BIRMINGHAM, AL, USA
N867US
Fokker F28 MK 0100
While flying in precipitation deviating within 10 miles from the edge of a level 5 thunderstorm associated with a squall line, the airplane was struck by lightning. Arching damage to the No. 1 elevator pressure and No. 2 elevator return hydraulic lines resulted in depletion of the hydraulic fluid from the Nos. 1 and 2 hydraulic system reservoirs. The airplane was landed on a wet runway and after touchdown, 2 of the 4 main landing gear tires ruptured. The airplane traveled off the left side of the runway, across grass, and came to rest with the nose landing gear separated. A loose canon plug at the parking brake shutoff valve was discovered which prevented the operation of the alternate antiskid system. That area was inspected 2 days earlier. The airplane was only equipped by design with 1 bonding strap located on the left side of the airplane for the horizontal and vertical stabilizer; which failed. Advisory Circular recommends that the area be designated for carrying substantial amounts of electrical current, but the airplane was not designed for such. The flight crew was not provided convective sigmets for the central U.S., which indicated severe thunderstorms over Birmingham. The destination airport was near the boundary of the east and central regions for convective sigmets. The airline does not conduct weather radar training in recurrent, upgrade, or requalification training. The dispatcher did not provide to the flight crew weather watches that were available 15 minutes before and after the flight departed.
HISTORY OF FLIGHT On February 26, 1998, about 1729 (all times central standard), a Fokker F28MK0100, N867US, registered to and operated by US Airways, Inc., as flight 861, experienced loss of directional control while landing at the Birmingham Municipal Airport, Birmingham, Alabama. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed for the 14 CFR Part 121 scheduled, domestic, passenger flight from Charlotte, North Carolina, to Birmingham, Alabama. The airplane was substantially damaged and the airline transport-rated captain and first officer, 87 passengers, and 3 cabin crewmembers were not injured. The flight originated about 1612, from the Charlotte/Douglas International Airport. At 1648, the flight dispatcher sent a message to the flightcrew via the ARINC Communicating Addressing and Reporting System (ACARS) that indicated thunderstorms were over the destination airport and north of the airport looked good on his radar. The message also stated that the thunderstorm should pass through within 10 minutes; Birmingham field should be "ok" after this line. This message was repeated twice. The dispatcher was sent a message by a flightcrew member 1 minute after the second message that they had received the previous message from the dispatcher. One minute after that message, the flightcrew advised the dispatcher that the flight was 90 miles east of the destination airport. The dispatcher acknowledged this then repeated the message that the thunderstorm passage should be in 10 minutes. While en route and in contact with the Atlanta Air Route Traffic Control Center (ARTCC), at 1701:11, the cockpit voice recorder (CVR) recorded the captain to state "let's side step over a little bit" and at 1702:13, the CVR recorded the first officer to state "ok, it looks like it's building a little now", to which the captain replied that he advised the flight attendants to sit down earlier. At 1702:15, the first officer radioed the ARTCC controller and stated "uh center US 861, we'd like to come right uh about twenty degrees if we could for weather." The request was approved. Sound similar to thunder was recorded from the cockpit area microphone at 1701:41, 1702:44, and at 1704:24. At 1704:33, the CVR recorded the captain to state, "I bet we took that one on the nose, I felt it on the rudder pedals", which was confirmed by the first officer. The captain reported after the accident that while deviating around adverse weather in clouds, about 20 miles from depicted adverse weather, he recognized that the airplane had been struck by lightning with no immediate affect to the airplane. At 1705:14, the CVR recorded the first officer to state "lightning strike" to a flight attendant who reported seeing and hearing it. At 1705:36, the CVR recorded the captain to state "***number 2" followed 5 seconds later by "we got low...