On the Flightdeck during Aviation Disasters

Posted by PITHOCRATES - March 19th, 2014

Technology 101

USAir Flight 427 on Approach to Pittsburgh flew through Wake Vortex and Lost Control

Malaysian Airlines Flight 370 search is still ongoing.  We’re seemingly no closer to understanding what happened than before.  There has been a lot of speculation.  And rebuttals to that speculation.  With many people saying things like why didn’t the crew radio?  Why didn’t they report a problem?  While others are saying that it is proof for their speculative theory.  That they were either under duress, had no time or were in on it and, therefore, went silent.  So what is it like on the flightdeck when something happens to an aircraft?  Well, because of past CVR (cockpit voice recorder) transcripts from previous accidents, we can get an idea.

On September 8, 1994, USAir Flight 427 flew into the wake vortex (little tornados trailing from a large plane’s wingtip) of a Delta Airlines Boeing 727 ahead of it.  This sideways tornado disrupted the airflow over the control surfaces of the USAir 737.  Disrupting it from level flight, causing it to roll left.  The autopilot tried to correct the roll as the 737 passed through the wake vortex core.  Causing more disruption of the airflow over the control surfaces.  The first officer then tried to stabilize the plane.  Control of the aircraft continued to deteriorate.  We pick up the CVR transcript just before this event (see 8 September 1994 – USAir 427).  CAUTION: The following recounts the final moments of Flight 427 and some may find it disturbing.

CAM-1 = Captain
CAM-2 = First Officer
CAM-3 = Cockpit Area Mike (cabin sounds and flight attendants)
RDO-1 = Radio Communications (Captain)
APP: Pittsburgh Approach

APP: USAir 427, turn left heading one zero zero. Traffic will be one to two o’clock, six miles, northbound Jetstream climbing out of thirty-three for five thousand.
RDO-1: We’re looking for the traffic, turning to one zero zero, USAir 427.
CAM-3: [Sound in engines increasing rpms]
CAM-2: Oh, yeah. I see the Jetstream.
CAM-1: Sheez…
CAM-2: zuh?
CAM-3: [Sound of thump; sound like ‘clickety-click’; again the thumping sound, but quieter than before]
CAM-1: Whoa … hang on.
CAM-3: [Sound of increasing rpms in engines; sound of clickety-click; sound of trim wheel turning at autopilot trim speed; sound similar to pilot grunting; sound of wailing horn similar to autopilot disconnect warning]
CAM-1: Hang on.
CAM-2: Oh, Shit.
CAM-1: Hang on. What the hell is this?
CAM-3: [Sound of stick shaker; sound of altitude alert]
CAM-3: Traffic. Traffic.
CAM-1: What the…
CAM-2: Oh…
CAM-1: Oh God, Oh God…
APP: USAir…
RDO-1: 427, emergency!
CAM-2: [Sound of scream]
CAM-1: Pull…
CAM-2: Oh…
CAM-1: Pull… pull…
CAM-2: God…
CAM-1: [Sound of screaming]
CAM-2: No… END OF TAPE.

At 19:03:01 in the flight there was a full left rudder deflection.  The plane yawed (twisted like a weathervane) to the left.  A second later it rolled 30 degrees left.  This caused the aircraft to pitch down.  Where it continued to roll.  The plane rolled upside down and pitched further nose-down.  The pilots never recovered.  The plane flew nearly straight into the ground at 261kts.  The crash investigated focused on the rudder.  Boeing redesigned it.  Pilots since have received more training on rudder inputs.  And flight data recorders now record additional rudder data.  This incident shows how fast a plane can go from normal flight to a crash.  The captain had time to radio one warning.  But within seconds from the beginning of the event the plane crashed.  Illustrating how little time pilots have to identify problems and correct them.

