# NTSB DCA23LA411: Embraer ERJ170, N776MS, Eleroy, IL, August 14, 2023

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Class 4 · Limited · Final report
- Date: August 14, 2023, 06:36 local (11:36 UTC)
- Place: Eleroy, IL · Lat/Long/alt from narrative section on 6120. Alt= 26,650 msl
City name/zip from google earth


- Coordinates: 42.338889, -89.7575 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=42.3389&lon=-89.7575&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute-descent: Turbulence encounter](https://openairdocs.org/ntsb-events/360)
- Highest injury: Serious injuries
- Injuries: 1 serious, 67 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 4 - Basic report with no Prelim publish
- NTSB office: Major Investigations Division
- Parties: FAA/AVP-100
- NTSB case key (mKey): 192864
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA23LA411
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/192864/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=192864
- Page: https://openairdocs.org/ntsb/DCA23LA411

## Probable cause

An encounter with clear air turbulence.

## Findings

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

- [Turbulence: clear air turbulence](https://openairdocs.org/ntsb-findings/03032015): Environmental issues › Conditions/weather/phenomena · Effect on personnel (probable cause); cases with it: [Embraer ERJ 170-100 SE, 1 case](https://openairdocs.org/ntsb-findings/03032015/cases.md?model=3260406), [All aircraft, 78 cases](https://openairdocs.org/ntsb-findings/03032015/cases.md)
- [Turbulence: clear air turbulence](https://openairdocs.org/ntsb-findings/03032015): Environmental issues › Conditions/weather/phenomena · Awareness of condition; cases with it: [Embraer ERJ 170-100 SE, 1 case](https://openairdocs.org/ntsb-findings/03032015/cases.md?model=3260406), [All aircraft, 78 cases](https://openairdocs.org/ntsb-findings/03032015/cases.md)

## Sequence of events

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

- [Enroute-descent: Turbulence encounter](https://openairdocs.org/ntsb-events/360) (defining event); cases with it: [Embraer ERJ 170-100 SE, 2 cases](https://openairdocs.org/ntsb-events/360/sequence.md?model=3260406), [All aircraft, 423 cases](https://openairdocs.org/ntsb-events/360/sequence.md)

## Analysis

Envoy Air flight 3788 encountered turbulence during initial descent into Chicago O’Hare International airport (ORD), Chicago, Illinois. The flight was a regularly scheduled passenger flight from Des Moines International airport (DSM), Des Moines, Iowa, to ORD. As a result of the turbulence, one flight attendant (FA) sustained serious injuries. The airplane was not damaged, and the flight continued to ORD without further incident. The cabin crew reported that before the flight, the captain briefed that there would be “nothing serious”, but they could expect some “bumps along the way”. The captain reiterated the same message twice during the flight. The first officer recalled that the cabin crew had been advised to use caution and left the decision to provide service during the flight at their discretion. FA2, (who was injured) had reviewed the weather conditions before the flight, and after the flight had experienced “some bumps”, ultimately decided not to perform a service and remained seated until the initial descent. The flight crew reported an uneventful take off and climb but decided to keep the fasten seatbelt sign on for the duration of the flight. Upon observing a “buildup of weather” on their route, the flight crew decided to climb to flight level (FL) 310 (31,000 ft above mean sea level) to stay on top of the developing weather. Upon reaching FL310, air traffic control (ATC) advised them to descend to 11,000 ft at pilot’s discretion. ATC further advised that other aircraft were making their way through the weather with “no complaints”. After initiating the descent, the captain advised the cabin crew to prepare for arrival and FA2 got up to recheck that the galley was secure. During the descent, the flight crew observed a “small cumulous cloud” (which was not towering) ahead. As the airplane descended into the cloud it encountered moderate turbulence at an altitude of 26,650 ft. The turbulence caused the airspeed to increase to an “overspeed” before the cabin crew used the touch control steering (TCS) to manually slow the aircraft down to the normal operating speed. The flight crew reported that the overspeed lasted no more than 2 seconds, at an airspeed of 321 knots. FA2 reported that the turbulence was “severe”, and it occurred before she could return to her seat. While attempting to sit, her left foot went out from under her and she “slammed down” to the floor, where she remained for the rest of the flight. Upon being notified of the injury, the flight crew advised company operations and requested paramedics at the gate upon arrival. FA2 was treated at the gate and then taken to the hospital via ambulance and was diagnosed with a fractured left ankle. A review of weather records revealed light to extreme precipitation in the accident area below about 25,000 ft. A vertical profile of the radar reflectivity indicated that the precipitation intensity decreased with altitude and was generally stratified and not characteristic of deepupdrafts. Infrared satellite imagery indicated the coldest cloud tops near the accident location were about -25°C, which along with an atmospheric model created from weather balloon sounding data, indicates cloud tops at a height of about 26,000 ft msl. This data suggests a relatively weak convective environment up to about 25,000 ft msl. There were no active significant meteorological information (SIGMETS) for the accident area. The atmospheric model identified some vertical shearing of the horizontal wind (speed sheer) between 25,000 and 30,000 ft msl. Wind speed calculations varied from 41 knots at 25,000 ft, and increased with altitude to 90 knots at 30,000 ft. Given the weak convective environment and the likelihood of wind speed shear, the airplane likely encountered clear air turbulence. The Federal Aviation Administration’s advisory circular AC 00-30C defines clear air turbulence as “sudden severe turbulence occurring in cloudless regions that causes violent buffeting of aircraft.” This term is commonly applied to higher altitude turbulence associated with wind shear. The most comprehensive definition is high-altitude turbulence encountered outside of convective clouds. This includes turbulence in cirrus clouds, within and in the vicinity of standing lenticular clouds and, in some cases, in clear air in the vicinity of thunderstorms. There were two pilot reports within a 40 nautical mile radius of the accident area. The first was about ½ hour after the accident and reported moderate chop at FL310, the second was 15 minutes later and reported consistent light chop and occasional light turbulence.

