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blindfinder

Procedure for Lost Nav & Communications?

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Hello,

 

We rely so much on navigation systems but what would the real world procedure be in the following scenario?

 

  • Full Electrical Failure with just your engines running (No Comm Radios, Nav Radios, MCDU, No RAT, I mean nothing at all). I know it's astronomically impossible but lets just assume for this scenario. 
     
  • Full IFR conditions with no ground visibility. An airbus pilot does not carry VFR charts so pilotage is not an option.

 

Would an airbus pilot use Dead Reckoning with data from the Nav Log to find their way? 

 

Thank you

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1 minute ago, blindfinder said:

Hello,

 

We rely so much on navigation systems but what would the real world procedure be in the following scenario?

 

  • Full Electrical Failure with just your engines running (No Comm Radios, Nav Radios, MCDU, No RAT, I mean nothing at all). I know it's astronomically impossible but lets just assume for this scenario. 
     
  • Full IFR conditions with no ground visibility. An airbus pilot does not carry VFR charts so pilotage is not an option.

 

Would an airbus pilot use Dead Reckoning with data from the Nav Log to find their way?

 

Thank you

 

It has actually happened real world, though I don't remember if it was an Airbus or not. The flight crew had a portable radio onboard, and they used that to speak to Air Traffic Control who vectored them.  This was made into one of those flight disaster TV shows, which is how I know of it.

 

If you're IMC with no radios and no instruments, the only thing  you can do is fly about the MSA and try to fly out of the conditions until you can obtain visual references.  To dead reckon, you have to have some type of positional reference.

 

Thanks for the post, many here enjoy such questions!  I'm going to move your post from the Support Area to the General Area as it's better suited.

 

Best wishes.

 

 

 

 

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As for electrical systems, there is always the possibility to lower the RAM Air turbine and thus generate some emergency power. That should allow you to operate the radios and other essential electrical systems.

 

By the way, I remember years ago there was a TU-154 somewhere over Russia that had lost all electrical systems. This included the fuel pumps as well, meaning that within 10 minutes the engines would run dry and shut down. In other words, they had 10 minutes to land the aircraft whilst having a total instrument black-out. The fact that they lost the radio was the least of their problems as they also lost the altitude and speed indicators. All they could do was descend and hope for the best. Once on low altitude with ground visibility, the pilot spotted a runway from the corner of his eye and went for it. It was overgrown with bushes as the small airport, which was never designed to handle something as big as a TU-154, had closed down decades ago. They managed to land just in time and even though the aircraft was severely damaged everybody made it out alive.

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Lost comm procedures for airspace under US FAA jurisdiction: https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap6_section_4.html

 

Lost nav is best avoided by carrying the right mix of redundant nav systems so the loss of a single system still leaves alternative methods, including radar vectors, to visual meteorological conditions. Properly equipped, loss of all nav is extremely rare in today's environment. 

 

This said, along with the comments from other contributors, probably doesn't really get to your first question. At some point, the probability of total total failure as you described would require the crew to use available resources as seen in such "non-survivable" incidents as the "Miracle on the Hudson", United Flight 232 (here) or DHL A300 OO-DLL. Granted, these were different factually from your scenario, but all  illustrate that crew resource management, using all available resources, offers the best outcome to any emergency.

 

With regard to your question 2, dead reckoning (DR) from a last known position would be my last resort. Too many variables in winds/weather and too many non-variable rocks. A DR letdown in full non-visual conditions isn't an option at all, considering the people on the ground you're putting at risk, plus whoever's on board. Backup comm resources used to get me to a safe alternate with a radar approach would be a better choice.

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