Delta Air Lines Flight 1557
Boeing 757-232 · Accident: turbulence encounter en route
From Salt Lake City International Airport (KSLC) to Seattle–Tacoma International Airport (KSEA)
Event
- NTSB case
- WPR11LA149
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Boeing 757-232
- Aircraft type
- Boeing 757
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N684DA
- Operator
- Delta Air Lines
- Onboard fatalities
- Unknown
- Route
- From Salt Lake City International Airport (KSLC), Salt Lake CityTo Seattle–Tacoma International Airport (KSEA), Seattle, WA
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · descent
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Turbulence encounter
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Environmental issues › Conditions/weather/phenomena
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The flight crew of the scheduled domestic air carrier passenger flight was advised by the air route traffic control center that, due to a pilot report associated with the area of their routing, they should expect light-to-moderate chop during their descent between 20,000 feet and 16,000 feet. The flight crew, therefore, advised the passengers and the flight attendants that the descent would be bumpy and then advised the flight attendants that all descent and before-landing cabin securing activities should be completed about 10 minutes earlier than normal. Before the descent, the flight crew turned on the seatbelt sign and upon reaching 25,000 feet, the flying pilot began reducing the airspeed to that prescribed for turbulence penetration. As the airplane passed through 24,000 feet (4,000 feet higher than the altitude of the turbulence noted in the pilot report), three flight attendants were just finishing their activities, and the airplane suddenly encountered moderate turbulence for about 30 seconds. Due to the sudden movement of the airplane, the one remaining standing passenger and two of the flight attendants were thrown to the floor, one of whom sustained multiple bone fractures in her right foot.
Probable cause
The airplane's encounter with moderate turbulence at a higher altitude than the flight crew expected, resulting in an injury to a cabin crewmember.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record WPR11LA149
- Event ID
- 20110228X54428
- Case number
- WPR11LA149
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status, damage. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2011-02-28.
- API snapshot SHA-256: 5798e190221e62e0f3d20477e036356369702302df87d9b4af5eb45beb9d80b4; retrieved 2026-09-15T15:51:38.092Z.