ONRecorD Roller Coaster Ride Ice buildup on pitot probes caused erroneous airspeed indications. BY MARK LACAGNINA The following information provides an aware- the air data system, degrading its ability to reli- ness of problems in the hope that they can be ably determine the airplane’s airspeed,” the re- avoided in the future. The information is based port said. The captain was about to ask the first on final reports by official investigative authori- officer to retrieve the quick reference handbook ties on aircraft accidents and incidents. when the autopilot disengaged and the airplane, which had been climbing through 19,300 ft, JETS pitched down and entered a steep dive. During the recovery, the first officer assisted Flight Crew’s Response Was Uncoordinated the captain on the flight controls. Both pilots Boeing 717-200. No damage. No injuries. told investigators that the controls felt heavy and hile departing from Kansas City, Mis- that the airplane did not respond to their control souri, U.S., for a scheduled flight to inputs. “The flight crew initially applied uncoor- WWashington the night of May 12, 2005, dinated control inputs, in the process reaching the 717 encountered weather conditions “favor- nearly 100 lb [45 kg] of differential force on the able for the accumulation of structural icing,” pitch-control column, while attempting to re- said the report by the U.S. National Transpor- cover the airplane,” the report said. “During this tation Safety Board (NTSB). “At some point, period … pitch continued to oscillate through the pitot-static system began accumulating ice five cycles, for a duration of eight minutes, because the air data heat system had not been reaching altitudes as low as 10,600 ft and as high activated.” as 23,300 ft.” The captain, who was flying the airplane on The pilots observed erroneous airspeed autopilot, maintained airspeed between 280 and indications that varied between 54 kt and 460 kt. 300 kt during the climb to cruise altitude. “The “The captain stated that while he was trying to crew felt they did not need to utilize airplane recover the airplane, he attempted to maintain anti-icing because the outside temperature was a level pitch attitude by placing the pitch of the still too warm to require it,” the report said. airplane in a fixed position and tried to level the “The first indication of something abnormal was wings of the airplane,” the report said. “The first when the captain noticed the master caution officer stated that, during the recovery, he was light was illuminated.” trying to keep the airspeed away from the stall The “RUDDER LIMIT FAULT” warning speed and away from the overspeed red zone.” light also illuminated because ice had accumu- The crew eventually regained control of the lated on the pitot probe for the rudder limiting airplane, declared an emergency and landed system, which reduces maximum allowable rud- without further incident at Kirksville (Missouri) der deflection as airspeed increases. “The icing Regional Airport. None of the 80 people aboard continued to accumulate on the other probes of the 717 was injured. WWW.FLIGHTSAFETY.ORG | AEROSAFETYWORLD | MARCH 2009 | 57 ONRecorD “Post-incident testing of the airplane’s an AAIB accident report, in which he “acknowl- mechanical and electronic systems revealed edged that the aircraft bounced on landing but no abnormalities that would have accounted stated that at all times he had control of the for the unreliable airspeed indications or the aircraft and maintained the runway centerline,” loss of control reported by the flight crew,” the the incident report said. The first officer filed a report said. “Post-incident computer modeling mandatory occurrence report with the U.K. Civil also confirmed that the airplane performed in a Aviation Authority, saying that the aircraft had manner consistent with all deviations from nor- reached heights of 10 to 15 ft during the bounces. mal flight having been initiated or exacerbated Noting that the difference between the by the control inputs of the flight crew.” indicated wind velocity at 2,000 ft and the reported surface wind velocity provided warn- Commander Overrules Go-Around Call ing that the pilots could expect significant wind Cessna Citation 550. No damage. No injuries. shear, the report said, “The selection of a speed nbound from Nice, France, the commander greater than minimum approach speed may was flying an autopilot-coupled instrument have provided a greater margin for wind shear.” Ilanding system (ILS) approach to Runway 21 at The report also said that a go-around conducted Biggin Hill Airport in Kent, England, the evening after the stall recovery “may have prevented the of Feb. 5, 2008. Night visual meteorological con- subsequent bounced landing.” ditions (VMC) prevailed, and surface winds were from 230 degrees at 15 kt. The pilots observed a Reversed Anti-Skid Wiring Leads to Excursion wind velocity indication of 