Improvements to FlightAware Maps & Understanding Map Behavior
понедельник, 21 Июль 2014 13:00
Last updated 3 years ago.
There has been a lot of attention and scrutiny to flight tracking maps in the last few days, so we've made some great improvements to route visualization and have a few updates to help everyone understand what they're seeing and how the data is derived.
In areas of limited coverage (for example, over an ocean or a rural part of the world), it is possible for FlightAware to not receive position updates from the airplane for an extended period. When tracking an airborne flight that has left our coverage area, you'll notice that the airplane icon changes from green to hollow white, a range ring is drawn around the airplane, and the word "ESTIMATED" is written next to the airplane icon. Once we receive the next position update, we suppress the estimated positions from the map and draw a line from the last known position to the next position. We've made two changes to improve how we handle this situation:
- When there's a coverage gap, we now draw the track gap in white, not green, so it's clear which part was out of range.
- When we draw the coverage gap, we no longer draw a flat, straight line on the image; we now project the great circle route that takes into account the curvature of the earth and the route an airplane will fly.
These changes will make it much easier to understand FlightAware maps and the changes are retroactive, so flight maps that you've looked at in the past might appear slightly different, although the underlying data hasn't changed. You can always click "track log & graph" on any flight to see the raw data, or click the Google Earth icon to export the positions to a KML file.
This example shows the lack of position updates over the Black Sea and the slight different track connecting the two coverage areas as a result of a great circle line.
Of course, it's still important to understand that the white line reflects a lack of data and you can't draw any conclusions from it, since it may suggest that, for example, a flight flew through a country that it really deviated around. We are constantly working to improve our coverage and more data sources are added almost daily.
When tracking an airborne flight, it's also important to understand that not all of FlightAware's data sources are real-time. For example, although the vast majority of our data is real-time, some data is intentionally delayed several minutes due to government restrictions or sent to us via satellite datalink takes minutes to reach us, so it's possible that we may estimate a plane's position for a few minutes if it's out of normal coverage and then receive a position update that's minutes old, and the track line will change retroactively to reflect this. In some circumstances, FlightAware's systems improve accuracy by scoring position reports based on data from other sources; real-time data (like ADS-B) isn't indiscriminately displayed on the site without automated analysis using our data verification algorithms. Although this can result in slightly delayed information, these automatic processes and updates are all part of the process of aggregating over a hundred data sources to provide the most accurate flight tracking possible.
Different Users with Different Access
Occasionally, you may see an airline release a FlightAware-branded map that contains data that is different or not available on FlightAware.com. This is because many airlines are customers of FlightAware's commercial services and have access to restricted data, either directly from the aircraft's flight management system or from a source that doesn't allow instant public dissemination of this data. Some airlines do allow us to redistribute their internal data and we're always working with customers and partners to make more available on our web site.We hope this clarifies the data you see on FlightAware and provides some insight into all the work that goes into providing it.
Thanks for using FlightAware!