ソウルから飛び立ったアシアナ航空214便が7月2日(米国時間)、サンフランシスコ国際空港で着陸時に滑走路の手前にぶつかって墜落した。同機には乗員乗客合わせて300名以上が乗っていたが、死者は2名のみだった(他に負傷者が182名)。

死者が少なかったのは、他の人を救おうとして自分の命を危険に晒した勇気ある人たちのおかげだけではない。現在の飛行機には、安全のための新しい技術が搭載されていることも一因だ。「The Wall Street Journal」紙は7日付の記事日本語版)で、次の3つの主要な技術進歩が人々の命を救うのに貢献したと報じている。

1.「16Gシート」の搭載

米連邦航空局(FAA)は、2009年からすべての航空機に「16Gシート」の搭載を義務付けている。事故時に座席がつぶれないようにするための、地球表面の重力より16倍大きな力に耐えられるシートだ。一部の16Gシートにはエアバッグさえ搭載されている。

16Gシートの開発では、頭に加速度計を搭載したダミー人形を使った衝突試験が行われ、頭部、頸部、脊髄を負傷する可能性がテストされてきた。このシートは、1988年以降に製造されたすべての飛行機に搭載されているが、1998年より前に製造されたすべての飛行機については、2009年になってようやくFAAが搭載を義務付けた。以前のFAAの基準で義務付けられていたのは、9Gシートのみだった。

[16Gは、時速48キロで衝突しほぼ瞬時に停止したときの加重に相当する。それによる衝撃をシートの変形で吸収し、人体への衝撃を和らげている。日本ではコイト(Koito)電工が製造しており、世界シェアは4%]

2.耐火素材の採用

今回の事故でも火災が発生したが、民間航空機では、多くの事故で発生する火災に耐えうる性質を持った素材が使われている。壁や天井からシートまで、航空機内のほぼすべての物は、TDCPP、HBCD、TBPHなど舌がもつれそうな名前を持つ何らかの耐火性素材でコーティングされている。

FAAでは、航空機内で使われるほとんどの素材について、自己消火性(火元がなくなれば火が消える性質)を持たせることを義務付けている。

こうした化学物質の利用には議論がないわけではない。2013年のある調査では、機内から採取した空気サンプルの中に、難燃剤から発生した塵の粒子が発見された。見つかった化学物質は、発がん物質として知られるTDCPP(トリス(1,3-ジクロロ-2-プロピル)リン酸塩)だった。

下の図は、難燃性素材がボーイング機内のどこで使用されているかを示したものだ。

3.カメラ搭載の消火ホース

WSJ紙は、「救助隊が使用したのは最新式のノズルで、ホースの先端にはカメラが取り付けられていた」と報じている。消防隊は、カメラが取り付けられたホースを客室内に挿入することで、危険度の高い場所に自ら入り込まなくても、燃えさかる炎を消すことができたのだ。

[Alexis Kleinman(English) 日本語版:佐藤卓/ガリレオ)

ハフポストの前に:

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  • People at the airport look out at the burning plane (<a href="https://twitter.com/Twitsnoop/status/353591155369312256" target="_blank">photo</a> via Twitsnoop)

  • A video shows a plume of smoke arising from the 777 jet.

  • ABC News photo

    The top of the plane is a large hole from a fire, evidently.

  • Photo from passenger on board plane

    "I just crash landed at SFO. Tail ripped off," said David Eun on Twitter.

  • <a href="https://twitter.com/mgescuro/status/353589605884383232" target="_blank">Picture of large gray smoke plume</a> via @mgescuro on Twitter

  • A photo from <a href="http://www.ktvu.com/" target="_blank">KTVU-TV</a> shows up close the burned-out plane.

  • <a href="https://twitter.com/DanielleLWells/status/353588752565825536" target="_blank">An eerie photo</a> from Danielle Wells on Twitter.

  • <a href="https://twitter.com/mcc_marilyn/status/353613523567398912" target="_blank">A scary photo</a> from the inside of a nearby plane (via Marilyn McCullough on Twitter)

  • Scary audio from air traffic controllers as Asiana Airlines Flight 214 crashed.

  • NBC appears to have a photo of an explosion happening as the plane crashes, which was <a href="https://twitter.com/wsfa12news/status/353631037441576962" target="_blank">tweeted by WFSA Channel 12</a>.

