What happened
On July 24, 2023, at 10:52 UTC, a Boeing 767-300, registration N189DN, departed Milan Malpensa Airport (MXP) for New York (JFK). While climbing through 13,000 feet and executing the DOGUB 6T standard instrument departure (SID), the aircraft encountered an intense hailstorm.
By the time the aircraft reached 15,000 feet, the hail had caused extensive damage to the airframe. Notably, the outer pane of the first officer's windscreen shattered. Due to the severity of the weather and the damage sustained, the crew initially considered returning to Malpensa but ultimately decided to divert to Rome Fiumicino (FCO). The aircraft landed at Fiumicino at 11:55 UTC, having landed overweight, without further incident. The flight carried 214 passengers and 12 crew members.
The investigation
The ANSV investigation focused on the sequence of events leading to the encounter with the hail and the decision-making process of the crew and dispatchers. Investigators examined the aircraft's damage, which included numerous dents and punctures across the fuselage, engine cowlings, and stabilizers. The investigation also reviewed available meteorological data, including METAR, TAF, and satellite imagery available via flight planning tools and mobile applications.
Investigators noted that while the official briefing pack provided standard meteorological reports, more detailed satellite imagery via tools like WidgetWeather could have indicated the high probability of adverse weather along the SID. The investigation also looked into the roles of both the flight crew and the company dispatcher in the strategic planning of the flight.
Findings
- The primary cause of the aircraft damage was the encounter with severe hail.
- The crew's decision to deviate from the planned route was made too late, as the aircraft was already entering the storm cell.
- The investigation identified the inadequate use of available meteorological information by both the crew and the dispatcher as a contributing factor, as more detailed satellite data could have predicted the hazard.
- There was evidence suggesting that some form of operational pressure may have influenced the decision-making of both the dispatcher and the crew during flight planning and execution.
- The lack of Cockpit Voice Recorder (CVR) data prevented a full analysis of the human factors and the specific pressures present in the cockpit during the event.