The film is about Kyle Pratt (Foster), an American aircraft engineer living in Berlin, Germany with her husband and six-year-old daughter. After her husband dies, Kyle decides to return to the U.S.A. with her daughter and the casket. A few hours into the flight, Kyle and Julia fall asleep. Kyle awakens to find that Julia is missing. She begins to panic when no one on board remembers seeing her daughter. When the flight attendants say her daughter's name is not on the flight manifest, the crew begin thinking that Kyle may be delusional. The plot's basic premise (albeit with a very different denouement) is similar to a 1955 episode of Alfred Hitchcock Presents titled, "Into Thin Air", as well as Hitchcock's 1938 film The Lady Vanishes.
Recently widowed Berlin-based American aircraft engineer Kyle Pratt is taking her husband David's body back to the U.S, after his untimely death. She and her six-year-old daughter, Julia, are flying aboard an Aalto Airlines Elgin 474, an aircraft Kyle helped design. When Kyle awakens from a short nap, Julia is missing. None of the passengers or crew recall seeing Julia. Flight attendant Stephanie later claims there is no record of Julia boarding and the passenger manifest registers the child's seat as unoccupied. Julia's boarding pass and backpack are also missing. Kyle insists that Captain Marcus Rich conduct a thorough search of the plane.
Julia is not found and Kyle becomes increasingly desperate. She unjustly accuses two Arab passengers, Obaid and Ahmed, of kidnapping Julia and plotting to hijack the plane. Captain Rich and the flight attendants (particularly Stephanie) suspect Kyle is unhinged by her husband's death and may have imagined bringing her daughter on board. Because of Kyle's increasingly erratic and panicked behaviour, Captain Rich orders sky marshal Gene Carson to guard and handcuff her.
Later, Captain Rich receives a wire from a Berlin hospital claiming Julia died with her father. Kyle furiously denies this and insists the search continue. A therapist, Lisa, consoles Kyle, who starts doubting her own sanity until she notices the heart Julia drew on the foggy window next to her seat. Kyle asks to use the bathroom and, once inside, climbs through a trapdoor into the plane's overhead crawl space. She sabotages the aircraft's electronics, deploying the oxygen masks and cutting power to the plane's lighting. During the ensuing chaos, she rides a dumbwaiter to the lower freight deck. She finds and opens David's casket using the lock code, suspecting Julia may be trapped inside, but it only contains her husband's body. Carson finds her and escorts her back to her seat in handcuffs. He says the flight is making an emergency stopover at Goose Bay Airport in Newfoundland, Canada where she will be taken into custody.
Kyle makes a final plea to Carson to search the plane upon landing. Before speaking to the captain, Carson sneaks down the freight deck and removes two explosives and a detonator concealed in David's casket, then goes to the avionics Section where Julia is sleeping (presumably drugged). He plants and arms the explosives. It is revealed at this point that Carson, Stephanie, and the Berlin mortuary director are part of a conspiracy to hijack the plane for $50 million and frame Kyle as the hijacker, as she knows the plane due to her job and therefore would make a credible hijacker. The conspirators kidnapped Julia in hopes of Kyle unlocking the casket as she is the only one who knows the code. Carson lies to Captain Rich that Kyle is a hijacker and is threatening to blow up the aircraft unless the money is transferred to a bank account and a G3 plane is readied upon landing. Carson plans to detonate the explosives, which will kill Julia and leave Kyle dead with the detonator in hand.
After landing in Newfoundland, the tarmac is surrounded by U.S. FBI agents. After the passengers disembark, Kyle apologizes to Captain Rich for disrupting the flight but is certain Julia will be found. Angered, Captain Rich demands she drop the charade, stating that the $50 million has been wired. Kyle realizes that Carson is the perpetrator and, assuming the role of the hijacker, demands Carson remain aboard and the crew leave. Carson realizes he cannot refuse without giving himself away.
When the plane's door closes, Kyle knocks Carson unconscious with a fire extinguisher, handcuffs him to a rail, and takes the detonator. Stephanie appears and uncuffs Carson as he regains consciousness. He fires a gun at Kyle, sending her running and locking herself into the cockpit. She fools Carson away from the cockpit by throwing a binder in the space above her. Meanwhile, a panicked Stephanie flees the plane after a small altercation with Kyle.
