BERLIN, Sept 21 (Reuters) - Some of Europe's biggest

airports, including the region's busiest, London's Heathrow,

raced to restore normal operations on Sunday after hackers

disrupted automatic check-in systems.

Hackers on Saturday targeted check-in and boarding systems

provider Collins Aerospace, owned by RTX, disrupting

operations at Heathrow, Berlin Airport and in Brussels, where

passengers faced long queues, cancellations and delays.

Disruption had eased significantly by early Sunday despite

some continuing delays, according to airport officials and data,

while regulators said they were investigating the source of the

cyberattack.

Brussels Airport said that 45 out of 257 scheduled departing

flights on Sunday were cancelled but operational adjustments had

kept waiting times down. "There are delays between 30 and 90

minutes," a spokesperson for the airport told Reuters, adding it

was not clear yet how much longer disruptions would last.

A passenger flying from Brussels said disruption had been

minimal.

"For me, it was business as usual. For those poor souls who

didn't do online check-in or have bags to check, they may be

waiting a bit," he said.

The disruption is the latest in a string of hacks to hit

sectors from healthcare to autos. A breach at carmaker Jaguar

Land Rover halted production, while another caused Marks &

Spencer ( MAKSF ) losses in the hundreds of millions of pounds.

RTX called the incident a "cyber-related disruption" and

said it had impacted its MUSE software, which is used by several

airlines. RTX was not immediately available for comment on

Sunday.

Berlin Brandenburg Airport said on Sunday problems persisted

but that it was working with the company to resolve the issue. A

manual workaround was in place and there were currently no major

delays or cancellations, it added.

Heathrow said early on Sunday work was continuing to recover

from the check-in system outage. It added that "the vast

majority of flights have continued to operate".

An analysis by aviation data provider Cirium said delays at

Heathrow were "low", Berlin had "moderate" delays, while

Brussels had "significant" delays, but were decreasing.

(Reporting by Christoph Steitz and Sabine Siebold;

Writing by Adam Jourdan;

Editing by Helen Popper and Ros Russell)