Aviation Incidents and Accidents

Posted by PITHOCRATES - March 12th, 2014

Technology 101

The Pilots of Aloha Airlines Flight 243 landed Safely after Fatigue Cracks caused Part of the Cabin to Disintegrate

The de Havilland Company introduced the jet airliner to the world.  The Comet.  A 4-engine jet airliner with a pressurized cabin that could carry 36 passengers.  It could fly at 40,000 feet at speeds close to 500 mph.  Just blowing the piston-engine competition away.  Until, that is, they started breaking up in flight.  A consequence of pressuring the cabin.  The inflating and deflating of the metal cabin fatiguing the metal of the cabin.  Until fatigue cracks appeared at stress points.  Cracks that extended from the cycles of pressurizing and depressurizing the cabin.  Until the cracks extended so much that the pressure inside the cabin blew through the cracks, disintegrating the plane in flight.

Japan is a nation of islands.  Connecting these islands together are airplanes.  They use jumbo jets like buses and commuter trains.  Packing them with 500+ passengers for short hops between the islands.  Putting far more pressurization cycles on these planes than typical long-haul 747 routes.  On August 12, 1985, Japan Airlines Flight 123 left Haneda Airport, Tokyo, for a routine flight to Osaka.  Shortly after takeoff as the cabin pressurized the rear pressure bulkhead failed (due to an improper repair splice of the pressure plate using a single row of rivets instead of a double row following a tail strike that damaged it).  The rapid force of the depressurization blew out through the tail section of the aircraft.  Causing great damage of the control surfaces.  And severing the lines in all four hydraulic systems.  Leaving the plane uncontrollable.  The crew switched their transponder to the emergency code 7700 and called in to declare an emergency.  But they could do little to save the plane.  The plane flew erratically and lost altitude until it crashed into a mountain.  Killing all but 4 of the 524 aboard.

Hawaii is similar to Japan.  They both have islands they interconnect with airplanes.  Putting a lot of pressurization cycles on these planes.  On April 28, 1988, Aloha Airlines Flight 243 left Hilo Airport bound for Honolulu.  Just as the Boeing 737 leveled off at 24,000 feet there was a loud explosive sound and a loud surge of air.  The pilots were thrown back in their seats in a violent and rapid decompression.  The flightdeck door was sucked away.  Looking behind them they could see the cabin ceiling in first class was no longer there (due to fatigue cracks radiating out from rivets that caused pressurized air to blow out, taking the ceiling and walls of the first class cabin with it).  They could see only blue sky.  They put on their oxygen masks and began an emergency descent.  The first officer switched the transponder to emergency code 7700.  The roar of air was so loud the pilots could barely hear each other as they shouted to each other or used the radio.  The flight controls were operable but not normal.  They even lost one of their two engines.  But the flight crew landed safely.  With the loss of only one life.  A flight attendant that was sucked out of the aircraft during the explosive decompression.

The Fact that 185 People survived the United Airlines 232 Crash is a Testament to the Extraordinary Skill of those Pilots

On June 12, 1972, American Airlines Flight 96 left Detroit Metropolitan Airport for Buffalo after arriving from Los Angeles.  The McDonnell Douglas DC-10 took on new living passengers in Detroit.  As well as one deceased passenger in a coffin.  Which was loaded in the rear cargo hold.  As the DC-10 approached 12,000 feet there was a loud explosive sound.  Then the flightdeck door was sucked away and the pilots were thrown back in their seats in an explosive decompression.  The aft cargo door (improperly latched—its design was later revised to prevent improperly latching in the future) had blown out as the cargo hold pressurized.  As it did the rapid decompression collapsed the floor above.  Into the control cabling.  The rudder was slammed fully left.  All three throttle levels slammed closed.  The elevator control was greatly inhibited.  The plane lost a lot of its flight controls but the pilots were able to bring the plane back to Detroit.  Using asymmetric thrust of the two wing-mounted engines and ailerons to compensate for the deflected rudder.  And both pilots pulling back hard on the yoke to move the elevator.  Due to the damage the approach was fast and low.  When they landed they applied reverse thrust to slow down the fast aircraft.  At that speed, though, the deflected rudder pulled them off the runway towards the terminal buildings.  By reapplying asymmetric thrust the pilot was able to straighten the aircraft out on the grass.  As the speed declined the rudder force decreased and the pilot was able to steer the plane back on the runway.  There was no loss of life.

