( CNN ) -- Delta Air Lines and American Airlines announced Thursday the cancellations of hundreds of flights so the companies can conduct inspections on bundles of wires in some of their jets . Delta cancellations will affect flights up until early Friday , according to a statement from the airline . The cancellations will affect flights through Friday , according to statements by both companies . A spokeswoman for Delta earlier said 325 flights would be canceled Thursday , but later said 275 flights were cut . `` Delta apologizes in advance for any inconvenience this may cause and is working to proactively contact and reaccommodate affected customers . Customers should call ahead to check flight status , '' a Delta statement said . Wednesday , American Airlines canceled 318 flights , said company spokesman Tim Wagner . The airline canceled 132 of its estimated 2,300 flights scheduled for Thursday , Wagner said , about 6 percent of the daily schedule . The cancellations forced dozens of people to spend the night in the atrium of Atlanta 's Hartsfield-Jackson International Airport . They slept wherever they could -- on couches , on the floor , some on non-moving baggage carousels . Kelly said the airline rebooked flights and covered the cost of hotel and food for passengers on canceled flights . It was initially believed that Delta 's MD-90 planes were part of the inspection but it was determined that the MD-88 planes were the only ones that needed to be inspected , a spokeswoman said . The airline said the checks are voluntary and are expected to be completed by week 's end . American Airlines , meanwhile , is examining wiring secured to its MD-80 aircraft . In Atlanta , the cancellations caused grousing among passengers who missed job interviews , connecting flights and the comfort of their beds , CNN affiliate WXIA reported . `` They told us 6:45 ( p.m. ) . Then they told us 7:30 . Then 8 , so on and so forth and they just canceled , '' passenger Fred Billizon told WXIA . `` So they had about 200 people just waiting on flights . And that 's not a lot of happy people . '' This latest round of inspections was prompted by questions raised by the FAA and American safety officials about how a certain bundle of wires is secured to the MD-80 aircraft . The MD-80 is the workhorse of the American fleet . American 's Web site says the aircraft accounts for 300 of the airline 's fleet of 655 jets . The jet debuted in 1980 from McDonnell-Douglas , which was purchased by rival Boeing in 1997 . Boeing discontinued production of the aircraft in 1999 . E-mail to a friend .
NEW : Delta cancelations only related to American , not Delta . NEW : 275 Delta flights were canceled Thursday for safety inspections . American Airlines canceled 318 flights Wednesday to accommodate MD-80 aircraft . American canceled all of its estimated 2,300 flights scheduled for Thursday .