# NTSB WPR18LA118: Diamond Aircraft Ind DA 42 NG, N621ZC, Bozeman, MT, April 4, 2018

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: April 4, 2018, 12:29 local (18:29 UTC)
- Place: Bozeman, MT
- Coordinates: 45.77861, -111.156112 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=45.7786&lon=-111.1561&mi=10
- Phase of flight: [Taxi](https://openairdocs.org/ntsb-phases/250) (OpenAirDocs' grouping)
- Defining events: [Taxi-from runway: Ground collision](https://openairdocs.org/ntsb-events/200); [Taxi-from runway: Ground collision](https://openairdocs.org/ntsb-events/200)
- Highest injury: No injuries
- Injuries: 4 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Western Pacific Region
- Parties: Federal Aviation Administration FSDO
- NTSB case key (mKey): 97004
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR18LA118
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/97004/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=97004
- Page: https://openairdocs.org/ntsb/WPR18LA118

## Probable cause (aircraft 1)

The student pilot and flight instructor's failure to see and avoid the stationary airplane during taxi, which resulted in a ground collision.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Attention/monitoring: monitoring other aircraft](https://openairdocs.org/ntsb-findings/02021540): Personnel issues › Psychological · Pilot of other aircraft (probable cause), aircraft 1; cases with it: [Diamond Aircraft Ind DA 42 NG, 1 case](https://openairdocs.org/ntsb-findings/02021540/cases.md?model=2990105), [All aircraft, 231 cases](https://openairdocs.org/ntsb-findings/02021540/cases.md)
- [Attention/monitoring: monitoring other aircraft](https://openairdocs.org/ntsb-findings/02021540): Personnel issues › Psychological · Student/instructed pilot (probable cause), aircraft 2; cases with it: [Piper PA-12, 1 case](https://openairdocs.org/ntsb-findings/02021540/cases.md?model=7101202), [All aircraft, 231 cases](https://openairdocs.org/ntsb-findings/02021540/cases.md)
- [Attention/monitoring: monitoring other aircraft](https://openairdocs.org/ntsb-findings/02021540): Personnel issues › Psychological · Instructor/check pilot (probable cause), aircraft 2; cases with it: [Piper PA-12, 1 case](https://openairdocs.org/ntsb-findings/02021540/cases.md?model=7101202), [All aircraft, 231 cases](https://openairdocs.org/ntsb-findings/02021540/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Taxi-from runway: Ground collision](https://openairdocs.org/ntsb-events/200) (defining event), aircraft 1; cases with it: [Diamond Aircraft Ind DA 42 NG, 1 case](https://openairdocs.org/ntsb-events/200/sequence.md?model=2990105), [All aircraft, 618 cases](https://openairdocs.org/ntsb-events/200/sequence.md)
- [Taxi-from runway: Ground collision](https://openairdocs.org/ntsb-events/200) (defining event), aircraft 2; cases with it: [Piper PA-12, 4 cases](https://openairdocs.org/ntsb-events/200/sequence.md?model=7101202), [All aircraft, 618 cases](https://openairdocs.org/ntsb-events/200/sequence.md)

## Analysis (aircraft 1)

The tailwheel-equipped airplane had completed a series of touch-and-go takeoffs and landings with the student pilot in the front seat and flight instructor in the rear seat. The airplane was equipped with large tundra tires which, in combination with the tailwheel configuration, provided limited forward visibility when on the ground. The tower controller cleared the pilots to cross the landing runway, and then subsequently cleared the airplane across the parallel runway, which led it onto a taxiway where a low-wing airplane, having just cleared the parallel runway after landing, was stopped and preparing to contact ground control. Neither of the pilots onboard the tailwheel airplane saw the low-wing airplane before they collided with it on the taxiway, resulting in substantial damage to both airplanes. The student pilot stated that he perceived that he should expedite the taxi across the parallel runway due to airplanes on approach to that runway, although review of air traffic control voice recordings revealed that the controller issued no instructions to expedite the taxi. Because of the faster taxi speed, the pilots did not perform any "S"-turn maneuvers to enhance forward visibility, which likely would have allowed them to see the low-wing airplane and prevented the collision.

