An investigation is underway after an Alitalia aeroplane operated by Romania's Carpatair veered off the runway upon landing at Rome's Leonardo da Vinci airport on the night of Saturday 2 February.

There were 6 people injured in the incident, two seriously. The plane flew to Rome from the Tuscan city of Pisa and had 50 people aboard. Some of the passengers said the aircraft hit the ground twice – damaging its landing gear – before coming to a halt in the grass about 300m off the runway.

Although the ATR-72 plane landed during strong winds, which had left the airport in Fiumicino with only one runway operational, the precise cause of the accident remains unclear and the pilot has been questioned by Italian police.

Alitalia has suspended domestic flights operated by Carpatair on its behalf from Pisa and Bologna to Rome. The day after the accident the Alitalia symbol was whitewashed from the Carpatair aircraft, in line with normal procedures "when these events happen" according to Alitalia operations chief Giancarlo Schisano.

It was reported in the Italian newspaper Corriere della Sera that Alitalia – Italy’s beleaguered national airline – saves up to 30 per cent by subcontracting its smaller planes to Carpatair, particularly on routes that it finds difficult to fill.

The accident has led to an Italian pilots' union demanding that Alitalia cancel its contract with Carpatair – which is based in Timisoara, Romania – while another Italian pilots’ union said that its members had raised concerns about Carpatair's safety standards over a month ago.

It is the latest in a run of negative publicity for the Romanian company which is responsible for a number of incidents on its Italian flights since last May. The most recent of these occurred in January when a Carpatair flight between Ancona and Rome was forced to make an emergency landing not long after taking off. The Romanian company later denied any reliability problems and claimed it was the victim of a “media campaign” by “Italian trade unions and pilots” unhappy with its partnership with Alitalia.

In addition to its now-suspended domestic flights in Italy, Carpatair operates international flights out of Romania, Moldova and Ukraine.