I drove past the crash site at about 15:05. The weather was 8/8 clag to the deck. I was on my way back from work and had been surprised all day that the freezing level was well above the safety altitude in that area. Surface temp was around 7-8 degrees and I had 3 at 2 400'.

I fly that area most days and often find visibility/cloud base around the ridge area can be far lower than the Benson area due to orographic effect. I flew 4 ILS on Sunday in different parts of the country, and three of them within 30 miles of the crash site were to minimums.

SND

It's by the by but my AFE VFR guide shows 13/31 as the only active runway at Chalgrove yet we seem to assume 24 in this case?

Is the PA30 injected or carbbed? I'd expect something mechanical will come into play, highly doubtful a vastly experienced guy is going to try and make a short 23 mile hop into a field with no published approach with the fog down to the deck and high ground around it.

Pretty sure it's fuel injected

It is injected - Lycoming IO-320.

It would be interesting if you would list some. I think the circumstances are often misunderstood.

The Graham Hill accident is a fairly good example. It is somewhat misleading to think of it as a homemade approach procedure.

It seems to have been standard practice to receive radar vectors on to final approach and dead reckon from there. Hill's Aztec was vectored to 4 miles and a height of about 1150 ft aal. There was an AOC holder authorised to operate into Elstree with an MDH of 550 ft and a visibility of 1750 m, apparently on that basis. Had Hill stuck to that MDH before positively identifying Elstree then the night would have ended differently.

I would wager that the majority of CFIT accidents on approach involve a loss of visual reference on the visual segment after leaving MDH (for example by misidentifying lights) rather than a collision with a known obstacle on the instrument segment. If you descend below the level of obstacles in your immediate vicinity without visual reference, the results are predictable. It doesn't really matter whether or not the approach is published. The key discipline is setting a minimum and sticking to it.

I guess we'll have to wait until the AAIB report to find out what really happened near Chalgrove that day.

I have the impression there have been several business jet accidents in Germany and IIRC a Jetprop in Austria that likely resulted from 'Visual' approaches to land in indisputably IMC conditions.

I find this accident completely perplexing. Anyone who flies in that part of the country is surely very, very aware of the Chilterns and, in particular, Stokenchurch mast? The latter is just so famous that I cannot believe that any local pilot cannot be aware of its existence.

What do I know about the area? I was posted in to Benson as a young sprog Argosy pilot in 1962. (My last Argosy flight from Benson was in 1971).

During that time I got involved in the Benson (Chilterns) Gliding Club in my spare time and ended up as the CFI. In fact, I completed the 5-hour duration part of my Silver 'C' in an Olympia 2b sailplane (RAFGSA 232) on Chinnor ridge on 06.09.64. During those five hours I just about got to know every tree!

In those days, we used to take a winch up to a field very close to the old Chinnor cement factory chimney and launch from there. In later days we would co-operate with the gliding club at Booker (I was a good friend of their CFI [NS] and the farmer, and we would aero-tow out of one of our friendly farmer's fields with a Super Cub.

So, why am I telling you this?

I am simply trying to tell you that, as someone who is intimately familiar with the crash site, I simply cannot imagine how he ended up where he was.

Perhaps the game plan was to fly south until 3 miles east abeam Chalgrove then a right turn onto final for the westerly runway or a modified base for the Northwesterly one but low viz prevented the turn pushing him into the higherground and lower bases.

I've driven down to London a few times many years ago and just past Oxford turn off there is a definitive break in the landscape that looks odd, where the highway has a dip then a climb into a densely forested area that's seems kind of out of place in comparison to what you have been driving thru till the dip. Is this the accident area?

Yes, that's the accident area. Although the mast is easily the highest point for miles around (and sets the MSA for the area), it's only just over 300' higher than the terrain surrounding it.

I'm inclined to agree with those that saying that, mechanical failure excepted, the pilot can't have been where he thought he was. I wonder what was being used for navigation at the time? Certainly wouldn't have been visual in the local Wx as reported by others.

Do birds fly in IMC? The ridge is home to hundreds (literally) of Red Kites; they weigh in around 1kg so could do some serious damage.

Seems nobody on here has even considered the possibility of pilot incapacitation.

Indeed

So many questions and 'wotifs'.

Perhaps the AAIB should be disbanded and all accident investigion left to the speculating experts of PPrune!

Well that didn't take long, it normally takes till about page 5 before us annoying, insensitive speculative buggers are met with the equally annoying "let's leave it to the AAIB" chorus.

There's much to be learned by all from the detailed discussion of the possibilities by more experienced, knowledgeable and qualified pilots. Even if those things prove not to be the cause.

Terry my dear chap - nobody is trying to be the AAIB and most of us have made that very clear. Are we all expected to have no opinion for the next 12 months?
We have some excellent restrained theories and observations, all made with the greatest respect. What on earth is wrong with surmising?
We have a 25 mile flight in a twin engined aircraft flown by a highly qualified pilot in dreadful weather which ended up in disaster. Perhaps we should discuss with the aforementioned respect. It may stop the same thing happening somewhere else.

I know nothing of Chalgrove, but people talk of various runways. That suggests an airfield and perhaps someone to have been phoned before takeoff to ascertain the weather. If it was as bad as posters report it does seem an odd decision to make such a short flight if there was small chance of landing. Is there any kind of IFR let down for Chalgrove, and one wonders what the pressure of the flight was?

I don't think there is a published Instrument Approach Procedure (can't see any plates for it in SkyDemon) for his destination field. As for an ad hoc homebrew procedure, others on here have suggested a nearby VOR and NDB could be used to fashion an approach but that carries enormous risks. And finally there is the option of utilizing another nearby fields published approach for cloud break then scud running back to Chalgrove. But based on the weather reports and terrain that also sounds like a very risky proposition.

I can confirm there is not. The UK AIP also shows it as VFR only. It's strictly PPR and the voice providing permission on the phone strongly stressed that point when I flew in there, as well as confirming the need to talk to Benson inbound.

If an emergency is declared would Benson accept an approach and landing from a GA aircraft, or would they provide a PAR/SAR or some kind of guidance into Chalgrove, again if an emergency was declared?