, the second stewardess opened the left forward overwing exit at seat row 12, through which she exited, and called to the passengers to follow.

“The first stewardess opened the main entry door after the airplane stopped. The escape slide deployed, but did not inflate. The first stewardess stated that she was pushed out of the airplane. From the out¬side, she called out to the passengers and assisted them down to the ground.

“The first officer escaped from the airplane through the sliding window on the right side of the cockpit. He went around the nose of the airplane to the main entry door, and from the ground he assisted passen¬gers escaping through that door.

“The captain entered the cabin through the cockpit door and called to the passengers to come forward. He then went outside through the main entry door. From a position outside the aircraft, he assisted passengers down to the ground. Then, reentering the airplane, the captain assisted other passengers through the main entry door.

“A passenger opened the right forward overwing exit through which he made his escape.

“The two aft overwing exits, the galley exit door, and the emergency exit at the tail cone were not opened.

“Nine of the 10 fatally injured passengers failed to escape from the aircraft. Two of these passengers who had left their seats were found in the cockpit area. Two others who had left their seats were found in the aft section of the airplane. Five others remained in their seats; one was an invalid who was unable to walk without assistance. These passengers received no traumatic injuries but succumbed instead to the effects of smoke inhalation or burns, or both.

“Thirty-two passengers successfully escaped from the airplane; how¬ever, one of them succumbed 5 days later. Four passengers followed the second stewardess through the left forward overwing exit. Another escaped through the right forward overwing exit. The other surviving passengers escaped through the main entry door.

“The four crewmembers survived. The second stewardess received serious injuries during her escape. The captain received minor injuries when he reentered the cabin.

“Passengers testified that there were no lights visible in the cabin during the evacuation. They also stated that the smoke was dense, par¬ticularly in the upper portion of the cabin. The portable emergency light, portable power megaphones, and crewmember flashlights were not used during the evacuation.

“In an emergency, the DC-9 cabin standby lights can be powered by the aircraft 28-volt batteries or separate emergency lights can be powered by rechargeable 2.5-volt nickel-cadmium batteries. The 28-volt power source provides a much greater light intensity than that produced by the 2.5: volt source.” (NTSB 1973, 11-12)

“Air Traffic Control (ATC) Phraseology/Terminology

“The basic guidance for the use of air traffic control terminology is provided for pilots in the Airman’s Information Manual, Part I, and for air traffic controllers in the Terminal Air Traffic Control Hand¬book. Both are FAA publications and have identical standards of usage and terminology.

“Transcripts of the O’Hare tower facility recordings, as well as the testimony of pilots and controllers, have confirmed that in the Chicago area, neither pilots nor controllers adhere strictly to standard ATC phraseology and terminology. Deviations include word omissions, abbreviations, phrase alterations, and colloquialisms.

“Controllers and supervisors both stated that deviations were often necessary to serve efficiently the large volume of traffic at O’Hare. It was their belief that strict adherence to published standards would sub¬stantially reduce the number of airport operations.

“Testimony also indicated that there was little control over the extent of the deviations. Both controllers and pilots originate terms and expressions that are accepted in the common interest of expediting the flow of traffic.

“Controller Workload

“When all of the control positions in the O’Hare tower cab are manned, the two ground controllers coordinate with each other before is¬suing taxi clearances. This is necessary to preclude conflicts among the taxiing aircraft. Each ground controller in turn coordinates with .the appropriate local controller before the control of flights on their respective frequencies is transferred.

“Usually, the resulting controller workload is directly proportional to the volume of traffic, but it can be affected by many other factors, including: (1) work environment, (2) volume of traffic, (3) volume of communications, (4) weather conditions, and (5) controller familiarity with the airport.

“The O’Hare tower cab is relatively new in design, and incorporates recent improvements in the controller work environment. In this instance, the weather conditions were poor, which accounted for the low volume of traffic and the decision to combine the ground control functions under one controller. The ground controller, though not fully qualified in all control positions, was fully qualified to perform ground control functions; he was also familiar with the O’Hare airport and its opera¬tion.

“The ATC transcript of the O’Hare ground control communications dis¬closed that during the 6-minute period preceding-the first transmission of Flight 954 to ground control, the controller was providing service to seven flights–four inbound and three outbound. The outbound flights were transferred to one of the local controllers within the first 2 minutes of that period of time. The ground controller made 29 trans¬missions while he was providing the necessary service to the seven flights. However, 15 of the 29 transmissions were directed to another Delta flight which was having difficulty finding the Penalty Box.

