‘Spatial disorientation’ caused Carnahan crash

 - April 16, 2008, 6:16 AM
The NTSB recently released its final report on the airplane crash that killed Missouri Gov. Mel Carnahan, his son Randy Carnahan (the pilot of the aircraft) and campaign aide Chris Sifford.

The Board determined that the probable cause of the accident was the pilot’s failure to control the airplane while maneuvering because of spatial disorientation. Contributing to the accident were the failure of the airplane’s primary attitude indicator and the adverse weather conditions, including turbulence.   

Cessna 335 N8354N was registered to Randy Carnahan’s law firm and had 2,299.4 total hours on the airframe. The younger Carnahan was flying the twin Cessna on an IFR flight plan in night IMC under FAR Part 91. The aircraft departed from St. Louis Downtown Airport (CPS) in Cahokia, Ill., on a trip to County Memorial Airport (EIW) in New Madrid, Mo.

According to ATC transcripts, on Oct. 16, 2000, at 1902 local time the pilot contacted East St. Louis Ground Control and requested an IFR clearance to EIW. He was cleared as filed, and the tapes indicate nothing unusual until 1920, when the aircraft was en route and the pilot said, “Five four November, we’re having some problems, uh, with primary attitude indicator; we’d like, uh, little bit…higher climb.”

The controller responded that he would be able to issue him a higher altitude “in about two miles.” The controller asked the pilot to state the airplane’s altitude and was told, “We’re at three thousand six hundred.” The controller responded, “Okay, the, uh, assigned altitude was two thousand six hundred, but climb and maintain four thousand.” The pilot responded, “We got our hands full right now.”

Less than a minute later the controller asked, “Uh roger, you in some sort of difficulty?” The pilot responded, “We got a primary attitude indicator that’s not, uh, reading properly; having to try and fly off of copilot.” The controller advised him to try to fly the airplane level on any heading and told him that he would try to get him to as high an altitude as possible. The pilot responded, “Appreciate it.”

The controller then told the younger Carnahan to fly “straight ahead” and said he would get him to VMC. Seconds later the controller instructed him to climb to and maintain 4,000 ft and to “let me know when you get on top.” The pilot acknowledged this instruction.

A pilot in the area at 5,000 ft reported he was not on top of the clouds, causing the controller to tell Carnahan, “I don’t have much hope for getting you on top, uh, people say it’s like about twelve five [12,500 feet].” The pilot replied he wanted to head toward Jefferson City (Mo.) Memorial Airport (JEF) because he understood that the weather conditions were better there.

The controller then asked him if his “instrument” was showing a heading of 150 deg, and the pilot responded, “Well the compass is showing due south one eight zero.” The controller instructed Carnahan to turn to a heading of 120 deg, and he acknowledged the instruction. There were additional interactions between the controller and the pilot, who reported continuing “attitude problems.”

ATC radar data indicated the airplane’s altitude had reached 7,400 ft and that the Cessna had entered a left turn to the southeast. The data showed that the airplane then descended slightly and that its altitude varied between 7,000 and 7,200 ft.

At 1929 the pilot said, “We’re gonna need some vectors somewhere where we can get down [to] VFR [conditions].” The controller said he would check around for other weather conditions and that, in the meantime, the pilot should “just go straight ahead…doesn’t make any difference what direction that is, just go straight ahead.”

At 1930 the controller told the pilot that the weather at Columbia (Mo.) Regional Airport was 7,000 ft overcast with seven miles visibility in light rain. The controller told the pilot that the further west he went the better the weather was going to be. He then asked the pilot if he wanted to head west and the pilot responded, “That would be great.” This was the pilot’s last transmission.

The controller then told the pilot to “make a slow right turn as much as you can the standard rate…as much as you can to make this a stabilized affair.” ATC radar data showed that after this instruction was issued, the airplane entered a right turn. ATC radar data further showed that at 1931 the airplane had descended to approximately 6,500 ft. The controller told the pilot to stop the turn and to fly straight ahead but received no response. At 1932 the controller transmitted, “November three five, uh, five four November, radar contact lost.”

The accident site was located in a heavily wooded area near Hillsboro, Mo. The impact created a crater that measured approximately 10 ft long by five feet wide and was approximately four feet deep at the center. There was no evidence of an in-flight fire or in-flight structural failure.

Randy Carnahan, 44, held a commercial pilot certificate with airplane multi-engine land and instrument airplane ratings, and a private pilot certificate with airplane single- and multi-engine land and single-engine sea ratings. The pilot’s estimated total flight time was 1,829.7 hr including about 735 hr of multi-engine and 513 in type. His estimated total night flight time was about 460 hr, and he had an estimated total actual instrument flight time of about 87 hr.

He held a valid FAA second-class airman medical certificate, and, according to his personal physician, was in “excellent health.” There was no evidence that medical issues, pilot fatigue, drugs or alcohol contributed to the accident.

The NTSB determined that the pilot received current and adequate weather information before conducting the night flight in known IMC and that there was turbulence and rain in the area. The pilot was properly certified and qualified to operate the aircraft, but because the pilot made no pilot logbook entries during the six months preceding the accident, it could not be determined if he met the instrument currency requirements to act as PIC in IMC.

The airplane was properly certified and equipped, and it was further determined the airplane did not experience an in-flight electrical failure. Examination of the airframe and engines did not reveal any preexisting mechanical failures or malfunctions in the structure or powerplants.

Radar data, ATC transmissions and other evidence indicate that the pilot lost control of the airplane at 7,700 ft as he was making a climbing right turn. Examination and distribution of the wreckage revealed that the airplane remained intact and was in an upright attitude when it contacted trees at a velocity exceeding 300 kt before hitting rocky terrain.

The pilot indicated to ATC several times that he was having problems with the airplane’s primary attitude indicator. He also told ATC that he was trying to use the right-side attitude indicator, which indicates that the airplane did not experience a total vacuum system failure.

Examination of the wreckage revealed rotational marks in the left- and right-engine vacuum pumps, indicating that they were most likely functioning on impact. Further, one of the vacuum gage system failure indicator buttons exhibited evidence of having been in almost the fully retracted position (the other indicator button was found in the partially retracted position), indicating that adequate vacuum existed for the airplane’s instruments to operate.

On the basis of the examination of the left-side (primary) attitude indicator, it was determined that the rotor was most likely spinning, but not at a high enough rpm to keep the display erect (the wreckage fragments of the left-side attitude indicator clearly aligned in an inverted attitude), revealing that this attitude indicator was not displaying properly on impact. Although the pilot reported that his primary attitude indicator had failed– and examination of the attitude indicator supported that report–the investigation could not determine the cause of the failure in that instrument.

After an examination of the right-side attitude indicator, it was concluded that the rotor was spinning, the display was erect when the airplane made initial contact with the trees and the attitude it displayed was consistent with the airplane’s attitude when it struck the trees (as determined by an inspection of the accident site and a 3-D model of the airplane’s flight path through the trees). These findings indicate that the attitude indicator was functioning properly until impact.