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On December 17, 1998, at 1840 eastern standard time, an Aerospatiale ATR42-300, N47AE, operated by American Eagle Airlines, Incorporated, as flight 4047, received substantial damage during landing on runway 28 (6,501 feet by 150 feet, asphalt/snow) at Cherry Capital Airport (TVC), Traverse City, Michigan. Night instrument meteorological conditions prevailed at the time of the accident. The 14 CFR Part 121 passenger carrying flight was operating on an instrument flight rules (IFR) flight plan. The 3 flight crew members and 40 passengers reported no injuries. The flight originated at Chicago O' Hare International Airport, Chicago, Illinois, at 1730, and was en route to its scheduled destination of TVC. Austin Straubel International Airport (GRB), Greenbay, Wisconsin was filed as an alternate airport.
During the flight, the captain was acting as the non flying pilot (NFP) and the first officer was the flying pilot.
At 1813:40, radar data indicates that the aircraft is approximately 65 nmi southwest of TVC at 15,000 feet msl. At 1813:40, the cockpit voice recorder indicates that the captain said, "information Lima, two two five six zulu. winds are three two zero at ten. two and a half, light snow, mist. ... one thousand scattered, three thousand broken, fifty five hundred broken, minus two, minus four, two niner niner four is already set left center. they're using the ILS to two eight. thin patchy, ice. sanding and chemicals are in progress. ... landing's gonna be, thirty five thousand pound landing with icing speeds... call it one twenty three, one twenty three squared.
In the Federal Aviation Administration's (FAA's) Air Traffic Control report of the aircraft accident, Minneapolis Air Route Traffic Control Center (ARTCC) told flight 4047 they were number two following a Cessna 152. Flight 4047 was then issued instructions to fly heading 300 to join the localizer with discretion to descend to 2,700 feet msl. Approximately three minutes later, ARTCC instructed flight 4047 to join the localizer for runway 28 and proceed inbound and to expect approach clearance after the Cessna 152 was on the ground. At 1837:53, the CAPT said, "...there's GWENN right there...". At 1838:28 Minneapolis Center cleared Flight 4047 for the ILS 28 approach at TVC and was instructed to maintain two thousand seven hundred feet until on a published portion of the approach.
Radar data indicates that the aircraft maintained an altitude of 2,700 feet msl until it was 1.6 nmi inbound from the outer marker, on the ILS 28 approach. Thirty six seconds later, the aircraft was at 1,500 feet msl and 3.3 nmi inbound from the outer marker.
At 1839:00 the cockpit audio mike recorded, "sink rate, sink rate, sink rate" followed by, "whoop whoop, pull up, whoop whoop, pull up, whoop whoop, pull up" at 1839:04. Five seconds later, the first officer called for 30 degrees of flaps.
At 1839:30 the TVC tower controller transmitted, "Eagle flight forty seven Tranverse City runway two eight. cleared to land. wind zero seven zero at one seven. altimeter's two niner niner five. ... runway two eight Mu is eight two eight five eight one, with chemically treated thin loose snow over patchy ice." (See Test and Research section for tailwind and crosswind components)
At 1839:44 a transmission from the accident aircraft responded, "cleared to land, Eagle forty seven."
At 1840:24 the TCV tower controller transmitted, "wind zero six zero at two zero." (See Test and Research section for tailwind and crosswind components)
At 1840:26 the cockpit audio mike recorded a "sound similar to aircraft touching down on runway".
In a debrief taken by American Eagle, Incorporated, on December 18, 1998, the captain reported:
"On approach to Traverse City we received a notice of weather change. This was approximately at the outer marker and made by the tower. The tower advised us of the change in direction and velocity of the wind. At approximately three to five hundred feet the first officer positively transferred control of the aircraft to me. I confirmed positive transfer of controls. The approach was stable. At touchdown the aircraft veered to the left. I returned the aircraft to the centerline and then continued to the gate. The passengers deplaned by jetbridge. Upon postflight inspection damage to the aircraft was noted. I then contacted the company."
