Boeing 737 7H4 accident near Philadelphia, Pennsylvania, April 17, 2018
On April 17, 2018 at about 3:03 pm local time, a 2000 Boeing 737 7H4, registered N772SW, was substantially damaged in an accident during enroute (climb to cruise) near Philadelphia, Pennsylvania (Philadelphia airport). It was flown under scheduled airline rules (Part 121). 1 person was killed, 8 people were seriously injured and 125 people had minor injuries; 6 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A low-cycle fatigue crack in the dovetail of fan blade No. 13, which resulted in the fan blade separating in flight and impacting the engine fan case at a location that was critical to the structural integrity and performance of the fan cowl structure. This impact led to the in-flight separation of fan cowl components, including the inboard fan cowl aft latch keeper, which struck the fuselage near a cabin window and caused the window to depart from the airplane, the cabin to rapidly depressurize, and the passenger fatality.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 17, 2018 · about 3:03 pm local time
- Place
- Philadelphia, Pennsylvania · Philadelphia · map
- Type
- Accident
- Injuries
- 1 person was killed, 8 people were seriously injured and 125 people had minor injuries; 6 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Boeing 737 7H4 7H4, built 2000 · all 737 7H4s on the register
- Registration
- N772SW · no longer on the register · serial 27880
- Damage
- Substantial damage
- Flight
- Flight · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
The NTSB's full report is available at http://www.ntsb.gov/investigations/AccidentReports/Pages/AccidentReports.aspx. The Aircraft Accident Report number is NTSB/AAR-19/03. On April 17, 2018, about 1103 eastern daylight time, Southwest Airlines flight 1380, a Boeing 737-7H4, N772SW, experienced a left engine failure while climbing through flight level 320 en route to the flight's assigned cruise altitude. The flight had departed from LaGuardia Airport, Queens, New York, about 30 minutes earlier. As a result of the engine failure, the flight crew conducted an emergency descent and diverted to Philadelphia International Airport (PHL), Philadelphia, Pennsylvania. Portions of the left engine inlet and fan cowl separated from the airplane, and fragments from the inlet and fan cowl struck the left wing, the left-side fuselage, and the left horizontal stabilizer. One fan cowl fragment impacted the left-side fuselage near a cabin window, and the window departed the airplane, which resulted in a rapid depressurization. The airplane landed safely at PHL about 17 minutes after the engine failure occurred. Of the 144 passengers and 5 crewmembers aboard the airplane, 1 passenger received fatal injuries, and 8 passengers received minor injuries. The airplane was substantially damaged. The regularly scheduled domestic passenger flight was operating under the provisions of Title 14 Code of Federal Regulations Part 121 with a destination of Dallas Love Field, Dallas, Texas. The National Transportation Safety Board determines the probable cause(s) of this accident as follows: A low-cycle fatigue crack in the dovetail of fan blade No. 13, which resulted in the fan blade separating in flight and impacting the engine fan case at a location that was critical to the structural integrity and performance of the fan cowl structure. This impact led to the in-flight separation of fan cowl components, including the inboard fan cowl aft latch keeper, which struck the fuselage near a cabin window and caused the window to depart from the airplane, the cabin to rapidly depressurize, and the passenger fatality.
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 from the NTSB's investigation tables, in plain English
What happened, in order
- Powerplant sys/comp malf/fail during enroute (climb to cruise) defining event
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (turbine/turboprop) › Compressor section › Fatigue/wear/corrosion
- cause Aircraft › Aircraft structures › Nacelles/pylons structure › Nacelle/pylon misc structure › Damaged/degraded
- cause Aircraft › Aircraft structures › Windows › windshield system › Passenger compartment windows › Damaged/degraded
- Organizational issues › Management › Resources › Availability of documents/info › FAA/Regulator
- Personnel issues › Action/decision › Action › Lack of action › Cabin crew
The aircraft
- Maximum gross weight: 154,500 lb
- Landing gear: fixed
- Engine 1: Cfm Intl. CFM56 SERIES (turbofan); 0 hours total
- Engine 2: Cfm Intl. CFM56 SERIES (turbofan); 0 hours total
- Operator: Southwest Airlines CO
The flight
- Departed from: LGA New York NY
- Destination: DAL Dallas TX
- Flight plan: IFR
- Runway 27L, 12,000 ft by 200 ft
- A second pilot was aboard
Weather at the time
- Light: daylight
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Cabi | 4 | |||
| Flight crew | 2 | |||
| Passengers | 1 | 8 | 125 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
53 documents, released by the NTSB on November 14, 2018. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.