[<< wikibooks] Understanding Air Safety in the Jet Age/Air Florida Flight 90
On a freezing night in Washington, 74 people would die due to a simple error by the pilots. On January 13, 1982 Air Florida Flight 90 was scheduled to depart from Washington National Airport (now Ronald Reagan Washington National Airport) to Fort Lauderdale–Hollywood International Airport with an intermediate stopover at Tampa International Airport. Less than two minutes after the Boeing 737-222 left the runway it crashed into the 14th Street Bridge over the Potomac River, killing four motorists on the bridge, before falling into the river to drown most of the survivors. What went wrong? Like all air accidents, multiple things contributed to the outcome, but the root cause was forgetting it was cold outside - despite the snow.
Striking the bridge, which carries Interstate 395 between Washington, D.C. and Arlington County, Virginia, it hit  seven occupied vehicles and destroyed nearly 100 ft of guard rail before plunging through the ice into the Potomac River. The aircraft was carrying 74 passengers and five crew members. Only four passengers and one crew member (a flight attendant) were rescued from the crash and survived. Another passenger, Arland D. Williams, Jr., assisted in the rescue of the survivors but drowned before he could be rescued. Four motorists on the bridge were killed. The survivors were rescued from the icy river by civilians and professionals. President Ronald Reagan commended these acts during his State of the Union speech a few days later.
The National Transportation Safety Board (NTSB) determined that the cause of the accident was pilot error. The pilots failed to switch on the engines' internal ice protection systems, used reverse thrust in a snowstorm prior to takeoff, tried to use the jet exhaust of a plane in front of them to melt their ice, and failed to abort the takeoff even after detecting a power problem while taxiing and having ice and snow buildup on the wings.


== Aircraft ==
The aircraft involved, a Boeing 737-222, registered as N62AF, was manufactured in 1969 and previously flown by United Airlines under the registration N9050U. It was sold to Air Florida in 1980. The aircraft was powered by two Pratt & Whitney JT8D-9A turbofan engines and had recorded over 27,000 hours before the crash.


== Cockpit crew ==
The pilot, Captain Larry M. Wheaton, aged 34, was hired by Air Florida in October 1978 as a first officer. He upgraded to captain in August 1980. At the time of the accident, he had about 8,300 total flight hours, with 2,322 hours of commercial jet experience, all logged at Air Florida. He had logged 1,752 hours on the Boeing 737, the accident-aircraft type, 1,100 of those hours as captain.
Wheaton was described by fellow pilots as a quiet person, with good operational skills and knowledge, who had operated well in high-workload flying situations. His leadership style was described as similar to those of other pilots. On May 8, 1980,  though,  he was suspended after failing a Boeing 737 company line check and was found to be unsatisfactory in these areas: adherence to regulations, checklist usage, flight procedures such as departures and cruise control, and approaches and landings. He resumed his duties after passing a retest on August 27, 1980. On April 24, 1981, he  received an unsatisfactory grade on a company recurrent proficiency check when he showed deficiencies in memory items, knowledge of aircraft systems, and aircraft limitations. Three days later, he satisfactorily passed a proficiency recheck.
The first officer, Roger A. Pettit, aged 31, was hired by Air Florida on October 3, 1980, as a first officer on the Boeing 737. At the time of the accident, he had around 3,353 flight hours, 992 with Air Florida, all on the 737. From October 1977 to October 1980, he had been a fighter pilot in the US Air Force, accumulating 669  hours as a flight examiner,  instructor pilot, and  ground instructor in an F-15 unit.
The first officer was described by personal friends and pilots as a witty, bright, outgoing individual with an excellent command of physical and mental skills in aircraft piloting. Those who had flown with him during stressful flight operations said that during those times, he remained the same witty, sharp individual, "who knew his limitations."  Several persons said that he was the type of pilot who would not hesitate to speak up if he knew something specific was wrong with flight operations.
Alternating the role of "primary pilot" between the pilot in command (PIC), the captain, and second in command (SIC), the first officer, is customary in commercial airline operations, with pilots swapping roles after each leg. One pilot is designated the pilot flying (PF) and the other as pilot not flying (PNF); however, the PIC retains the ultimate authority for all aircraft operations and safety. The first officer was on the controls as the PF during the Air Florida Flight 90 accident.


== Background ==


=== Weather conditions ===
On Wednesday, January 13, 1982, Washington National Airport (DCA) was closed by a heavy snowstorm that produced 6.5 in (16.5 cm) of snow. It reopened at noon under marginal conditions as the snowfall began to slacken.
That afternoon, the plane was to return to Fort Lauderdale–Hollywood International Airport in Dania, Florida, with an intermediate stop at Tampa International Airport. The scheduled departure time was delayed about 1 hour and 45 minutes because of a backlog of arrivals and departures caused by the temporary closing of Washington National Airport. As the plane was readied for departure from DCA, a moderate snowfall continued and the air temperature was well below freezing.