* lot lot of stuff goin' on. It's all right though." The captain then requested to "run that procedure" to which the first officer acknowledged and at 1706:24, the CVR recorded the first officer to state "ok, hydraulic system number two, low quantity" then 30 seconds later the captain stated "we lost the number one too chief." See legend of the CVR transcription which is an attachment to this report for explanation of the asterisks. The CVR recorded the first officer to read the checklist for total hydraulic system failure and at 1711:53, while in contact with Birmingham Tower North Radar (NR) controller, the first officer radioed the controller and stated "US 861, we had a lightning strike" then 6 seconds later, he requested the current weather conditions at the Birmingham airport. The controller provided the weather conditions and at 1713:01, the first officer radioed the controller and stated "...we've got a double hydraulic failure... so we'd like you to vector us right over the top of the airport at 2,500 feet..." which was acknowledged by the controller. At 1715:48, the first officer informed the controller "...we will need the equipment standing by on this approach and uh we'll not be able to clear the runway...." At 1718:00, the Birmingham Tower Flight Data/Clearance Delivery position controller notified the airport rescue and fire fighting of an Alert II, then at 1718:45, the first officer informed the controller, "we'll be declaring an emergency also we'd like the equipment as we previously stated...." At 1718:54, the NR controller transmitted "US Air 861 roger the equipment has been called and activated and they'll be standin by for ya." The airport fire rescue vehicles were positioned along predetermined locations adjacent to and along the length of the intended runway. The captain reported after the accident that the landing gear and flaps were extended via the alternate method. At 1723:30, the NR controller transmitted "are you ready to come in" to which the first officer responded "we're ready." The flight was vectored then cleared for the Instrument Landing System approach to runway 23. While on final approach at 1725, the flight dispatcher sent a message via the ACARS system for the flight to divert to Charlotte. The approach was continued and the captain reported post accident that the touchdown was normal. After touchdown he applied the brakes with the knowledge that he would not have nose landing gear steering and he reported feeling a pronounced vibration. The airplane veered off the left side of the runway, across grass, and came to rest with the nose section of the airplane resting on a taxiway; the nose landing gear separated from the airplane. After the airplane came to rest, fire rescue personnel who responded to the airplane advised the captain who had his cockpit sliding window open that the airplane was "fire safe." The captain ordered that the passengers not be deplaned until transportation arrived. The passengers remained seated until transportation arrived then exited the airplane out the left forward door without using the escape slide, assisted by fire rescue personnel. A copy of air traffic control transcriptions are an attachment to this report. PERSONNEL INFORMATION The captain, age 42, was hired by USAir on December 12, 1982. He holds an airline transport pilot (ATP) certificate with type ratings in the CV-340, CV-A440, LR-Jet, B-737, and FK-100. His most recent proficiency check occurred on January 14, 1998, and his most recent line check occurred on July 8, 1997. The pilot's statement and records supplied by US Airways reveal that he had accumulated 16,759 hours total flying time at the time of the accident. He has accumulated while at US AIRWAYS, a total time of 10, 833 hours which included a total time of 2,283 hours as pilot-in-command in a Fokker F-100 type airplane. Review of all training records supplied by US Airways revealed no unusual or unsatisfactory training events from May 28, 1993, until the date of the accident. Prior to joining USAir, he had experience as a civilian pilot flying corporate and cargo operations. According to FAA documents, he had no prior accident, incident, or enforcement actions. Additional information pertaining to the captain is contained on page 2 of the Factual Report-Aviation and in the Operational Factors Group Chairman's Factual Report. The first officer, age 47, was hired by Pacific Southwest Airlines (PSA) on June 20, 1986. In 1988, as a result of the merger between USAir and PSA he joined USAir. He holds an ATP certificate with type ratings in the CE-500, IA-JET, SK-76, CL-600, HS-125, Fk-28, and B-767 aircraft. His most recent proficiency check occurred on January 9, 1998, and his most recent line check occurred on July 6, 1994. The pilot's statement and records supplied by US Airways reveal that he had accumulated 12,800 hours total flying time at the time of the accident. He has accumulated a total flight time of 6,045 hours with US AIRWAYS, which includes a total time of 2,057 hours in the Fokker F-100 type airplane. Review of all training records supplied by US Airways revealed no unusual or unsatisfactory training events from June 21, 1994, until the date of the accident. He had