“NCA Emergency Evacuation Training

“North Central Airlines provided emergency evacuation training to its crewmembers under two separate programs. One program involved the flightcrew members, the other involved the stewardesses. An NCA train¬ing instructor testified that much of the stewardess’ training involved the use of audio-visual aids. The stewardess trainees operated emergency exits only during initial training. None of the company stewardesses had operated the tail cone exit on the DC-9 aircraft. Stewardesses stated that they were advised during training that they could be among the first to exit the aircraft, if necessary. None of the training they received was conducted under conditions of real or simulated cabin emer¬gency lighting or a smoke-filled environment.

“The primary positions and duties of NCA crewmembers during an emergency evacuation of a DC-9 are:

Captain — in the cabin area: direct and assist passengers as conditions dictate.
First Officer — At the right forward galley service door: open door and assist passengers through that exit.
First Stewardess — At the left forward main entry door: open door and assist evacuating passengers through that exit.
Second Stewardess — Open either the tail cone exit or over- wing exits; assist passengers evacuating through those exits.” (NTSB 1973, 13-14)

“Analysis

“….The captain of the DC-9 was operating the airplane within the scope of a valid clearance, and, under the circumstances, he did all that could be reasonably expected of a pilot to avoid the collision. Because of the restricted visibility and the short time interval available after they saw the CV-880, the flightcrew of the DC-9 was unable to take any other course of action to avoid the collision. Although the exact visibility in the accident area could not be determined, the recorded RVR nearest the accident site was about 2,000 feet or more than one-fourth mile. A review of the recorded visibilities at various points on the airport indicates that the fog was homogeneous, with little variation in visi¬bility at any specific time.

“With 1/4-mile visibility, the flightcrew of the DC-9 could not have seen the CV-880 until they were approximately 1,600 feet from the col¬lision point. The first officer was making an instrument takeoff which the captain was monitoring, with particular attention to the airspeed. The captain looked outside the aircraft after he called “Rotate” at 1800:03.4. When he saw the CV-880 at 1800:07.2, the captain reacted with the order, “Pull ‘er up!” In the 5.3-second interval between “Rotate” and the impact, the captain first had to see the CV-880, next evaluate the probability of a collision, then decide on a course of action, and finally initiate an action; the aircraft had to respond to the control inputs. There was insufficient time for the flightcrew of the DC-9 to avoid the collision; and there was no other reasonable course of action that the captain could have taken in the time and distance available to him.

“The attention of the flightcrew of the CV-880 was divided between taxiing the aircraft and intracockpit conversations. They did not see the DC-9 in time to take any action to avoid the collision.

“The investigation confirmed that after the collision occurred, the DC-9 was incapable of sustaining flight. The flightcrew’s skill in maintaining control of the aircraft most likely averted more serious consequences.

“The principal causal area in this accident involved the exchange of communications between the O’Hare ground controller and the flightcrew of the CV-880. However, the sequence of events that established the conditions for the accident probably began when the CV-880 crew listened to ATIS broadcast “Golf.” That broadcast announced to the flightcrew that Runway 14R and Runway 14L were being used for departures. When the O’Hare operation was subsequently changed to use Runways 14R and 14L for approaches, the flightcrew was not informed that departures had been started on Runway 27L. Consequently, the flightcrew was unaware that Runway 27L had become an active runway, and the information they subsequently received con¬tained nothing to indicate that the runway was being used for takeoffs.

“After the CV-880 had landed on Runway 14L, the local controller re¬quested the flight to report when it was clear of the departure end of the runway. The flightcrew acknowledged and complied with that request. While the local controller was clearing the flight to the ground control frequency, the ground controller was attempting simultaneously to contact the flight. Consequently, the ground controller was aware of the flight’s arrival and anticipated radio contact with the flightcrew.

“Meanwhile, the ground controller was also occupied with another Delta flight, which was having difficulty locating the Penalty Box. Im¬mediately after the other flight appeared to have located the Penalty Box, the first officer of the CV-880 established contact with the ground controller by transmitting “Delta nine fifty four is with you inside the bridge and we gotta go to the box.”