An In-Flight Deployment of a Thrust Reverser breaks up Lauda Air Flight 004

A plane wants to fly.  It is inherently stable.  As long as enough air flows over its wings.  Jet engines provide thrust that push an airplane’s wings through the air.  The curved surfaces of the wings interacting with the air passing over it creates lift.  As long as a plane’s jet engines push the wing through the air a plane will fly.  On May 26, 1991, something happened to Lauda Air Flight 004 to disrupt the smooth flow of air over the Boeing 767’s wings.  Something that isn’t supposed to happen during flight.  But only when a plane lands.  Reverse thrust.  As a plane lands the pilot reverses the thrust on the jet engines to slow the airplane.  Unfortunately for Flight 004, one of its jet engines deployed its thrust reverser while the plane was at about 31,000 feet.  We pick up the CVR transcript just as they receive a warning indication that the reverse thruster could deploy (see 26 May 1991 – Lauda 004).  CAUTION: The following recounts the final moments of Flight 004 and some may find it disturbing.

23.21:21 – [Warning light indicated]

23.21:21 FO: Shit.

23.21:24 CA: That keeps, that’s come on.

23.22:28 FO: So we passed transition altitude one-zero-one-three

23.22:30 CA: OK.

23.23:57 CA: What’s it say in there about that, just ah…

23.24:00 FO: (reading from quick reference handbook) Additional system failures may cause in-flight deployment. Expect normal reverse operation after landing.

23.24:11 CA: OK.

23.24:12 CA: Just, ah, let’s see.

23.24:36 CA: OK.

23.25:19 FO: Shall I ask the ground staff?

23.25:22 CA: What’s that?

23.25:23 FO: Shall I ask the technical men?

23.25:26 CA: Ah, you can tell ’em it, just it’s, it’s, it’s, just ah, no, ah, it’s probably ah wa… ah moisture or something ’cause it’s not just, oh, it’s coming on and off.

23.25:39 FO: Yeah.

23.25:40 CA: But, ah, you know it’s a … it doesn’t really, it’s just an advisory thing, I don’t ah …

23.25:55 CA: Could be some moisture in there or somethin’.

23.26:03 FO: Think you need a little bit of rudder trim to the left.

23.26:06 CA: What’s that?

23.26:08 FO: You need a little bit of rudder trim to the left.

23.26:10 CA: OK.

23.26:12 CA: OK.

23.26:50 FO: (starts adding up figures in German)

23.30:09 FO: (stops adding figures)

23.30:37 FO: Ah, reverser’s deployed.

23.30:39 – [sound of snap]

23.30:41 CA: Jesus Christ!

23.30:44 – [sound of four caution tones]

23.30:47 – [sound of siren warning starts]

23.30:48 – [sound of siren warning stops]

23.30:52 – [sound of siren warning starts and continues until the recording ends]

23.30:53 CA: Here, wait a minute!

23.30:58 CA: Damn it!

23.31:05 – [sound of bang]

[End of Recording]

The 767 Emergency/Malfunction Checklist stated that upon receiving the warning indicator ADDITIONAL system faults MAY cause an in-flight deployment of the thrust reverser.  But that one warning indication was NOT expected to cause any problem with the thrust reversers in stopping the plane after landing.  At that point it was not an emergency.  So they radioed no emergency.  About 10 minutes later the thrust reverser on the left engine deployed in flight.  When it did the left engine pulled the left wing back as the right engine pushed the right wing forward.  Disrupting the airflow over the left wing.  Causing it to stall.  And the twisting force around the yaw axis created such great stresses on the airframe that the aircraft broke up in the air.  The event happened so fast from thrust reverser deployment to the crash (less than 30 seconds) the crew had no time to radio an emergency before crashing.