In a debrief taken by American Eagle Airlines, Incorporated, on December 18, 1998, the first officer reported:
"I was flying an ILS 28 to TVC. At approximately the outer marker there was a reported wind change. I flew the approach normally. At approximately 400-500 feet agl, control of the aircraft was transferred to the captain. We continued visually upon touchdown the aircraft veered left. The captain brought the aircraft back to the centerline and a normal taxi to the gate was accomplished. Upon postflight of aircraft, aircraft damage was discovered. To my knowledge the captain contacted the company."
During a postaccident interview, the captain stated that he was inbound from Ft. Wayne on another flight, swapped aircraft in Chicago, obtained weather and greeted the first officer at the gate. He reported that he reviewed the weather packet and maintenance logs, which did not have any open write ups. He described the takeoff, flight and approach as normal into Traverse City, Michigan. He obtained information Lima and was vectored and subsequently cleared for the ILS 28 approach. He stated that the winds were reported as 030 at 17 knots, the crosswind component chart was pulled out on approach. He stated he was visual at 800 feet, and at approximately 500 feet, the first officer indicated to him that he [first officer] wanted to transfer control. He also stated that there was a positive transfer of control. He stated that shortly after touchdown, the aircraft veered to the left and that he could not see the centerline. He stated that there were "windrows" of snow 10-15 feet from the edge of the runway. The captain added that he believed that he applied toe brakes shortly after touchdown and applied some reverse. He also added that he could not remember if the aircraft began to veer before or after braking. He added that shortly after all three gear on the aircraft touched down, the aircraft veered to the left. The captain stated that he had applied aileron control into the wind with slightly forward pressure. He reported that he did not notice an anti skid fault.
During a postaccident interview, the first officer stated that it felt like a normal touchdown but that the nose went left. There was a "windrow" of snow 10 feet from the edge of the runway. He stated that the captain hit the windrow and taxied back out. The first officer stated that he was not touching any of the flight controls during the landing. He stated that the approach speed was 125-130 knots and bugged for icing speeds. He stated that the captain had given the ATIS information. The first officer stated that prior to the outer marker the winds were reported as 030 at 17 knots and visibility went to 1/2 mile. He stated that they discussed that it would be a crosswind and calculated the crosswind component with the tailwind component. The first officer stated that he transferred control since he did not feel comfortable landing the aircraft after seeing the snow covered runway.
The TVC Airport Operations Manager reported that runway lights 12, 13, 14, 15, and 16, located on the south side of runway 28, were "knocked down". The "knocked down" lights were between taxiway H and the approach end of runway 23. The location of light 12 was reported to be 2,574 feet from the threshold of runway 28. The distances between lights 12, 13, 14, 15, and 16 were reported to be 184 feet, 185 feet, 184 feet and 184 feet respectively.
The captain, age 41, was hired by American Eagle, Incorporated on June 25, 1990. He held an airline transport pilot certificate with an airplane multiengine rating, and type ratings in the ATR42 and ATR72. He was upgraded to captain on March 27, 1998, and received a recurrent training check on September 26, 1998. The captain had accumulated 8,000 total flying hours, 365 hours of which were as pilot-in-command in the ATR42. He had accumulated 90 hours in the ATR42 in the preceding 90 days of the accident. The captain was issued a first class medical certificate on October 20, 1998. Duty time records showed that he was off duty on December 15, 1998. On December 16, 1998, the captain reported, at 0830 CST, for a flight in the ATR72. The captain completed his duty period at 1020. On December 17, 1998 the captain reported for duty at 1500 CST and had flown two flights in the ATR72 prior to the accident flight.
The first officer, age 41, was hired by American Eagle, Incorporated on July 20, 1998. He held a commercial pilot certificate with airplane single-engine land and multiengine ratings. He was line qualified on September 17, 1998. The first officer had accumulated 3,520 total flying hours, 130 hours of which were in the ATR42. He had accumulated 100 hours in the ATR42 in the preceding 90 days of the accident. The first officer was issued a first class medical certificate on September 9, 1998. Duty time records showed that he was off duty for a 48-hour period preceding the day of the accident. On December 17, 1998, the first officer reported for duty 1054 CST and had flown two flights in the ATR42 prior to the accident flight.