“The Board is of the opinion that the controller did not hear the words “inside the bridge” in that transmission, but is unable to deter¬mine why he failed to hear those words. Had he heard the position given by the CV-880 crew, he would not have directed the crew to the 32R pad, his stated intention. From their reported position, the CV-880 crew would have had to turn the airplane around and taxi against the flow of traffic from 14L toward the terminal. Had the controller intended to direct the CV-880 to the 32L pad, he would have had to coordinate the clearance with the local controller before he could allow the flight to cross Runway 27L. This coordination was not effected. It is significant that when the ground controller directed the CV-880 crew to the 32 pad, he entered on a scratch sheet a written notation that the flight was hold-ing at the 32R pad. For these reasons, the Board concludes that the con¬troller did not hear the full transmission from the CV-880 and that he intended to clear the flight to the 32R pad. The CV-880 crew’s response “Okay we’ll do it” satisfied the controller and reinforced his belief that the CV-880 was going to the 32R pad.

“The controller should have been particularly alert to the position report from the CV-880 because of the limited visibility which prevented him from seeing the airplane. There was no evidence of a physical reason for his not hearing the complete transmission. The transmission was recorded, and a review of the recording showed that the transmission was both audible and intelligible. If the controller did not hear the crew report their position, he should have immediately requested a position report, rather than issuing what constituted a clearance to taxi to a holding point. The controller stated that had he heard the phrase “in¬side the bridge,” he would have asked for additional information regard¬ing the position of the airplane. The transmission without the position report was incomplete in that it did not contain information the controller needed to control the ground movement of the airplane. It is the Board’s opinion that if any transmission is unclear or ambiguous, the recipient should immediately request clarification.

“The controller stated that at the time he received the initial trans¬mission from the CV-880 crew, he believed that the airplane was just clear of Runway 14L near the 32R pad. Since the crew had notified the local con¬troller that they were clear of the runway more than a minute before the initial transmission to the ground controller, the Board can find no valid reason for such an assumption. Pilots testified that the normal procedure after clearing a runway was to continue to taxi and call ground control as soon as possible for taxi clearance. Delta aircraft clearing Runway 14L normally taxied via the Bridge taxi route to the terminal. The initial call from an airplane to ground control normally contained the position of the flight and its destination on the airport. The crew of the CV-880 ex¬perienced a delay in getting their destination on the airport from the station agent and did not call the ground controller until more than 1 minute after they were clear of the runway. Controllers testified that they commonly received initial radio contact from aircrews at various points on taxiways. The handling of the flight that followed the CV-880
is an example. The flightcrew contacted the ground controller and, in response to the controller’s request for their position, reported that “… just getting ready to cross the bridge.”

“The flightcrew of the CV-880 stated that since they had reported their position “inside the bridge,” they believed that the controller was referring to the 32L pad in his transmission. They said it would have been impractical to go to the 32R pad from their position. However, since the controller’s transmission was not clear in that it did not specify which 32 pad was to be used as a holding point, the crew should have requested clarification of the transmission before taxiing approxi¬mately 1 mile in limited visibility. Separation of aircraft on the ground, as well as in the air, is a joint responsibility of controllers and aircrews. Each has a duty in the interest of safe operations to request either additional information or clarification when transmissions are ambiguous, unclear, or incomplete. In this case, there was a need for a request for additional information and for clarification on the part of both the flightcrew and the controller.

“The manner in which the ASDE equipment in the O’Hare tower was used by the controllers did not comply with the provisions of Section 20 2/ of the Terminal Air Traffic Control Handbook and the provisions of O’Hare Tower Order 7110.26.10/ The ground controllers were not required to be qualified in the use of the ASDE, nor were they encouraged to use it. Al-though the display in the tower cab did not provide a clear picture of the airport environment, it is the Board’s conclusion that the use of the ASDE equipment was mandatory and that it should have been used by the con¬troller. The Board recognizes that the difficulties with the tower cab display might lead to controller reluctance to rely on the equipment, but the Board is also cognizant of the manner in which other facilities use similar equipment to control ground traffic effectively. Consequent¬ly, the Board believes that to overcome the limited and discretionary use of the ASDE, and to improve the effectiveness of the equipment, standard operating procedures should be established for all ASDE-equipped facilities…

“Fire broke out almost immediately, and smoke developed very rapidly in the DC-9 after it came to a stop. This reduced the time available to effect an evacuation and made a coordinated crew response extremely important in this accident.

“The Board concluded that the DC-9 cabin emergency lights did illumi¬nate. However, because the aircraft battery ground lead was severed, the power was supplied by the 2.5-volt batteries, which resulted in low intensity illumination. This made the emergency lights difficult to see in the concentration of smoke near the ceiling of the aircraft.

