Friday, January 12, 2007

Accident of the Week

This week's accident deals with the danger of inadvertent VFR flight into IMC at night.
NTSB Identification: DFW07FA049
14 CFR Part 91: General Aviation
Accident occurred Tuesday, January 02, 2007 in Armstrong, TX
Aircraft: Cessna 172H, registration: N3940R

Injuries: 3 Fatal.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On January 02, 2007, at 2035 central standard time, a single-engine Cessna 172H airplane, N3940R, was destroyed upon impact with terrain following an in-flight encounter with weather while maneuvering near Armstrong, Texas. The non-instrument rated private pilot and his two
passenger were fatally injured. The airplane was owned and operated by a private individual. Night instrument conditions prevailed in the vicinity of the accident for the personal flight conducted under 14 Code of Federal Regulations Part 91. A weather briefing was received and no flight plan was filed for the 371-nautical mile night cross-country flight. The flight originated from the Mid valley Airport (T65), near Weslaco, Texas, at approximately 2010, with Jacksonville, Texas, as the flight's intended destination.

According to preliminary data received from air traffic control (ATC), the flight started receiving VFR traffic advisories from Valley Approach Control soon after departure and was established in cruise flight at 3,500 feet. At 0825, the pilot requested to change the flight's destination to the Hallettsville Municipal Airport (34R), near Hallettsville, Texas, to refuel the airplane. Abou
t 7 minutes later, at approximately 2032, the pilot reported that he was descending to 2,500 for avoid clouds at his altitude. A few seconds later ATC advised the pilot that they were showing him at 1,700 feet and asked him if he needed assistance, to which he replied affirmatively and stated that he needed to turn to the south. The pilot was also told by ATC that the Armstrong Airport was located 6 miles to the northwest of his location. Radio and radar communications were lost at that time.

The pilot of a twin-engine Cessna 421 that was on an IFR flight plan in cruise flight in IMC at 5,000 feet on a flight from Harlingen to Corpus Christi, also monitored the radio transmissions between ATC and the pilot of N3940R. He was initially asked by ATC to attempt to establish radio contact with N3940R to no avail. He was then vectored to the last radar position of the airplane and was cleared to descend from 5,000 feet to 2,000 feet in an attempt to locate the missing airplane. The Cessna 421 pilot reported that there were multiple broken and overcast layers in the area, and the tops of the overcast were unknown. He added that at 2,000 feet, his airplane was "in and out of a broken layer of clouds." He reported that it appeared to be clear to the south of the area were the airplane disappeared, with visibilities in excess of 10 miles.

There were no reported eyewitnesses to the mishap. The wreckage of the airplane was located by the crew of a law enforcement helicopter within an hour of the mishap. The wreckage of the airplane was found on a private ranch, approximately 46 nautical miles north of the flight's point of departure. There was no fire.

All of the aircraft components were located at the accident site. Flight control continuity was established to all flight controls. The wing flaps were found in the retracted position. The examination of the airframe and the engine at the accident site did not disclose any mechanical
problems.

The transcripts from the weather briefing provided to the pilot, as well as of the pertinent communications (and radar data) between ATC and the pilot, have been requested.

The pictures show that the impact was devestating, shattering the airplane into numerous pieces:


(Images from www.kristv.com)

It's often said that accidents are the results of a series of events, any of which -- if changed -- could have resulted in the accident not happening.

The accident pilot chooses to make a flight at night. He elects not to file a flight plan. That decision doesn't appear to contribute to the cause of the accident. The PIC does obtain flight following and is therefore talking to ATC.

The pilot did the right thing and obtained a pre-flight weather briefing. We don't yet know what he was told about prevailing conditions. But, given that the nearby Cessna 421 reported bring in IMC at 5000', we can assume that the accident pilot was informed of an overcast sky somewhere at least as low as 5000'. That's significant, because it means any moonlight from the full moon prevailing that evening would have been obscured by the overcast. Night flight with overcast is like being in IMC even outside the clouds. Review this AOPA article if you're a member.

The report is a big unclear in how it reports the sequence of events, probably because radar tapes haven't been fully analyzed. But it recounts that the pilot advises that he was descending "to" 2500' to avoid clouds. But then, "a few seconds later," ATC advises the pilot that he is at 1700'. So, that's a descent of at least 800 feet in only a "few seconds." Even if was only ten seconds, that translates into about a 5000 FPM descent rate. Sounds like a possible spin resulting from lost of control, ne c'est pa?

The preliminary examination shows no anamolies with the engine or airframe. By all accounts, this appears to be a in-flight loss of control. So, it doesn't look like there are all that many places that the chain of events leading to this accident could have been avoided. Perhaps the only chance was to help the pilot realize that the weather conditions were much more challenging than he appears to have perceived.

News reports indicate that the accident pilot was a youth minister and the passengers were two teenage members of the congregation. That's tragic. Interestingly, one report indicates that the pilot had flown to South Texas to have dental surgery in Mexico. Certainly, if that's accurate, attention will have to be paid to the question of whether the pilot had fully recovered and the potential of the surgery to adversely affect his aeronautical decision making. Another report indicates that the pilot had taken the teenagers to Mexico to talk about missionary work there.

Folks, be careful when you fly at night. Especially if you aren't instrument rated and comfortable on the gauges, make sure that you're night flight doesn't bring you close to tangling with weather.

1 comment:

TJ Hunter said...
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