BERLIN (Reuters) - Lufthansa's LHAG.DE first flight from Berlin to the United States in over 16 years took off on Wednesday, although a slow start to sales shows the difficulties involved in trying to replace the gaps left by insolvent rival Air Berlin.

FILE PHOTO: A Lufthansa Airbus A321-200 plane is seen at Tegel airport in Berlin, Germany, November 2, 2017. REUTERS/Axel Schmidt

Germany's second largest carrier Air Berlin AB1.DE filed for insolvency in August and carried out its last flight at the end of last month, leaving a gap in the market for long-haul flights from the German capital in particular.

“Of course bookings are slow at this stage,” Lufthansa board member Harry Hohmeister told Reuters at Berlin’s Tegel airport ahead of the departure of the flight to New York’s JFK on Wednesday.

He said that usually Lufthansa would give 12 months notice of a new long-haul route, or eight months at a minimum, but in this case it had only six weeks to sell tickets ahead of the first flight.

“The next four weeks will be difficult, then we get a peak at Christmas time and then it will develop better, otherwise we wouldn’t do it,” Hohmeister said.

Lufthansa has traditionally shied away from long-haul flights from Berlin, instead flying intercontinental routes from its hubs in Frankfurt and Munich.

Hohmeister said the Lufthansa group was currently looking at other long-haul options from Berlin, but that any would likely be flown by its budget arm Eurowings.

Lufthansa is currently awaiting EU approval for a deal to take over large parts of Air Berlin, which will see it adding 81 planes to the group.

The collapse of Air Berlin means Berlin Airports will see a dip in passenger number growth this year after a period of strong demand.

Britain's easyJet EZJ.L, which is planning to take over some Air Berlin operations at Tegel, has said it expects to run a reduced schedule this winter from the airport.

“We expect that new partners will quickly bring growth,” Berlin Airports CEO Engelbert Luetke Dalderup said, urging Lufthansa to “never say never” to the idea of Berlin as a hub.