Well, the accident crew must have had some reasonable expectation of getting away with it, going VFR into IMC.

There have been a couple of similar accidents at Egelsbach, near Frankfurt am Main, so that it's not that unusual a thing to see happen, a bizjet crew hitting obstructions while trying to make it into a place without aids or even one with weather below minimums. You try it and get away with it, you are an ace; you divert, you are a putz, so ....

There was even a profile of an ex-CEO of a big German manufacturer that showed him boasting about how his crew made it into someplace or other when lesser mortals were all forced to divert because of bad weather, due to the force of his personality. The point was to show what a hard charger the CEO was, and this was in a mass-circulation non-aviation magazine so that his sheer stupidity went unremarked. (I think it was a guy running Daimler-Benz, profiled in Stern, certainly not the incumbent. I might have those details wrong; it was a while ago that I read the article, when it caught my eye since I am a pilot.)

Before we condemn the pilots I noticed that one of the local newspapers noticed a large number of birds around the aircraft and concluded they had been pheasant shooting in the UK? I had seen the UK chart earlier and it did not seem like pheasant shooting weather to me. Perhaps this is a clue, as I had seen a large number of ducks in the area a few days before flying in formation.
As for a GPS approach High voltage power lines in fog generate a large amount of interference. In hindsight a safe look at the conditions knowing a safe diversion airfield is in reach, and next thing all the holes in the cheese line up fast.

F900 EX
I initially have spend some thoughts to that possibility of a self braided GPS procedure.What doesn´t fit as I see it is the fact they where at field elevation 2 NM prior target coordinates. At the same time off the centre line by about 700 m.
Hard to believe that an experienced crew would fall for such faults. And GPS is in generell a much too precise device for navigation.
JGBC
Kind of honest try that should be appreciated to point towards the possibility of a multiple bird strike. The mystery of the many reported pheasants around the wreckage might be lifted. However what speaks against a birdstrike is the fact that part of the right wing was located on the pole they hit.As one can see on div. Foto of the inverted wreckage the right wing and gear is missing.

I believe, as was mentioned by others, most likely the "big boss" in the rear of the plane wanted them to try. Probably they got a glimps of the Autobahn and tried to follow it. The tricky part of that idea is, the Autobahn follows the valley of river Salm and one has to swing to the right to get onto final. The impacted power pole stands on a terrain step that rises roughly 150 ft from the valley floor. Terrain elevation at crash site is comparable to that of the airport.
Though we will not know what actually made them take that decision, the fact they were that low so early in approach doesn´t leave much different possibilties. Especially if one considers what ATC Watcher wrote in his post about the fog situation.
Jo

Birds congestion around garbage landfills are very common. However most birds have a stronger conservation instinct than humans and they do not fly in formation in Fog. Certainly not ducks. And birds do not Fly VFR on top either. So I do not believe bird strike was a factor, but , seen the wreckage, the investigation surely will detect if it was.

But the decision to enter a dense fog layer so close to terrain for a VFR/Visual APP is the primary cause.

A German news agency (Sueddeutsche Zeitung Newsticker) is reporting that the crew might have actually violated aviation rules by cancelling IFR flight plan and changing to VFR for a destination without VMC.:ugh:

Flying VFR under IMC is a basic tenet that I was constantly reminded of when I started my PPL training. It is hard to believe that some pilots out there put their lives at risk by not observing this simple rule.

WP

WP, most likely they were VMC the time they cancelled. Their destination wasn´t.

If it was fog or low cloud no amount of home made GPS approach accuracy would make any difference!
It would not matter if there was an ILS on the field unless the pilot was prepared to go below minima.
No pilot should use GPS on its own! In my piston twin days I used to operate into an airfield with terrain around. There was an NDB and a DME but no approved approach.
I overlayed a GPS approach over the NDB/DME used the GPS for precision and the NDB/DME as well a a RadAlt to confirm the GPS.
Just to use GPS would be very foolhardy.
More likely with areas being in the clear that the pilots were flying in visually and seeing cloud ahead made some mistake on their location especially if you think you know the area well.
That fact alone will make a pilot less cautious but more prone to a serious mistake.
Hence why Graham Hills crash came to mind as he misidentified visually albeit at night where he was and continued beleving he knew where he was on an approach he had made many times.