On July 19, 1989, United Airlines Flight 232 took off from Stapleton International Airport in Denver for Chicago.  About an hour into the flight there was a loud bang from the rear of the plane.  The aircraft shuddered.  The instruments showed that the tail-mounted engine had failed.  As the crew responded to that the second officer saw something more alarming.  Hydraulic pressure and fluid quantity in the three hydraulic systems were falling (a fan disc in the tail-mounted engine disintegrating and exploded like shrapnel from an undetected manufacturing flaw, taking out the 3 hydraulic systems).  The flight crew soon discovered that they had lost all control of the airplane.  The plane was making a slight turn when the engine failed.  And the flight control surfaces were locked in that position.  The captain reduced power on the left engine to stop the plane from turning.  The two remaining engines became the only means of control they had.  Another DC-10 pilot traveling as a passenger came forward and offered his assistance.  He knelt on the floor behind the throttle levels and adjusted them continuously to regain control of the plane.  He tried to dampen the rising and falling of the plane (moving like a ship rolling on the ocean).  As well as turn the aircraft onto a course that would take them to an emergency landing at Sioux City.  They almost made it.  Unfortunately that rolling motion tipped the left wing down just before touchdown.  It struck the ground.  And caused the plane to roll and crash.  Killing 111 of the 296 aboard.  It was a remarkable feat of flying, though.  Which couldn’t be duplicated in the simulator given the same system failures.  As flight control by engine thrust alone cannot provide reliable flight control.  The fact that 185 people survived this crash is a testament to the extraordinary skill of those pilots.

On July 17, 1996, TWA Flight 800 took off from JFK Airport bound for Rome.  About 12 minutes into the flight the crew acknowledged air traffic control (ATC) instructions to climb to 15,000 feet.  It was the last anyone heard from TWA 800.  About 38 seconds later another airplane in the sky reported seeing an explosion and a fire ball falling into the water.  About where TWA 800 was.  ATC then tried to contact TWA 800.  “TWA800, Center…TWA eight zero zero, if you can hear Center, ident…TWA800, Center…TWA800, if you can hear Center, ident…TWA800, Center.”  There was no response.  The plane was there one minute and gone the next.  There was no distress call.  Nothing.  The crash investigation determined that an air-fuel mixture in the center fuel tank was heated by air conditioner units mounted below the tank, creating a high-pressure, explosive vapor in the tank that was ignited by an electrical spark.  The explosion broke the plane apart in flight killing all 230 aboard.

The Greatest Danger in Flying Today may be Pilots Trusting their Computers more than their Piloting Skills

On December 29, 1972, Eastern Airlines Flight 401 left JFK bound for Miami.  Flight 401 was a brand new Lockheed L-1011 TriStar.  One of the new wide-body jets to enter service along with the Boeing 747 and the McDonnell Douglas DC-10.  Not only was it big but it had the latest in automatic flight control systems.  As Flight 401 turned on final approach they lowered their landing gear.  When the three landing gear are down and locked for landing there are three green indicating lights displayed on the flightdeck on the first officer’s side.  On this night there were only 2 green lights.  Indicating that the nose wheel was not down.  So they contacted ATC with their problem and proceeded to circle the airport until they resolved the problem.  ATC told them to climb to 2000 feet.  The 1st officer flew the aircraft on the course around the airport.  The captain then tried to reach the indicating light to see if it was a burnt out lamp.  Then the flight engineer got involved.  As did the first officer after turning on the automatic altitude hold control.  Then another person on the flightdeck joined in.  That indicating lamp got everyone’s full attention.  Unable to determine if the lamp was burnt out the pilot instructed the flight engineer to climb down into the avionics bay below the flightdeck to visually confirm the nose gear was down and locked.  He reported that he couldn’t see it.  So the other guy on the flightdeck joined him.  During all of this someone bumped the yoke with enough pressure to release the automatic altitude hold but no one noticed.  The airplane began a gradual descent.  When they approached the ground a ground proximity warming went off and they checked their altitude.  Their altimeters didn’t agree with the autopilot setting.  Just as they were asking each other what was going on the aircraft crashed into the everglades.  Killing 101 of the 176 on board.

