Some elaboration to the above:
- At 15.47UT/17.47LT, TWR reported the target was approaching Noordwijk at 900ft. This was the lowest target position mentioned during the 8 minutes of the attempted intercept.
- At 15.49UT/17.49LT, TWR indicated, by relative position to ZXP04, the target was over Katwijk and estimated its ground speed slightly less than 100kts. This matches the position reports as it amounts to the nearly 3.5NM ECZAF apparently covered in two minutes.
ZXP04 reported its own GS as 114kts (adsb track says 113, very accurate) with IAS 120, so a slight headwind and consistent with the EHAM weather at the time.
- At 15.53UT/17.53LT, TWR described a target position in the vicinity of Scheveningen. At that time, ZXP04 was not gaining on it anymore. This again matches the target's calculated GS, now based on some 8NM in four minutes: around 120kts.
When working with a police flight, there are generally two reasons for ATC to refer to anything as 'the target': either the nature of the target should not be broadcast on a radio channel that anyone can monitor, or its identification is not known. We may assume the latter was the case here.
In retrospect, a radar track was available to trace the TMA-intruding light aircraft back to Groningen and before. That would have been sufficient to identify it and contact the pilot later on and review the incident, in order to avoid repetition (specific and perhaps in general) and keep safety at a very high level for all. We can be sure this track is now part of the accident investigation.
However, at the time, this was not known with Schiphol ATC. Light aircraft outside controlled airspace are not actively monitored, there is no reason for that. Schiphol APP must have just seen an airplane with mode A+C (likely code 7000, plus altitude) enter the TMA and no-one knew at that moment which flight it was. Calls on various frequencies will not have resulted in contact, hence the try to catch up by helo. The airspace infringement was serious enough to attempt that intercept, in case it would turn out there was no other way to identify the plane afterwards (i.e. transponder signal lost before landing and origin of track not traceable either).
Thoughts for now:
Based on available info, ECZAF was used by its Norwegian pilot for long international VFR flights with a controlled international airport as a home base (Bergen - ENBR/BGO). This implies a certain level of competence. My initial impression of an 'ill-prepared flight' may well have been wrong.
That said, a working Mode S transponder is mandatory almost everywhere for motorised VFR flight and certainly on ECZAF's route. Theoretically, we do not even know if it had one, although it likely did. I have not been able to find its signal on adsb-playbacks between ENBR and the crash site for 5 June, while others do show.
The most likely scenario to me is that of an electrical problem, in combination with the rapidly deteriorating weather. A failing mode S could have been the first indication. The pilot not being in contact with any station after EHGG makes me suspect there was a radio failure as well. Such a comm failure may have led to the pilot wanting to avoid controlled airspace and, moreover, avoid landing at a controlled airport. There have been no reports of ECZAF squawking 7600. We do not know what instrumentation still worked.
Eventually, the flight could have ended up in IMC conditions (low cloud/heavy rain shower) despite the pilot's efforts. A VFR pilot has an extremely hard time trying not to get disoriented without enough visibility and loss of control can happen. This was a very light aircraft too, highly effected by air movements around it. It seems to have been a high-energy crash, as just some debris were found; Rijnmond.nl has
a photo. This makes loss of control more likely than an attempted emergency landing - but both are possible. However, why try to land on water after flying along a beach for 20 minutes?
Other catching details:
- Maintaining altitude and speed that indeed fit the tightest conditions for legal VFR along the coast at that time.
- Flying somewhat lower and slower near Noordwijk than further on: looking for Langevelderslag, or just a coincidence or surveillance inaccuracy?
- Indeed not divering to EHAM or EHRD, possibly trying for EHMZ if the suspected problems indeed existed.
This is an animation of my estimate at the flight's progression combined with the shower activity. Base images (C) Buienradar of course:
It is extra tragic to see that apparently, ECZAF almost made it through the worst of the weather when it crashed.
Again, PLEASE DO NOTE that much of the above is speculation, there is little confirmed information available.
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