hwybear wrote:Have Bookm run around the tarmat with a pie plate strapped to his chest and a aluminum foil helmet?
hwybear wrote:how do you externally test a radar built into a plane?
Glad you asked. When we're safely clear of the apron/ramp area, during taxi we turn the radar on and point the nose (radar antenna is in the nose cone) at a distant object or set of buildings. If there is a rainshower in the area, even better; we tilt up the antenna and see if the rain shows up on our Multi-Function Display (MFD). Only takes a couple of seconds for the radar sweep to pick it up. We then check that the pattern on the MFD "jives" with what we see outside. So more of a practical test than anything.
En route, a lot of pilots keep the radar at a tilt setting where it's just picking up some "ground clutter" at the edge of the range. Clutter's pretty easy to distinguish, so this is basically an on-going test. I had one case where the internal self-check was showing that it was working, even en route, but the antenna had failed (that was one fun afternoon
)... which is why I'm a bit skeptical of internal circuit tests proving that the device is working. As for Air Traffic Control radar, they've usually got multiple feeds from different radar sites, depending on the area. Not sure of all the tests they do for those, though.
Not saying that this is applicable to any outcome in court, but I think it's worthwhile mentioning.