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 - j...@west.net Network Engineering - CCIE #7880 503 897-8550 - WB6RDV
