文章来源: 科学传播局    发布时间: 2019-11-18 19:54:56|马会推荐足球   【字号:         】


  I'm waiting on the ramp at San Francisco International Airport for a flight to arrive from Houston. It's a typical late September morning for the Bay Area: bright with a clear azure sky and just a whisper of fog lingering over the coastal mountains. It's beautiful weather for flying, but today I'm staying firmly on the ground.

  See more great stories from CNET Magazine.

  Sam Almira, a ramp service lead for United Airlines, shouts above the din of constant jet noise to tell me United Airlines Flight 1998 has landed and is taxiing to Gate 89 where we stand. Though we have an extraordinary view of airliners arriving from New Zealand, China and around the world -- an aviation geek's dream -- we're here to see only this plane. Just a few minutes later, at 11:30 a.m., the Boeing 777 in United's blue-and-white livery rolls into view. Flight 1998 is 10 minutes early, and Almira pauses briefly to watch as the enormous engines wind down. But for the next couple of hours, he'll have no time to rest.

  A 40-year veteran of United, Almira today is leading an army of ground crew at the United domestic terminal. Their task? For every flight that arrives, offload the passengers and cargo, clean and service the aircraft, and send it on its way again with a fresh load as fast as possible. In the airline business, this process is known as a turnaround, or "turn." And for this 777, a wide-body aircraft that holds 366 passengers and 50,000 pounds of cargo, they have just 90 minutes before it's scheduled to return to Houston.

  United's Station Operations Center at SFO overlooks the airline's domestic terminal.

  The pressure to keep United's nearly 4,700 daily flights on time is real. A delayed departure will annoy passengers, disrupt crew schedules and block a gate at a busy airport like San Francisco. It can also make an aircraft late for every other flight it takes that day. Turning around a flight quickly isn't just about keeping customers happy, it's also essential to an airline's bottom line. Sitting on the ground empty, a 777 is a depreciating asset -- sort of like a hotel room without a guest. In the air carrying paying passengers, though, it's making an airline money. By following this particular airplane, I'll get to see how a turn happens.

  Bryan Quigley, senior vice president of United's operations at SFO, says every step of the turnaround process is connected. "It's a dynamic situation here," he says. "Every departure starts with a good arrival."

  At the gate, rubber wedges called chocks are placed around the landing gear to keep the plane from moving. 

  About an hour before Flight 1998 arrives, I first meet Almira in United's Station Operations Center above the airline's domestic terminal. Here is where a team of employees runs United's operations at SFO by assigning one of the airline's 34 allocated gates to arriving domestic flights and managing ground activities.

  With an expansive view over United's gates, and staff sitting in front of banks of computer screens speaking softly into headsets, it looks like an air traffic control tower. Given the SOC's role as the nerve center of United's roughly 300 daily flights at SFO when they're on the ground, the room's resemblance is intentional. It crackles with activity, but the energy inside is focused and decidedly calm.

  Representatives from all of the airline's divisions and vendors work here around the clock: pilots, flight attendants, staff in ramp operations (people like Almira), customer service (who work inside the terminal), catering and aircraft cabin cleanup. Most of the time their job is to keep operations flowing smoothly, but late-connecting passengers and cargo, medical emergencies, bad weather and maintenance problems all can cause delays. When that happens, they work to get passengers and aircraft back on schedule (about 46,000 United passengers pass through SFO on a summer day).

  A hub of activity forms around an aircraft during each turn.

  "It's important that all these things happen concurrently because we have a limited amount of time to get the airplane into the gate and get ready for the next departure," Quigley says. "It's difficult when things happen that aren't in our control."

  While United controls its domestic gates and assigns them to incoming domestic flights, airport officials assign gates at the international terminal. That means United has little control over how long it has to complete a turn for its 30 daily international flights. It all depends on how busy airlines' schedules are.

  For example, if a Boeing 787 arrives from Tokyo and is scheduled to return to Japan in three hours, it will typically stay at the gate to complete its turn. But if the 787 isn't flying again for six hours and another arriving aircraft needs the gate during that time, United will have to tow it away and complete the turn somewhere else. Once the gate is free again, another tow crew can bring the airliner back and prepare it for boarding.

  Arriving international flights also go through more checks. Customs officials have to clear cargo and luggage, and they enter the cabin to perform security inspections. What's more, international rubbish isn't just removed from the aircraft, it's quarantined and burned.

  The day I visit there's good weather across the country, and there are no extraordinary events at SFO -- like a visit from Air Force One, for example -- that could cause delays, or "operational slide" in airline parlance. But as I'm about to find out, a successful turnaround depends on a complicated orchestra of instruments. If an instrument plays out of tune, the whole orchestra suffers.

