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MIAMI (CBSMiami) – As Delta struggles to recover from Monday’s computer problems, the issue that caused the whole thing is shedding light on the systems used to keep flights in the air and on time.

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Airlines’ computer systems are in many cases older than the planes themselves.

Monday’s Delta outage disabled their flight status alerts.

“We found out we’re four hours delayed,” said Delta passenger Shanese Sims.

Airport monitors incorrectly listed flights as on time. The delays and cancellations prompted an apology from Delta’s CEO Ed Baston who said, “It’s an all hands on deck effort.”

Related: Delta Passengers Frustrated By Delays, Long Lines

Delta’s network outage raises questions about the reliability of computer systems used by airlines which are not regulated by the Federal Aviation Administration (FAA.)

Last year, United and American Airlines both suffered computer problems. In July, a faulty router forced Southwest Airlines to ground flights – a disruption that lasted days.

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“They’re running on a reservation system that is more than 35 years old,” said Travel Industry Analyst  Henry Harteveldt.

Airlines now rely on computers to handle pretty much everything from reservations and seat assignments to how much fuel and snacks to load on a plane.

Harteveldt says Delta has been rebuilding its core technologies for more than six months. The airline industry generally has reliable systems, but portions can be decades old.

“Airlines are technology companies that fly airplanes. Their technology systems have to be as reliable as their aircraft,” said Harteveldt.

The Department of Transportation said it is having discussions with Delta about the outage and continues to monitor the situation.

The airline is offering compensation for people who have had cancelled flights or delays of more than three hours in the form of a $200 flight voucher.

The delays may not end Tuesday.  Experts say travelers should expect delays into Wednesday.

Flight Status At Miami International Airport

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Flight Status At Ft. Lauderdale-Hollywood International Airport