The “Prime Air,” cargo flight was operated by a subcontractor for Amazon; believed to be 21 Air. An airport video shows the approach and attempted landing and it is clear from that that it was not a normal landing. Airborne data backs up the view that the aircraft was too high and too fast during the approach to the airport and it seems to have landed very long; possibly half way down the runway.
Data shows fluctuations in altitude and speed during the approach, which would account for the unstable arrival at runway level. The left wing of the aircraft appears to still be generating lift at touchdown and the left wheel is off the runway surface most of the time that the video is clear enough to judge. Thunderstorms were in the area and the surface wind was reported to be from the left and gusting to 26 knots, which would be enough to require into wind control inputs to keep the left wing down.
When aircraft land, Weight on Wheel (WOW) switches sense that the aircraft is now on the ground, which allows otherwise inhibited systems to operate. There did not appear to be ground spoilers on the wing, which would have killed any lift if activated and that would lower the wing/wheel. No reverse thrust activation was visible or audible and that would be important to help slow the aircraft down. The lack of these to systems would compound an already difficult situation.
With thunderstorm activity this can also produce sudden and variable wind conditions and so there may have been additional wind problems for the crew to counter. However, that would simply compound and already unstable situation. It seems that the aircraft passed the far end of the runway at around 130 knots, which is closer to the speed we would expect at the runway threshold just before touchdown. Speed creates lift and so counters all attempts that stay grounded and stop.
Whilst each airline will have its own specific criteria, it is standard to have basic requirements to be met before an approach can be continued to a landing. Commonly this would be to be stable, on the correct approach profile, at the correct speed and configured for landing with wheels and flaps where they should be, by 5 miles or 1000 ft above runway threshold. In the absence of this criteria being met, the approach should be abandoned. Public transport aircraft can initiate a missed approach at any point, even after contacting the runway.
Whilst we know quite a lot about this event, there are still things we do not know. Why did the crew press on with an unstable approach? Were they dealing with a problem that we do not know about? Did they feel under pressure to land this time for some reason? That could be commercial pressure (always best resisted but it can influence some people) or were they concerned about their fuel state? Normal fuel reserves should prevent situation that but we do not as yet know what the fuel level was and so it cannot be discounted at this point.
In any well run airline the safety culture is paramount and crews should never feel intimidated by making decisions that puts correct practice before commercial needs. It is a balance not always well met but in a safety critical industry, crews should never feel that they cannot take the safest possible option. Thankfully the crew survived and so can be interviewed by investigators, which will help them reach a conclusion quite early we hope.
Sadly, some on the ground were not so fortunate and at least 5 died as the aircraft crossed roads and public areas before stopping in a car park. A preliminary report from the NTSB should be available within a month.