What happened
Prior to departure, the flight crew reviewed airline dispatch release documents that contained incomplete weather information, specifically lacking pertinent Convective SIGMETs and a tornado watch bulletin. Although the crew had observed a line of adverse weather on a computerized display before takeoff, they proceeded with the flight.
During the initial climb phase, the crew identified an approaching line of thunderstorms. The captain observed a 10-mile gap in the thunderstorm line via the onboard weather radar and noted the same gap visually outside the aircraft. The captain elected to fly through this gap, a decision that was not challenged by the first officer.
Data from radar and weather observations indicate the aircraft penetrated an extreme weather echo (VIP level 6). This cell likely contained severe thunderstorms, hail, and severe to extreme turbulence, with thunderstorm tops exceeding 45,000 feet. During the encounter, hail shattered the front windshield and caused damage to the engines, wings, tail, radome, and pitot system.
Because the flight attendants and passengers had not received an adequate or timely briefing regarding potential turbulence, the aft flight attendant and one passenger sustained serious injuries. The crew subsequently performed a successful emergency landing at a nearby airport.
Findings
The investigation determined that the airline lacked sufficient procedures for notifying flight attendants of potential turbulence and lacked adequate training and guidance for interpreting and avoiding hazardous weather. Additionally, it was noted that the captain had been involved in two previous air carrier incidents involving adverse weather conditions. The investigation also highlighted that FAA guidance recommends avoiding intense or extreme radar echoes by at least 20 miles and maintaining a 40-mile separation when attempting to fly between such echoes.