Investigators have disclosed that an in-flight upset involving an Avianca Airbus A319 resulted in a 2,500ft loss of altitude.

The aircraft had been operating a San Jose-Bogota flight and was cruising at 37,000ft, with the captain as the flying pilot, when the incident occurred.

French investigation authority BEA, citing Costa Rican counterparts, says the twinjet experienced “changes in the attitude, speed and vertical acceleration”.

It lost 2,500ft and suffered an overspeed relating to the maximum operating Mach number, as well as a hydraulic system alert.

The aircraft had been flying in the vicinity of the Panama-Colombia border when the upset occurred, and it diverted to Panama City.

Avianca had previously indicated that the diversion followed an alert from aircraft systems, and that four of the 113 occupants – including crew members – were hospitalised after the 23 January event.