N47AE, an ATR42-300, serial number 0047, was manufactured by Aerospatiale in 1987 and had accumulated a total airframe time of 24,339 hours and 30,354 cycles. The aircraft was maintained on an approved inspection program and had last been inspected on October 16, 1998, at an airframe time of 23,993 hours and 29,904 cycles. The aircraft was fitted with two Pratt and Whitney 120 turboprop engines rated at 2,000 shaft horsepower each. The aircraft accommodates a crew of 4 with 46 passengers and has a maximum landing weight of 36,160 lbs.
The load manifest from Flight 4047 indicated an actual aircraft landing weight of 34,958 lbs. The ATR42-300 operating speeds for icing conditions is listed in AE's ATR42/72 Aircraft Operating Manual (AOM). For "conservative maneuvering" at 15 degrees of flaps, the airspeed is 145 knots for all weights. Vapp is defined as the minimum approach speed in a landing configuration prior to threshold and is equal to VmHB Flap + Wind. At an aircraft landing weight of 35,000 lbs, VmHB 15 is 115 knots and VmHB 30 is 120 knots.
The ATR42 Flight Crew Operating Manual describes the Ground Proximity Warning System (GPWS) alert modes by stating that, "When the aircraft penetrates the outer envelope, the "SINK RATE" voice alert is given and the red GPWS warning lts [lights] illuminate. If the inner envelope is penetrated, the "WHOOP WHOOP PULL UP" alert is given. This mode does not depend on the aircraft configuration." A graph of descent rate versus radio altitude (RA) depicts the "SINK RATE" envelope as being bounded by the following coordinates: 1,000 fpm at 50 feet, 5,000 fpm at 2,450 feet, 7,000 fpm at 2,450 feet, 7,000 fpm at 2,300 feet, 1,500 fpm at 200 feet and 1,500 fpm at 50 feet. The "PULL UP" envelope is bounded by the following coordinates: 1,500 fpm at 50 feet, 1,500 fpm at 200 feet, 7,000 fpm at 2,350 feet and 7,000 fpm at 50 feet.
The ATR42 Aircraft Flight Manual indicates that the tail wind limit of the ATR42 was 15 knots and also states:
"The capability of the airplane has been satisfactorily demonstrated for take off and manual landing with tailwinds up to 15 knots. This finding does not constitute operational approval to conduct take off and landing with tail wind components in excess of 10 knots."
The American Eagle ATR 42/72 AOM states, under "Operation Limits", the limiting tailwind component to be 10 knots.
The dispatch release for flight 4047 indicates that the TVC Field Report issued on December 17, 1998 at 1706 stated that runway 28 conditions were wet in .00 water with a braking action/remarks of 100, 95, 99. A special advisory within in the field report states, "use caution-10/28 wet, men and eqp [equipment] on field plowinf [plowing] in progress". It also reported the TVC terminal area forecast, issued at 1318 to be, wind 330 degrees at 13 knots; 4 smi visibility in light snow showers; overcast clouds at 2,500 feet; temporary conditions of wind 180 degrees at 2 knots; visibility of 1 smi in snow showers; overcast clouds at 800 feet agl.
At 1840:26, the TVC automated surface observing system (ASOS) special observation recorded wind from 050 true degrees at 16 knots; prevailing visibility of 1/2 smi in snow and freezing fog; few clouds at 1,000 feet agl, broken clouds at 2,400 feet agl and overcast clouds at 5,000 feet agl; temperature and dewpoint of -3 degrees Celsius (C); altimeter setting of 29.95 inches of Mercury (Hg); remarks of visibility 1/4 variable 1 smi. At 1853:26, the TVC ASOS recorded wind from 060 true degrees at 14 knots gusting 20 knots; prevailing visibility of 1/4 smi in heavy snow and freezing fog; overcast clouds at 100 feet agl; temperature and dewpoint of -3 degree C and -4 degrees C; altimeter of 29.96 inches of Hg; remarks of tower visibility 1/2 smi; snow increasing, 1/4 smi visibility.
