ewandennis / ConTrails

Render an airline noise heat map given historical flight tracks

An Airline Noise Heatmap

This little repo will pull flight tracks from a MongoDB and produce a heatmap of airline noise.

Prerequisites

• Cairo graphics library: for PNG rendering - tested on v1.14.8
• libmongoc 1.0 and libbson 1.0: for flight track data access
• C++ compiler with C++11 support - tested on Apple LLVM version 8.0.0 (clang-800.0.42.1)
• GNU Make 3.81

Flight Track Data

• Track: FlightPos[]
• FlightPos: latitude, longitude, altitude
• All values are double precision floating point numbers

Assumptions

• The listener is at sealevel: their altitude is 0
• Aircraft are considered point sources of sound
• Sound perception is not accounted for (ie no A-weighting is calculated)
• Atmospheric conditions used for absorption losses:
  • frequency: 250Hz
  • temperature: 20C
  • humidity = 30%
  • ergo absorption coefficient = 1.42 reference

The Calculation

1. Distance field: each cell contains distance to closest flight track
2. Noise field: each cell contains dB SPL from sea level of closest flight track
3. Heatmap: 4-step colour map from normalised noise field cell values:
   • Blue, green and yellow: below noise level of a car @ 10m
   • Red: between car @ 10m and plane @ 100m

Issues And Limitations

• Sound perception is not accounted for (ie the map is not A-weighted)
• Flight track data is inaccurate - some flights seem to land kilometres from GLA
• Only the closest flight is considered, no weighting is applied for flight path probability