Re: What do you think about this airline vs 5G brouhaha?

[Tom Beecher <beecher () beecher cc>]

> Jay, one thing you’re missing is that a maximum of 2 (and almost always
1) radar altimeter will be in use per airfield, as one aircraft will be
landing at a time.

I believe that Lady Benjamin may have conflated the radar altimeter on
aircraft with the instrument landing system transmitters.

On Wed, Jan 19, 2022 at 3:52 PM Jay Hennigan <jay () west net> wrote:

> On 1/19/22 01:53, Lady Benjamin Cannon of Glencoe, ASCE wrote:
> > Jay, one thing you’re missing is that a maximum of 2 (and almost always
> 1) radar altimeter will be in use per airfield, as one aircraft will be
> landing at a time.
>
> Really? I was under the impression that radar altimeters were pretty
> much always active during flight. If not, what triggers the "PULL UP -
> TERRAIN" audible warnings that are often heard on CVR recordings just
> before an airplane flies into cumulo-granite weather (mountains) miles
> from an airport?
>
> If in fact they are only used for IFR approach, is there a lockout to
> ensure that the radar is only active on approach? If pilots forget to
> turn them off after landing, does the radar transmitter automatically
> shut itself off?
>
> > Apparently some old gear has trouble with even a 500MHz guard band,
> which I also find astonishingly bad for any time, but a lot of aviation
> tech is truly from another century.
>
> This is absolutely horrible receiver design on equipment critical to
> aviation safety and it's surprising that tighter specs weren't enforced.
> That adjacent spectrum hasn't exactly been silent until now. It's been
> in use for decades going way back to Bell System TD-2 microwave that at
> one point criss-crossed the country.
>
> > They also have main lobes approx 80* wide so they still function when
> the plane is in 40* of bank.
>
> That makes sense.
>
> --
> Jay Hennigan - jay () west net
> Network Engineering - CCIE #7880
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