BERLIN (Reuters) - A German aviation watchdog is scrutinising a fly-past by Air Berlin's (>> Air Berlin Plc) last long-haul flight to its hub in Duesseldorf, which German media said was the pilot's unique way of saying "goodbye" to his passengers and the insolvent airline.

The pilot of the flight from Miami on Monday pulled up the aircraft above the runway in Duesseldorf and made a low pass over the airport before coming around and landing.

"That was a go-around manoeuvre. The Federal Aviation Office is examining the incident," a spokesman for Air Berlin said on Tuesday.

He declined to provide further details or confirm reports that said the manoeuvre was an intentional "lap of honour".

The Federal Aviation Office said while go-around manoeuvres were a normal procedure in air traffic, it had asked Air Berlin for details of Monday's incident involving the A330 plane because it differed from ordinary go-arounds.

"We are awaiting the results of an internal investigation at Air Berlin," a spokesman for the watchdog said, without providing further details.

German daily Tagesspiegel reported that the Airbus aircraft was welcomed by a water salute in Duesseldorf, with the airport fire brigade ceremonially spraying the aircraft with plumes of water.

Air Berlin, which has struggled to turn a profit over the last decade, filed for insolvency on Aug. 15, and a government loan has kept its planes aloft while its administrator negotiated with prospective buyers for parts of the business.

German flagship carrier Lufthansa signed a deal last week to buy large parts of Air Berlin for 210 million euros (£187.2 million).

(Reporting by Klaus Lauer; Writing by Maria Sheahan; Editing by Adrian Croft)

Stocks treated in this article : Deutsche Lufthansa, Air Berlin Plc, EasyJet