Overall Trends
Total, fatal, and serious accidents in the selected range.
Premium research interface
The modern interface for aviation safety intelligence.
Search investigations, review source evidence, monitor watched reports, and trace long-term patterns from one calm, data-first workspace.
63k+
Reports indexed
1940-2026
Coverage
Recent
Last data refresh
Search everything
Fast key and full-text search with live filters, watches, and precise metadata.
Use quotes for exact phrase matches (for example "fuel selector valve").
Featured Report
Safety trends by operating rule
Track fatal and non-fatal accident patterns across Part 91, Part 135, and Part 121 operations.
Loading trend charts…
High-signal investigations
Major cases, deep-report coverage, and investigation media across decades of NTSB history.
Browse the aviation graph
Move quickly by aircraft, airport, operator, and time with indexes built for research, not wandering.
Last Data Update
By Decade
By Month
Aircraft Manufacturer
More manufacturersAirports
More airportsOperators
More operatorsAbout
Aviation safety reports, made easier to study
NTSB Reports is an independent research and search tool for public aviation accident and incident records. It brings NTSB aviation reports, structured fields, docket files, extracted figures, photos, videos, and update history into one searchable interface.
The goal is practical safety education: make it faster to find relevant investigations, compare similar events, review factual records, and understand the evidence behind probable-cause and preliminary reports.
The investigative work and source records belong to the National Transportation Safety Board and the published investigation record. This site is not affiliated with or endorsed by the NTSB.
FAQs
NTSB Report
July 28, 1990 · Gulfstream G-II · N405MM
Cheyenne, WY
Overview
Report Status
Probable Cause
Event Type
Accident
Date
July 28, 1990
Injury Outcomes
8 injuries (1 serious injury, 7 minor injuries), 2 uninjured
Location
Cheyenne, WY
Aircraft
Gulfstream G-II
Tail Number
N405MM
Operator
Martin Marietta
Injuries
Serious
NTSB Number
DEN90LA168
THE AIRPLANE WAS APPROXIMATELY 100 NM NORTHEAST OF DENVER, DEVIATING AROUND THUNDERSTROM ACTIVITY, WHEN CLEAR AIR TURBULENCE (CAT) WAS ENCOUNTERED. THE CAPTAIN STATED AFTER THE ACCIDENT THE FLIGHT ATTENDANT HAD LEFT HIS SEAT TO PERFORM CABIN DUTIES AND WAS SQUATTING DOWN IN THE GALLEY WHEN THE AIRPLANE WAS BUFFETED BY THE TURBULENCE. TH FLIGHT ATTENDANT INJURED HIS ANKLE WHILE IN THIS POSITION. THE AIRPLANE RETURNED TO ENGLEWOOD, CO., AND THE FLIGHT ATTENDANT WAS TRANSPORTED TO THE HOSPITAL. ACCORDING TO THE DENVER ARTCC, THERE WERE NO REPORTS OF TURBULENCE BY OTHER AIRCRAFT PRIOR TO THE ENCOUNTER.
NTSB Probable Cause
AN UNFORESEEN ENCOUNTER WITH CLEAR AIR TURBULENCE.
Full Narrative
THE AIRPLANE WAS APPROXIMATELY 100 NM NORTHEAST OF DENVER, DEVIATING AROUND THUNDERSTROM ACTIVITY, WHEN CLEAR AIR TURBULENCE (CAT) WAS ENCOUNTERED. THE CAPTAIN STATED AFTER THE ACCIDENT THE FLIGHT ATTENDANT HAD LEFT HIS SEAT TO PERFORM CABIN DUTIES AND WAS SQUATTING DOWN IN THE GALLEY WHEN THE AIRPLANE WAS BUFFETED BY THE TURBULENCE. TH FLIGHT ATTENDANT INJURED HIS ANKLE WHILE IN THIS POSITION. THE AIRPLANE RETURNED TO ENGLEWOOD, CO., AND THE FLIGHT ATTENDANT WAS TRANSPORTED TO THE HOSPITAL. ACCORDING TO THE DENVER ARTCC, THERE WERE NO REPORTS OF TURBULENCE BY OTHER AIRCRAFT PRIOR TO THE ENCOUNTER.
Flight
Event TypeAccident
Event Time18:00 MDT
Nearest Airport0nm N
Runway0
Runway Length0
Runway Width0
Flight Plan FiledIFR
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftGulfstream G-II
Tail NumberN405MM
Aircraft CategoryAir
OperatorMartin Marietta
Operating RulePart 91
Engines2
Engine TypeTurbofan
Engine DetailsRolls-Royce · SPEY MK 511-8 · Turbofan · 11400
Seats15
People & Injuries
Injury Summary8 injuries (1 serious injury, 7 minor injuries), 2 uninjured
Fatal0
Serious1
Minor7
Uninjured2
Total10
Crew 1Unknown
Conditions
ConditionsVMC
LightDaylight
Wind210° @ 12 kt, gusting 16 kt
Visibility50 sm
CeilingBroken clouds 16000 ft
Temperature / Dew Point45 C
Altimeter30.00 inHg
Observation Time23:50
Weather SourceWFAC