On June 1, 2009, Air France Flight 447 was en route from Rio de Janeiro to Paris.  This was a fly-by-wire Airbus A330 aircraft.  With side stick controllers (i.e., joysticks) instead of the traditional wheel and yoke controls.  The A330 had sophisticated automatic flight controls.  They practically flew the plane by themselves.  With pilots spending more of their time monitoring and inputting inputs to these systems than flying.  Flight 447 flew into some turbulence.  The autopilot disengaged.  The aircraft began to roll from the turbulence.  The pilot tried to null these out but over compensated.  At the same time he pitched the nose up abruptly, slowing the airplane and causing a stall warning as the excessive angle of attack slowed the plane from 274 knots to 52 knots.  The pilot got the rolling under control but due to the excessive angle of attack the plane was gaining a lot of altitude.  The pitot tube (a speed sensing device) began to ice up, reducing the size of the opening the air entered.  Changing the airflow into the tube.  Resulting in a speed indication that they were flying faster than they actually were.  The engines were running at 100% power but the nose was pitched up so much that the plane was losing speed and altitude.  There was no accurate air speed indication.  For pilot or autopilot.  The crew failed to follow appropriate procedures for problems with airspeed indication.  And did not understand how to recognize the approach of a stall.  Despite the high speed indicated the plane was actually stalling.   Which it did.  And fell from 38,000 feet in 3 and a half minutes.  Crashing into the ocean.  Killing all 228 on board.

It takes a lot to bring an airplane down from the sky.  And when it happens it is usually the last in a chain of events.  Where each individual event in the chain could not have brought the plane down.  But when taken together they can.  Most times pilots have a chance to save the aircraft.  Especially the stick and rudder pilots.  Who gained a lot of flying experience before the advanced autopilot systems of today.  And can feel what the airplane is doing through the touch of their hand on the yoke and through the seat of their pants.  They are tuned in to the engine noise and the environment around them.  Processing continuous sensations and sounds as well as studying their instruments and the airspace in front of them.  Because they flew the airplane.  Not the computers.  Allowing them to take immediate action instead of trying to figure out what was happening with the computers.  Losing precious time when additional seconds could trigger that last event in a chain of events that ends in the loss of the aircraft.  That’s why some of the best pilots come from this stick and rudder generation.  Such as Aloha Airlines Flight 243, American Airlines Flight 96 and United Airlines Flight 232.  Sometimes the event is so sudden or so catastrophic that there is nothing a pilot can do to save the aircraft.  Such as Japan Airlines Flight 123 and TWA Flight 800.  And sometimes pilots rely so much on automated systems that they let themselves get distracted from the business of flying.  Even the best stick and rudder pilots adjusting to new technology.  Such as Eastern Airlines Flight 401.  Or pilots brought up on the new technology.  Such as Air France Flight 447.  But these events are so rare that when a plane does fall out of the sky it is big news.  Because it rarely happens.  Planes have never been safer.  Which may now be the greatest danger in flying.  A false sense of security.  Which may allow a chain of events to end in a plane falling down from the sky.  As pilots rely more and more on computers to fly our airplanes they may step in too late to fix a problem.  Or not at all.  Trusting those computers more than their piloting skills.

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The Government Subsidized Fisker Hybrid Manufacturer is Liquidating its Assets

Posted by PITHOCRATES - November 24th, 2013

Week in Review

The Boeing 787 Dreamliner has had some problems with its lithium-ion batteries.  And now there is an icing problem with its engines.  Which is a bug to fix in their radical new design that eliminated the bleed-air system from its engines.  Reducing weight and increasing the efficiencies of the engines.  Which translates into lower fuel/operating costs.  Making the Boeing 787 Dreamliner a winning economic model.  And why airlines are waiting anxiously to add it to their fleets.  Now contrast this to a losing economic model.  The electric/hybrid car (see Fisker sells its assets to Hong Kong tycoon, files for bankruptcy by Jerry Hirsch posted 11/22/2013 on the Los Angeles Times).

An investor group headed by Hong Kong tycoon Richard Li purchased the federal loan made to Karma plug-in hybrid sports car maker Fisker Automotive and acquired the assets of the nearly defunct automaker.

Fisker has voluntarily filed petitions to liquidate under the U.S. Bankruptcy code, and Li’s Hybrid Technology has committed up to $8 million in financing to fund the sale and Chapter 11 process.

The federal government, which had lent money to the Anaheim auto company under a Department of Energy clean vehicles program, will lose about $139 million on the deal.

“Because of these actions, along with the sale announced today, the Energy Department has protected nearly three-quarters of our original commitment to Fisker,” said Bill Gibbons, a department spokesman.

