skylight.

UAL900 United

LHR → SFO

· 1:02Quality 98side-on

3D replay

Software-steadied: the hops of the camera motor are smoothed out (plane wobble −78%). Download

Trace

Where the aircraft sat in the frame, second by second. Click the chart to jump the video there.

—FOV —az —el —pose —
Lock

Events

Tracking metrics

How well the camera kept the aircraft centred. Tap a metric for what it means and what good looks like.

Lockshare of the pass
85%
First lockfrom target selected
7.1 s
Centring, medianaz / el while locked
0.15° / 0.16°
Centring, 90th pctaz / el while locked
0.42° / 0.39°
Tightest field of viewhorizontal
4.1°
Time to 8°from first lock
6.8 s
Time to tightestfrom first lock
9.5 s
Time at telefield of view ≤ 5.5°
32.8 s
Jitter at teleaz / el, standard deviation
0.18° / 0.18°
Swing at teleaz / el, peak to peak
0.91° / 0.90°
Pan reversalsper 10 s at tele
0.0
Largest pan hopin any 1 s at tele
5.02°
Largest tilt hopin any 1 s at tele
3.17°
Pose error, mediancommand vs camera
0.77°
Largest correctionvision vs prediction
1.09°
Zoom steps
35

Aircraft & route

Flight
UAL900
Registration
—
Type
—
Airline
United
From
LHR · London
To
SFO · San Francisco
Ground speed
245 kt
Altitude at closest
11,500 ft
Vertical rate
-128 ft/min
Category
A5
ICAO hex
ab0f8b

Pass geometry

Max elevation
70.2°
Elevation at start → end
22.9° → 70.2°
Azimuth at start → end
329° NNW → 53° NE
Closest-approach azimuth
48° NE
Minimum slant range
3.7 km
Heading at closest
140° SE
Aspect at closest
side-on (89°)
Turn
straight (0°)
Departure
No
Zenith pass
No
Dead-zone wrap
No
Duration
1:02 (61.6 s)
Lock
85%

Build & tuning

The tracker build that flew this pass and the live settings that mattered, so passes can be compared across changes.

Build
2026-10-16b — silhouette fallback reach 0.8° + multipart uploads
Commit
2ed816b
Node
v22.22.2
Camera
TONGVEO 20x PTZ · 1920×1080 @ 30 fps
Clip
30.5 MB · 61.0 s · offset -0.9 s
pursuit
velocity
maxLeadSec
3
panLatencySec
0.6
tiltLatencySec
0.4
rippleDeg
0.5
rippleTeleDeg
0.25
maxSpeedStepFwps
0.45
speedReachFrac
0.8
lockedSigmaDeg
0.35
sigmaGrowthDps
0.1
aimLeadSec
-0.03
correctionSlewDps
2.5
kp
1
ki
0.6

This clip and poster are © Skylight (Cameron Paczek): free for non-commercial use with credit to skylightceiling.com, not MIT. License