# N722BD: back-of-the-envelope speed estimate from dashcam video

Working estimate — November 1, 2026 accident  
Prepared November 3, 2026

STATUS: PROVISIONAL. This is not an official accident reconstruction. The camera's position, lens and exposure are unknown, and the measurements were read from a re-encoded social media copy of the video, with the aircraft heavily motion-blurred. No cockpit voice recorder or flight data recorder information was used.

Shared in the hope that it might be found useful as a rough outline. Not a forensic analysis.

## Result

- **Dashcam frames, using the aircraft as its own ruler: about 670 mph (roughly 600–765 mph).**
- **Dashcam frames, using a utility pole as the ruler: about 640 mph (roughly 560–725 mph), if the pole is 35–45 ft tall.**
- **ADS-B data, as an independent comparison: about 590 mph.**

Together these suggest a final speed of **around 600 mph**, with 550–700 mph a fair range. They establish a very fast, steep descent to the ground. They do not establish an exact impact speed.

These are total speeds along the flight path, measured relative to the ground. True airspeed differs from them only by the wind, which is unknown here but small next to speeds this high.

## Video timing

The video is 30 frames per second, or 33.3 ms per frame. As a check, the dashcam's burned-in clock advances every 30 frames across the clip, apart from one change that falls among frames disturbed by the impact flash. The copy therefore appears to run at real-time speed.

The burned-in clock reads 13:51:50 during these frames. It was not used for timing, because it is about an hour ahead of the ADS-B-derived impact estimate of about 12:49:34 EST. Daylight saving time ended that morning, so the camera may still have been on EDT, but even then it would read about 2 minutes 16 seconds later than that estimate.

## Measurements

Positions are approximate pixel coordinates in the 1920 × 1080 frame, read by eye from enlarged crops. "Tail" means the top of the fin.

| Video time | Frame | Nose (x, y)                              | Tail (x, y) |
| ---------- | ----- | ---------------------------------------- | ----------- |
| 1.700 s    | 52    | 1020, 38 (just entering at the top edge) | above frame |
| 1.733 s    | 53    | 1120, 238                                | above frame |
| 1.767 s    | 54    | 1218, 472                                | 1062, 72    |
| 1.800 s    | 55    | at the ground; impact under way          | 1163, 283   |

Motion per frame:

- Nose, frame 52 to 53: about 224 px
- Nose, frame 53 to 54: about 254 px
- Tail, frame 54 to 55: about 234 px

This analysis uses **240 px per frame (range 225–255)**.

Frame 54 is the only frame showing the whole airframe. Its apparent length, tail to nose, is about **429 px (range 400–450)**, with the axis about 69° below the image's horizontal. The direction of motion is about 67° below horizontal, so the aircraft appears to be traveling almost exactly nose-first (i.e. the direction of motion and the orientation of the aircraft appears very similar).

## Calculation: the aircraft as ruler

The Learjet 60 is 58 ft 8 in (58.67 ft) long.

- 240 px ÷ 429 px = 0.56 aircraft lengths per frame
- 0.56 × 58.67 ft = 32.8 ft per frame
- 32.8 ft × 30 frames per second = 985 ft/s = **about 670 mph**

Pairing the low and high measurements gives the range:

- 225 px ÷ 450 px gives 880 ft/s, or **600 mph**
- 255 px ÷ 400 px gives 1,122 ft/s, or **765 mph**

## Cross-check: a utility pole as ruler

The pole near the impact point spans about 305 px in frame 54, from its top at about y = 265 to its base at about y = 570. Its height is not known. Assuming 35–45 ft:

| Assumed pole height | Distance per frame | Speed   |
| ------------------- | ------------------ | ------- |
| 35 ft               | 27.5 ft            | 563 mph |
| 40 ft               | 31.5 ft            | 644 mph |
| 45 ft               | 35.4 ft            | 724 mph |

This is valid only if the aircraft is about as far from the camera as the pole. If the aircraft is closer, as it would be if it passed in front of the pole, the true speed is lower than the table shows.

## Comparison: ADS-B

From the separately reported ADS-B data:

- **Vertical:** a straight-line fit to the changing altitude reports from 17:49:12 to 17:49:22.955 UTC gives 761 ft/s, or **519 mph** downward. Those reports end at 8,750 ft.
- **Horizontal:** the last reported ground speed is 238 kt, or **274 mph**, at about 17:49:32 UTC.
- **Combined:** the square root of (519² + 274²) gives **about 590 mph**, on a path about 62° below horizontal.