The all-electric car suffers from range anxiety.  The dread a person feels as they are far from home and their battery looks like it won’t have enough charge to get them home.  Hybrids are expensive.  But carrying around that extra internal combustion engine in addition the electric system makes the car heavier.  And reduces its battery range.  Meaning that if you drive more than, say, a 45-mile round-trip you’ll be using that internal combustion engine most of the time.  Which will burn more fuel than in a gasoline-only powered car.  Because they don’t have the extra weight of the electric system to drag around.

This is why there isn’t a long list of orders for these electric/hybrid cars like there is for the Dreamliner.  For the Dreamliner is what most airlines are looking for in a jetliner for solid economic reasons.  While the electric/hybrid car is more of a novelty.  Few people are buying them.  And because of this they need government subsidies to remain in business.  Whereas Boeing’s strong sales are one of the few things driving the nation’s GDP into positive territory.

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Allegiant Air the most Profitable Airline despite being the least Fuel-Efficient

Posted by PITHOCRATES - September 21st, 2013

Week in Review

When people fly on vacation they’re about to spend a lot of money.  And a big cost is airfare.  Which they will try to book in advance to lock in some low prices.  This is what people think about when they are about to fly on vacation.  Not carbon emissions (see America’s greenest airlines by N.B. posted 9/17/2013 on The Economist).

IN THEORY, fuel efficiency should be a win-win proposition for airlines. Burning less fuel is better for the environment and the carriers’ bottom lines—fuel is generally their biggest single cost. That’s why one finding from a recent fuel-efficiency study is so surprising. In a new report (pdf), the International Council on Clean Transportation (ICCT) found that Allegiant Air, the most profitable airline on domestic American routes between 2009 and 2011, was also the least fuel-efficient airline during 2010.

…The upshot is obvious: according to the researchers, the financial benefits of fuel efficiency have not been enough to force convergence—”Fuel prices alone may not be a sufficient driver of in-service efficiency across all airlines…. Fixed equipment costs, maintenance costs, labour agreements, and network structure can all sometimes exert countervailing pressures against the tendency for high fuel prices to drive efficiency improvements.”

So if the bottom line cannot force airlines to be more fuel efficient, what can? The researchers suggest that airlines can start by making more data available to the public…Cars come with fuel-efficiency ratings, and appliances come with energy-efficiency stickers. Maybe flights should include that kind of data, too, so that concerned passengers can make an informed choice.

Allegiant Air is a low-cost no-frills airline that caters to people going on vacation.  And when you’re on vacation you are taking a break from worrying.  About the bills.  The job.  Even the environment.  You may drive a Prius back at home.  But for two 4-hour flights a year (to and from your vacation spot) you’re just not going to worry about carbon emissions.  Because you’re on vacation.

Allegiant Air flies predominantly MD-80s that sit about 166 people.  An MD-80 is basically a stretched out DC-9.  These have two tail-mounted turbojet engines.  The least fuel-efficient engines on planes.  But these turbojet engines are small and can attach to the fuselage at the tail.  Allowing it to use shorter landing gear.  These planes sit lower to the ground and can be serviced with the smaller jet-ways you see at smaller airports.  Where Allegiant Air flies out of nonstop to their vacation destinations.  People like not having to make a connecting flight.  And will gladly dump a few extra tons of carbon into the atmosphere for this convenience.

The Allegiant Air business model includes other things to help keep costs down.  They are nonunion.  They also fly only a few flights a week at each airport.  Allowing a smaller crew to service and maintain their fleet.  These labor savings greatly offset the poorer fuel efficiency of their engines.  The airlines that have unions (pilots, flight attendants, maintenance, etc.) all share something in common.  Recurring bankruptcies.  Which Allegiant Air doesn’t have.  Despite their higher fuel costs.

Fuel costs are an airlines greatest cost.  Especially for the long-haul routes.  Which burn a lot more fuel per flight than the typical Allegiant Air flight.  Which is why the fuel-efficient Boeing 787 is so attractive to them.  As they need to squeeze every dime out of their fuel costs as they can.  To offset their high union labor costs.  Those very costs that return a lot of airlines to bankruptcy.

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Boeing 787 Dreamliner, Fuel Costs, Electric Systems, Auxiliary Power Unit and Lithium-Ion Batteries

Posted by PITHOCRATES - January 23rd, 2013

Technology 101

Auxiliary Devices reduce the Power Output of the Engine available to Drive a Car Forward

If you’re middle age (or old) you may remember looking under the hood of a car.  When you could see things.  In the days of rear-wheel drive cars and big engines.  The front of the engine had a power takeoff pulley attached to the crank shaft.  The thing the pistons spun when it converted reciprocal motion into rotational motion.  Wrapped around that pulley were a lot of belts.  Sometimes three or more.  They transferred the rotational motion of the crankshaft to auxiliary devices.

