Inadvertently flew VFR into bad IMC today, never again

Aside from the whole time/processing delay with ADSB, I have noticed ADSB makes things look FAR, FAR worse than live radar, or internet feed prior to takeoff.

Crap, if I just went by ADSB, I would never fly.
 
MauleSkinner said:
Technically it’s 14CFR worse.
Click to expand...
Okay. I’m not a super duper reg guy like many of you, but I do fly almost daily in the severe weather using airborne radar, and an ADSB feed…. Not to mention what I see out the windscreen.

So, please clue me in to exactly what you mean by this…??
 
If one trusts the technology too much, without understanding the physics at play here, one can get into serious trouble real quick. When the clouds and cells are all over the place, the air between them is plenty humid and the temperature and dewpoint in those gaps can be nearly the same, and cloud can form in that clear air nearly instantly as cool air or rain falls into the gap.
 
I will just add this… one persons rain/clouds, are another persons cells.

Personally I use “cells” sparingly.
 
My understanding of the latency inherent in ADS-B/Nexrad is as such:

The excessive time delay isn't due to network latency. That would be measured in milliseconds or maybe seconds on a very slow network. The delay comes from the data being subject to human analysis. Easy to see how that could add 5-10 minutes to the green/yellow/red blobs' journey to your screen.

-Radar antennas sweep and collect the raw data
-that data needs to be processed into a useable form
-that data then needs to be aggregated along with other stations' data to form the full "map"
-I believe this is when an actual human needs to step in and review the data. They go over it to iron out any anomalies, compensations, etc etc. This is where the bulk of the latency comes from. Especially with composite radar, where the end user is actually seeing data that is amalgamated from multiple different kinds/configurations of radar scanning. This is what makes the user-friendly, simple, easy-to-read displays that everyone has become accustomed to.
-It then gets sent out to however many servers package it up for distribution to many different users. FAA, XM, weather apps, etc.

I could be very wrong, but that's my take on it. Pretty amazing if you ask me.
 
Last edited:
drummer4468 said:
-I believe this is when an actual human needs to step in and review the data. They go over it to iron out any anomalies, compensations, etc etc. This is where the bulk of the latency comes from
Click to expand...


First I’ve heard of human involvement. Yes, organic processing would slow it down considerably.
 
Non internet transmission also depends on

position of plane relative to ground stations?
other traffic?
Type and location of adsb antenna?
 
exncsurfer said:
If this delay is unavoidable, why not make the processing interpolate and project a 'now' image based on all of the recent images, perhaps in a different color scheme to signify its 'guesstimation-ness'. Maybe it has fizzled out or intensified but based on the movement and recent images here is where it would be NOW! IDK?
Click to expand...
That’s exactly how most real-time computer games handle latency with client side prediction … one side effect is that if latency gets too big and your prediction logic goes into wrong direction,now and then you will end up with “instant teleport/time warp” effect when the client finally gets synched up - in this case this would manifest itself with the entire cloud echo suddenly jumping 10 miles into a new location.
 
Last edited:
Warmi said:
That’s exactly how most real-time computer games handle latency with client side prediction … one side effect is that if latency gets too big and your prediction logic goes into wrong direction,now and then you will end up with “instant teleport/time warp” effect when the client finally gets synched up - in this case this would manifest itself with the entire cloud echo suddenly jumping 10 miles into a new location.
Click to expand...
Yeah, but the prediction could require a minimum interval to be valid(displayed) otherwise, mark the display as stale and show last valid data with time stamp.
 
I can recall once trying to stay under a layer to my destination due to the chance of icing at the MEA...I was instrument rated and current and talking to ATC who asked if I needed a clearance so I had an out...but recall heading through a TIGHT pass with clouds closing in struggling to maintain VFR and thinking to myself..."oh, THIS is how pilots die!"
 
Kritchlow said:
I will just add this… one persons rain/clouds, are another persons cells.

Personally I use “cells” sparingly.
Click to expand...

An airliner, you are flying a super duper machine compared to what most of us fly. You have a machine with awesome performance, on board radar and two pro pilots. You are going fast enough to get through, over or around building areas before they become a problem. You have the ability to climb high enough in most cases to visually confirm what you see on radar and avoid it. Plus you see more weather in a month than most of us will see in a year. All good stuff.

For me, I'm flying an airplane that has better equipment and performance than most SE piston aircraft, so I've seen (and avoided) some wild weather. The difference is that I'm doing this at 170 ktas, not 500 like you. My ceiling is maybe 14,000 feet, not 38,000+ feet, so I can't climb over the bad stuff. I'm the only pilot most of the time, so I don't have someone to bounce stuff off of when it is most important. So when I see a t storm that's over 8 or 9 thousand feet, that's a cell to me, bad news. If I'm able to go over that stuff I will, depends on what the atmosphere is doing. By "over" I mean, above the scuz, and around the protruding cumulus with a wide berth. If I can't get over it, or above the scuz, I fly below the clouds so I can see what's going on. If I can't get above or below, and it is anything more than an isolated cell, I land and wait.

ADSB is good, but it's only part of the picture, and it's dated, giving you a picture of where the weather was, not where it is now. That's why for convective stuff, I want to visually see it, since I don't have onboard radar. Also, for me, understanding the atmosphere and what it is doing is key. I'm not an expert, but I know now about CAPE, lifting indexes, instability and fronts. When the weather is not perfect my briefings take much longer. When I was a VFR pilot, my briefings consisted of the Foreflight briefing, which while legal, is very lacking, especially on days that are less than perfect. I learned that looking at TAFs along your route is a very poor way to weather plan, especially if the weather is less than ideal. I now have tools that give a much more comprehensive view of what is going on weatherwise. I am an advanced novice in using these tools, still learning, so I always keep that in mind while making go/no-go decisions.
 
I disagree with the blanket statement that ADS-B is not a tactical tool. Like any other source of information, it is subject to limitations. As long as the pilot factors those limitations into the decision making process, more information is generally preferable to less. WRT latency, it is easy enough to estimate the rate of movement of a system and judge the maximum extent of possible change since the last snapshot. Most software provides a timestamp on radar data to help with that judgement.

The OP's error was in not understanding that a 2 mile gap is much smaller than the margin of error on ADS-B. If you are going to scud run in those kinds of conditions, the only reliable information is that gathered by your Mark I Eyeballs and processed by your BHG (Brain Housing Group) using a hefty dose of experience in the local weather conditions.
 
Ed Haywood said:
If you are going to scud run in those kinds of conditions, the only reliable information is that gathered by your Mark I Eyeballs and processed by your BHG (Brain Housing Group) using a hefty dose of experience in the local weather conditions.
Click to expand...

Part of that BHG system is the DWR system:

 
Ed Haywood said:
I disagree with the blanket statement that ADS-B is not a tactical tool. Like any other source of information, it is subject to limitations. As long as the pilot factors those limitations into the decision making process, more information is generally preferable to less. WRT latency, it is easy enough to estimate the rate of movement of a system and judge the maximum extent of possible change since the last snapshot. Most software provides a timestamp on radar data to help with that judgement.
Click to expand...

The time stamp is when the composite was fully assembled and published. Individual areas of the picture may be a lot older than the time tamp.
 
Old Thread: Hello . There have been no replies in this thread for 365 days.
Content in this thread may no longer be relevant.
Perhaps it would be better to start a new thread instead.
Back
Top