Teacher:In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Teacher: Now, understand the problem? Solve this instance: Every American Airlines flight has been grounded by the FAA following a computer outage. Jack Nicas reports. Photo: AP. 
  
 AMR Corp.'s American Airlines canceled or delayed at least 1,950 flights after losing access to a key computer system, a hit to the airline's reputation as it prepares for a complicated merger with US Airways Group Inc. that poses the risk of similar disruptions. 
  
 View Slideshow David Goldman/Associated Press An American Airlines ticket agent talked on the phone while assisting passengers at Hartsfield-Jackson International Airport in Atlanta Tuesday. 
  
 American held most of its flights that were scheduled to depart between 1 p.m. and 5 p.m. EDT on Tuesday while the carrier tried to regain access to its reservations system, which is the heart of many of the airline's operations, including passenger lists and flight schedules. 
  
 By 6:30 p.m. Eastern time, American had canceled about 880 flights and delayed 1,070 flights, said Mark Duell of FlightAware.com, a flight-tracking website. Mr. Duell said he expects the disruptions would cascade into Wednesday because many aircraft and crews would be out of position. 
  
 American said that it would reposition aircraft and crews and would add flights as needed to accommodate disrupted travelers. The airline said it expects operations to run normally on Wednesday. 
  
 Bobby Gordon, a 27-year-old finance manager for a national retailer, said his American flight scheduled to depart Fort Lauderdale, Fla., at noon EDT was stranded on the tarmac for an hour before returning to the gate. By 4:30 p.m. EDT, he and his family were trying to arrange a flight home to San Francisco on another airline, but American employees said they couldn't release the family's checked bags. 
  
 Enlarge Image Close Associated Press An American Airlines ticket agent talks assists passengers checking in at Hartsfield-Jackson airport in Atlanta on Tuesday. 
  
 "We're being held captive by our luggage," Mr. Gordon said. "It's bizarre." 
  
 Computer outages in the highly automated airline industry occur several times a year. The problems can be caused by power failures, inadvertent severing of telecommunications links, corrupted software, bad hardware or human error. They disrupt airline operations because the systems handle everything from flight dispatching to crew scheduling, from ticket sales to frequent-flier accounts. If its system is down, an airline effectively can't fly. 
  
 American didn't immediately say what triggered Tuesday's outage. American's reservations system is hosted by Sabre Holdings Corp., an airline ticketing company. American said that the problem wasn't with Sabre, but rather the carrier's ability to access the system. Part of the reservations system calculates the weight of the airplane based off passenger, fuel and luggage data, which is necessary for the airplane to safely take off. 
  
 American said it told the Federal Aviation Administration that it was holding its flights, and the FAA instituted a nationwide "ground stop," holding all American flights at their origin airports until the order was canceled at most airports at about 5 p.m. EDT. American's aircraft that were airborne during the ground stop continued to their destinations, the FAA said. 
  
 Network outages are big risks for airline mergers. Integrating reservations systems is a complex and enormous task for airlines, partly because they have to take the systems temporarily offline, even though flight operations must continue. 
  
 In 2007, following the merger of US Airways and America West Airlines, the integration of the carriers' reservation systems caused the airline's check-in kiosks to crash across the country. Last year, United Continental Holdings Inc. was hit by computer snafus when it combined United and Continental Airlines' reservation systems. 
  
 United Airlines also suffered widespread computer-network problems last summer that caused hundreds of flight delays around the world. The carrier delayed flights when a computer system shut down for two hours, forcing gate agents to manually process passengers. 
  
 American and US Airways disclosed plans to merge in February. If federal antitrust officials approve the merger, they would have to eventually meld their computer systems, raising the possibility of similar disruptions. 
  
 During the United and Continental integration, United migrated to the smaller Continental's computer system, causing problems. Tom Horton, AMR's chief executive, said in an interview last month that "it is important to adopt the systems and processes of the larger airline unless there is a compelling reason not to. We're not going to go re-engineer the company." American is almost twice the size of US Airways. He added that the American and US Airways management teams were approaching the integration "with an appropriate level of humility." 
  
 Write to Jack Nicas at jack.nicas@wsj.com 
  
 A version of this article appeared April 17, 2013, on page B1 in the U.S. edition of The Wall Street Journal, with the headline: Outage Snarls American Airlines. ||||| Focused crawls are collections of frequently-updated webcrawl data from narrow (as opposed to broad or wide) web crawls, often focused on a single domain or subdomain. |||||
Student:
American Airlines is flying once again after a massive computer glitch grounded all flights nationwide for about four hours this afternoon, reports the Wall Street Journal. The airline had to cancel or delay more than 1,300 flights starting about 1pm Eastern because it couldn't access its reservations system, which controls pretty much every aspect of its flight operations. Despite the all-clear to fly again, American passengers can expect delays and logjams through the night and probably into tomorrow. The airline is offering updates and apologies via Twitter. No word yet on what caused the tech trouble.