Erratic flight path


#1

I am new to FlightAware so forgive me if this topic has been discussed before. Please look at the flight below. It is a short flight from LSE to RST. I was in and out of the cloud tops for most of the trip. I was on autopilot for almost the entire trip and I do not belive the small heading deviations that I am seeing on this chart. Could the clouds have caused deviations in the radar returns that would explain this erratic flight path?

http://flightaware.com/live/flight/N429CP/history/20060826/2001Z/KLSE/KRST


#2

If you think it might have been disscused before why don’t you search the forum? BTW it hasn’t, but please search the Forum/FAQ before you post. Uhhhhh. I don’t really know the answer to your question. Maybe Daniel or Mark could help you (moderators).

Welcome to the forum! 8)


#3

It is possible that FA was receiving position reports from two radar sites. As the crusie alt was 4000, I would suspect that the signal return was marginal on one or both of the radar sites. Typically, the result of this is a jagged, or sawtoothed path, but it is conceivable that the spurious reports merged and got smoothed by the processing done on the flight path to make the 1 minute resolation of data from FAA less visible.

PS- Welcome to FA and the forums!


#4

I bet it was one of those guys who got his private in 40 hours and wasn’t capable of tracking the vor because of the lack of experience (sarcasm).


#5

That’s actually one of the better “bad flight paths” I’ve seen.


#6

Yea, looks like two radar sites were reporting postions for that 172. Note that there are two position reports per minute in the tracklog; usually there is only one.
The short distance of the flight also magnifies the side-to-side motion.


#7

What a great example of the positional accuracy of the FAA’s enroute radar.

That graphic track really does a good job of showing the reason for the 5 mile enroute separation. It looks like the two radars differ by 1-2 nm.


#8

We have some advanced automation that we’ll be rolling out in a large forthcoming map update, where our software will pick the “best” radar source when we’re getting returns from multiple radars. This will eliminate, in most cases, the stair-step or sawtooth patterns people often see in radar tracks. It will also, for the most part, eliminate the “mad slip on final” phenomenon where people will sometimes see an aircraft apparently turned 90 degrees to its flight track.

Also in that update, track logs will identify the radar source for each position shown.


#9

Are you saying, for instance in this case, you would be showing the Minneapolis Center Radar Site (I assume they have more than one) and the overlapping Rochester TRACON site? I have flown over Rochester and they have an approach control even though they are Class D.

What location is the site data going to show? Just a city and responsible TRACON and Center, or will it include the Sector # which we don’t have access to and wouldn’t mean anything to us?

Actually, if you had distance from the site via lat/long of the aircraft you could assume the radar closest to the aircraft was the most accurate. If you cross referenced that with the MEA you could probably throw out some bad returns.


#10

I’m not certain that every single radar’s data is collected, but we do get TRACONs as well as centers. We do routinely get data from two different radar sites within the same minute for a given aircraft. In any case, the radar source of each position will be identified in the track logs, and we will be reprocessing historical data to have this be consistent as well.

What location is the site data going to show? Just a city and responsible TRACON and Center, or will it include the Sector # which we don’t have access to and wouldn’t mean anything to us?

It’s an identifier code, like KZLA, KZOA, etc. We’re lookin’ to see what all we can make available referencing those sites.

Actually, if you had distance from the site via lat/long of the aircraft you could assume the radar closest to the aircraft was the most accurate. If you cross referenced that with the MEA you could probably throw out some bad returns.

Going with the closest radar will produce the best answer most of the time. My instinct is not to filter values below the MEA as there’s no certainty that those values are incorrect. For example, VFR aircraft with radar flight following routinely fly below the MEA.

karl