• Actor Patrick Dempsey presents the award for favorite pop/rock band duo or group during the 42nd American Music Awards in Los Angeles, California November 23, 2014

Actor Patrick Dempsey presents the award for favorite pop/rock band duo or group during the 42nd American Music Awards in Los Angeles, California November 23, 2014 (Photo : REUTERS/Mario Anzuoni)

As "Grey's Anatomy" Season 11 gets closer to its finale, things get even more dramatic for doctors of Grey Sloane Memorial hospital. ABC's long running medical drama is set to air Episode 20 titled "One Flight Down." The upcoming segment revolves around a tragic accident that brings back the memories of the traumatic past. Meanwhile, the episode is expected to reveal the answer to the question: Where is Derek? Here are few spoilers for the next episode of "Grey's Anatomy" Season 11. Read on to find out what's next for Derek and Meredith.

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[Spoiler alert! This article contains updates for "Grey's Anatomy" Season 11 Episode 20 "One Flight Down." Please do not read further if you don't want to know more about it.]

Derek and Meredith's future looks hazy as Derek remains missing. ABC has released a synopsis for "Grey's Anatomy" Season 11 Episode 20 "One Flight Down" on its official website. According to the press release, Grey Sloane doctors come face to face with a similar disaster that left irreparable impact on them in the past. There will be a small plane crash in Seattle leaving several people injured.

The tragedy will bring back the memories of the plane crash that happened in "Grey's Anatomy" Season 8 finale. During that plane crash, Cristina, Arizona, Derek and Meredith were left badly injured and Mark and Lexie lost their lives. As for this plane crash, it is going to have a major impact on Arizona and Meredith as they try to keep calm.

The Canadian promo video (as published on YouTube.com by TV Box Promos) gives a glimpse of events of Episode 20. As the casualties come in, Meredith and Arizona freak out. They hide in the supply room and try not panicking. "We're okay. We're okay," Arizona and Meredith tell each other in the video.

As for Derek, there is no news about him. Another promo video (as published on YouTube.com by Television promos) gives a glimpse at Meredith, who looks like she is beginning to lose her composure. Scroll down to watch the video.

Several theories about Derek are floating around. According to TV Fanatic's "Grey's Anatomy" Round Table, Derek's absence might have something to do with the girl who he was seen kissing in Washington DC. At the same time, it is said he might be involved in some tragedy, such as an accident, hostage or death.

Meanwhile, the show will dig deeper into Amelia and Owen's storyline. The conflict between them will put Stephanie in a sticky situation as she gets on board to work with them.

What do you think of this episode? What are your predictions about Derek? Are Meredith and Derek coming to an end? Sound off in comments section below.

"Grey's Anatomy" Season 11 Episode 20 "One Flight Down" airs April 16, 2015 at 8:00 pm on ABC. Come back for more spoilers.