accumulated a total of 6518 hours total flying time when hired by PSA. Prior to joining PSA his experience was in corporate aviation. According to FAA documents, he had no prior accidents, incidents, or enforcement actions. Additional information pertaining to the first officer is contained in Supplement E, and in the Operational Factors Group Chairman's Factual Report. AIRCRAFT INFORMATION The Fokker F28 Mark 0100 aircraft was issued type certificate number A20EU and certified in the transport category (14 CFR part 25) with a minimum flight crew of two pilots. The accident aircraft (N867US) was issued a Standard Airworthiness Certificate on July 31, 1990. The last "A" check was accomplished on February 24, 1998, which included Card No.J5-55-3220A-1; this indicates a check for the left main landing gear/wheel bay hydraulic tubing, couplings, and components for signs of leakage, general condition, and security. The maintenance records indicate that the parking brake shutoff valve had been replaced on August 26, 1995, and operationally checked good. Testing of the parking brake shutoff valve last occurred on November 12, 1996, in accordance with a "C3" check and job card No. J5-50-3213C. The airplane is equipped with two hydraulic systems with the normal brake system operated by the No.2 system. In the event of failure of the No. 2 system, the alternate brake system is automatically operated by the No. 1 system. In the event of failure of both the Nos. 1 and 2 systems, the alternate brake system is automatically operated by an accumulator which as indicated by the flight manual, allows for a specified number of brake applications. The anti-skid system schematic for the airplane indicates that the return of hydraulic pressure for the alternate brake system is routed through the alternate brake dual skid control valves then through the electrically energized "open" parking brake shut-off valve. With the shut-off valve in the "closed" position, the hydraulic pressure is prevented from being released from the brake assemblies, resulting in no anti-skid protection. Failure of the parking brake shut-off valve due to either a disconnected cannon plug or by an inoperative parking brake shut-off valve is not annunciated in the cockpit. At the time of the accident, there were no published procedures for the flight crew to determine the functionality or status of the parking brake shutoff valve. The airplane was equipped by design, with only one bonding strap for the vertical to horizontal stabilizer, which is located on the left side of the airplane. That bonding strap is 5 inches long, AWG 12 tinned stranded soft copper wire, with seven groups of 37 AWG size 36 strands. According to the airplane manufacturer, that design was chosen for "Compliance of the requirements regarding the direct effects of lightning and static electricity." That requirement allowed compliance with the test requirement that voltages should be less than 500 volts to prevent arching and a steady state current of 400 amps for 0.5 seconds, to be safely drained. Compliance demonstration was based on the accident make and model airplane and the similarities to the F28 make and model airplane, and by additional analysis and testing. With respect to the hydraulic system installation in the airplane, the manufacturer determined that since the "tail section" is all metal; there is no exposure to indirect effects of lightning which was also applicable for electrical wiring, conducting lines, and hydraulic tubes. METEOROLOGICAL INFORMATION About 3 hours 20 minutes before the flight departed, weather watch (WW) number 68 was issued by the National Weather Service Storm Prediction Center (SPC) which encompassed the area of the destination airport. The watch indicated a few severe thunderstorms with hail at the surface and aloft to 1inch, extreme turbulence and surface wind gusts to 70 knots, covering Alabama and Mississippi. The report discussed the squall line that was accelerating towards the Birmingham area with a well pronounced bowing of the line. Weather watch (WW) number 68 was in effect at the actual time of departure, and was not provided to the flight crew as part of the dispatch weather package. About 2 hours 54 minutes before the flight departed, the Atlanta Center Weather Service Unit issued Meteorological Impact Statement (MIS) number 2. The advisory indicated almost the entire area of Alabama that contained scattered Digital Video Imaging Processor (DVIP) Level 3 to 5 thunderstorms and rain, with isolated severe thunderstorms with 60 knot wind gusts possible. The advisory indicates that the thunderstorms were moving from 240 degrees at 30 knots with tops to 40,000 feet. The MIS advisory was available to the US Airways dispatcher; the information was not contained in the weather package disseminated