These devices included the water pump that pumped engine coolant to remove the heat of combustion.  An alternator to generate electric power.  A power steering pump to make steering easier.  An air pump to inject air into the exhaust system to help complete the combustion process to reduce emissions.  (An electronic air pump has since replaced this belt-driven device.)  And an air conditioner compressor.  All of these devices reduce the power output of the engine available to drive the car forward.  Requiring more fuel.

Today’s cars have a lot more stuff under the hood.  Engines are often mounted transversely.  And the multiple belts have been replaced with one serpentine belt that winds around all of these auxiliary devices.  And engines are smaller.  With on board computers that maximize the power output of smaller engines.  That drive lighter cars.  But one thing hasn’t changed.  When you turn on the air conditioning you can still hear the engine labor under the additional load.  While burning more fuel.

The Boeing 787 Dreamliner can do what other Planes can do while Burning less Fuel

In the airline industry the greatest cost is fuel.  So anything that allows airlines to burn less fuel greatly interests the airlines.  And it’s why pilots do careful calculations to determine how much fuel to carry.  That is, to determine the absolute minimum amount of fuel to carry.  If it were up to pilots they’d top off the fuel tanks.  But if they did that the airlines could not operate profitably.  Because you have to burn fuel to carry fuel.  And the more fuel you carry the more you have to burn.  Increasing your fuel costs to the point an airline loses money.  Especially if you’re landing with a lot of fuel in your tanks.  So pilots load less fuel than they would want.  Because to get a paycheck their company has to operate at a profit.  But it doesn’t stop there.  Not for aircraft designers.

Designers have been using more plastic in airplanes.  Because plastic is lighter than metal.  So engines can burn less fuel.  These composite materials are also stronger than metal.  So less of them can replace equivalent metal components.  So engines can burn less fuel.  Airlines have also been charging more for carry-on luggage.  In part to help offset their rising fuel costs.  And in part to encourage people to carry less onto the airplane.  So engines can burn less fuel.  Then Boeing raised the bar on burning less fuel.

The Boeing 787 Dreamliner is a remarkable design.  Remarkable because it delivers what airlines want most.  An airplane that can do what other planes can do.  But does it while burning less fuel.  Boeing has used more composite material than any other manufacturer.  Making the 787 the lightest in its class.  And lighter things allow engines to burn less fuel.  But Boeing did more than just make the airplane lighter.  They used electric systems to replace hydraulic and pneumatic systems normally found on an airplane.

The 787 Dreamliner uses Lithium-Ion Batteries to start their Auxiliary Power Unit

Hydraulic and pneumatic systems bleed power from the aircraft engines.  As the engines drive pumps and compressors for these systems.  By converting these to electric systems more of the power of the engines goes to producing thrust.  Which means they burn less fuel to fly to their destination.  They even replaced the pneumatic starters (that spin the engines during starting) with a combination electric starter/generator.  Saving weight.  And reducing the complexity.  By replacing two parts (pneumatic starter and electric generator) with one (combination starter/generator).

To start the aircraft engines they first start the auxiliary power unit (APU).  The APU is typically mounted near the tail of the aircraft.  The APU provides power, lights, heating, air conditioning, etc., when the main engines aren’t running.  Some provide back up power (electric and pneumatic) should the main engines fail in flight.  The APU also drives an air compressor to provide the pneumatic power to spin the main engines for starting.  Going to all electric systems (except for the engine anti-ice system) removes the air compressor from the APU.  Reducing the weight.  And they further reduced the weight by making another change.  To the battery that starts the APU.

The 787 uses lithium-ion batteries.  Which can provide the same power larger batteries of different technologies can provide.  As lithium-ion batteries has a very high energy density.  But with great energy density comes great heat.  Some of these batteries have actually caught fire.  In electric cars.  Laptop computers.  Cell phones.  Even in Boeing 787 Dreamliners.  They’re not sure why.  And they’ve grounded the fleet until they figure out why.  It may be because they are overcharging.  Or that there are internal shorts causing a thermal runaway (releasing all the stored energy at one time).  Or the caustic electrolyte is leaking and causing a fire.  Until they determine what the problem is the 787 will remain grounded.  Making it very difficult to enjoy the cost savings of that remarkable design.

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