Douglas DC-9-32 incident near Mount Vernon, Illinois, May 4, 1984
On May 4, 1984 at about 3:24 pm local time, a Douglas DC-9-32, registered N923L, was involved in an incident near Mount Vernon, Illinois. It was a flight of an unrecorded kind under scheduled airline rules (Part 121). No one was hurt; 84 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The NTSB has not yet published a probable cause for this incident. Investigations usually take one to two years; this page updates when the final report is released.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 4, 1984 · about 3:24 pm local time
- Place
- Mount Vernon, Illinois · map
- Type
- Incident
- Injuries
- No one was hurt; 84 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Douglas DC-9-32 · all DC-9-32s on the register
- Registration
- N923L · registry record · serial 47109
- Damage
- Not recorded
- Flight
- Flight of an unrecorded kind · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
KANSAS CITY ARTCC (ZKC) HAD CLEARED OZARK FLT 709 (A DC-9, N923L) TO CRUISE AT FL270. WHILE PROCEEDING ESE NEAR THE EDGEOF THE ZKC AREA, THE DC-9 CONVERGED ON ZORRO 11 (A FLT OF 3 F-4'S). THE F-4'S HAD BEEN CLEARED BY INDIANAPLOLIS ARTCC (ZID) TO PROCEED WESTBOUND AT FL260 TO RENDESVOUS WITH A KC-135 TANKER (SHAKE 81) TO REFUEL ON AERIAL REFUELING ROUTE AR110W. THE BEGINNING OF AR110W WAS IN THE ZID AREA; FROM THERE IT CONTINUED WESTBOUND INTO THE ZKC AREA. THE TANKER WASORBITING UNDER CONTROL OF ZKC & WAS CLEARED TO MAINTAIN BLOCK ALT FL260 TO FL290. ZID CLEARED THE F-4'S TO THE TANKER FREQ WITHOUT HANDING THEM OFF TO ZKC & WITHOUT OBTAINING APPROVAL FROM EITHER ZKC OR THE TANKER. AFTER ESTABLISHING RADIO CONTACT, THE TANKER CREW INCORRECTLY CLEARED THE F-4'S TO CLIMB TO FL270. WHEN THE ZKC CONTROLLER REALIZED THE F-4'S & DC-9 WERE CONVERGING, HE TOLD THE DC-9 CREW TO IMMEDIATELY TURN LEFT. THE DC-9 CREW SAW THE F-4'S & TOOK EVASIVEACTION. ZID HAD NOT PROPERLY COORDINATED THE F-4S' POSITION & NONE OF THE PLTS WERE INFORMED OF CONFLICTING TRAFFIC.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane; rotorcraft: glider; rotorcraft: helicopter
- Flight time: 13,727 hours in all; 8,061 in this make and model; 7,949 as pilot in command
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 43,480 hours
- Last inspection: continuous airworthiness programme, July 23, 1983; 2,098 hours since
- Maximum gross weight: 108,000 lb
- Seats: 110
- Landing gear: retractable
- Engine: P&W JT8D-9A (turbofan); 0 hours total
The flight
- Departed from: STL St. Louis MO at 3:05 pm
- Destination: SDF Louisville KY
- Flight plan: IFR
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 5 | |||
| Passengers | 79 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.