Peter wrote:
Does the ADL display indicate tops? I didn’t think any ground based radar did that.
The ADL shows not only radar, but also IR, sferics, wind/temp, ground observations…
ADL – indispensable!
chrisparker wrote:
Karen’s pulse-ox never got below 90% so she stayed on the cannula.
@chrisparker : Which mode (F…. I guess) did you switch on the O2D2 to achieve this?
We use D10 up to FL200 and F2 above.
I would have been very nervous using the ADL for such a tactical approach. You were visual most of the time so that’s fine, but what would you have done otherwise?
Re: flying in the green bits. When using onboard radar, the advice is to avoid the green parts as well, as long as they belong to stuff with yellow or more in them. I actually don’t know what the guidance would be for downlink radar. I have had flight where I was in the green parts of the DL and the onboard radar was showing absolutely nothing.
Thanks, Chris. I achieved merely 90% @ FL200 with the D10-setting. Next time I’ll also switch to the F-mode.
I too have used the O2D2 with the “mask” setting, to get 95%+ at FL200. It works really well. I’ve done it with passengers too so it isn’t just me.
Regarding radar, I don’t think uplink radar (basically, meteox.com) is good for wx penetration in IMC unless you have separately established the probable total absence of CBs. At best, it will give you an overly cautious impression (which is good) because you can have really dense radar regions but the tops might be FL100-150.
The images of the ADL come from ground-based weather radar that measures moisture content. So the more moisture is present the more alarming the color will be. Some moisture is green, then yellow, then red, then purple …
As more “content” also means “more violent precipitation”, the more alarming colors signify trouble. Either a towering cumulus with a shower underneath or a fully grown CB. Green can also mean rain out of a stratus cloud. Totally benign but wet.
Together with the estimated cloud tops one can figure out a bit more of the current situation. If the ADL shows very high cloud tops (based on infrared) around a yellow spot with green around it, then something might be developing there. It may become a CB shortly.
What I wrote represents my current understanding. Please correct me where needed.
Peter wrote:
At best, it will give you an overly cautious impression (which is good) because you can have really dense radar regions but the tops might be FL100-150.
I thought the rule of thumb was that if it’s red, it’s high and you shouldn’t even think about flying over it in a SEP. At least without an on-board radar. You shouldn’t get that heavy precipitation otherwise. Of course, even ground based radar can catch some clutter. Anyway, IR coverage the ADL offers is better than radar coverage and strike coverage is good too, so you can correlate it.
denopa wrote:
When using onboard radar, the advice is to avoid the green parts as well, as long as they belong to stuff with yellow or more in them. I actually don’t know what the guidance would be for downlink radar. I have had flight where I was in the green parts of the DL and the onboard radar was showing absolutely nothing.
I was told to stay at least 20 NM away from a core (horizontally). Green on an image from a ground based radar can easily be a low level stratus slowly raining, nothing that would concern you in cruise (unless your machine has low service ceiling). It will blend with ground clutter on an image from an on-board radar.
I don’t know much about this (I would not fly in those conditions in IMC in the plane I have) but I think the difference between on-board radar and the ground based weather radar is the vertical beam width. The former has an adjustable tilt so the vertical extent of the wx can be estimated, whereas the latter is a fixed beam.