Fire in the Cargo Hold brought down ValuJet Flight 592

One of the most dangerous things in aviation is fire.  Fire can fill the plane with smoke.  It can incapacitate the crew.  It can burn through electric wiring.  It can burn through control cables.  And it can burn through structural components.  A plane flying at altitude must land immediately on the detection of fire/smoke.  Because they can’t pull over and get out of the plane.  They have to get the plane on the ground.  And the longer it takes to do that the more damage the fire can do.  On May 11, 1996, ValuJet Flight 592 took off from Miami International Airport.  Shortly into the flight they detected smoke inside the McDonnell Douglas DC-9.  We pick up the CVR transcript just before they detected fire aboard (see 11 May 1996 – ValuJet 591).  CAUTION: The following recounts the final moments of Flight 592 and some may find it disturbing.

CAM — Cockpit area microphone voice or sound source
RDO — Radio transmissions from Critter 592
ALL — Sound source heard on all channels
INT — Transmissions over aircraft interphone system
Tower — Radio transmission from Miami tower or approach
UNK — Radio transmission received from unidentified source
PA — Transmission made over aircraft public address system
-1 — Voice identified as Pilot-in-Command (PIC)
-2 — Voice identified as Co-Pilot
-3 — Voice identified as senior female flight attendant
-? — Voice unidentified
* — Unintelligible word
@ — Non pertinent word
# — Expletive
% — Break in continuity
( ) — Questionable insertion
[ ] — Editorial insertion
… — Pause

14:09:36 PA-2 flight attendants, departure check please.

14:09:44 CAM-1 we’re *** turbulence

14:09:02 CAM [sound of click]

14:10:03 CAM [sound of chirp heard on cockpit area microphone channel with simultaneous beep on public address/interphone channel]

14:10:07 CAM-1 what was that?

14:10:08 CAM-2 I don’t know.

14:10:12 CAM-1 *** (’bout to lose a bus?)

14:10:15 CAM-1 we got some electrical problem.

14:10:17 CAM-2 yeah.

14:10:18 CAM-2 that battery charger’s kickin’ in. ooh, we gotta.

14:10:20 CAM-1 we’re losing everything.

14:10:21 Tower Critter five-nine-two, contact Miami center on one-thirty-two-forty-five, so long.

14:10:22 CAM-1 we need, we need to go back to Miami.

14:10:23 CAM [sounds of shouting from passenger cabin]

14:10:25 CAM-? fire, fire, fire, fire [from female voices in cabin]

14:10:27 CAM-? we’re on fire, we’re on fire. [from male voice]

14:10:28 CAM [sound of tone similar to landing gear warning horn for three seconds]

14:10:29 Tower Critter five-ninety-two contact Miami center, one-thirty-two-forty-five.

14:10:30 CAM-1 ** to Miami.

14:10:32 RDO-2 Uh, five-ninety-two needs immediate return to Miami.

14:10:35 Tower Critter five-ninety-two, uh, roger, turn left heading two-seven-zero.  Descend and maintain seven-thousand.

14:10:36 CAM [sounds of shouting from passenger cabin subsides]

14:10:39 RDO-2 Two-seven-zero, seven-thousand, five-ninety-two.

14:10:41 Tower What kind of problem are you havin’?

14:10:42 CAM [sound of horn]

14:10:44 CAM-1 fire

14:10:46 RDO-2 Uh, smoke in the cockp … smoke in the cabin.

14:10:47 Tower Roger.

14:10:49 CAM-1 what altitude?

14:10:49 CAM-2 seven thousand.

14:10:52 CAM [sound similar to cockpit door moving]

14:10:57 CAM [sound of six chimes similar to cabin service interphone]

14:10:58 CAM-3 OK, we need oxygen, we can’t get oxygen back here.

14:11:00 INT [sound similar to microphone being keyed only on Interphone channel]

14:11:02 CAM-3 *ba*, is there a way we could test them? [sound of clearing her voice]

14:11:07 Tower Critter five-ninety-two, when able to turn left heading two-five-zero.  Descend and maintain five-thousand.

14:11:08 CAM [sound of chimes similar to cabin service interphone]

14:11:10 CAM [sounds of shouting from passenger cabin]

14:11:11 RDO-2 Two-five-zero seven-thousand.