  As Flight 1998 rolls into view, a crew member guides the Boeing 777 into the gate.

  Turning Flight 1998 starts at 11:32 a.m., when a member of the ground crew guides the 777 into the gate by waving the familiar batons. Once the nosewheel meets a painted line on the ground, the aircraft comes to a stop, and other workers rush to place rubber wedges called chocks around each set of landing gear to keep the plane from moving when it's parked. After the pilots turn off the engines, the jet bridge slowly extends to the fuselage, crew open the aircraft door and passengers begin to disembark.

  It's about 11:45 a.m. by the time the last passenger leaves, giving the six-person ground crew just over an hour before the 777 is scheduled to depart back to Houston at 1:05 p.m. as Flight 1615. There's still a lot to do, but things are going well so far.

  Once the jet bridge extends to the aircraft the passengers can disembark. 

  As soon as the plane is parked, the ground crew opens the cargo hold doors to begin one of the most laborious parts of the turn process. On a wide-body aircraft like the 777, passenger bags are packed into 32 large metal containers called Unit Load Devices. Removing them requires a large fleet of vehicles, including cargo loaders that lower the ULDs to the ground, and a train of flatbed trolleys (officially called dollies) pulled by a noisy tug that transports them around the airport.

  On a wide-body airliner like the 777 most passenger baggage is stored in metal containers called Unit Load Devices. Motorized rollers on the floor of the cargo hold move each container to the unloading door. 

  Though the process initially appears chaotic, with Almira shouting directions to the ground crew and the various ground vehicles jockeying for position, it's actually efficient and finely organized. Rollers set into the floor of the 777's cargo hold allow the crew to slide each ULD into position for unloading. Power-driven wheels in the base of the cargo loaders then pull the containers out of the hold and transfer them onto the dollies. Bulk cargo is unloaded the same way before being driven to United's cargo facility across the airport.

  The bulk pit is a smaller cargo hold at the rear of the 777 that holds loose baggage. 

  Loose bags that have a quick transfer at SFO (less than an hour for domestic flights) or require special handling are coming out of a smaller cargo hold in the rear of the 777 called the bulk pit. They'll be driven directly to their next flights, but luggage from the ULDs is taken to a sorting area under the terminal. There, the bags are loaded onto conveyor belts that wind up into the ceiling to form a labyrinth of tracks under the terminal 6.5 miles long.

  Scanners on the belts read the barcodes on luggage tags to automatically route each bag where it needs to go, whether it's to the terminal's claim area or onto another flight later in the day. It's fascinating to watch the bags zip speedily by, and I'm almost run over by a tug rushing a train of dollies to a waiting flight, but it's time to head upstairs.

  Before the new passengers board, catering crews load food onboard and remove used carts and rubbish from the previous flight.

  Just after noon, we're in the 777's cabin. Even before the last passenger leaves, a crew of 12 people spreads throughout the cabin to vacuum the floor, check overhead bins for left items, wipe tray tables, clean the galleys and lavatories, and replace headphones and blankets. They also remove all rubbish. It's hard work, but it all happens astonishingly quickly. Most of the cleaning crew is gone after about 20 minutes.

  Deeper in the cabin, cleaning crews vacuum the floor and check the overhead bins for left items.

  At the same time, maintenance staff walk through the cabin performing checks -- the outgoing flight crew will leave a list of items that need inspection -- and outside around the entire fuselage to ensure that nothing on the aircraft looks out of order. The catering crew goes to work as well, clattering empty drink and meal carts across the metal bridge to the raised service truck and replacing them with fresh catering, glasses, plates and cutlery for the outgoing flight. The new crew then boards to prepare the cabin for passengers and perform safety checks like inspecting medical kits, life rafts and oxygen bottles.

   Even the cockpit gets a once-over.

  About 12:20 p.m., the nearly empty cabin enjoys a brief moment of peace: Empty seats await new passengers, and rows of open bins are ready to be stuffed with carry-on luggage. But with the 1:05 p.m. departure time fast approaching, boarding needs to begin. Boarding on a 777 typically starts 50 minutes before departure, but it isn't until almost 12:30 p.m. when passengers begin to stream down the jetbridge.

  Up in the cockpit, the flight crew is going through the preflight checklist and reviewing the weather forecast, the passenger and fuel load, and potential diversion airports in case they can't land in Houston. Meanwhile, flight attendants take their boarding positions in the cabin. Some stand at the door to welcome passengers while others pour predeparture drinks in the first-class galley. I'd love to settle into a lie-flat seat for lunch and a glass of wine -- this 777 has United's new Polaris seats -- but we head back outside. We have 30 minutes to departure, and there's still much to do.