At 1856 CST (1956 EST), the GRB ASOS recorded, wind from 300 true degrees at 3 knots; prevailing visibility of 10 smi; clear sky conditions; temperature and dewpoint of -5 degrees C and -11 degrees C; an altimeter setting of 30.01 inches of Hg. Night visual meteorological conditions with a wind of 7 knots or less prevailed for the remainder of the day.
At 1856, the Kent County International Airport (GRR) ASOS, Grand Rapids, Michigan, reported, wind 300 true degrees at 7 knots; prevailing visibility of 10 smi; clear sky conditions; temperature and dewpoint of -2 degrees C and -9 degrees C; altimeter setting of 29.99 inches of Hg. Night visual meteorological conditions with a wind of 6 knots or less prevailed for the remainder of the day.
The magnetic variation at TVC was 5 degrees west.
Advisory Circular 00-45D, Aviation Weather Services, states that the ASOS wind is a 2-minute average wind computed once every 5 seconds.
AIDS TO NAVIGATION
TVC is served by one precision and three nonprecision approaches. The ILS runway 28 approach possesses straight-in minimums of 200 feet and 1/2 mile visibility and circling minimums of 800 feet and 2-1/4 miles visibility for all categories. The minimum altitude at the intermediate segment of the ILS 28 approach was 3,000 feet msl. The outer marker, GWENN, is located 5.8 nmi from runway 28 and has a glidepath altitude of 2,549 feet msl. The ILS 28 approach chart indicates that the glideslope for the approach is 3 degrees.
TVC airport elevation is 624 feet msl. Runway 28 lighting includes high intensity runway lights (HIRL) and a medium intensity approach lighting system (MASLR) with runway indicator lights.
At 1828, TVC reported that the runway center was 80 feet wide and chemically treated. The remainder of the runway had loose snow over patchy thin ice. Runway friction was reported as 82, 85 and 81.
GRB and GRR are both AE stations located 110 nmi west and 112 nmi south of TVC respectively.
TESTS AND RESEARCH
In a written statement, a pilot stated that he had written up N47AE's #2 main landing gear (MLG) tire on December 16, 1998. He stated, "I noticed no abnormalities during any portion of the ORD-EVV [Evansville Regional Airport, Evansville, Indiana] flight until the landing at EVV. I was the NFP, with the FO making the landing. The landing was made on runway 22, which was damp/dry, and as I recall, the winds were fairly light. The landing, made by the FO, was a normal landing with little if any braking applied by him. As I took control of the A/C, started to apply braking, and continued to apply reverse, we smelled an odor like hot rubber. Braking seemed to be a little sluggish, but I noted no anti-skid faults, or any other abnormal indication, other that the smell. I commented that we might have a tire problem. At the gate, during the postflight inspection, we discovered the #2 MLG tire was flat with a large flat area worn completely through the cord layers." On December 16, 1998, the pilot entered into the mechanical discrepancy log, "On post flight inspection, found #2 MLG tire flat with large hole completely through cord". The corrective action indicated that the #1 and #2 MLG tire assemblies were ran and inspected and the operational check was described as good.
On December 17, 1998, there were three flights accepted by two different captains and no mechanical discrepancies, relating to MLG, were entered into the aircraft maintenance log prior to the accident flight.
Following the accident, the TVC station manager submitted a diagram of one of the tires from the accident aircraft which had a flat spot on it approximately 8-10 inches in length with a build up of melted rubber spanning the width of the tire.
Following the accident, an AE crew chief stated that the #1 MLG tire was peeled off the rim and "ripped up bad." He described the #2 MLG tire as having side ways scuff marks on the treaded portion of the tire. He stated that he performed an A/S test and if it was bad that he would have entered it into the minimum equipment list.
The aircraft received a ferry permit, after the accident, to be flown to Marquette for repair. The ferry captain reported that he flew the aircraft from TVC to Marquette. Prior to leaving the gate, he tested the A/S system and one of the fault lights came on momentarily in which the captain described the duration as "just a blink". The Captain then executed a high speed taxi, braked and then stopped the aircraft. He then tested the A/S light, and no light illuminated. He also reported that there were no problems en route or upon landing at Marquette. He added that there was no fault light illumination during or after landing at Marquette. The captain stated that he saw tires in the cargo hold and that one of the tires felt as if it was melted on an 8 - 10 inch area in length and spanning the full length of the tire. He stated that he did not know which tire it was. He also reported that he did not see any skid or burn marks on the other tires.