14:11:12 CAM-3 completely on fire.

14:11:14 CAM [sounds of shouting from passenger cabin subsides]

14:11:19 CAM-2 outta nine.

14:11:19 CAM [sound of intermittant horn]

14:11:21 CAM [sound similar to loud rushing air]

14:11:38 CAM-2 Critter five-ninety-two, we need the, uh, closest airport available …

14:11:42 Tower Critter five-ninety-two, they’re going to be standing by for you. You can plan runway one two to dolpin now.

14:11:45 one minute and twelve second interruption in CVR recording]

14:11:46 RDO-? Need radar vectors.

14:11:49 Tower critter five ninety two turn left heading one four zero 14:11:52

RDO-? one four zero

14:12:57 CAM [sound of tone similar to power interruption to CVR]

14:12:57 CAM [sound similar to loud rushing air]

14:12:57 ALL [sound of repeating tones similar to CVR self test signal start and continue]

14:12:58 Tower critter five ninety two contact miami approach on corrections no you you just keep my frequency

14:13:11 CAM [interruption of unknown duration in CVR recording]

14:13:15 CAM [sounds of repeating tones similar to recorder self-test signal starts and continues, rushing air.]

14:13:18 Tower critter five ninety two you can uh turn left heading one zero zero and join the runway one two localizer at miami

14:13:25: End of CVR recording.

14:13:27 Tower critter five ninety two descend and maintain three thousand

14:13:43 Tower critter five ninety two opa locka airports aout ah twelve o’clock at fifteen miles

[End of Recording]

The cargo hold of this DC-9 was airtight.  This was its fire protection.  Because any fire would quickly consume any oxygen in the hold and burn itself out.  But also loaded in Flight 592’s hold were some oxygen generators.  The things that produce oxygen for passengers to breathe through masks that fall down during a loss of pressurization.  These produce oxygen through a chemical reaction that produces an enormous amount of heat.  These were hazardous equipment that were forbidden to be transported on the DC-9.  Some confusion in labeling led some to believe they were ’empty’ canisters when they were actually ‘expired’.  The crash investigation concluded that one of these were jostled on the ground and activated.  It produced an oxygen rich environment in the cargo hold.  And enough heat to start a smoldering fire.  Which soon turned into a raging inferno that burned through the cabin floor.  And through the flightdeck floor.  Either burning through all flight controls.  Or incapacitating the crew.  Sending the plane into a nose dive into the everglades in less than 4 minutes from the first sign of trouble.

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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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Autopilots and Lawyers take Flying Time away from Pilots, Increase Stalls

Posted by PITHOCRATES - November 3rd, 2013

Week in Review

Flying has never been safer.  Air craft incidents make the news because they are so rare.  Such as two planes clipping wings on the tarmac.  And any crash is on the news 24 hours a day.  Because they are so rare that statistically they just don’t happen.  But as rare as they are they still happen.  And planes fall out of the sky (see Crash investigator urges stall training for pilots by Bart Jansen posted 10/30/2013 on USA Today).

A federal crash investigator urged a conference of aviation safety officials Tuesday to better train pilots to avoid stubborn problems such as stalls.

Earl Weener, a member of the National Transportation Safety Board, recalled four separate fatal crashes over the past two decades that he said involved stalls, with pilots basically pulling the plane’s nose up too much until the aircraft fell to the ground.

“The question in my mind is why did the crew continue to pull back on the elevator all the way to the ground,” Weener told about 300 people attending the Flight Safety Foundation’s International Aviation Safety Summit, rather than leveling off to regain power and speed.

Lack of training is feared to be one culprit…

A NASA study of voluntary reporting by pilots found stalls 28% of the time while cruising at high altitude, Weener said. And an airline database study by the International Air Transport Association found 27% of stalls occurred while cruising, he said.