## Factual narrative (aircraft 1)

On April 4, 2018, at 1229 mountain daylight time, a Piper PA-12, N7709H, collided with a Diamond Aircraft Inc. DA42 NG, N621ZC, during taxi at Bozeman Yellowstone International Airport (BZN), Bozeman, Montana. Both airplanes sustained substantial damage. Neither the student pilot or the flight instructor in the PA-12, nor the flight instructor and pilot receiving instruction in the DA-42 were injured. Both airplanes were operated as Title 14 Code of Federal Regulations Part 91 instructional flights. The pilots of the DA-42 were conducting an instrument approach for runway 12 and the tower controller cleared the airplane to land. The PA-12, which had been conducting touch-and-go takeoffs and landings in the pattern for runway 11, requested to switch to runway 12 and was instructed by the tower to follow the DA-42 for landing on runway 12. Shortly thereafter, the controller contacted the PA-12, advised that they were unable to approve a landing on runway 12, and cleared the airplane to land on runway 11. The PA-12 subsequently landed on runway 11 and was instructed to taxi back to the approach end. Over the next minute, the tower controller provided a landing clearance to another airplane that was on the right downwind leg for runway 12, and then instructed the DA-42, which had landed, to exit runway 12 and contact the ground controller. The DA-42 exited the runway at taxiway A3 and stopped short of taxiway A. At this time, while two airplanes were now in the final approach stages for landing on runway 12, the tower controller cleared the PA-12 to cross runway 11 and hold short of runway 12. Shortly thereafter, the controller cleared the PA-12 to cross runway 12 and contact the ground controller. At this time, the DA-42 was still stationary on taxiway A3, and about 30 seconds later, the controller exclaimed, "09H, STOP;" however, the PA-12 collided with the tail of the DA-42. At the time of the collision, the DA-42 was positioned about 220 ft beyond the runway 12 hold short lines (440 ft from the edge of runway 12). According to the instructor onboard the DA-42, after landing on runway 12, they were instructed to exit at taxiway A3 and hold short of taxiway A. After exiting at A3, he stated that they stopped short of A, and just as they were switching to the ground control frequency, they felt a collision. Neither pilot onboard the DA-42 saw the airplane that struck them. Both the student and instructor onboard the PA-12 stated that the tower controller issued a clearance to cross runway 12 while they were still holding short of runway 11. As such, they felt pressure to perform a fast taxi and did not execute the typical "S"-turns for enhanced forward visibility. Air traffic control audio recordings revealed that the tower controller issued the PA-12 with progressive instructions to hold short of and cross runway 11, and subsequently, to hold short of and then cross runway 12. Those instructions were read back correctly by the student as the taxiprogressed, and at no time did the tower controller provide the PA-12 with instructions to expedite the taxi. Both occupants stated that they did not see the DA-42 on the taxiway. The instructor did notice the student pilot glance down at the instrument panel to switch to the ground control frequency just before the impact. The airport was equipped with four runways, including the parallel runways 12/30 and 11/29. Taxiway A3 branched from runway 12, 4,300 ft beyond the displaced threshold. It was 630 ft long and connected runway 12 to the parallel taxiway A. Taxiway C3 was directly in line with A3 and connected the landing threshold of runway 11 to runway 12 at midfield. (see Figure 1.) The Piper PA-12 was a high-wing, single-engine airplane with a tandem seating configuration and was equipped with conventional (tailwheel) landing gear and tundra tires. The student pilot was seated in the front seat, and the instructor in one of the rear seats. The instructor stated that the forward visibility from the front seat was limited and that the forward visibility from the rear seats was even worse. Figure 1. Landing and Taxi Paths

## Aircraft 1

- Registration: [N621ZC](https://openairdocs.org/aircraft/N621ZC), registered now, S/N 42.NC002, built 2012 (OpenAirDocs)
- Reported make and model: DIAMOND AIRCRAFT IND INC DA 42 NG (NG)
- Registry model: [Diamond Aircraft Ind DA 42 NG](https://openairdocs.org/model/diamond-aircraft-ind-da-42-ng) (registry code 2990205) (OpenAirDocs)
- Registry engine: [Austro E4 series](https://openairdocs.org/engine/austro-e4-series) (registry code 06400, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 42.NC002
- Year built: 2012
- Airframe hours: 1801.5
- Engines: Austro E4B 170 horsepower reciprocating; Austro E4B 170 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Summit Aviation Inc, doing business as Summit Aviation Inc
- Registered owner: Summit Aviation Inc
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, March 26, 2018
- Departed: BZN, Bozeman, MT
- Destination: BZN, Bozeman, MT
- Airport: BZN, Bozeman Yellowstone Intl, runway 12, 8,994 × 150 ft, asphalt
- Equipment: Electronic primary flight display, Onboard weather, Stall warning system, ADS-B, Auto-pilot, Electronic multifunction display

