F-5 Flyover / 97-0400 Encounter Visualization

Animated reconstruction of the July 4, 2026 encounter near Joint Base Andrews between the C-37A 97-0400 (SAM963, arriving from the north) and the four-ship F-5 formation N591EM / N593EM / N595EM / N592EM (GHOST1–4, recovering from a National Mall flyover), built from ADS-B Exchange KML track exports.

Output: 1920x1080, 30 fps MP4 with:

• OSM (muted) or satellite basemap with labeled landmarks and highways
• Trailing trajectories with raw ADS-B fix markers, aircraft glyphs oriented to track heading, live callsign + altitude labels
• Live range line and distance readout between 97-0400 and the nearest F-5
• Closest-point-of-approach markers and per-aircraft CPA summary
• Altitude and separation strip charts with a time cursor
• Variable playback speed (medium through Mall approach, ~3× through the closest-approach window, fast through the 97-0400 holding pattern)
• Persistent data-quality disclaimer (raw uncorrected pressure altitude)

Quick start

pip install -r requirements.txt
# ffmpeg must be on PATH (apt install ffmpeg / brew install ffmpeg)

# OSM basemap, muted (default; network needed on first run; tiles cached
# in basemap_cache/ so later runs are offline-capable):
python render_video.py -o output/encounter_osm.mp4

# Satellite imagery basemap instead:
python render_video.py --basemap satellite -o output/encounter_satellite.mp4

# Fully offline schematic basemap (no network, no requests/Pillow needed):
python render_video.py --basemap offline -o output/encounter_offline.mp4

Useful options: --fps, --width/--height, --start/--end (UTC HH:MM:SS on 2026-07-04), --crf (x264 quality), --tile-cache.

What the numbers mean (and their limits)

Methodology: each pair of tracks is interpolated onto a common 1 s grid using cubic spline interpolation; horizontal separation is haversine great-circle distance; vertical separation is the difference of the two reported pressure altitudes; "closest approach" minimizes the combined 3D distance sqrt(h² + v²).

Computed CPA of each F-5 relative to 97-0400:

Callsign	Aircraft	Horizontal	Vertical (baro delta)	Time (UTC)
GHOST1	N591EM	0.52 NM	416 ft	17:15:09
GHOST2	N593EM	0.59 NM	245 ft	17:15:08
GHOST3	N595EM	0.53 NM	362 ft	17:15:10
GHOST4	N592EM	0.58 NM	649 ft	17:15:12

Caveats -- treat all separations as estimates:

• Altitude is uncorrected pressure altitude (29.92 inHg reference) as exported from ADS-B Exchange, in meters in the KML, converted to feet for display. It is not geometric height and not corrected to local QNH. Baro differences between aircraft are more meaningful than either absolute value, assuming both feeds report pressure altitude consistently -- which has not been independently verified.
• ADS-B position error, altitude quantization, receiver timing jitter, and multi-receiver merge artifacts are not modeled.
• Cubic spline interpolation smooths between fixes but can slightly over- or undershoot during sharp turns when the update rate is low.
• Ground speed and heading shown in the video are derived by finite differences of the interpolated positions (smoothed ~7 s), not taken from the ADS-B velocity messages.
• Aircraft type labels: 97-0400 is labeled C-37A and the N59xEM aircraft F-5 based on prior notes accompanying the data, not independently verified from the track files themselves (KML carries no type field).

Aircraft roster

Callsign	Reg	ICAO	Type
SAM963	97-0400	AE010D	C-37A
GHOST1	N591EM	A7A18E	F-5
GHOST2	N593EM	A7A8FC	F-5
GHOST3	N595EM	A7B06A	F-5
GHOST4	N592EM	A7A545	F-5

Basemap accuracy

• Landmark points (monuments, airports) use well-known surveyed coordinates, good to ~100 m -- sub-pixel at these map scales.
• Offline mode rivers and highways are schematic approximations (roughly 0.5-2 km), hand-digitized through high-confidence anchor points (bridges, interchanges). They are labeled "(approx.)" and are for orientation only. See encounter/landmarks.py.
• In satellite/osm modes the imagery itself provides the ground truth; schematic lines are not drawn, only landmark labels.
• The runway-like line at Andrews is derived from 97-0400's own on-ground track points (data-driven, not an airport diagram).

Improving the basemap: for survey-grade roads/water, replace the schematic polylines with an OSM extract (e.g. osmnx or a Geofabrik shapefile clip) and plot in Web Mercator alongside the tiles.

Tile usage: Esri World Imagery and OSM tiles are fetched at zoom 11/13/14 for the two coverage boxes (a few hundred tiles total), cached under basemap_cache/, and attributed on-frame. Respect the providers' terms for anything beyond light personal use.

Project layout

render_video.py            CLI entry point
closest_approach.py        original standalone CPA script (reference)
data/                      ADS-B Exchange KML exports (5 aircraft)
encounter/
  kml.py                   gx:Track parser (multi-segment, dedup, cubic spline)
  geometry.py              Mercator, haversine, CPA, speed/heading
  timeline.py              variable-speed playback + camera keyframes
  landmarks.py             landmark points + schematic line data
  basemap.py               tile fetch/cache/mosaic + offline schematic
  animate.py               figure/artists + ffmpeg pipe renderer
output/                    rendered videos

Timeline in the video (all UTC)

• 17:11 -- visualization opens on the Mall approach (F-5s already airborne)
• 17:13:30 -- ~1,000 ft (raw baro) pass over the Washington Monument
• 17:14-17:16 -- 97-0400 descends toward Andrews from the north; CPA ~0.52 NM / ~416 ft at 17:15:09; 97-0400 descends to ~1,350 ft then climbs away to the east and holds ~1,900 ft
• 17:20-17:22 -- F-5s land at Andrews
• 17:22-17:56 -- 97-0400 holds east of Andrews (video plays at 70×)
• ~17:56 -- 97-0400 lands at Andrews