British Airways is poised to announce the next stage of its move to Heathrow Terminal 5, possibly as early as next week.

The first of BA’s long-haul operations will transfer from Terminal 4 to T5 on June 5 and the remaining services are likely to move in two phases, with the final stage not until October.

The carrier will avoid switching operations in July, August and early September so any move before the peak summer period must be announced shortly.

One-quarter of BA’s long-haul services will move on June 5, including the eight daily flights to New York JFK. However, the complicated rosters required to make the best use of aircraft mean it is unlikely the airline could move the remainder of its US services ahead of the summer.

BA had originally intended to switch all its long-haul services at Heathrow to the new terminal on April 30, but that idea was scuppered following T5’s disastrous opening on March 27.

Chief executive Willie Walsh told a committee of MPs last week that his first plan had been to transfer the entire operation – short-haul and long – on a single day.

BA head of sales Drew Crawley told the Guild of Travel Management Companies’ conference in Istanbul: “The remaining 75% of long-haul operations will move in two phases, with the date of the next to be announced possibly next week.”