But a survey found only 26% of airlines trained for high-altitude stalls – even though 71% of stalls occur when the autopilot is typically engaged, Weener said.

Lack of training?  With 71% of stalls happening while flying on autopilot try lack of flying.

Most accidents today are pilot error.  Is it because we have bad pilots?  No.  It’s because we’re not letting them fly.  In the risk-averse world we live in today we try to avoid all risk.  We have autopilot systems that are so sophisticated that they can fly a plane without a pilot aboard.  In our litigious society airlines feel machines will make fewer mistakes than people.  So they have the machines fly the plane most of the time.  While pilots monitor the systems.  Entering set-points into the flight computers.  While the computers fly the plane.  And when there is a problem pilots try to get the flight computers working.  Instead of taking the controls themselves.

Before pilots turned flying over to the machines they flew the planes.  They felt the planes.  They listened to the planes.  And flew by the seat of their pants.  If there was an odd vibration they felt it.  If there was an engine problem they heard it.  And if the plane stalled they felt it in the pit of their stomach.  And instinctively pushed forward on the column and applied full power. 

Today, because of lawyers, airlines want pilots to fix the autopilot.  Not take the controls.  So the machines can start flying again as soon as possible.  As they feel they are less likely to make a mistake than a pilot doing some real flying.  Unfortunately, a machine will only fly as well as a human can tell it to fly.  By entering those set-points.  And if the human makes a mistake at data entry the computer will assume that the human didn’t make a mistake.  And follow those instructions exactly.  Even if the plane flies into the ground.  Or stalls and falls out of the sky.

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Feedback Loop Control System

Posted by PITHOCRATES - October 30th, 2013

Technology 101

Living through Winters became easier with Thermostats

When man discovered how to make fire it changed where we could live.  We no longer had to follow the food south when winter came.  We could stay through the winter.  And build a home.  As long as we could store enough food for the winter.  And had fire to stay warm.  To prevent our dying from exposure to the cold.

There’s nothing like sitting around a campfire.  It’s warm.  And cozy.  In large part because it’s outside.  So the smoke, soot and ash stayed outside.  It wasn’t always like that, though.  We used to bring that campfire inside the home.  With a hole in the roof for the smoke.  And families slept around the fire.  Together.  Even as some fornicated.  To propagate the species.  But that wasn’t the worst part about living around an indoor campfire.

Your distance from the fire determined how hot or cold you were.  And it was very hot by it.  Not so hot away from it.  Especially with a hole in the roof.  Worst, everyone got colder as the fire burned out.  Meaning someone had to get up to start a new fire.  The hard way.  Creating an ember.  Using it to start some kindling burning.  Then adding larger sticks and branches onto the kindling until they started to burn.  Which was a lot harder than turning the thermostat to ‘heat’ at the beginning of the heating season and forgetting about it.  Then turning it to ‘off’ at the end of the heating season.

A Feedback Loop Control System measures the Output of a System and Compares it to a Desired Output

Replacing the indoor campfire with a boiler or furnace made life a lot simpler.  For with a supply of fuel (natural gas, fuel oil, electricity, etc.) the fire never burned itself out.  And you never had to get up to start a new one.  Of course, that created another problem.  Shutting it off.

Boilers and furnaces are very efficient today.  They produce a lot of heat.  And if you let them run all day long it would become like a hot summer day inside your house.  Something we don’t want.  Which is why we use air conditioners on hot summer days.  So heating systems can’t run all day long.  But we can’t keep getting up all night to turn it off when we’re too hot.  And turning it back on when we’re too cold.  Which is why we developed the feedback loop control system.

We did not develop the feedback loop control system for our heating systems.  Our heating systems are just one of many things we control with a feedback loop control system.  Which is basically measuring the output of a system and comparing it to a desired output.  For example, if we want to sleep under a cozy warm blanket we may set the ‘set-point’ to 68 degrees (on the thermostat).  The heating system will run and measure the actual temperature (at the thermostat) and compare it to the desired set-point.  That’s the feedback loop.  If the actual temperature is below the desired set-point (68 degrees in our example) the heat stays on.  Once the actual temperature equals the set-point the heat shuts off.

