N186CB PA46 accident report

Peter wrote:

It was a DIY approach (descent navigation method unknown) into a VFR only airfield, in BKN003.

As I’ve written elsewhere, I think that’s a rather unfair characterisation of the accident. The aircraft departed Fairoaks at 1041 and the accident occurred at 1134. The arrival airfield was Dunkeswell, elevation 840 ft.

The 1100 SYNOP, which was not available to the pilot, reported 7000 BKN003.

The weather at Dunkeswell was given to the pilot at 1115 as “visibility to the north of the airfield is five kilometres, to the south-west its four kilometres, its overcast between eight hundred and a thousand feet, moderate rain, surface wind is one nine zero degrees twelve knots, their qnh one zero two four.” (i.e. an overcast base between 1640 and 1840 ft amsl)

Here’s the other weather from the day.

Exeter is 10 miles to the SW of Dunkeswell and elevation 100 ft

METAR EGTE 141150Z 21014KT 9999 -RA SCT020 BKN035 11/10 Q1022=
METAR EGTE 141120Z 20009KT 9999 -RA SCT020 BKN035 10/10 Q1023=
METAR EGTE 141050Z 21011KT 9999 -RA SCT018 BKN048 10/10 Q1024=
METAR EGTE 141020Z 22010KT 9999 RA SCT018 BKN048 10/10 Q1024=
METAR EGTE 140950Z 18008KT 9999 RA SCT018 SCT048 10/09 Q1025=
METAR EGTE 140920Z 17007KT 9999 RA FEW034 BKN040 09/09 Q1025=

TAF EGTE 140802Z 1409/1418 20007KT 9999 FEW015 SCT040
TEMPO 1409/1415 7000 RA
PROB30 TEMPO 1411/1415 BKN012
BECMG 1412/1415 23017KT
PROB40 TEMPO 1413/1418 24020G30KT
PROB40 TEMPO 1415/1418 7000 -DZ BKN008=

Yeovilton is 25 miles to the ENE of Dunkeswell and elevation 75 ft

METAR EGDY 141150Z AUTO 21010KT 9999 RA BKN045/// 11/09 Q1022=
METAR EGDY 141050Z AUTO 21011KT 9999 -RA FEW025/// BKN030/// 11/08 Q1024=
METAR EGDY 140950Z AUTO 22007KT 9999 -RA FEW043/// BKN050/// 10/08 Q1025=

The witness statements, not necessarily accurate, and the 1200 SYNOP, imply much lower cloud base?

IR training is quite weak on AP use. Some SOPs require you to use Control Wheel Steering if touching the control column, others to press AP disconnect when you go to manipulate the control column. None of this is ever covered in either basic IR training or the short period the examiner might want you to demonstrate AP use. Let alone all the other gotchas related to the AP.

Peter wrote:

There is some speculation on whether the pilot tried to override the autopilot – a KFC150 – and a loss of control resulted partly due to an out of trim condition

The way I read the report, this is not some speculation but the most likely cause and the loss of control was directly caused by the out of trim condition.

This is a very sad accident as it took out a whole family.

I have a certain urticaria about DIY GPS or Pseudo ILS approaches, but setting this aside, what would the correct MDA be for descending to acquire VMC at Dunkeswell? Is the GTN 750 in en route mode RNP 5 or 2? Without an IFR approach in the database LNAV sensitivity would be enroute?

RobertL18C wrote:

Without an IFR approach in the database LNAV sensitivity would be enroute?

Not necessarily. Provided Dunkeswell was the destination in the active flight plan, the GPS would automatically switch to 1.0 NM sensitivity when you get sufficiently close and you can anyway always set the sensitivity manually.

I have been to Dunkeswell but not for a few years. I dont recall what the disused airfield looks like. However, if I hadnt read the report, but just looked at the graphics, I would have thought this was intended as an entirely visual approach, and that the pilot or passenger saw an airfield out of the murk which they thought was Dunkeswell but realised it wasnt. I did go in once a poor conditions and well recall that the weather does seem to have a tendency to collect around the terrain there, whereas not many miles away it was a great deal better. It doesnt feel like the pilot was attempting a DIY approach. The radar plot doesnt entirely look like an aircraft flying on autopilot for much of the time.

I agree re DIY approaches.

Re GPS sensivity: anyway, these crashes never happen because the GPS lateral guidance is too coarse, but because people mess something up.

Bookworm, unusually for you, I feel you’re being bit selective with the information. Firstly, you’ve omitted:

At 1113 hrs, ATC passed the pilot the following unofficial weather observation from Dunkeswell: (My bold)

There’s also an earlier conversation:

At approximately 0930 hrs, the pilot, who was the owner of the aircraft, telephoned Dunkeswell Air eld to let them know that he was planning to y there and to enquire about the weather. He was informed by an air/ground radio operator that Dunkeswell had a 500 ft agl cloudbase, with rain. The radio operator recalled the pilot asking if the weather had been “coming and going in patches” and advising him that “it had been constantly raining throughout the morning”. The pilot replied that he would delay his departure and planned to arrive at Dunkeswell at about 1130 hrs.

Regardless, it can’t be realistically disputed that the actual weather conditions at the time precluded a sensible VFR recovery. Of course, we can argue about an interpretation of ‘sensible’. Equally, the radar data indicates that the aircraft did not descend to an unusually low height before pitching-up, although this is contradicted by some of the witness reports.

One other thought – there is an interesting occurrence on the MOR database involving the same type, from the same operating base, some weeks before the crash. The report refers to an unstable and dangerous low IFR approach. I wonder….

boscomantico wrote:

I agree re DIY approaches.

We also made a DIY non precision approach for our VFR base. We practice it with hood on from time to time. We think it can help us land home safely in marginal VMC. We never used it in IMC. We have EBLG a few miles away with ILS… and 150€ less in our pocket.
Anyway, with G1000 + SVT, it’s hard to get lost.