  • An Asiana Airlines Boeing 777 is seen on the runway at San Francisco International Airport after crash landing on July 6, 2013. There were no immediate reports of casualties and one apparent survivor tweeted a picture of passengers fleeing the plane. Video footage showed the jet, Flight 214 from Seoul, on its belly surrounded by firefighters. AFP PHOTO/JOSH EDELSON (Photo credit should read Josh Edelson/AFP/Getty Images)

  • An Asiana Airlines Boeing 777 is seen on the runway at San Francisco International Airport after crash landing on July 6, 2013. There were no immediate reports of casualties and one apparent survivor tweeted a picture of passengers fleeing the plane. Video footage showed the jet, Flight 214 from Seoul, on its belly surrounded by firefighters. AFP PHOTO/JOSH EDELSON (Photo credit should read Josh Edelson/AFP/Getty Images)

  • SAN FRANCISCO, CA - JULY 6: Traffic backs up on the US Route 101 South after a Boeing 777 airplane crashed landed at San Francisco International Airport July 6, 2013 in San Francisco, California. A passenger aircraft from Asiana Airlines coming from Seoul, South Korea crashed landed on the runway. No word so far on injuries or deaths. (Photo by Sarah Rice/Getty Images)

  • An Asiana Airlines Boeing 777 is seen on the runway at San Francisco International Airport after crash landing on July 6, 2013. There were no immediate reports of casualties and one apparent survivor tweeted a picture of passengers fleeing the plane. Video footage showed the jet, Flight 214 from Seoul, on its belly surrounded by firefighters. AFP PHOTO/JOSH EDELSON (Photo credit should read Josh Edelson/AFP/Getty Images)

  • SAN FRANCISCO, CA - JULY 06: A Boeing 777 airplane lies burned on the runway after it crash landed at San Francisco International Airport July 6, 2013 in San Francisco, California. An Asiana Airlines passenger aircraft coming from Seoul, South Korea crashed while landing. There has been at least two casualties reported. (Photo by Ezra Shaw/Getty Images)

  • SAN FRANCISCO, CA - JULY 06: A Boeing 777 airplane lies burned on the runway after it crash landed at San Francisco International Airport July 6, 2013 in San Francisco, California. An Asiana Airlines passenger aircraft coming from Seoul, South Korea crashed while landing. There has been at least two casualties reported. (Photo by Ezra Shaw/Getty Images)

  • SAN FRANCISCO, CA - JULY 06: A Boeing 777 airplane lies burned on the runway after it crash landed at San Francisco International Airport July 6, 2013 in San Francisco, California. An Asiana Airlines passenger aircraft coming from Seoul, South Korea crashed while landing. There has been at least two casualties reported. (Photo by Ezra Shaw/Getty Images)

  • SAN FRANCISCO, CA - JULY 6: The remains of a Boeing 777 airplane sits on a tarmac after having crashed while landing at San Francisco International Airport July 6, 2013 in San Francisco, California. A passenger aircraft from Asiana Airlines coming from Seoul, South Korea crashed landed while on it's decent. No word so far on injuries or deaths. (Photo by Kimberly White/Getty Images)

  • SAN FRANCISCO, CA - JULY 6: (EDITORS NOTE: Retransmission with alternate crop.) A Boeing 777 airplane lies burned on the runway after it crashed landed at San Francisco International Airport July 6, 2013 in San Francisco, California. A passenger aircraft from Asiana Airlines coming from Seoul, South Korea crashed landed while on it's landing decent. No word so far on injuries or deaths. (Photo by Justin Sullivan/Getty Images)

  • This photo provided by Wei Yeh shows what a federal aviation official says was an Asiana Airlines flight crashing while landing at San Francisco airport on Saturday, July 6, 2013. (AP Photo/Wei Yeh)

  • This photo provided by Zach Custer shows smoke rising from what a federal aviation official says was an Asiana Airlines flight crashing while landing at San Francisco airport on Saturday, July 6, 2013. It was not immediately known whether there were any injuries. (AP Photo/Zach Custer)

  • Emergency responders work at the site of the crash of Asiana Flight 214 at San Francisco International Airport in San Francisco, Saturday, July 6, 2013. (AP Photo/Bay Area News Group, John Green)

  • Smokes rises from Asiana Flight 214 after it crashed at San Francisco International Airport in San Francisco, Saturday, July 6, 2013. (AP Photo/Bay Area News Group, John Green)

