They where having problems before the approach
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20080422X00528&key=1
IFR flight plan and conditions prevailed.
It appears CARTWRIGHT JR, MARION HAMILTON (builder/pilot/owner) was a private pilot, with out an instrument rating. The other pilot in the plane, Robert Lloyd was a private instrument rated pilot. The other builder of the RV-10 is listed as COTTRELL, (M)ICHAEL STEVEN.
The report is very upsetting:
"The airplane deviated 400 feet above its assigned altitude and 1,200 feet below on multiple occasions throughout the last 14 minutes of the flight. The controller twice relayed low altitude alert warnings to the pilot. The pilot did not declare an emergency to the controller at any point during their conversations."
[400 feet is significant deviation en-route; of course on approach 40 feet could get you in trouble. "1,200 feet multiple below on multiple occasions" means they where having some problem.]
Initially cleared to VOR RWY 18 approach to (EUF) Eufaula:
"The pilot then explained to the controller "We may, I think we are not going to fly the whole approach here, I think we'll let you know when," and further stated "We're going to have to come up with an alternate plan here."
[It sounds like an unwillingness to fly an IFR approach, at least not fly a VOR approach.]
The ask for a diversion about 42 miles NNW
"The pilot then requested, and was provided, vectors to Auburn-Opelika Airport (AUO), Auburn, Alabama. While en-route to Auburn, he amended his request and instead asked for vectors to Columbus Metropolitan Airport (CSG), Columbus, Georgia, stating that he required an airport with an ILS approach."
[Than they change plans to an airport 34 miles NNE of Auburn to get an ILS approach which seems reasonable. However AUO list an ILS as well. From EUF CSG is about 7 miles closer than AUO. So may be they wanted the closer airport.]
Something went really wrong:
"The controller subsequently provided vectors to Columbus (CSG) [ILS 6 I assume], and about 13 miles southwest of the airport, at an altitude of 2900 feet, the radar target began a sharp descending right turn. The target descended to 1,200 feet halfway through the turn, and then began a steep right climb. The last recorded radar target occurred at 1226 and was observed at an altitude of 2,600 feet. The wreckage was located approximately 400 feet east of the location where the final radar target was observed, at an elevation of 270 feet."
"At 1251, the weather reported at Columbus, included overcast clouds at 1400 feet, and 7 statute miles of visibility in mist. The winds were 080 degrees at 8 knots. The temperature was 18 degrees Celsius and the dew point was 14 degrees Celsius. Rain began 35 minutes past the hour and ended 44 minutes past the hour."
[I have no idea what happened and will not speculate.]
Some personal thoughts with my CFI cap on, RV's are very fast slick planes. They can develop huge speed very quickly when pointed towards the ground. VFR or IFR rated get a safety pilot or CFI and practice unusual attitudes under the hood, often. While you are at it, throw in some stalls including accelerated stall recoveries under the hood. That sluggish slow Cessna has some advantage in IMC. On one hand low drag with fast accurate control response of a RV is great. On the other hand it can be an adversary in IMC if you are not current and on top of the plane.
I flew my old RV-4 IFR, no autopilot. I have to admit, I never was totally comfortable in the RV-4 when solid IMC. I realized if I screwed up and got distracted I could end up near Vne and inverted pretty quick in clouds. That never happened but did concentrate when it was for real; I was never real totally relaxed when in solid IMC with the RV-4. An autopilot when single pilot IMC in a RV of course is a great help and the common wisdom, but it's no substitute for PIC skill and currency.
Early Mooney's had an issue of being a handful, single pilot IFR, so some models came standard with a
full time wing leveler. You had a disconnect button on the yoke to press to turn the stability helper (wing leveler) off to turn the plane, but if you let go the stability augmentation button (autopilot), it leveled the wings.
If you get into IMC, even if you are IFR but not current or practice in airplane type, its an emergency or can be. Just because you can fly IMC in a C-172 does not make you IFR qualified in a RV. Just admit it to ATC and declare an emergency. Just do it. Don't worry about getting in trouble. Say you are having a hard time flying the plane and need vectors to VFR weather. Be safe. RIP and condolences to the family.