# NTSB DCA18CA042: Mcdonnell Douglas MD 88, N924DL, Detroit, MI, December 12, 2017

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Data collection · Final report
- Date: December 12, 2017, 07:35 local (12:35 UTC)
- Place: Detroit, MI
- Coordinates: 42.212501, -83.353332 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=42.2125&lon=-83.3533&mi=10
- Phase of flight: [Standing](https://openairdocs.org/ntsb-phases/150) (OpenAirDocs' grouping)
- Defining event: [Standing: Ground handling event](https://openairdocs.org/ntsb-events/080)
- Highest injury: No injuries
- Injuries: 61 uninjured
- Status: Completed, report July 8, 2020
- Report: Approved by Office Director
- NTSB office: Major Investigations Division
- Lead agency: Other
- NTSB case key (mKey): 96468
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA18CA042
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96468/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96468
- Page: https://openairdocs.org/ntsb/DCA18CA042

## Probable cause

failure of the flight crew to confirm the left engine throttle lever was at idle during engine start.

## Findings

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

- [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Flight crew (probable cause); cases with it: [Mcdonnell Douglas MD-88, 2 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=3023688), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md)

## Sequence of events

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

- [Standing: Ground handling event](https://openairdocs.org/ntsb-events/080) (defining event); cases with it: [Mcdonnell Douglas MD-88, 3 cases](https://openairdocs.org/ntsb-events/080/sequence.md?model=3023688), [All aircraft, 108 cases](https://openairdocs.org/ntsb-events/080/sequence.md)

## Analysis

On December 12, 2017, about 0735 EST, Delta flight 2421, Boeing McDonnell Douglas MD-88, N924DL, after being pushed back from the gate, with the towbar still connected, was substantially damaged after the airplane moved forward after engine start and struck the tug at Detroit Metropolitan Airport (DTW), Detroit, Michigan. There were no injuries to the 61 passengers and crew onboard. The flight was operating under 14 Code of Federal Regulations Part 121 as a scheduled domestic passenger flight from DTW to Raleigh-Durham International Airport (RDU), Morrisville, North Carolina. During pushback, the tug driver informed the flight crew they were cleared to start. After the left engine was started, the airplane started to unexpectedly move forward. Both flight crew members were focused inside the cockpit, running checklists, when the tug driver asked if the brake was set on the airplane. The captain responded "no" and the first officer then noticed the position of the tug and told the captain that they needed to stop the airplane. The airplane struck the tug before stopping. After the airplane's brake was set, the flight crew noticed that the engine throttles were not at idle as expected. Ground conditions were reported as slippery. The tug struck the right forward lower fuselage causing damage to the pressure vessel (skin, stringers, and frames).

## Factual narrative

On December 12, 2017, about 0735 EST, Delta flight 2421, Boeing McDonnell Douglas MD-88, N924DL, after being pushed back from the gate, with the towbar still connected, was substantially damaged after the airplane moved forward after engine start and struck the tug at Detroit Metropolitan Airport (DTW), Detroit, Michigan. There were no injuries to the 61 passengers and crew onboard. The flight was operating under 14 Code of Federal Regulations Part 121 as a scheduled domestic passenger flight from DTW to Raleigh-Durham International Airport (RDU), Morrisville, North Carolina. During pushback, the tug driver informed the flight crew they were cleared to start. After the left engine was started, the airplane started to unexpectedly move forward. Both flight crew members were focused inside the cockpit, running checklists, when the tug driver asked if the brake was set on the airplane. The captain responded "no" and the first officer then noticed the position of the tug and told the captain that they needed to stop the airplane. The airplane struck the tug before stopping. After the airplane's brake was set, the flight crew noticed that the engine throttles were not at idle as expected. Ground conditions were reported as slippery. The tug struck the right forward lower fuselage causing damage to the pressure vessel (skin, stringers, and frames).

## Aircraft

- Registration: [N924DL](https://openairdocs.org/deregistered/N924DL-2019-09-16), registration cancelled 2019-09-16, S/N 49711, built 1988 (OpenAirDocs)
- Reported make and model: MCDONNELL DOUGLAS AIRCRAFT CO MD 88 (88)
- Registry model: [Mcdonnell Douglas MD-88](https://openairdocs.org/model/mcdonnell-douglas-md-88) (registry code 3023688) (OpenAirDocs)
- Registry engine: [Pratt & Whitney JT8D series](https://openairdocs.org/engine/pratt-whitney-jt8d-series) (registry code 52053, turbo-jet) (OpenAirDocs)
- Category: Airplane
- Serial number: 49711
- Year built: 1988
- Airframe hours: 74998
- Engines: Pratt and Whitney JT8D-219 turbo jet; Pratt and Whitney JT8D-219 turbo jet
- Damage: Substantial damage
- Flight: Part 121
- Operator: Delta Air Lines
- Registered owner: Delta Air Lines Inc
- Airworthiness certificate: Standard, Transport
- Last inspection: December 11, 2017
- Departed: DTW, Detriot, MI
- Destination: RDU, Raleigh/Durham, NC
- Flight plan: IFR
- Airport: DTW, Detroit Metropolitan Wayne Cou
- Equipment: Electronic primary flight display, Onboard weather, Stall warning system, Angle of attack indicator, Data recorder, Electronic multifunction display

## Weather

- Conditions: Visual (VMC), Day
- Wind: 320° at 14 knots, gusting 24
- Visibility: 8 statute miles
- Temperature: 23 °F, dew point 9 °F
- Altimeter: 29.80 inHg
- Observed at: KDTW

## Other investigations on N924DL (2)

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.

- [NTSB DCA09IA018](https://openairdocs.org/ntsb/DCA09IA018), Dec 11, 2008: Mcdonnell Douglas MD88 (N924DL), Greer, SC, incident, minor damage. Probable cause: The overheating and arcing of the DC Ground Service Relay and Block Diodes component for undetermined reasons.
- [NTSB MIA88IA240](https://openairdocs.org/ntsb/MIA88IA240), Aug 1, 1988: Mcdonnell Douglas MD-88 (N924DL), Pensacola, FL, incident, no damage

## Docket (3 files)

The files NTSB released with the investigation on October 9, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96468. 1.1 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 485 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9650539&FileExtension=pdf&FileName=DCA18LA042-Rel.pdf
- Flight crew and ground crew statements (item 2, PDF, 7 pages, 526 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9643214&FileExtension=pdf&FileName=Statements-Rel.pdf
- Photo of damage to airplane (item 3, JPG, 81 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=10091053&FileExtension=jpg&FileName=924%202-Rel.jpg

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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