Boeing 757-222 N518UA

Summary

On 15 March 2006 at about 22:14 local time, a Boeing 757-222 registered N518UA was involved in an accident near Omaha, Nebraska, United States. 98 people were on board and one was seriously injured. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

15 March 2006 at 22:14

Classification

Accident

Location

Omaha, Nebraska, United States

Nearest airport

Eppley Airfield (OMA)

Coordinates

41.3031, -95.8942

Aircraft

Boeing 757-222

Registration

N518UA

Category

Airplane

Engines

2

Operator

Not recorded

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

San Francisco → New York

Aircraft damage

Not recorded

Weather

VMC

Light

Day

NTSB number

CHI06LA099

1 person was seriously injured.

An inadvertent encounter with unforecast mountain wave turbulence during cruise flight. A contributing factor was the mountain wave (terrain induced) turbulence.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The air carrier flight encountered turbulence associated with mountain wave activity during cruise at flight level 390 (FL390). One flight attendant located in the aft galley sustained serious injuries. The passengers and remaining crew were not injured. The aircraft was not damaged. The captain reported that the airplane was established in cruise at FL390 with smooth air conditions. She stated that the turbulence encounter began with a "slight buffet" and "rapidly increasing" airspeed. She attempted to maintain cruise airspeed by decreasing engine power and climbing to a higher altitude. She noted that as she initiated the climb, the aircraft experienced moderate turbulence. She reported that as the airplane reached FL400, the airspeed began a "rapid decrease" and she initiated a descent back to FL390. The flight subsequently descended to FL350 before the conditions smoothed out. She noted that the turbulence was encountered "suddenly and without warning." The flight data recorder indicated that the airspeed increased from 236 knots to 273 knots during the encounter. A vertical acceleration spike of 1.81 g's, followed by 0.61 g's, was recorded 64 seconds after the initial increase in airspeed. The weather forecast provided to the crew listed a risk of moderate turbulence between 20,000 and 38,000 feet. While ATC communications were describing light turbulence and moderate chop at lower altitudes, no reports from ATC, company dispatch, or other aircraft were received regarding mountain wave activity or turbulence at 39,000 feet.

Quoted verbatim from the NTSB record.