Sunday, January 23, 2022

A pilot's view of the 5G problem


Full story here.

Any system that relies on a radio altimeter to function will be impacted. Both the equipment and the pilot’s operating it must be certified to land in low visibility conditions. We are essentially taking the certification of the equipment away. For example, in the Q400 our HGS (heads up guidance system) will be impacted, this is required for any Category 3 approach. The autonomous flare cue may indicate improper flare symbology or no symbology at all. 

Other systems in the Q400 that are affected that rely on radio altimeter are configuration systems (warnings for improper gear or flap settings), our TCAS (Traffic Collision Avoidance System) system could give us a “descend” command while at low altitude whereas before that would be inhibited, and most worrisome is the stall protection equipment, which includes the stick pusher, could be triggered at low altitude when normally inhibited by the radio altimeter. I have spoken with other pilots and on the Embraer E175, the auto land system will be unavailable in addition to similar TCAS warnings, configuration warnings, and autothrottle issues. Although I can’t comment for certain, I have heard that Airbus aircraft rely on the radio altimeter for many functions and will be impacted more than Boeing.

Uncertainty is the one word that describes it the best. Those of us not scheduled to fly on the 18th are glad because we honestly don’t know what’s going to happen from a flight deck point of view.  We understand the operational aspects (i.e. canceled flights and diversions) but in regard to how the plane will react, we have only been provided cursory guidance.

13 comments:

  1. Lots of experiments going on these days!

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  2. What's the reason for all this 5G stuff? Is it supposed to make something better?

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    1. Better tracking of phones (they'll tell you more precise GPS and wayfinding to make you feel better). More bandwidth so they can collect and transmit constantly instead of pick/choosing of which phone to monitor. Your phone is already collecting 24/7 and transmitting when network is available, just not constantly because of 'not enough speed' without bogging the network down. Cliff notes, as an end user, you won't see much difference outside of a tiny bit more speed, and a lot less battery life.

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    2. As I figured, more benefit to the state and the costs borne by the productive.

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  3. @ghost ... yes, oligopoly profits

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  4. Much ado about nothing:
    78% of the fleet has already been certified, others are pending (and use the same sort of radar altimeter, they just haven't been tested)

    https://www.cnbc.com/2022/01/20/faa-warns-5g-related-landing-restrictions-could-divert-flights-as-snow-hits-airports.html If you read it, you'll find that the restrictions are being cancelled. Nearly all Boeing 7XX planes, and all Airbus planes are ok'd to use CatIII approaches.

    The issue has been massively overblown by people that don't know what they are talking about....

    You really only use the RA in the last 500 feet or so of your descent, and that is for less than a mile along the final flight path.
    The bands are adjacent, but separated by well over 200 MHZ, well within the ability of the radar altimeter to discriminate.
    The issue was that the FAA didn't bother to TEST, not that there was any real worry, nor was there any proven interference.
    Much like the folks that said, many years ago, that your cell phone would cause issues in navigation on takeoffs and landings...which was bullshit to anyone who knew radio. But to be cautious, the bureaucrats made everyone turn off their phones....for no real reason except ignorance. This is a similar situation.

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    1. Cell phones did cause trouble on some airplanes. At least one crash in mainland China was caused by cell phones interfering with the navigation systems. About a month later, before descent, a more careful captain noticed his heading indicators didn't match the magnetic compass. He required the flight attendants to pick up all the cells phones. Sure enough, when they were turned off, the heading indicators returned to normal.

      I was on a two captain crew departing Anchorage in a B747 Classic and immediately after takeoff, the heading indicators rolled off 30 degrees in different directions. The other captain's older style cell phone had fallen out of his bag onto the flight deck floor and turned on. As soon as he found it and turned it off again, the headings returned to normal. He was an old head and made sure we both turned our phones off at the gate.

      There is always more to the story and there is always a good fix.

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  5. I do know radio. The no cellphones requirement was from the FCC, not the FAA. Every digital device has a clock, every radio has an oscillator. Clocks are oscillators that generate frequency F and multiples called harmonics at 3F, 5F, 7F... Every pair of frequencies generated by an oscillator create 4 frequencies. Call two oscillators F1 and F2. These would also generate ( F1 + F2 ) and ( F1 - F2 ). If every passenger has a device, hundreds of frequencies generated in an aluminum tube get ducted to the cockpit and do who knows what to the electronics. The decision to disallow electrtonics is a rare specimen of a wise decision by informed educated government officials.

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    1. FAA advisory circular regarding cell phones and all other radio frequency devices...note that it was put out in 1961:

      https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_91.21-1D.pdf


      And you show that you know just enough about radio to be dangerous, but not enough to know.

      Believe what you want, however. You can have your own version of reality if you wish.

      my first comment shows the data that the FAA has cleared all Boeing 7XX and Airbus 3XX series to continue CatIII approaches (others are pending), even where 5g is happening. If you bother to use Google, you can come up with the actual FAA advisory circular regarding this.

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  6. Phone companies have been advertising 5G 7*24 since I graduated from high school back in 1967.
    There was no time to figure these things out?

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  7. As an electrical engineer with 25 years experience in RF and cellular phone work I can tell you that any potential conflicts between the 5G rollout and airplane guidance systems did not materialize overnight. The potential impact is a matter of physics which has not changed since the beginning of the universe. The problem is money. Always is.
    Here is a non-technical explanation: The airlines put off any changes or upgrades in hopes of creating enough fear porn to get the feds, aka the taxpayer, to pay for the changes as opposed to getting the airline's customers to pay for them.

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  8. Meh, only peasants fly public airlines, we in the American Nomenklatura of Bureaucrats, legislators and the wealthy fly private planes, so screw the peasants, as usual, what ever they ever done for us?

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