Piper PA-31-350 accident at Tusayan, Arizona, 17 Aug 1983

Accident narrative

On August 17, 1983, Las Vegas Airlines Flight 88, a Piper PA-31-350, crashed into the west wall of a mesa inside the Grand Canyon in Arizona. The scheduled sightseeing flight had departed North Las Vegas Airport for the Grand Canyon National Park Airport in Tusayan, Arizona. The pilot and all nine passengers were killed, and the airplane was destroyed by impact and post-impact fire.

**The flight**

Flight 88 was the second of five Las Vegas Airlines airplanes scheduled to conduct Grand Canyon tours that day. The pilot, a 48-year-old retired military pilot, had accumulated 8,053 total flight hours, including 1,732 hours in the Piper PA-31-350. The nine passengers aboard were Italian nationals.

The preferred tour route took flights south over the Las Vegas strip, east over Hoover Dam and Lake Mead, across the Shivwits Plateau, and then into the Grand Canyon to follow the Colorado River to Tusayan. The flights operated under visual flight rules (VFR).

**Sequence of events**

Flight 88 departed North Las Vegas at 1142 p.s.t. At 1148, the pilot contacted the Las Vegas Flight Service Station to activate his VFR flight plan. The station advised him of a convective SIGMET for Arizona, reporting embedded thunderstorms moving north with maximum tops to 38,000 feet. The station also informed him that another departing aircraft had been unable to maintain visual conditions below the clouds and had broken out.

En route, the company pilots communicated with each other on discrete radio frequencies to discuss weather and routing. Flight 88 passed the first company airplane, Las Vegas 33, near Temple Bar, Arizona. Over Sandy Point, the pilot of Flight 88 reported proceeding north to avoid a rain shower. Shortly after, he reported entering the Canyon west of the Shivwits Plateau.

In a radio exchange with Las Vegas 33, the pilot of Flight 88 stated that the weather looked bad to the north on the Shivwits Plateau and that he was heading south to the Colorado River. Flying at 5,000 feet, he began calling out radials from the Peach Springs VORTAC. He then transmitted that he was just short of Twin Peaks, but could not see them yet.

The last transmission overheard from Flight 88 was, "Its getting too bad in here, I'm getting out." The pilot of Las Vegas 33 attempted twice to contact Flight 88 to suggest an alternate route north of Mt. Dellenbaugh, but received no response.

Another company airplane, Las Vegas 19, was flying in the Canyon ahead of Flight 88. Its pilot reported that cloud cover south of Twin Peaks precluded visual flight, prompting him to climb in visual meteorological conditions between cloud layers to 9,000 feet before reentering the Canyon further east.

Flight 88 crashed at about 1227.

**What the investigation found**

Company pilots searching for the missing airplane found the wreckage the following day on the west face of a freestanding mesa on the eastern shore side of the Colorado River, about 66 miles from the Grand Canyon Airport.

Initial impact occurred in a crevasse on the vertical face of the mesa wall, about 160 feet below the rim. Impact marks indicated the airplane struck in a near wings-level attitude on a north-northeasterly heading. The main wreckage fell onto a talus slope about 200 feet below the initial impact point. An airspeed indicator recovered from the site indicated about 170 knots, and a vertical speed indicator showed an ascending vertical speed of about 2,000 feet per minute.

The National Transportation Safety Board found no evidence of pre-accident failure or malfunction of the airplane's structure, flight controls, or powerplants. Maintenance records showed the altimeters had been replaced and tested two days before the accident. An altitude encoder had also been replaced but not calibrated with the transponder; however, the Board noted this lack of calibration would not have affected the accuracy of the altimeters.

Reviewing the weather, the Board noted that radar overlays from 1230 showed the northern edge of a cloud system with light to moderate rain showers over the accident site. A helicopter pilot flying 14 miles north of the site reported that clouds were "literally rolling along at ground level, which was 4,500 feet." The Board noted that clouds at 4,500 feet would obscure both rims of the Canyon.

The Board analyzed the pilot's radio transmissions. Shortly before his final call, the pilot indicated he was just short of Twin Peaks. However, the accident site was located about 20 miles southwest of Twin Peaks. The Board concluded that the pilot probably misidentified his position. Had he actually been in the area of Twin Peaks when he decided to abort the flight, the flightpath he selected to climb out of the Canyon probably would have enabled the airplane to clear the rim. Because he believed he was near Twin Peaks, he likely did not consider alternate courses of action. Instead, from his actual position, the selected flightpath took the airplane into the face of the mesa. The Board found it probable that the pilot was not operating clear of the clouds when the airplane struck the terrain.

**Probable cause**

The National Transportation Safety Board determined that the probable cause of this accident was "the pilot's failure to maintain adequate visual flight references to positively identify his position while flying below the rim of the Grand Canyon which resulted in his selection of an inappropriate flightpath and subsequent collision with the terrain during an attempt to climb in instrument meteorological conditions to a safe altitude above the rim of the Canyon."