Final Report: Mountain wave downs Westwind

 - March 30, 2007, 1:19 PM

ISRAEL AIRCRAFT INDUSTRIES 1124A, TAOS, N.M., NOV. 8, 2002–The NTSB determined the probable cause of this accident was the pilot’s inadvertent flight into mountain-wave weather conditions while IMC, resulting in loss of aircraft control.

Examination of the airframe and engines did not disclose any structural or mechanical anomalies that would have prevented normal operation. The National Weather Service (NWS) had issued a sigmet for severe turbulence and mountain-wave activity. Satellite images depicted bands of altocumulus undulates and rotor clouds over the accident-site area.

The Westwind 1124, N61RS, was destroyed when it crashed after passing the initial approach fix while executing the VOR/ DME-B approach to Taos Municipal Airport (SKX). The aircraft was registered to Abrams Aviation of Auburn, Ala., and was operated by Richmor Aviation of Hudson, N.Y. Both ATP pilots–the sole occupants–were killed. VMC prevailed, and an IFR flight plan was filed for the Part 91 positioning flight, which originated from Las Vegas at 1:53 p.m. The airplane passed the Taos Vortac at 2:56:39 and 15,000 feet msl. Albuquerque Center controllers heard a mayday call, and radar contact was lost at 2:57:08 and 14,700 feet msl, with no further communication with the airplane’s crew. The captain and the first officer had completed Westwind recurrent training; the captain had 80 hours in type and the FO had 682 hours in type.

A witness heard distressed engine noises and saw a small jet flying overhead. Its engines seemed to be cutting in and out, and it “attempted to bank to the south as it dove down till my view was blocked by the ridge to the west.” An explosion and big cloud of smoke rising over the ridge followed. A second witness reported seeing a small white airplane with two engines, “which started to turn left with the nose of the airplane slightly pointing toward the ground,” apparently “trying to land on the road [U.S. 64].” The airplane appeared to be above the wires when it caught fire. Then “a cloud of dust rose up and blew away.” A third witness saw the airplane in a near-vertical descent hit the ground, and heard the engines “all the way to the ground, followed by a huge fireball and puff of smoke.”

Taos reported wind from 200 degrees at 12 knots gusting to 17 knots, visibility 10 miles, ceiling broken at 3,100 feet agl, temperature 7 degrees C, dew point -1 degree C and altimeter 29.92 inches.

The NWS warned of strong west-northwesterly wind flow across the mid and upper levels across the area, with occasional severe turbulence between 12,000- and 34,000 feet, with occasional moderate rime to mixed icing in the northern portion of the area between the freezing level and 24,000 feet. A sigmet for severe turbulence between 12,000- and 34,000 feet warned of strong updrafts and mountain-wave activity. Conditions were expected to continue beyond 5:45 p.m.

The cockpit voice recorder (CVR) transcript shows that before passing the initial approach fix, as flaps and gear were lowering, the first officer asked, “Do I have to shoot a procedure turn?” “Ah…I don’t know. Probably should,” the captain replied.

The captain called for power, and the GPWS cautioned repeatedly, “Bank angle.” Then the first officer called, “Mayday” repeatedly as the GPWS sounded, “Caution, terrain, terrain.” At 2:57:04, Albuquerque ARTCC radioed, “Aircraft calling, say again.” At 2:57:05, the first officer stated, “Unload it, unload it.” The recording ended at 2:57:08.

The accident site was approximately 18 miles northwest of Taos, at an elevation of 7,574 feet. Ground scars indicated that the airplane hit the ground left wing low at a slight nose-down attitude.