“The emergency evacuation of the DC-9 was impeded by dense smoke and inadequate cabin illumination. Also, the supervision of the evacuation by the flight and cabin crewmembers from a position outside the aircraft delayed the egress of some of the passengers.

“The Safety Board concludes that individual crewmember actions and crew coordination during the evacuation were less than adequate and prob¬ably detracted from the success of the evacuation. All of the North Central DC-9 crewmembers received FAA-approved emergency evacuation train¬ing, which was conducted in much the same manner as many other air car¬riers train their crewmembers. Such training emphasizes that crewmembers must take control of an evacuation, open all usable exits, direct pas¬sengers expeditiously through those exits, and assure that all passengers are out of the aircraft before they themselves exit.

“An individual crewmember’s response to an emergency situation is almost wholly a product of his training, particularly when time is criti¬cal. The assessment and response must be swift and accurate, and the crewmember’s actions must be coordinated with little or no direction. In addition, because of the possibility of disabling injuries or unusual circumstances, each crewmember must be prepared to assume command of the evacuation.

“Each crewmember must have a firm understanding of the duties of the others so that his efforts will complement theirs. Crewmembers must understand that they are the leaders of the evacuation, and that most passengers will immediately seek their aid and guidance. Passengers also may experience negative panic and may need to be physically aroused to action. To achieve maximum effectiveness, the crewmembers must remain inside the aircraft as long as possible.

“Crewmembers must be familiar with the location and operation of the installed evacuation aids, such as voice amplifiers, portable emergency lights, flashlights, and smoke goggles.

“To achieve this degree of efficiency, crewmember evacuation training must be such that individual reaction to an emergency situation will be reflexive. Ideally, such training should be conducted in an environment approximating that of an actual aircraft evacuation. Environmental fac¬tors such as lighting, smoke, and confusion should be introduced into evac-uation training. Training should be conducted in facilities which simulate an aircraft as closely as possible and should be conducted on a crew basis, rather than on an individual basis, so that each crewmember can become familiar with the duties and responsibilities of the others.

“Prior accident experience shows that crewmembers who have received approved emergency evacuation training often exhibit exemplary perform¬ance when faced with an emergency situation. This leads the Board to believe that this crew’s performance was the result of an inadequate training program. If the evacuation training of this crew had been oriented toward coordinated activities and had been conducted under emer¬gency conditions, simulated more realistically, crew performance during the actual evacuation could have been more effective. The corrective action taken by the FAA regarding the carrier’s training program is outlined in section 3 of this report.

“A discrepancy was found in the maintenance of the evacuation slide at the main entry door. Examination of the slide after the accident showed that the slide would not have inflated when the inflation lanyard was pulled because the lanyard was wrapped around the neck of the infla-tion bottle. An evaluation of the effect of not inflating the slide in¬dicates that the escape of those persons who used the main entry door might have been expedited. Had the slide been inflated, it would have extended at a shallow angle because of the attitude of the airplane. Therefore, the evacuees would not have been able to slide out of the aircraft, but rather, they would have had to walk or run out on an unstable slide. This would have increased the possibility of a fall and subsequent injury. On the other hand, had the slide been inflated, it would have been easier for crewmembers to return to the cabin when the flow of passengers slowed or stopped.

“There was a 3-minute lapse between the time of the collision and the first communication from the CFD which indicated that they arrived at the DC-9. This delay occurred because the tower personnel did not know at first that an accident had occurred. About 1:50 minutes were required for the controllers to learn that the DC-9 was not visible as a radar target, that the DC-9 flightcrew did not respond to radio calls, and for the pilots on the ground to report a fire on the ground south of the Penalty Box. This fire was not visible from the tower. The CFD response to the alarm was timely, and the first unit reported “on scene” within 1 minute of the time the alarm was sounded.

“Conclusions
Findings

1. The visibility at O’Hare at the time of the accident was one-fourth mile in fog.
2. Airport traffic beyond the confines of the main terminal area could not be observed visually from the control tower.
3. The ASDE “BRITE” equipment at the O’Hare tower provided in¬distinct displays of airport ground traffic.
4. The ground controller’s transmission to the CV-880 was am¬biguous because he did not specify which of two similarly numbered runup pads was to be used as a holding point.
5. The flightcrew of the CV-880 did not request clarification of the ground controller’s ambiguous transmission.
6. Flightcrews and controllers in the Chicago terminal area both deviated from the prescribed ATC communication pro¬cedures.
7. The captain of the DC-9 was operating under a valid clearance.
8. Neither the local controller nor the flightcrew of the DC-9 was aware of the proximity of the CV-880 to Runway 27L.

b. Probable Cause
The National Transportation Safety Board determines that the probable cause of this accident was the failure of the traffic control system to insure 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 flightcrew 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 flightcrew did not request clarification of the controller’s communications.