  • Fire crews work the crash site of Asiana Flight 214 at San Francisco International Airport in San Francisco, Saturday, July 6, 2013. (AP Photo/Bay Area News Group, John Green)

  • This aerial photo shows the wreckage of the Asiana Flight 214 airplane, right, after it crashed, as another plane approaches at the San Francisco International Airport in San Francisco, Saturday, July 6, 2013. (AP Photo/Marcio Jose Sanchez)

  • Planes from various airlines are docked at the terminals after Asiana Flight 214 crashed at the San Francisco International in San Francisco, Saturday, July 6, 2013. (AP Photo/Marcio Jose Sanchez)

  • Investigators comb the end of a runway at San Francisco International Airport following the crash of Asiana Flight 214 on Saturday, July 6, 2013, in San Francisco. (AP Photo/Noah Berger)

  • SAN FRANCISCO, CA - JULY 7: In this handout photo provided by the National Transportation Safety Board, the wreckage of Asiana Airlines flight 214 lies near the runway following yesterday's crash, on July 7, 2013 in San Francisco, California. The Boeing 777 passenger aircraft from Asiana Airlines coming from Seoul, South Korea crashed landed on the runway at San Francisco International Airport. Two people died and dozens were injured in the crash. (Photo by NTSB via Getty Images)

  • SAN FRANCISCO, CA - JULY 7: In this handout photo provided by the National Transportation Safety Board, oxygen masks hang from the ceiling in the cabin interior of Asiana Airlines flight 214 following yesterday's crash, on July 7, 2013 in San Francisco, California. The Boeing 777 passenger aircraft from Asiana Airlines coming from Seoul, South Korea crashed landed on the runway at San Francisco International Airport. Two people died and dozens were injured in the crash. (Photo by NTSB via Getty Images)

  • SAN FRANCISCO, CA - JULY 7: In this handout photo provided by the National Transportation Safety Board, NTSB investigators examine the wreckage of Asiana Airlines flight 214 following yesterday's crash, on July 7, 2013 in San Francisco, California. The Boeing 777 passenger aircraft from Asiana Airlines coming from Seoul, South Korea crashed landed on the runway at San Francisco International Airport. Two people died and dozens were injured in the crash. (Photo by NTSB via Getty Images)

  • People take a photo of the crashed Asiana Airlines Boeing 777 at San Francisco International Airport on July 7, 2013. US officials were combing through the wreckage of an Asiana Airlines Boeing 777 passenger jet in San Francisco as they tried to determine why it crashed onto the runway, killing two people and injuring 182 others, on July 6. AFP PHOTO/JOSH EDELSON (Photo credit should read Josh Edelson/AFP/Getty Images)

  • INCHEON, SOUTH KOREA - JULY 08: Passengers who were involved in the San Fransisco plane crash arrive at Incheon International Airport on July 8, 2013 in Incheon, South Korea. Two people are dead and more than 180 injured after an Asiana Airlines Boeing 777 aircraft coming from Seoul, South Korea crash-landed at San Francisco International Airport on July 6, 2013. (Photo by Chung Sung-Jun/Getty Images)

  • SEOUL, SOUTH KOREA - JULY 08: Passengers from San Fransisco plane crash arrive at Incheon International Airport on July 8, 2013 in Incheon, South Korea. A Boeing 777 Asiana Airlines passenger aircraft coming from Seoul, South Korea crashed while landing. Two fatalities have so far been reported. (Photo by Chung Sung-Jun/Getty Images)

  • INCHEON, SOUTH KOREA - JULY 08: Passengers who were involved in the San Fransisco plane crash arrive at Incheon International Airport on July 8, 2013 in Incheon, South Korea. Two people are dead and more than 180 injured after an Asiana Airlines Boeing 777 aircraft coming from Seoul, South Korea crash-landed at San Francisco International Airport on July 6, 2013. (Photo by Chung Sung-Jun/Getty Images)

  • INCHEON, SOUTH KOREA - JULY 08: Passengers who were involved in the San Fransisco plane crash arrive at Incheon International Airport on July 8, 2013 in Incheon, South Korea. Two people are dead and more than 180 injured after an Asiana Airlines Boeing 777 aircraft coming from Seoul, South Korea crash-landed at San Francisco International Airport on July 6, 2013. (Photo by Chung Sung-Jun/Getty Images)