VFR Flight at 7,000 MSL

[Bill]

I was just looking at the NTSB Preliminary Accident Report on the Cherokee accident that claimed the lives of the Oklahoma State women's basketball coach and three others. One thing that puzzled me was, "Radar data showed the airplane level at 7,000 feet mean sea level on a southeasterly heading." Why was an experienced CFI flying at an IFR altitude while operating as a VFR flight? "Visual meteorological conditions prevailed for the flight, which operated without a flight plan." The accident occurred in Arkansas, so the plane was more than 3,000 feet above the surface.

I image that we'll never know, since there frequently isn't enough data in these kind of accidents to reach a probable cause, but it has me wondering.

[Mike M]

mightabin uperdown for a bit above or below a cloud, mightabin altimeter mis-set, mightabin above the bump layer and sorting out what to do next, mightabin a lot of things. the terrain in the impact area was over 5000' below that altitude, how would being 500' off VFR hemispherical cruise rules have affected the outcome?

[Joe Delene]

Maybe he was in some type of slow descent? Of course 500' of altitude difference wouldn't matter. I think he's just saying most would of been at a proper VFR altitude.

[steveinindy]

since there frequently isn't enough data in these kind of accidents to reach a probable cause

I wouldn't say "frequently". I believe the percentage of cases that are left "undetermined" is in the single digits most years.

[Dana]

Preliminary NTSB report

Not in the NTSB report, but the NY Times reported the pilot as being 82 years old... a medical issue perhaps?

[steveinindy]

Preliminary NTSB report

Not in the NTSB report, but the NY Times reported the pilot as being 82 years old... a medical issue perhaps?

It's not mentioned because the toxicology results are still pending most likely. I'd guess it unlikely given that less than 5-10% of GA crashes are due to medical issues. Maybe they were just looking at something on the ground and he stalled the plane in. It's cases like this that make me wish there were CVRs at a minimum (preferably in concert with a FDR) on GA aircraft. Given the press attention this crash received, it's likely that if they found something glaringly apparent on the gross at autopsy (heart attack, stroke, etc), it would have already been reported in the press.

[Bill]

I wouldn't say "frequently". I believe the percentage of cases that are left "undetermined" is in the single digits most years.

That is true for the entire set of accidents that occur in a year. But for the cases where there is (unfortunately) no CVR data, no mechanical factors ascertainable from the wreckage, nor any witnesses whose observations can shed light on the causal factors for the accident (in this case, while there were witnesses, "Witnesses who were in the vicinity of the accident site reported that the airplane was flying at a low altitude and making turns. They then observed the airplane enter a steep nose-low attitude prior to descending toward the terrain." Their observations, at first glance, seem unlikely to shed light on the accident cause), I expect that the percentage of "undetermined" is significantly larger and could be considered frequent. One of the airplanes that I used to fly crashed in August, 2010, killing the pilot. Even with witnesses, the probable cause is still undetermined and, given the paucity of data, I would be surprised if there ever is a probable cause determination.

[steveinindy]

"Witnesses who were in the vicinity of the accident site reported that the airplane was flying at a low altitude and making turns. They then observed the airplane enter a steep nose-low attitude prior to descending toward the terrain." Their observations, at first glance, seem unlikely to shed light on the accident cause

It sounds like they descended to look at something on the ground, circled around it and stalled out into the ground. I'm a big believer in the Occam's razor approach to aviation accident investigation: the simplest answer is the one most likely to be correct. In this case, given a description of a nose drop and barring the discovery of the pilot being drunk, high or some form of significant mechanical issue, the most plausible explanation is a stall. It might not be PC to "blame the pilot" but the truth isn't always pleasant.

One of the airplanes that I used to fly crashed in August, 2010, killing the pilot. Even with witnesses, the probable cause is still undetermined and, given the paucity of data, I would be surprised if there ever is a probable cause determination.

Which crash was that?

[Bill]

Maybe he was in some type of slow descent? Of course 500' of altitude difference wouldn't matter. I think he's just saying most would of been at a proper VFR altitude.

The NTSB said, "Radar data showed the airplane level at 7,000 feet mean sea level on a southeasterly heading. At 1610:49, the airplane entered a right turn and began descending. The airplane disappeared from radar shortly after. There were no reported air traffic control communications with the airplane." I, perhaps wrongly, interpret that to mean the aircraft was level at 7,000 MSL for a significant period of time prior to the descending right turn. Therefore, I thought that he should have been at 7,500 MSL for the level portion of flight under VFR.

But we shouldn't read to much into a preliminary report that may well be significantly modified or expanded when the final report is released in a year or more.

[Dana]

Witnesses who were in the vicinity of the accident site reported that the airplane was flying at a low altitude and making turns. They then observed the airplane enter a steep nose-low attitude prior to descending toward the terrain....The initial ground impact scar was consistent with the airplane’s right wing leading edge contacting the ground first. An impact crater, about 10 feet in diameter and about 3.5 feet deep contained most of the airplane. Ground scars and witness marks to trees surrounding the accident site were consistent with the airplane being in a steep nose-low attitude at the time of impact.

Certainly sounds like a stall/spin. The report doesn't say whether the engine was running at the time of impact, or whether there was a post crash fire (which would make medical analysis difficult). Why he descended is a good question; you don't generally descend from 7000' (ground level is around 600' in that area) for no reason.