  During the turn, the ground crew refuels the aircraft, adds fresh drinking water and removes lavatory waste.

  With the new crew and passengers aboard, Flight 1615 to Houston is alive. It just needs to be fed, and for that, the ground crew is adding about 70,000 pounds of jet fuel to the 777 from underground storage tanks. Other vehicles have added new drinking water and removed lavatory waste.

  Under the terminal, luggage for departing flights is sorted on conveyor belts that carry it from the passenger check-in desks. Bags are then loaded into containers and driven to each flight.

  At 12:45 p.m., baggage loading is well underway. The process is the reverse of what we saw earlier: Crews pick up bags from the sorting belts beneath the terminal, pack them into empty ULDs and drive them to the aircraft for loading. Loose bags destined for a quick transfer in Houston or bags that were checked at the gate also arrive and are carried up a conveyor belt into the bulk pit.

  The crews work quickly, but bags from connecting flights continue to arrive, and at departure time they're still being loaded in the hold.  Up in the cabin, passengers with connections in Houston are no doubt checking their watches. Fortunately, the next flight at Gate 89 isn't arriving until later that afternoon, but Almira's team starts to work even faster.

  As the clock clicks toward departure, baggage containers are loaded into the cargo hold. 

  Finally, at 1:20 p.m., the last ULD is loaded and the cargo door is closed. The jet bridge retracts, and the giant pushback tractor rumbles to life. Five minutes later, as ground crew walk along under both wingtips to ensure they won't hit another plane, the tractor slowly pushes the massive 777 back from the gate. Once on the taxiway, the aircraft pauses momentarily as the tractor detaches from the nosewheel, and by 1:35 p.m. the 777 is lumbering out of sight to the runway.

  And we're off! A tractor pushes Flight 1615 back from the gate.

  We race around to the other side of the terminal to watch Flight 1615 take off. Ground control, though, directs it to depart from a runway on the far side of the airport, so we catch only a brief glimpse of the 777 as it soars into the sky above San Francisco Bay at 1:54 p.m. Turn accomplished, Flight 1615 is on its way to Houston.

  This story appears in the Spring 2019 edition of CNET Magazine. For other magazine stories, click here.



  马会推荐足球P【城】【的】【房】【子】【很】【多】,【但】【是】【多】【数】【房】【子】【都】【是】【成】【片】【区】【划】【分】【的】。 【李】【海】【清】【大】【概】【扫】【了】【一】【眼】【其】【余】【五】【个】【人】【飞】【的】【地】【方】,【自】【己】【这】【五】【栋】【楼】【房】【处】【没】【人】,【马】【路】【对】【面】【飞】【过】【去】【两】【个】,【主】【城】【区】【飞】【了】【四】【个】【人】,【他】【则】【处】【于】【相】【当】【偏】【僻】【的】【位】【置】! 【李】【海】【清】【立】【刻】【钻】【进】【了】【一】【栋】【两】【层】【小】【楼】【内】,【一】【阵】【搜】【索】【之】【后】,【一】【把】UMP9,【一】【个】【二】【级】【背】【包】,【二】【级】【防】【弹】【衣】,【一】【级】【绿】【帽】【子】【和】

【这】【样】【的】【结】【果】【怕】【是】【最】【好】【的】【安】【排】,【让】【司】【马】【君】【亲】【自】【去】【迎】【战】【自】【己】【的】【三】【位】【兄】【弟】,【自】【家】【事】【自】【家】【解】【决】。 【这】【不】【仅】【是】【大】【晋】【王】【朝】【的】【国】【事】,【也】【是】【他】【们】【司】【马】【世】【家】【的】【家】【事】,【家】【事】【又】【怎】【么】【能】【劳】【烦】【外】【人】【插】【手】【那】。 【朝】【堂】【之】【上】,【众】【人】【默】【默】【的】【看】【着】【大】【笑】【的】【司】【马】【君】,【他】【们】【不】【理】【解】,【司】【马】【君】【哪】【来】【的】【自】【信】,【可】【以】【挡】【住】【三】【位】【王】【爷】【的】【三】【百】【万】【大】【军】。 【要】【知】【道】,【哪】【里】