Pace

F900 EX
Fully agree with what you write about all the many faults that can slip into a normal operation. Humans tend to forget that human error is a very common desease.
WP
There is nothing wrong with cancelling IFR with that type of aircraft as long as one stays in VMC afterwards. Flying fully IMC into a landing site with zero Navaid or published Instrument Procedure is what makes the case illegal.

One other point that rises additional questions and came to scene in a local TV report this afternoon where the controller on duty was interviewed. Apparently neither a standard radio contact nor a hint they were trying an approach was made.
Jo

Annex 14 : Just a point of semantics , but there is no ATC in Trier, so no controllers. Just an AFIS run but the local flying school. But journalists ususally call them Controllers.

ATC Watcher
it´s not a case of semantics, just another case of human error and trying to relay a story 1 : 1.
You are of course correct, no ATC at Trier - Föhren and I should have known better!!
Jo

DFS statement yesterday: Airport only approved for VFR with 1500m visibility. Visibility at time of accident:100m

Full stop....

Well, in theory maybe. But we have quite a few GPS-only RNAV approaches here (I fly one of them once per week) where no other navaid is in useful range. Approved, official procedures.

From today's paper...
 

There's a picture of a high-tension mast with a large piece of Citation wing jammed into it, at about 30 metres (100 feet) AGL. In the accompanying article they speak of "pilot error."

I don't think Citations are usually equipped with FDRs or CVRs, so that there probably will not be much more than guessing about what the crew were saying and doing as they entered what was reported as 100 metres (330 feet) visibility under VFR, but it should be fairly easy to guess it was something on the order of "Expletive deleted" (sound of impact).

What a waste. Divert to someplace with suitable weather, let the pax take a taxi to Trier, and catch up with them later once the fog had cleared... what's wrong with that? Hindsight: it's a wonderful thing!

"Just to use GPS would be very foolhardy"

My airplanes approved to fly the North Atlantic just with 2 GPSes. Granted - no power lines there....

Anyhow, possibly you meant no pilot should use his DIY GPS approach ? That I would sign...

To split hairs further, visibility in Trier can be "measured" only by the pilot, nobody else. (unless there is an approved and calibrated VAISALA or the like installed)
Given the white I saw 1,5 hrs after the accident on Triers Webcam, the WX reports and the witness account - "we did not see the airplane but heard a jet noise and then a crash, it was very foggy" I´d say its save to assume the weather being very well below anything remotely close to VMC.

ATCwatcher hitted the nail on the head:

In this Video - at the very end - one can see the birds, pheasants, some of them in plastic bags. I guess we can discard the birdstrike theory....

Nach Flugzeugabsturz: Pilot hätte in Föhren nicht landen dürfen - Nachrichten :: Rheinland-Pfalz | SWR.de

What next : do not compare following a published RNAV APP with trying to get to a VFR field , buiding an APP on your own using a GPS .
For info the requirements to follow a published RNAV RNP 1 GPS APP procedure :
No single-point-of-failure can cause the loss of guidance compliant with the RNP value associated with a missed approach procedure. Typically, the aircraft must have at least dual GNSS sensors, dual flight management systems, dual air data systems, dual autopilots, and a single inertial reference unit.

His dudeness. Thanks for the link to the video. explains a lot ,if not everything , unfortunately.

Just a final remark, contary to what the Jounalist ( or the Trier Staatanwalt ) said , it is not against the rules to cancel IFR in this situation, i.e. you can always divert to another open VFR field, what is against the rules is flying VFR in IMC.

Are you sure on the "and" ?

My airplane has no IRS/U, no second A/P and is RNP compliant dwon to .3.

Sorry for the offtopic.

Same for me His Dudeness, although the statement does say "typically", and wondering if you have AHRS on your aircraft? ;-)

F/o

HD and FO : I am not sure, not being an expert on RNP APP and RNAV, but based on my doc ( for ATC) it would seem that the min requirements are what I said, the word " typically " is probably there as you can mitigate the non avail of some component(s) , e.g. . an IRU if you use DME/DME. But not sure.

From another book :
The RNAV system may be based on:
• DME/DME
• DME/IRU
• GNSS/IRU

Also maybe continent specific , in the USA , they use Ground GPS augmentation systems for instance.

The commentator in the video makes reference to a GPS unit that survived the crash. That said, it'll only show the flightpath.....