The Autopilot System includes Independent Control Systems for Speed, Heading and Altitude

Speed control on a car is another example of a feedback loop control system.  But this control system is a little more complex than a thermostat turning a heating system on and off.  As it doesn’t shut the engine off once the car reaches the set-point speed.  If it did the speed would immediately begin to fall below the set-point.  Also, a car’s speed varies due to terrain.  Gravity speeds the car when it’s going downhill.  And slows it down when it’s going uphill.  The speed controller continuously measures the car’s actual speed and subtracts it from the set-point.  If the number is negative the controller moves the vehicle’s throttle one way.  If it’s positive it moves the throttle in the other way.  The greater the difference the greater the movement.  And it keeps making these speed ‘corrections’ until the difference between the actual speed and the set-point is reduced to zero.

Though more complex than a heating thermostat the speed control on a car is pretty simple.  It has one input (speed).  And one output (throttle adjustment).  Now an airplane has a far more complex control system.  Often called just ‘autopilot’.  When it is actually multiple systems.  There is an auto-speed system that measures air speed and adjusts engine throttles.  There is a heading control system that measures the aircraft’s heading and adjusts the ailerons to adjust course heading.  There is an altitude control system that measures altitude and adjusts the elevators to adjust altitude.  And systems that measure and correct pitch and yaw.  Pilots enter set-points for each of these in the autopilot console.  And these control systems constantly measure actual readings (speed, heading and altitude) and compares them to the set-points in the autopilot console and adjusts the appropriate flight controls as necessary. 

Unlike a car or an airplane a building doesn’t move from point A to point B.  Yet they often have more complex control systems than autopilot systems on airplanes.  With thousands of inputs and outputs.  For example, in the summer there’s chilled water temperature, heating hot water temperature (for the summer boiler), supply air pressure, return air pressure, outdoor air pressure, indoor air pressure, outdoor temperature, outdoor humidity, indoor temperature (at numerous locations), indoor humidity, etc.  Thousands of inputs.  And thousands of outputs.  And unlike an airplane these are all integrated into one control system.  To produce a comfortable temperature in the building.  Maintain indoor air quality.  Keep humidity levels below what is uncomfortable and possibly damaging to electronic systems.  And prevent mold from growing.  But not keep it too dry that people suffer static sparks, dry eyes, dry nasal cavities that can lead to nose bleeds, dry and cracked skin, etc.  To prevent a blast of air hitting people when they open a door.  To keep the cold winter air from entering the building through cracks and spaces around doors and windows.  And a whole lot more.  Far more than the thermostat in our homes that turns our heating system on and off.

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Airbus proposing Measures to Reduce the Aviation Carbon Footprint that may make Flying more Dangerous

Posted by PITHOCRATES - September 9th, 2012

Week in Review

Airplanes are very complex machines.  They fly at speeds 3-4 times the speeds they land and take off at.  Which requires leading edge slats and trailing edge flaps to curve the wing more at low speed to increase lift.  While flattening it out more at high speeds to reduce drag.  When landing pilots put the engines into reverse thrust to help slow the plane down.  So they even use fuel to slow down.

And speaking of fuel it’s expensive.  Airlines carry as little of it as possible in their airplanes to reduce weight which reduces costs.  Sometimes bad weather forces planes to go to an alternate airport.  Sometimes there are strong headwinds.  Sometimes they fly into Heathrow and have to circle for a half hour or so to land.  Because they only have two runways.  Compounding this problem planes are getting lighter and engines are getting more efficient.  Allowing airlines to carry even less fuel.  So it is not uncommon for a pilot to declare a fuel emergency because of unexpected additional flying time.