## Aircraft

- Registration: [N776MS](https://openairdocs.org/aircraft/N776MS), registered now, S/N 17000050, built 2004 (OpenAirDocs)
- Reported make and model: EMBRAER ERJ170 (100SE)
- Registry model: [Embraer ERJ 170-100 SE](https://openairdocs.org/model/embraer-erj-170-100-se) (registry code 3260406) (OpenAirDocs)
- Registry engine: [GE CF34 series](https://openairdocs.org/engine/ge-cf34-series) (registry code 30015, turbo-fan) (OpenAirDocs)
- Category: Airplane
- Serial number: 17000050
- Year built: 2004
- Airframe hours: 48782
- Engines: GE CF34-8E5 G01 13420 lbs thrust turbo fan; GE CF34-8E5 G01 13420 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 121
- Operator: Envoy Air, doing business as American Eagle
- Registered owner: Wilmington Trust Company Trustee
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, August 13, 2023
- Departed: DSM, Des Moines, IA
- Destination: ORD, Chicago, IL
- Flight plan: IFR
- Equipment: Onboard weather, Satellite tracking device, Stall warning system, ADS-B, Electronic primary flight display, Electronic flight bag or handheld device, Data recorder, Auto-pilot, Angle of attack indicator

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; injuries: none; airline transport, commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review July 12, 2023; seat: left; restraint: 5-point; flight hours: 9,188 total, 985 in this make and model
- Co-pilot; age 25; injuries: none; airline transport; airplane ratings: single-engine land, single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review May 7, 2023; seat: right; restraint: 5-point; flight hours: 1,904 total, 882 in this make and model
- Cabin crew; injuries: none; restraint: 3-point
- Cabin crew; injuries: serious; restraint: 3-point

## Weather

- Conditions: Visual (VMC), Day
- Wind: 100° at 5 knots
- Visibility: 10 statute miles
- Lowest ceiling: 7,000 ft broken
- Temperature: 72 °F, dew point 63 °F
- Altimeter: 29.92 inHg
- Turbulence: Moderate
- Observed at: KORD, 1 nm away
- METAR: KORD 141151Z 10005KT 10SM FEW050 BKN070 BKN090 OVC250 22/17 A2992 RMK AO2 SLP127 T02220172 10222 20211 58007 $

## FAA reports on this event (1)

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

- [Accident 20230814021969A](https://openairdocs.org/incident/20230814021969A), Aug 14, 2023: Embraer ERJ 170-100 SE, Chicago, IL, No damage. Prior to departure from dsm on 3788 on 8/14/23 I checked the weather and noticed rain bands between dsm And ord. At our preflight, the CA said there would be…

## Docket (3 files)

The files NTSB released with the investigation on October 9, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=192864. 2.8 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17424208&FileExtension=pdf&FileName=01-01%20NTSB%20Form_6120_DCA23LA411_print_Redacted-Rel.pdf
- Flight crew statements (item 2, PDF, 2 pages, 81 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17422992&FileExtension=pdf&FileName=01-02%20Crew_Statements_DCA23LA411_print2-Rel.pdf
- Weather reports and records (item 3, PDF, 4 pages, 610 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17424593&FileExtension=pdf&FileName=06-01%20Weather%20Reports%20and%20Records_DCA23LA411-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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