Because of 120- to 140-knot headwinds, two Circuit City Citations were making a refueling stop at Pueblo (Colo.) Memorial Airport (PUB), on Feb. 16, 2005, en route to California from Richmond, Va., the chain’s headquarters. One of the Citations, N500AT, crashed on the approach; the other landed without incident. Last month the NTSB released a wealth of factual information about the crash, which killed all eight people on board, but the Safety Board has yet to determine the probable cause of the accident.
Included in the release is the complete transcript of the cock- pit voice recorder (CVR), which reveals the pilots’ attempts to shed the ice the airplane had accumulated on the descent to Pueblo. (The captain of the other Citation said his flight was in and out of the clouds descending from 10,000 feet, picking up perhaps half an inch of rime ice. The de-icing boots were shedding it.)
The copilot of N500AT noted at 8:55:07 that the Citation V was picking up ice on the leading edge of the wings, “not the real white ice like we had yesterday; it’s more grayish.” He continued, “The descent accumulation comes a little bit different [from] the climb accumulation.”
The pilot agreed that it was “a whole lot faster in the descent than in the climb.” At 9:03:50, the copilot noted that one static wick on the aileron was vibrating. The controllers vectored the aircraft to the south briefly around a Skywest Bombardier Regional Jet. (The RJ captain reported ice accumulation at 8,000 feet.)
At 9:09 the Citation copilot noted the ice was different, clear. The pilot said, “Open up those valves all the way.” As they were cleared for the approach and the glideslope came alive, the copilot noted, “Ignition is on with the anti-ice; now it’s on for sure.” At 9:11:10, the pilots lowered the gear, then the flaps. At 9:12:37, the copilot said, “I don’t know if you want to run your ice a little bit. You got the Vref there.” Then the CVR picked up the warning, “Bank angle, bank angle…bank angle.” The Citation crashed at 9:13, four miles from the runway.
After the accident airplane was cleared to land, the sister ship heard the controller issue a low-altitude warning of about 4,900 feet, which was not included on the CVR transcript. There was no response from 500AT.
The PUB automated weather system reported eight knots of wind; eight-mile visibility; broken at 900 feet, overcast at 1,400 feet, temperature -3 degrees C, dew point -5 degrees C; remarks: ceiling varying between 700 and 1,100 feet. An airmet forecast occasional moderate rime ice and/ or mixed icing in clouds and precipitation to 22,000 feet.
The Citations were owned by Circuit City and managed by Martinair, which employed the two pilots. The sister-ship captain had flown the accident airplane the day before and reported no maintenance problems. The pilot’s body contained Metoprolol, a beta blocker medicine used to treat high blood pressure and angina.
Included in the information released was a 1996 memo from Carlos Blacklock of the Wichita Aircraft Certification Office that discussed five recent Citation accidents involving three different models. A Model 560 crashed on a nonprecision approach at Eagle River, Wis., on Dec. 30, 1995, with minimums of 700 feet, with a 300-foot overcast.
The next day a Model 550–also on a nonprecision approach–crashed at March Island, Fla.; the pilot descended too low and hit a tower. The crash of a Model 500 at Ensenada, Mexico, on Feb. 6, 1996, involved an approach to landing in mountainous terrain with zero-zero visibility reported. A local pro- cedure involved letting down through the overcast over the ocean and proceeding to land visually.
In Salzburg, Austria, and in Augsburg, Germany, Citations appeared to have stalled or otherwise departed controlled flight on final approach, and icing may have been a factor. The flight crew of an Ultra that crashed in Germany reported ice accumulation, but the ice protection systems were not on or activated during descent. The airplane experienced an aerodynamic stall and roll to the right. Cessna made changes to the flight manual in 1996 to address the icing and freezing-rain issues.
After the Circuit City accident, an A&P mechanic who used to work for Martinair shared with the NTSB his concerns about aircraft that used pneumatic de-icers. He thought “many operators, aircraft cleaners and maintenance personnel are not aware of the hazards involved when a de-icer protectant or shield is applied to the wings and not to all the tail de-icers.” If the tail is not treated, he noted, the pilot is unaware of ice accumulation there and by the time ice is noted on the treated wings, it is too late.