RECOMMENDATIONS

“On March 20, 1973, the Federal Aviation Administration issued Air Carrier Operations Bulletin 73-1. This bulletin requested that each Principal Operations Inspector review his assigned carrier’s emergency evacuation training program to assure compliance with 14 CFR 121.417. The bulletin recommended that the initial and recurrent training programs provide for operation of each emergency exit by individual crewmembers either on the aircraft or on a suitable mockup.

“On March 21, 1973, the FAA advised North Central Airlines that the portion of its emergency evacuation training program which authorized training by demonstration on the operation and use of emergency exits was cancelled. Also, provisions were set forth that required: (1) all crewmembers individually to operate each type of emergency exit during initial and recurrent training; (2) all DC-9 crewmembers, except those who had done so in the preceding 12 months, to operate the DC-9 tail cone exit within the succeeding 90 days; and (3) North Central Airlines to demonstrate an emergency evacuation of a DC-9 within the succeeding 30 days.

“The Board has submitted six recommendations (A-73-21 through 26) to the FAA concerning air traffic control procedures….

“Five recommendations (A-73-39 through 43) concerning the crash sur¬vival aspects of this accident and two other recent accidents were sub¬mitted to the Federal Aviation Administration in a letter issued June 25, 1973….

“An additional survival aspect, a need for improved emergency evacu¬ation capability in darkness and smoke conditions, was illustrated by this accident. In the darkness and smoke, the passengers had extreme difficulty in finding their way to the main exit and in locating exits. Four passengers left their seats and apparently attempted to find an exit but were unable to do so under the conditions that existed.

“In January 1968, a study entitled, “New Concepts for Emergency Evacuation of Transport Aircraft Following Survivable Accidents” was prepared by North American Rockwell Corp., Aerospace and Systems Group. This study discussed a number of concepts to improve egress from aircraft involved in survivable accidents. These concepts included among others, sonic indicators at emergency exits; “chemical light” to outline aisles, exits and egress devices; revised cabin lighting; floor level lighting; and tactile indicators for exit routes.

“Our evaluation of this accident as well as other recent survivable accidents indicates that egress from the aircraft would have been easier and faster if some or all of the above listed items had been available in the aircraft.

“Therefore, the National Transportation Safety Board recommends that the Federal Aviation Administration:

1. Amend the existing certification and operating rules for air carrier and air taxi aircraft to include provisions requiring tactile guidance and improved visual guidance to emergency exits, as well as more efficient methods of indicating the location of emergency exits in a dark or smoke environment. (Recommendation A-73-53)

A major factor in this accident was that the ground controller did not know the position of the CV-880 following initial radio contact because he did not hear the position given by the flightcrew. Additionally, the con¬troller did not use the ASDE to verify or determine the position of the aircraft, the controller did not issue instructions to taxi via a specific route to a specific destination, and the flightcrew did not request ad¬ditional clarifying information from the controller. To eliminate these problems, the Board recommends that the Federal Aviation Administration:

2. Require flightcrews to report their aircraft position on the airport when establishing radio communications with controllers, and require the controllers to read back the reported aircraft position when it cannot be verified either visually or by means of radar. (Recommendation A-73-54)

Require flightcrews to read back taxi clearances when operating in visibilities of less than one-half mile. (Recommendation A-73-55).” (NTSB 1973, 14 -22)

Sources

Kimura, Chris Y. World Commercial Aircraft Accidents 3rd Edition, 1946-1993, Volume 1: Jet and Turboprop Aircrafts. Livermore, CA: Lawrence Livermore National Laboratory, Risk Assessment and Nuclear Engineering Group. 4-11-1994.

National Transportation Safety Board. Aircraft Accident Report. North Central Airlines, Inc. McDonnell Douglas DC-9-31, N954N and Delta Air Lines, Inc., Convair CV-880, N8807E, O’Hare International Airport, Chicago, Illinois, December 20, 1972 (NTSB-AAR-73-15). Washington, DC: NTSB, adopted July 5, 1973, 43 pages. Accessed at: http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR73-15.pdf