When flying in the air highways air traffic controllers keep airplanes separated by large distances.  To keep them from running into each other.  The more distance the better so they can take evasive actions to avoid bad weather cells.  Or allow a plane some leeway in case they have a system malfunction (like plugged pitot tubes feeding false air speed and altimeter readings into the autopilot) that takes the plane off course.  Or in case a plane flies into some clear air turbulence (CAT) and it drops out of the sky 1,000 feet or so.  Or rises 1,000 feet or so.  Two things that allow a plane to recover from unplanned events like these are empty skies around you and altitude.

Aviation has come a long way.  And Boeing and Airbus are making some incredible airplanes.  So they know a thing or two about flying an airplane.  And it shows in their planes.  Which makes it hard to take them seriously when they talk about ways to reduce their carbon footprint by making flying more risky (see Airbus To Present Measures To Reduce Industry’s Environmental Footprint by Jens Flottau posted 9/6/2012 on Aviation Week).

Airbus on Sept. 6 will unveil five measures it says will make the aviation industry environmentally sustainable by 2050 despite projected growth for global air transport…

Airbus also foresees a new method for takeoff, with renewably powered propelled acceleration allowing aircraft to climb steeper and reach cruise altitude faster. This in turn would allow airports to build shorter runways and minimize land use.

Once in cruise, aircraft should be able to self-organize and select the most efficient routes, says Airbus. On dense routes, aircraft could fly in formation, like birds, to take advantage of drag reduction opportunities.

In Airbus’ vision, aircraft will descend without using engine power or air brakes and would be able to decelerate quicker and to a lower final approach speed enabling them to use shorter runways…

Fuel is a key component of Airbus’ proposal, and the manufacturer says the use of biofuels hydrogen, electricity and solar energy will be required to reduce the industry’s environmental footprint.

You simply can’t build shorter runways.  Because planes aren’t perfect.  Sometimes things happen.  If we had shorter runways what would happen to a plane landing with damaged leading edge slats or trailing edge flaps?  And they have to land at a higher speed than normal because they can’t curve the wing to create more lift at lower speeds?  And what if a plane’s thrust reversers failed to deploy?  This is why we have long runways.  To give planes with problems a better chance to land safely.

Flying commercial jets in formation?  Not a good idea.  One of the most dangerous things to do in the Air Force is aerial refueling.  Where two large planes get real close to each other.  If they bump into each other they could cause some damage.  Even cause them to crash.  Flying in formation would be exhausting for a pilot.  Or they could entrust their formation flying to an autopilot.  But if they hit some CAT and get thrown around in that airspace they could get thrown into each other.  Even while flying on autopilot.  Planes also make their own turbulence.  Which is why there are larger distances between the big planes (i.e., the heavies) and the small ones.  So the small ones don’t get flipped over by some spiraling wingtip vortex turbulence off the heavy in front of it.

Solar energy?  Really?  How?  It’s not going to propel a jumbo jet.  And if they think they’re going to save on engine emissions by using solar panels on the wings to produce electricity for the cabin lights and electronics I don’t think that will work.  The emissions from the electrical load on those engines may be negligible compared to emissions they make producing thrust for flight.  And if they add more weight (solar panels) that will only take more fuel for flight.  Which will release more emissions.  Finally, a lot of planes fly at night.  When there is no sunshine.  What then?

Trying to reduce a plane’s carbon footprint will only make flying more dangerous.  It’s one thing to throw money away building solar panels and windmills on the ground.  For that’s just ripping the people off.  But applying this nonsense to aviation may end up killing people.  It’s hard to believe that Airbus is serious with these suggestions.  One wonders if they’re just proposing this to get those proposing that carbon trading scheme to back off as it will increase the cost of flying.  Which will reduce the number of people flying.  And reduce the number of planes Airbus can sell.  Perhaps by dangling this green future of aviation they may buy some time before the carbon trading scheme kills the aviation industry.

Fighting nonsense with nonsense.  It’s just as good an explanation as any.

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