On January 16, 1999, a mechanical discrepancy was entered as, "severe nose wheel vibration above 50 KIAS both t/o and landing - directional control not a problem". The corrective action taken states that the #1 tire was found to have torn plies.
The American Eagle Flight Manual states, under Stabilized Approach Criteria, "when any approach fails to meet the following stabilized approach criteria, an immediate missed approach (or go around as appropriate) is mandatory. Aircraft specific procedures outlined in the Aircraft Operating Manual Vol. 1 [AOM] supersede this section." It goes on to say that, "the stabilized approach criteria is divided into three phases of flight, and applies to both instrument and visual approaches..."
The AOM states that for ILS approaches, prior to beginning the final approach segment, the desired altitude is maintained +/-100 feet, the desired airspeed within +/- 10...
Phase 1 1) 2,000 Feet AFL to 1,000 Feet AFL [above field elevation] 2) Maximum Descent Rate: 2,000 FPM [feet per minute] 3) Maximum Course Deflection Once Established: +-1.5 dots or +- 7 degrees on RMI [Radio Magnetic Indicator]
Phase 2 1) 1,000 Feet AFL to 300 Feet AFL 2) Maximum Descent Rate: 1,200 FPM 3) Maximum Course Deflection: +-1 dot or +-5 degrees on RMI 4) Minimum Speed briefed approach speed as appropriate.
Phase 3 1) 300 Feet to 59 Feet AFL 2) Maximum Descent Rate: 900 FPM 3) Maximum Course Deflection: (ILS/LOC only) +-1 dot 4) Maximum Speed Deviation: Deceleration, as required, to cross end of runway at a speed difference not in excess of +10/-0 knots of appropriate threshold speed.
ATR reported that with a wind from 070 degrees at 17 knots, relative to a runway heading of 280 degrees, the tailwind component would be 14.722 knots with a crosswind component of 8.5 knots. With a wind from 060 degrees at 20 knots, relative to a runway heading of 280 degrees, the tailwind component would be 15.320 knots with a crosswind component of 12.855 knots.
A readout of the Digital Flight Recorder (DFDR) was performed by the National Transportation Safety Board (NTSB) Vehicle Recorders Laboratory. Data from the aircraft's DFDR shows that at a RA of 945 feet, the aircraft's indicated airspeed was 160 knots. At a RA of 100 feet the aircraft's indicated airspeed was 122.8 knots. The NTSB's factual report of the DFDR readout defines a subframe reference number (SNR) as being equivalent to one second. The factual report of the readout includes the following statement:
"... At 2343, the aircraft is on runway heading of 279 degrees, at a radio altitude of 27 feet, -5 degrees left bank, 5 degrees left aileron, a pitch of 0 degrees, above the glidesplope and on the localizer. At SRN 2347, the radio altitude is at 3 feet, the airspeed is 103 knots, a magnetic heading of 277 degrees, a roll of -7 degrees left, the rudder moves from -5 degrees to 4 degrees, and the glidesplope is full-scale above. At SRN 2348, there is a vertical acceleration spike of 1.4 g's, and lateral acceleration starts to increase as longitudinal acceleration starts to decrease and the localizer indicates left of the beam. Over the next 4 seconds, the roll decreases from -6 degrees left to zero, the aileron increases, the magnetic heading changes from 279 degrees to 284 degrees, and the rudder fluctuates. During SRN 2352, the roll increases to the right, positive lateral acceleration reaches a maximum value of .232 g's and the heading is 290 degrees. ..."
The Airline Pilot's Association (ALPA) submitted 19 pages of comments regarding the accident. ATR submitted 2 pages of comments regarding the accident. Both comments by ALPA and ATR are attached to this report.
The FAA, American Eagle, Incorporated, ALPA and ATR were parties to the investigation.