54 kt on the electronic Airbus A320-200. Minor damage. Two minor injuries. flight instrument system (EFIS) as the Citation urface winds were from 330 degrees at 17 descended through 2,000 ft, said the report by the kt, gusting to 23 kt, when the A320 was U.K. Air Accidents Investigation Branch (AAIB). Slanded on Runway 22R at Chicago O’Hare After the autopilot captured the glideslope, International Airport the night of Oct. 9, 2007. the commander reduced airspeed to 115 kt, Perceiving no deceleration by the autobrakes, which he described as the “minimum approach the captain applied manual wheel braking when speed” — reference landing speed (Vref) plus airspeed decreased below 100 kt. 10 kt. “At two miles from the runway threshold, “The aircraft immediately swerved hard [the Citation] encountered severe wind shear, right,” the captain told NTSB investigators. “I After the second and the EFIS speed tape showed the speed corrected with full left rudder and brake, but trending to below 100 kt,” the report said. “The the aircraft continued to the right. I then used bounce, the first autopilot pitched up to maintain the glideslope, nosewheel steering to attempt to straighten the and the aircraft appeared to stall with a right- aircraft, but it was ineffective.” officer called for wing drop. The [commander] recovered from The nosewheel and right main landing gear a go-around. the stall by lowering the nose and increasing ran off the right side of the runway. The captain power, and decided to continue the approach.” was able to steer the aircraft back onto the runway The commander The pitch attitude was described as “flat” on and bring it to a stop. A flight attendant and a pas- touchdown, and the aircraft began to “porpoise,” senger received minor injuries during the excur- responded, “Why?” bouncing off the runway an unspecified number sion; the other 125 occupants were not injured. of times. After the second bounce, the first of- “Although I knew there was some aircraft ficer called for a go-around. The commander damage, there was no indication of fire,” the cap- responded, “Why?” tain said. “Since the aircraft taxied normally, I The Citation was brought to a stop on the run- taxied … and parked at the gate.” After shutting way and taxied to its parking position. There was down the engines, the captain observed that the no damage, and none of the four people aboard indicated temperature of the brakes on the left was injured. Nevertheless, the commander filed main landing gear was about 60˚ C (140˚ F), and 58 | FLIGHT SAFETY FOUNDATION | AEROSAFETYWORLD | MARCH 2009 ONRecorD that the indicated temperature of the brakes on forecast severe turbulence in the area. Neverthe- the right main gear was about 375˚ C (707˚ F). less, wind shear data included in the preflight He then was informed by maintenance person- paperwork had caused the captain to anticipate nel that the left inboard tire had burst and that turbulence. Although the ride had been smooth the engine nacelles had been damaged. during descent, the captain said that the DC-9 The captain Examination of the A320 revealed that the was descending through 13,000 ft when he described the wiring for the anti-skid braking system tachom- “chimed the flight attendants early,” indicating eters on the inboard and outboard wheels on the that they were to prepare the cabin for landing turbulence encounter left main landing gear had been misrouted and and then be seated. The captain described the reversed during replacement of the tachometers turbulence encounter as a “violent jolt” that oc- as a “violent jolt” by a maintenance contractor the day before the curred with no warning. accident. This resulted in a high level of brak- that occurred with ing on the inboard wheel but no braking of the Pallet Loader Catches Fire no warning. outboard wheel. Airbus A320-200. No damage. No injuries. “The operator reported that the reference he A320 was being readied for departure documentation associated with the scheduled from Melbourne (Australia) Airport on maintenance involving both of the left main TDec. 31, 2007. “The flight crew was in the landing gear tachometers was unclear and that cockpit preparing the aircraft for the flight, the the procedure for that maintenance was revised,” passengers were boarding the aircraft through the report said. the left-forward door via the airbridge, and the ground handlers were loading and unloading Turbulence Warning Not Passed to Crew baggage and other items,” said the report by the McDonnell Douglas DC-9-83. No damage. Two serious injuries. Australian Transport Safety Bureau (ATSB). he DC-9 was descending through 8,300 ft The operator of a pallet loader on the right during an approach in VMC to Ontario side of the aircraft detected the odor of an T(California, U.S.) International Airport when electrical fire while restarting the engine, which it encountered severe turbulence the morning of had stalled.