Flight Replay Website Help Page
Last Updated: July 2004
This page provides additional information regarding the use and operation of the Flight Replay web page. Select from one of the categories below, or just scroll through the entire page.
The WebTrak system provides a general overview of flight operations in the Airport Area. For safety reasons the flight data is delayed. Depending on the airport and regulatory authority requirements the data may delayed by as little as ten minutes or for more twenty-four hours.
A system that has a ten minute delay is classified as "nearly live". In this case WebTrak will automatically display the slightly delayed track data when it starts up.
WebTrak is less sophisticated than an air traffic control or a noise and flight track monitoring system. This may lead to the occassional anomaly in the presentation of flight tracks. Examples of anomalies are flights momentarily disappearing or jumping around in unlikely ways. These issues are caused by reflections in the radar data or by transponder responses from the aircraft being scrambled by other radio signals. A more sophisticated system, such as those used by Air Traffic Control or Noise Abatement Offices, cleans up these issues before presenting the flight track data.
Select the start date by clicking on a day on the calendar. Navigate through the months with the 'back' and 'forward' triangles to the left and right of the month name, respectively. If either of these triangles change to a lighter color, then there is no flight track information for previous or subsequent months, and that triangle cannot be selected. Likewise, if a date changes to a lighter color, then there is no flight track information for that day, and that day cannot be selected.
NOTE: Once a date is selected, a request is made to the database server to acquire the hourly flight operation counts for that day (see 'Selecting the time' below). Repeated, rapid selection of different dates may cause unreasonable delays on this web page. After selecting a date, wait for one or two seconds for the hour bar-graph to update.
Just below the calendar is an hour bar-graph showing how many flight operations occurred during each hour on the selected date. The bar graph is seperated into three sections - Day, Evening and Night - from left to right. Click on one of the bars on the bar graph to select an hour.
Just to the right of the calendar is a minute slider which you can use to select how many minutes past the hour to start the replay. Click anywhere on the slider, or drag the slider handle with the mouse.
When WebTrak is operating in historical mode the speed of replay can be adjusted at any time. WebTrak steps through the replay in increments of 1, 2, 5 and 10 seconds depending on the selected replay speed. As higher replay speeds place additional load on your computer and Internet connection, you may not always be able to use the highest settings.
CONTROLLING ANIMATED FLIGHT REPLAY
Starting replay
Once the start date and time have been selected, click the VCR-like Play button below the map to the left. Flight tracks will begin animation from the selected date and time and continue for a duration of 30 minutes. Map views may be changed by zooming and scrolling during replay.
Pausing replay
While flight tracks are animating, click the Pause button (to the left of Play) to suspend replay. Map views may be changed by zooming and scrolling while paused. Click the Play button again to resume replay.
If you leave pause on for too long then WebTrak will time out and and the replay will stop.
Stopping replay
Click on the Stop button (to the left of Pause) to stop replay. All animated flight tracks will be removed from the display. A new start date and time can be selected while stopped.
The information displayed on the map is controlled by the map buttons.
Flight Tags
WebTrak is able to display a flight information tag for each aircraft that is animated on the screen. The contents of the tag will vary depending on the information known about the selected flight.
The Flight ID button toggles the display of tags. If the tags are not being displayed then hovering your mouse over an aircraft will cause its tag to be displayed.
You can see what information is displayed for the most recently selected (clicked on) aircraft on the Map Legend. The map legend is displayed by clicking the Legend button.
Flight Information
WebTrak is able to display more detailed information about a flight operation in the Flight Info panel.
Clicking on a aircraft icon will select the aircraft and display additional information into the Flight Information panel. The information displayed will vary depending on how much WebTrak knows about a flight.
For some data items, WebTrak has more information available than is
conveniently displayed. This is shown by making the text light
blue. If you hover your mouse over the text additional information
will be displayed (
).
The dark blue text indicates that WebTrak is able to refer you to sites with further information, such as photographs of the aircraft. If you click on the text then your web browser will be pointed at the site. (You must enable pop-ups for this site to use the feature).
Noise Levels
WebTrak is capable of showing noise levels measured at the Airport's noise monitoring terminals. The position of the monitoring terminals is shown by small grey circles.
The current 1 second noise sample (LAeq,1s) in dB is shown when the noise monitoring terminal measures significant periods of noise. The colour of the circle is changed depending on whether the noise is linked to air traffic or other sources. The Map Legend shows how the colors are matched to the type of noise.
The display of the noise monitoring location is toggled using the Noise button
Map Display Performance
The maps used on this web site are in format referred to as Scalable Vector Graphics (or SVG). The processing power of your computer is used to transform this SVG formatted map into a format that can be displayed on the Flight Replay web page. If your computer is an older, slower model, or if you have other applications running (which consume some or all of your computer's resources), map rendering and display performance may be affected. Please close down all other applications if you experience performance problems with this web page.
Zoom Levels
There are ten zoom levels provided in order to view a particular map area in greater detail. Zoom Level 1 is an overview of the Bay Area while Zoom Level 10 represents neighborhood views. Street names begin to appear at Zoom Level 8.
Map Loading
A variety of maps are available in order to support different detail at varying zoom levels. When zooming in or out, a different map may be requested from the server. While the map is loading, a message "loading map ..." will appear in the status bar at the bottom of the Flight Replay window. The map area might also change to white during this time. Depending on the speed of your Internet connection (56K, DSL, T1, ...) and the processing power of your browser-enabled computer, this can take anywhere from 5 to 15 seconds. Please be patient while a map is loading and wait to perform any other action in the Flight Replay window until the new map and view are displayed.
©2005 Lochard. All rights reserved.
