Amateur-built DH-7 and Cessna 441 incident near Denver, Colorado, February 17, 1988
On February 17, 1988 at about 1:20 am local time, 2 aircraft, amateur-built DH-7 (N9058P) and Cessna 441 (N1WB), were involved in the same incident near Denver, Colorado (Stapleton Intl airport). No one was hurt; 16 people were on board or involved. The weather was instrument conditions (cloud, fog or low visibility).
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
- February 17, 1988 · about 1:20 am local time
- Place
- Denver, Colorado · Stapleton Intl · map
- Type
- Incident
- Injuries
- No one was hurt; 16 people were on board or involved.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft 1
- Amateur-built DH-7
- Registration
- N9058P · no longer on the register · serial 5
- Damage
- Not recorded
- Flight
- Flight of an unrecorded kind · charter and air-taxi rules (Part 135)
- Aircraft 2
- Cessna 441 · all 441s on the register
- Registration
- N1WB · registry record · serial 441-203
- Damage
- Not recorded
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative for the amateur-built DH-7 final · quoted from the NTSB record
AS ROCKY MTN AIRWAY FLT 2129 (DE HAVILLAND DH-7, N9058P) & CESSNA 441, N1WB, WERE ARRIVING, THERE WAS MODERATE TO HVY TRAFFIC & A RWY CHANGE WAS IN PROGRESS. N1WB & FLT 2129 WERE PROVIDED INITIAL SEQUENCING BY FEEDER CTLRS (AR-1 & AR-4). BOTH FLTS WERE HANDED OFF TO THE FINAL CTLR (AR-2), WHO WAS RESPONSIBLE FOR ESTABLISHING ARRIVAL SEQUENCE. AR-2 WAS A DEVELOPMENTAL CTLR, WHO HAD JUST BEGUN TRAINING IN THAT POSITION. N1WB & FLT 2129 WERE VECTORED FOR SIMULTANEOUS IFR APCHS TO RWYS 17L & 18. AS THE TWO ACFT WERE ON THEIR RESPECTIVE FINAL APCHS, MINIMUM SEPARATION STANDARD WAS LOST. WHEN THE LOCAL CTLR DETERMINED THE ERROR, HE ISSUED INSTRUCTIONS TO CORRECT THE SITUATION.
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 NTSB's narrative for the Cessna 441 final · quoted from the NTSB record
AS ROCKY MTN AIRWAY FLT 2129 (DE HAVILLAND DH-7, N9058P) & CESSNA 441, N1WB, WERE ARRIVING, THERE WAS MODERATE TO HVY TRAFFIC & A RWY CHANGE WAS IN PROGRESS. N1WB & FLT 2129 WERE PROVIDED INITIAL SEQUENCING BY FEEDER CTLRS (AR-1 & AR-4). BOTH FLTS WERE HANDED OFF TO THE FINAL CTLR (AR-2), WHO WAS RESPONSIBLE FOR ESTABLISHING ARRIVAL SEQUENCE. AR-2 WAS A DEVELOPMENTAL CTLR, WHO HAD JUST BEGUN TRAINING IN THAT POSITION. N1WB & FLT 2129 WERE VECTORED FOR SIMULTANEOUS IFR APCHS TO RWYS 17L & 18. AS THE TWO ACFT WERE ON THEIR RESPECTIVE FINAL APCHS, MINIMUM SEPARATION STANDARD WAS LOST. WHEN THE LOCAL CTLR DETERMINED THE ERROR, HE ISSUED INSTRUCTIONS TO CORRECT THE SITUATION.
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 for the amateur-built DH-7 from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instrument: airplane; rotorcraft: glider
- Flight time: 12,500 hours in all; 3,000 in this make and model; 180 in the last 90 days; 50 in the last 30 days; 1,800 as pilot in command; 3,100 on instruments
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Last inspection: continuous airworthiness programme
- Maximum gross weight: 44,000 lb
- Seats: 50
- Landing gear: retractable
- Engine: P&W PT6A-50 (turboprop); 0 hours total
The flight
- Departed from: ASE Aspen CO
- Destination: DEN
- Flight plan: IFR
- Runway 18, 5,650 ft by 150 ft
- A second pilot was aboard
Weather at the time
- Light: night, dark
- Wind: from 012° at 3 knots
- Visibility: 4 statute miles
- Sky: broken clouds at 900 ft; not recorded
- Temperature: 28°F (-2°C), dew point 27°F (-3°C)
- Altimeter: 30.00 inHg
- Observation at 1:00 am from DEN, 3 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 3 | |||
| Passengers | 12 |
The factual record for the Cessna 441 from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; single-engine land; single-engine sea; instructor: airplane multi-engine; instructor: airplane single-engine; instrument: airplane
- Flight time: 4,848 hours in all; 247 in this make and model; 125 in the last 90 days; 4,638 as pilot in command
- Medical certificate: Class 1 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 3,171 hours
- Last inspection: continuous airworthiness programme, February 1, 1988; 12 hours since
- Maximum gross weight: 9,850 lb
- Seats: 10
- Landing gear: retractable
- Engine: Airesearch TPE 331-8 (turboprop); 0 hours total
The flight
- Departed from: JAX Jacksonville FL
- Destination: DEN
- Flight plan: IFR
- Runway 17, 12,000 ft by 200 ft
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
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.
Other NTSB records under N9058P the same tail number, which may have belonged to a different aircraft at the time
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.