## Aircraft 2

- Registration: [N7709H](https://openairdocs.org/aircraft/N7709H), registered now, S/N 12-601 (OpenAirDocs)
- Reported make and model: PIPER PA 12 (NO SERIES)
- Registry model: [Piper PA-12](https://openairdocs.org/model/piper-pa-12) (registry code 7101202) (OpenAirDocs)
- Registry engine: [Lycoming 0-235 series](https://openairdocs.org/engine/lycoming-0-235-series) (registry code 41505, 4 cycle) (OpenAirDocs)
- Category: Airplane
- Serial number: 12-601
- Year built: 1946
- Airframe hours: 1635.8
- Engines: LYCOMING O-290 SERIES 135 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, July 25, 2017, 46 hours before
- Departed: BZN, Bozeman, MT
- Destination: BZN, Bozeman, MT
- Airport: BZN, Bozeman Yellowstone Intl, runway 11, 5,050 × 75 ft, asphalt
- Equipment: None

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Flight instructor, aircraft N621ZC; age 26; injuries: none; commercial, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review July 27, 2017; seat: right; restraint: 3-point; flight hours: 1,780.8 total, 211.8 in this make and model, 1,723 as pilot in command, 130.3 in the last 90 days, 41.2 in the last 30 days, 5.5 in the last 24 hours
- Pilot, aircraft N621ZC; age 21; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review October 17, 2017; seat: left; restraint: 3-point; flight hours: 127.6 total, 3 in this make and model, 15.6 in the last 90 days, 5.8 in the last 30 days, 1.2 in the last 24 hours
- Student pilot, aircraft N7709H; age 45; injuries: none; student; medical: class 3, without waivers/limitations; seat: front; restraint: lap only; flight hours: 20 total, 20 in this make and model
- Flight instructor, aircraft N7709H; age 74; injuries: none; flight instructor, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review January 14, 2015; seat: front; restraint: lap only; flight hours: 25,638 total, 200 in this make and model, 25,451 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: 70° at 7 knots
- Visibility: 10 statute miles
- Lowest ceiling: 7,000 ft overcast
- Temperature: 46 °F, dew point 23 °F
- Altimeter: 29.94 inHg
- Observed at: KBZN, 1 nm away

## FAA reports on this event (2)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20180404003311A](https://openairdocs.org/incident/20180404003311A), Apr 4, 2018: Diamond Aircraft Ind Inc DA 42 NG, Bozeman, MT, Substantial damage. On April 4, 2018 at 1130 MST, a Piper PA-12, N7709H, registered to valhalla aviation, collided with N621ZC, a Diamond DA-42, rgistered to summit aviation,…
- [Accident 20180404003301A](https://openairdocs.org/incident/20180404003301A), Apr 4, 2018: Piper PA-12, Bozeman, MT, Substantial damage. On April 4, 2018 at 1130 MST, a Piper PA-12, N7709H, registered to valhalla aviation, collided with N621ZC, a diamond DA-42, rgistered to summit aviation,…

## Docket (7 files)

The files NTSB released with the investigation on February 18, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=97004. 56.3 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 ( DA-42, N621ZC) (item 1, PDF, 9 pages, 752 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8876861&FileExtension=pdf&FileName=r_6120%20N621ZC%20Redacted-Rel.pdf
- Pilot/operator aircraft accident report, NTSB form 6120.1 (PA-12, N7709H) (item 2, PDF, 9 pages, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8877128&FileExtension=pdf&FileName=r_6120-PA-12_Redacted-Rel.pdf
- Flight instructor statement (DA-42, N621ZC) (item 3, PDF, 1 page, 92 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8876870&FileExtension=pdf&FileName=r_Statement%20DA42%20CFI%20DA42_Redacted-Rel.pdf
- Flight instructor and student pilot statements (PA-12, N7709H) (item 4, PDF, 3 pages, 563 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8876049&FileExtension=pdf&FileName=r_Statements%20-%20PA12_Redacted-Rel.pdf
- Bzn air traffic control audio recordings - local controller (item 5, WAV, 21.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8877034&FileExtension=wav&FileName=YEL61-N7709H%20LC%204-4-18-Rel.wav
- Bzn air traffic control audio recordings - ground controller (item 6, WAV, 30.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8876934&FileExtension=wav&FileName=YEL61-N%20N7709H%20GC%204-4-18-Rel.wav
- Photographs (item 7, PDF, 3 pages, 953 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8876887&FileExtension=pdf&FileName=Photos-Rel.pdf

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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