Kyle finds the unconscious Julia in the avionics and narrowly avoids Carson. He reveals that David was murdered to conceal explosives in his casket (as caskets are not required to be x-rayed) and how he abducted Julia and dumped her in the food bin before disparaging the people aboard who would never care enough to notice. Kyle, carrying Julia, escapes into the cargo hold and closes the hatch. Leaning on David's casket with Julia in the non-combustible hold, she detonates the explosives, killing Carson. Everyone watches in shock and amazement as Kyle carries her daughter out onto the tarmac, realizing that she was telling the truth the whole time.
At an airport hangar the next morning, Captain Rich apologizes to Kyle and comments on how she and Julia look alike. As Stephanie is escorted by FBI agents in handcuffs, an agent approaches Kyle asking her to identify the Berlin mortuary director who has been detained. She carries the still unconscious Julia through the crowd of passengers to a waiting SUV while the passengers realize the truth. As an act of respect and forgiveness, Obaid appears and hands Kyle her luggage. Julia awakes and sleepily asks "are we there yet" as the SUV drives away.
Peter A. Dowling had the idea for the film in 1999 on a phone conversation with a friend. His original pitch for producer Brian Grazer involved a man who worked on airport security doing a business trip from the United States to Hong Kong, and during the flight his son went missing. A few years later, Billy Ray took over the script, taking out the terrorists from the story and putting more emphasis on the protagonist, who became a female as Grazer thought it would be a good role for Jodie Foster. The story then focused on the main character regaining her psyche, and added the post-September 11 attacks tension and paranoia. There was also an attempt to hide the identity of the villain by showcasing the different characters on the plane. Both Dowling and Ray were allowed to visit the insides of a Boeing 747 at the Los Angeles International Airport to develop the limited space on which the story takes place.
Schwentke said that to make the film as realistic as possible, he wanted naturalistic, subdued performances. One example was Peter Sarsgaard, whom he described as an actor "who can all of a sudden become a snake uncoiling". First-time actress Marlene Lawston became Foster's daughter Julia. Sean Bean was cast to subvert his typecasting as a villain, and mislead audiences into thinking he was part of the villainous plot. The director also picked each of the 300 passengers through auditions.
Schwentke described Flightplan as a "slow boiling" thriller, where the opening is different from the faster ending parts. The director added that sound was used to put audiences "off-kilter".
The art direction team had to build all the interiors of the fictional E-474 from scratch, including the cockpit. The interior design and layout is similar to an actual airplane, the Airbus A380. It is noted that the amount of dead space within the cabin, cargo and avionic areas do not reflect the actual amount of dead space within any aircraft. Of special note in the movie is the avionics computer seen below the cockpit and the clean space between the upper deck passenger areas and the fuselage. To allow for varied camera angles, the set had many tracks for the camera dolly to move, and both the walls and the ceiling were built on hinges so they could easily be swung open for shooting. BE Aerospace provided various objects of the decoration. The design and colors tried to invoke the mood for each scene - for instance, a white room for "eerie, clinical, cold" moments, lower ceilings for claustrophobia, and wide open spaces to give no clues to the audience. Most exterior scenes of the plane involve a model with one tenth of the aircraft's actual size, with the images being subsequently enhanced through computer-generated imagery. The explosion in the nose involved both life sized and scaled pieces of scenery. A one-half scale set of the avionics area was constructed to make the explosion and fireball look bigger.
The score was released September 20, 2005, on Hollywood Records. The music was composed and conducted by James Horner and the disc contains 8 tracks. Horner stated that film's score tried to mix the sound effects with "the emotion and drive of the music", and the instruments were picked to match the "feelings of panic" Kyle goes on through the film. These included Gamelan instruments, prepared piano, and string arrangements. No brass instruments are used in the soundtrack.
Flightplan grossed $89,707,299 at the domestic box office and $133,680,000 overseas for a worldwide total of $223,387,299. It also grossed $79,270,000 on DVD rentals.
The film received mixed reviews from critics. On Rotten Tomatoes, the film has a 38% rating based on 173 reviews, with an average rating of 5.3/10. The site's consensus states: "The actors are all on key here, but as the movie progresses, tension deflates as the far-fetched plot kicks in." Metacritic reports a 53 out of 100 rating, based on 33 critics, indicating "mixed or average reviews".
The Association of Professional Flight Attendants called for an official boycott of the film, which they say depicts flight attendants as rude, uncaring, indifferent, and even one as a "terrorist".