What aircraft was involved and where did it happen?

The accident on 2010-03-26 involved a B737-8AS, registration EI-DCP, at Aeroporto di Bergamo Orio al Serio, IT.

What was the probable cause of the accident?

The near-collision was caused by the issuance of conflicting altitude clearances to an arriving and a departing aircraft, which placed them on intersecting flight paths, necessitating an emergency climb by the inbound aircraft to restore vertical separation.

Near-collision of two Boeing 737s at Bergamo Orio al Serio

Two Ryanair Boeing 737-8AS aircraft narrowly avoided a mid-air collision at Bergamo Orio al Serio airport after conflicting altitude instructions were issued during simultaneous departure and arrival operations.

What happened

On March 26, 2010, at approximately 14:57 UTC, a serious loss of separation occurred between two Boeing 737-8AS aircraft at Bergamo Orio al Serio Airport. The first aircraft, registration EI-DPC (operating flight RYR9463), was on the final approach for an ILS RWY 28 approach, intending to perform a circling maneuver for runway 10. Simultaneously, a second Boeing 737-8AS, registration EI-DCP (operating flight RYR4535), was cleared for takeoff from runway 10.

During the sequence, the Tower controller issued an amendment to the departing aircraft, instructing it to climb to 3,000 feet. However, due to the conflicting flight paths, the controller was forced to intervene and instruct the arriving aircraft to climb to 4,000 feet to maintain vertical separation. The two aircraft were traveling on opposing tracks, and the sudden change in altitude instructions was necessary to prevent a collision.

The investigation

The ANSV investigation examined radio and telephone communications between the Bergamo Tower (TWR) and the Milan Area Control Centre (APP/ADE). The investigation focused on the coordination between the two air traffic service (ATS) entities during a period of deteriorating weather conditions, which had necessitated the use of runway 10.

The investigators reviewed the sequence of clearances, noting that the management of departures from runway 10, while inbound traffic was present, relied on the coordination between the Tower and the Approach controller. The investigation also looked into the specific instructions given to the departing aircraft and the subsequent emergency climb ordered for the arriving aircraft.

Findings

The primary cause of the loss of separation was the conflicting altitude instructions issued to the two aircraft, which placed them on intersecting flight paths.
The Tower controller had authorized the departing aircraft (EI-DCP) to climb to 3,000 feet, but the arrival of the second aircraft necessitated an immediate instruction for the inbound aircraft (EI-DPC) to climb to 4,000 feet to avoid a collision.
The incident occurred during a period of high traffic demand and deteriorating weather, which required complex coordination between the Tower and the Approach sectors.
While the controllers maintained a high level of coordination, the simultaneous management of a departure and an arrival in the same airspace created a situation where vertical separation was only restored through rapid corrective action.