This assumes the fitted rate held to the ground and that the ground speed is in knots. The last changing altitude report comes about 9 seconds before the last ground speed report, so the two components are not from the same moment. The 62° is a path angle over the ground, and is not directly comparable to the 67–69° measured in the image.

## Mach number and the sound before impact

**The estimates point to a subsonic aircraft at impact, possibly with some transonic airflow.** At an assumed 70–80°F near sea level, the speed of sound is about 770 mph:

| Speed   | Approximate Mach |
| ------- | ---------------- |
| 550 mph | 0.71             |
| 600 mph | 0.78             |
| 700 mph | 0.91             |
| 765 mph | 0.99             |

The whole range stays below Mach 1. Air can still go locally supersonic over parts of an aircraft below Mach 1, which becomes more likely toward the upper end of the table.

The video's audio supports subsonic flight. Measured from the waveform:

- The sound rises smoothly from about 1.5 s, roughly 0.3 s before the visible impact at about 1.78 s.
- A much larger jump comes at about 2.0 s. If that is the impact sound, its 0.22 s delay puts the camera about 250 ft from the impact.
- No abrupt, shock-like step appears between 1.4 s and 2.4 s.

The noise therefore leads the apparent impact sound by about 0.5 s. A subsonic aircraft can outrun little of its own earlier noise, so that noise arrives first. A supersonic one outruns it, which limits any lead. For a camera 250 ft from the impact, on a straight path at constant speed:

- **590 mph:** noise made 1,000 ft up leads the impact sound by about 0.47 s.
- **850 mph (about Mach 1.1):** no noise leads it by more than about 0.13 s.

This argues against supersonic flight, but it does not separate one subsonic speed from another. At 765 mph, noise made 1,000 ft up would lead by about 0.2 s, and noise from much higher up by more.

Caveats:

1. **Audio sync:** everything assumes the sound and picture stayed aligned through re-encoding. A slip of 0.1 s would noticeably change the delay, the distance and the lead.
2. **Identifying the sounds:** treating the jump at 2.0 s as the impact, and the earlier rise as the aircraft, is an interpretation.
3. **Recording conditions:** a dashcam microphone inside a car in rain, possibly with automatic gain, and lossy audio compression can all reshape the sound. Compression could soften a real shock.

## Limitations

1. **Motion blur:** blur lengthens the aircraft's apparent size, which makes the aircraft ruler read low. The camera's exposure time is unknown, so this cannot be corrected.
2. **Rolling shutter:** if the sensor reads rows from top to bottom, an object moving down the frame appears stretched. The aircraft ruler is largely immune, because its length and its motion stretch together. The pole is stationary and does not stretch, so the pole ruler would read high.
3. **Foreshortening:** a ruler tilted toward or away from the camera looks shorter. If the aircraft is traveling nose-first, its length and its motion shorten together and the effect largely cancels.
4. **Perspective:** the aircraft is close to the camera, so its scale may change between frames. Its full length is visible in only one frame, so this could not be tested.
5. **Camera motion:** the dashcam vehicle's own movement was ignored. The fixed background shifts only a few pixels per frame, far less than the aircraft does.
6. **Reading error:** the positions were read by eye from a blurred, compressed image. Different readings of the same frames will give somewhat different results.

## What these frames do not show

- **Speed or Mach number earlier in the descent:** these figures apply only to the last moments near the ground. The speed of sound falls with altitude, so the same speed higher up would be a higher Mach number.
- **Pitch or flight-path angle:** the 67–69° figures are angles in the image, not calibrated angles relative to the real horizon.
- **Structural condition:** the port horizontal stabilizer is hard to see in these frames, but almost all of the port wing is also nearly invisible in frame 54. Thin, fast-moving surfaces are unreliable here, and these frames do not establish that any part was missing.

## Sources

- Dashcam video, posted by OSINTtechnical on X and downloaded as a 7.2-second, 1920 × 1080, 30 fps copy: https://x.com/osinttechnical/status/2116984658185322592
- Flightradar24 granular ADS-B data for N722BD (`Flightradar24_N722BD_Granular_Data.csv`).
- Learjet 60 dimensions: https://en.wikipedia.org/wiki/Learjet_60
- Companion documents: *N722BD: back-of-the-envelope synchronized ATC / ADS-B timeline* and *N722BD: back-of-the-envelope check of the radar data*.