【刘】【老】【鬼】【散】【发】【的】【气】【势】【压】【迫】,【一】【重】【高】【过】【一】【重】,【是】【想】【要】【兵】【不】【血】【刃】,【轻】【松】【拿】【下】【叶】【唐】。 【但】【对】【面】【那】【小】【子】,【似】【乎】【也】【只】【是】【略】【感】【压】【力】【而】【已】,【直】【过】【去】【了】【半】【晌】,【依】【然】【还】【坚】【挺】【不】【已】,【双】【拳】【紧】【握】【负】【于】【身】【后】,【没】【有】【动】【弹】【分】【毫】。 “【咳】,【我】【要】【不】【要】【出】” “【不】【用】!” 【另】【一】【名】【执】【事】【刚】【要】【开】【口】【询】【问】,【一】【同】【出】【手】,【但】【李】【老】【鬼】【想】【都】【没】【想】,

  @: 3419:【苏】【醒】 “【咦】?【竟】【然】【昏】【死】【过】【去】【了】!【这】【小】【子】【的】【身】【子】,【还】【是】【不】【行】【啊】!”【当】【修】【罗】【大】【帝】【看】【到】【庞】【风】【昏】【死】【过】【去】【的】【时】【候】,【便】【忍】【不】【住】【的】【叹】【了】【一】【口】【气】。 【这】【个】【时】【候】,【刀】【皇】【也】【回】【到】【了】【卷】【轴】【空】【间】【之】【中】,【不】【过】【此】【刻】【他】【的】【脸】【色】【却】【是】【变】【得】【苍】【白】【无】【比】,【很】【明】【显】,【刚】【才】【的】【战】【斗】,【让】【他】【损】【耗】【了】【不】【少】【的】【神】【魂】。 “【你】【个】【老】【家】【伙】,【都】【快】【不】【行】【了】马会推荐足球【在】【洛】【夫】【人】【的】【娘】【家】,【想】【尽】【办】【法】【把】【洛】【夫】【人】【和】【洛】【先】【生】【送】【到】【了】【国】【外】【之】【后】。【被】【唐】【俊】【琪】【和】【周】【晓】【晨】【盯】【上】【的】【原】【主】,【却】【被】【他】【们】【找】【各】【种】【原】【因】,【限】【制】【在】【国】【内】,【根】【本】【就】【没】【有】【办】【法】【出】【国】。 【洛】【夫】【人】【的】【娘】【家】【虽】【然】【也】【想】【帮】【忙】,【但】【是】,【他】【们】【家】【族】【的】【势】【力】【和】【唐】【家】【确】【实】【没】【有】【办】【法】【相】【比】。【为】【了】【保】【住】【自】【己】【的】【家】【族】,【他】【们】【也】【不】【敢】【做】【的】【太】【过】【于】【明】【显】。 【所】【以】,【原】【主】【自】【然】

  “【不】【算】【数】,【这】【么】【卑】【鄙】【的】【手】【段】【明】【明】【已】【经】【输】【了】!” “【是】【啊】,【这】【不】【公】【平】,【明】【明】【不】【该】【是】【输】【的】。” “【如】【果】【不】【是】,【那】【个】【蓝】【色】【衣】【服】【的】【有】【心】【在】【留】【着】【手】【根】【本】【不】【可】【能】【赢】【得】【了】,【真】【没】【想】【到】【到】【了】【这】【样】【的】【地】【步】,【他】【居】【然】【真】【的】【下】【得】【去】【手】。” “【这】【么】【卑】【鄙】,【真】【的】【适】【合】【做】【我】【们】【守】【护】【一】【族】【的】【王】【吗】?” 【武】【斗】【台】【下】【方】【的】【观】【众】【席】【上】【都】【陷】【入】【了】【一】【片】【哗】【然】


  【数】【名】【官】【兵】【堵】【在】【门】【口】,【亲】【眼】【目】【睹】【项】【志】【诚】【操】【刀】【剐】【肉】,【听】【着】【渔】【民】【撕】【心】【裂】【肺】【的】【叫】【喊】,【不】【禁】【感】【同】【身】【受】,【一】【个】【个】【眼】【角】【抽】【搐】,【咧】【开】【嘴】【倒】【吸】【凉】【气】。 “【项】【兄】,【这】【怎】【么】【回】【事】?”【林】【逸】【刚】【问】【完】,【肩】【膀】【就】【被】【人】【轻】【轻】【一】【拍】。【他】【转】【过】【头】,【便】【瞧】【任】【定】【北】【正】【盯】【着】【自】【己】【手】【中】【长】【刀】,【立】【马】【会】【了】【意】,【对】【周】【围】【兵】【卒】【吆】【喝】【道】:“【诸】【位】【当】【心】,【别】【被】【锋】【刃】【伤】【着】。” 【说】





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