EDINBURGH/MADRID/SEOUL - Air passengers around the world faced delays, cancellations and problems checking in as airports and airlines were caught up in a massive IT outage that also affected industries ranging from banks to media companies.

Out of over 110,000 scheduled commercial flights on Friday, 1,390 have been cancelled globally so far and more are expected to be called off, according to data from global aviation analytics firm Cirium.

In Edinburgh, a Reuters witness said boarding pass scanners carried a "server offline message", with the airport saying passengers shouldn't travel to the airport without checking their flight status online first.

Elsewhere, airports and airlines advised customers to arrive earlier than normal for flights. Analysts said the outage was likely tied to a glitch in Microsoft software used globally.

Microsoft said users might be unable to access various Office 365 apps and services due to a "configuration change in a portion of our Azure-backed workloads".

Hong Kong International Airport said a Microsoft outage was affecting several airlines and it had switched to manual check-in, but flight operations had not been affected. Singapore's Changi airport also said check-ins were being handled manually.

Cybersecurity firm Crowdstrike said it was working with customers impacted by a defect found in a single content update for Microsoft Windows hosts.

CHAOS

The outage sparked chaos for passengers from Madrid to New Delhi, with European air traffic control body Eurocontrol saying it was unclear how many flights had been impacted on the continent.

Even airlines that weren't directly affected said they would have to grapple with delays due to the global nature of the disruption.

At Madrid-Barajas Airport, passengers complained of queues and a lack of information.

"Nobody was around to tell us where we could check in when we arrived ... so different groups queued in different places and then in the end someone, after a bottleneck of people was formed, told us to come here," Ana Rodriguez, a tourist from Mexico, said.

The aviation sector is hit particularly hard due to its sensitivity to timings. Airlines rely on a closely coordinated schedule often run by air traffic control. Just one delay of a few minutes can throw off a flight schedule for take-offs and landings for an airport and airline for the rest of the day.

Airlines across the United States, Asia and Europe, including major carriers such as Ryanair, Delta Airlines and Air India, said they had either faced delays or disruption.

Several U.S. carriers including American Airlines, United Airlines and Delta issued ground stops for all their flights early on Friday due to communication problems, according to the U.S. Federal Aviation Administration (FAA). American Airlines later said it had resumed operations.

The FAA added it was closely monitoring the situation.

In Europe, Amsterdam's Schiphol airport, Berlin airport, London Gatwick, Edinburgh airport and others said they were impacted by the outage, with flight tracking service FlightRadar24 citing Schiphol as the airport with the worst disruptions globally.

A Schiphol spokesperson said flights to and from the airport had been affected, adding it was not yet clear how many and that travellers were advised to contact their airline.

"We expect longer waiting times and some flight cancellations. Not all airports in Europe were impacted as the issue is linked with a specific OS, Microsoft Azure," said Agata Lyznik, a spokesperson for airports group ACI Europe.

In Europe, airlines are required to compensate passengers for delays of more than three hours but it was unclear to what extent they would be held legally responsible for the outage.

SLOW RESOLUTION

Some airlines and airports said they were already back online, with Spanish carrier Iberia saying it had managed to avoid flight cancellations.

"From 9:25 a.m. onwards the electronic check-in counters and online check-ins were reactivated. There have been some delays," a spokesperson said.

Others came up with temporary workarounds.

In India, airlines at New Delhi airport's Terminal 3 were giving handwritten boarding passes to flyers, while airport staff were using white-boards to display gate information for flights, according to an official for the airport.

At Dubai International (DXB), the world's busiest international airport, check-ins for some flights at Terminals 1 and 2 were affected, but the airlines switched to an alternative system, Dubai Airports said.

(Reporting by Reuters bureaux, James Pearson in London, David Shepardson in Washington, Alexander Cornwell in Dubai; Writing by Joanna Plucinska; Editing by Mark Potter)