to the flightcrew by dispatch. The crew received weather information as part of the flight plan and release (FP/R) paper work 1 hour 32 minutes before the flight departed which included departure, destination, alternate, and en route METAR observations, and terminal aerodrome forecasts (TAF). Review of the provided data revealed that the airmet data was only valid up until 1 hour 5 minutes before the estimated time of departure. Additionally, the destination TAF issued about 4 hours 37 minutes before the flight departed, with a valid time of 1300 local on the day of the occurrence, to 1300 local the following day, revealed that between 1400 to 1800 local, the forecast was for 4 miles visibility, thunderstorms, and light rain with a broken ceiling at 2,000 feet. The weather data provided to the flightcrew included the convective sigmets for the eastern United States, but did not include the convective sigmets for the central United States. The destination airport was approximately 15 minutes of longitude east of the line that separates the east and central regions. There were no convective sigmets issued for the eastern United States disseminated with the weather information provided to the flightcrew. A convective outlook that was contained in the eastern convective sigmets issued 2 hours 19 minutes before the flight departed, and disseminated to the flightcrew, valid for the flight, indicates a line of severe thunderstorms along and ahead of the cold front expected to move across southeastern Louisiana and southern and eastern Mississippi, into western Alabama. The outlook also referenced Severe Weather Watch bulletin number 67 and 68. Convective sigmet 72C (central United States), issued about 1 hour 17 minutes before the flight departed (15 minutes after the captain received his weather information package from dispatch), and Convective sigmet 74C (central United States), issued about 17 minutes before the flight departed, to replace the previous convective sigmet, were not provided to the flightcrew. The sigmets indicated a line of severe thunderstorms 30 miles wide with tops to 45,000 feet. Also, about 1 hour 17 minutes before the flight departed, the SPC issued Severe Weather Forecast Alert (AWW) number 69 for the potential for tornadoes over Alabama, Mississippi, and adjacent waters valid from 42 minutes before the flight departed, until 2100 hours. This AWW was not provided to the flightcrew. About 15 minutes before the flight departed, a status report on WW number 68 was issued by the SPC. The report confirmed reports of damaging winds that had been received over portions of west central and central Alabama. The report continued discussing the squall line that was accelerating towards the Birmingham area with a well pronounced bowing of the line. This status report was not provided to the flightcrew by the dispatcher. About 15 minutes after the flight departed, the SPC issued WW number 70, which indicated severe thunderstorms over Alabama, from 48 minutes after the flight departed until 2100 local. The discussion of the watch referred to a line of se
Were the 1) the inoperative alternate anti-skid control valve due to the disconnected electrical connector on the parking brake shut-off valve, the area was inspected 2 days earlier 2) the total loss of the hydraulic system resulting in the inability of the flight crew to maintain directional control. Factors in the accident were the 1) inadequate lightning protection design of the airplane by the manufacturer between the horizontal and vertical stabilizers which resulted in arching damage to hydraulic lines and depletion of the hydraulic fluid from the Nos. 1 and 2 hydraulic systems 2) inadequate weather information disseminated to the flight crew during the preflight briefing by the company dispatcher for failing to provide current up-to-date information of the intensity, and location of adverse weather 3) the failure of the company dispatcher to relay pertinent weather information to the flight crew while en route which included convective sigmets, and the current extent and intensity of the squall line 4) the operation of the airplane by the flight crew within 10 miles from the northern edge of a ground based weather radar depicted level 5 thunderstorm resulting in a lightning strike 5) insufficient standards/requirements, operation/operator by the company management to require weather radar training in recurrent, upgrade, and requalification training, and 6) the limitations of the weather products provided to the flight crew by the airline for failure to include convective sigmets for the central U.S., based on the geographic location of the destination airport being east of the eastern/central boundary.
Source: NTSB Aviation Accident Database
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