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March 11th, 2014
10:29 PM ET

Frustrated families wait for answers about Flight 370

In the four days since Malaysia Airlines Flight 370 disappeared the families of the 239 people on board have received few answers. As the mystery deepens, so do their frustrations. Anderson takes a look at what these families are going through.

Jim Clancy has the latest from Kuala Lampur.

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  1. terirose@windstream.net

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    April 3, 2014 at 8:46 am |
  2. davekochcolumbus

    With regard to the reporting on the missing Flight 370, I am astonished by the utter absence of practical aviation knowledge being regurgitated by the “expert” guests CNN is using on AC 360, Wolf Blitzer, etc.

    One former FAA bureaucrat referred to navigating without electronic navigation aids as “Dead Heading Navigation.” No, that would be called Dead Rreckoning Navigation.” Comparatively, Dead Heading and Dead Rreckoning is about the same as a comparison of an erupting volcano to eating a banana split at Dairy Queen on a Thursday evening. No relationship whatsoever.

    Given the sketchy facts now known, it appears that the Boeing 777 suffered a catastrophic AC failure.

    Aircraft generators and batteries produce the primary electrical power. Both the generators and the batteries produce Direct Current “DC” power. DC power is used for many of the aircraft electrical system components that require high amounts of energy – high amperage.

    All of the aircraft navigation, communication and flight instrumentation requires Alternating Current “AC” power. Aircraft are equipped with “inverters,” which take DC power and convert it into AC power.

    The communication radios, navigation radios, GPS systems, signal transmission systems, transponders, EFIS flight instrumentation systems all operate on AC power.

    Although the Boeing 777 is equipped with multiple inverters, if they are located in close proximity, perhaps in the same rack, or if they are interconnected in any way, it is possible to have a catastrophic failure of all of the primary and redundant inverters, and consequently, all of the AC power.

    If a crew experiences a total failure of of its inverters and consequently all AC power, the transponders would have no power, and would therefore cease operating. There would be no communication radios, and the crew would be unable to contact Air Traffic Control. There would be no navigation radios, VOR, GPS, NDB, or any other electronic form of navigation. The autopilot system would be without power and cease operating.

    The crew would be completely limited to hand flying the aircraft and using Dead Reckoning Navigation.

    It is possible that the only flight instrumentation the crew would have are vacuum powered instruments, which is likely limited to a small gyro instrument that depicts an artificial horizon, and an airspeed indicator and altimeter. These instruments are adequate to fly the aircraft by hand.

    It is uncertain if the Boeing 777 is equipped with a fundamental kerosene filled magnetic compass, which in today’s technology seems prehistoric, but it’s a great instrument to have when all the high-tech electronics fail. Without a compass, the crew was lost pretty much immediately upon an AC failure.

    I have no doubt that the aircraft experienced a total AC failure. It is unlikely that the aircraft experienced a total DC failure, and then exhausted all battery power.

    If the DC generators had failed, the AC power would continue working, being fed by the aircraft batteries. AC power would continue operating in a DC power failure scenario, and therefore, the crew would still have communication and navigation radios, and transponders.

    This aircraft lost its transponders, then reportedly made a turn back toward its originating airport. Without AC powered navigation, that turn was a guess, particularly if the aircraft did not have a prehistoric basic good’ol compass.

    Depending on meteorological conditions, the crew may have descended for better visual reference. Fuel burn-rate would have increased substantially.

    Aircraft pressurization systems are failsafe to keep the aircraft pressurized. However, some aircraft require AC power to condition the bleed air from the aircraft engines’ compressors to cool it. The crew may have descended to an altitude where the pressurization was not needed (10,000’). In either scenario, fuel burn rate would have doubled or tripled. Endurance could have gone from 4 – 5 hours at altitude to two hours or less. The aircraft may have simply exhausted its fuel, or it may have been unable to transfer fuel depending on how the aircraft fuel transfer pumps are powered – AC or DC.

    This aircraft suffered a catastrophic AC failure. The question is what caused the AC failure.

    Questions for Boeing:

    1. How many inverters are installed on this specific aircraft?
    2. What systems are powered by each inverter?
    3. Where are the inverters located?
    4. Are any of the inverters located within close proximity to one another?
    5. Are more than one inverter incorporated in a multi-inverter unit?
    6. How are the inverters interconnected?
    7. From where do the inverters receive DC power, individually and collectively?
    8. How many separate and independent DC feeds do each inverter receive?
    8. Do the inverters have a single point of failure, individually and collectively?
    9. Are the inverters located proximate to any baggage compartment?
    10. How are the inverters shielded from electromagnetic interference?
    11. Are the fuel transfer pumps powered by AC or DC power on this specific aircraft?

    With answers to these questions, it is possible to develop more accurate theories as opposed to all of the assumptions people are arriving at via total speculation.

    Talk to Boeing. Get these answers.

    Dave Koch, ATP

    March 12, 2014 at 2:17 pm |

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