=== Improper de-icing procedures ===
The Boeing 737 was de-iced with a mixture of heated water and monopropylene glycol by American Airlines, under a ground-service agreement with Air Florida. That agreement specified that covers for the pitot tubes, static ports, and engine inlets had to be used, but the American Airlines employees did not comply with those rules. One de-icing vehicle was used by two different operators, who chose widely different mixture percentages to de-ice the left and right sides of the aircraft. Subsequent testing of the de-icing truck showed that "the mixture dispensed differed substantially from the mixture selected" (18% actual vs. 30% selected). The inaccurate mixture was the result of the replacement of the standard nozzle, "...which is specially modified and calibrated, with a non-modified, commercially available nozzle." The operator had no means to determine if the proportioning valves were operating properly because no "mix monitor" was installed on the nozzle.


== Events of crash ==


=== Flight ===
The plane had trouble leaving the gate when the ground-services tow motor could not get traction on the ice. For roughly 30 to 90 seconds, the crew attempted to back away from the gate using the reverse thrust of the engines (a powerback), which proved futile. Boeing operations bulletins had warned against using reverse thrust in those kinds of conditions.
Eventually, a tug ground unit properly equipped with snow chains was used to push the aircraft back from the gate. After leaving the gate, the aircraft waited in a taxi line with many other aircraft for 49 minutes before reaching the takeoff runway. The pilot apparently decided not to return to the gate for reapplication of deicing, fearing that the flight's departure would be even further delayed. More snow and ice accumulated on the wings during that period, and the crew was aware of that fact when they decided to make the takeoff. Heavy snow was falling during their takeoff roll at 3:59 pm EST.
Though the outside temperature was well below freezing and it was snowing, the crew did not activate the engine anti-ice system. This system uses heat from the engines to prevent sensors from freezing, ensuring accurate readings.
While running through the takeoff checklist, the following conversation snippet took place (CAM-1 is the captain, CAM-2 is the first officer):
{{quote|CAM-2 Pitot heat?
CAM-1 On.
CAM-2 Engine anti-ice?
CAM-1 Off.

Despite the icing condition with weather temperature of about 24 °F (-4 °C),  the crew failed to activate the engine anti-ice systems, which caused the engine pressure ratio (EPR) thrust indicators to provide false readings. The correct engine power setting for the temperature and airport altitude of Washington National at the time was 2.04 EPR, but it was later determined from analysis of the engine noise recorded on the cockpit voice recorder that the actual power output corresponded with an engine pressure ratio of only 1.70.
Neither pilot had much experience flying in snowy, cold weather. The captain had made only eight takeoffs or landings in snowy conditions on the 737, and the first officer had flown in snow only twice.

Adding to the plane's troubles was the pilots' decision to maneuver closely behind a DC-9 that was taxiing just ahead of them prior to takeoff, due to their mistaken belief that the warmth from the DC-9's engines would melt the snow and ice that had accumulated on Flight 90's wings. This action, which went specifically against flight-manual recommendations for an icing situation, actually contributed to icing on the 737. The exhaust gases from the other aircraft melted the snow on the wings, but during takeoff, instead of falling off the plane, this slush mixture froze on the wings' leading edges and the engine inlet nose cone.
As the takeoff roll began, the first officer noted several times to the captain that the instrument panel readings he was seeing did not seem to reflect reality (he was referring to the fact that the plane did not appear to have developed as much power as it needed for takeoff, despite the instruments indicating otherwise). The captain dismissed these concerns and let the takeoff proceed. Investigators determined that plenty of time and space on the runway remained for the captain to have aborted the takeoff, and criticized his refusal to listen to his first officer, who was correct that the instrument panel readings were wrong. The pilot was told not to delay because another aircraft was 2.5 miles (4 km) out on final approach to the same runway. The following is a transcript of Flight 90's cockpit voice recorder during the plane's acceleration down the runway.
{{quote|15:59:32 CAM-1 Okay, your throttles.
15:59:35 [SOUND OF ENGINE SPOOLUP]
15:59:49 CAM-1 Holler if you need the wipers.
15:59:51 CAM-1 It's spooled. Really cold here, real cold.
15:59:58 CAM-2 God, look at that thing. That don't seem right, does it? Ah, that's not right.
16:00:09 CAM-1 Yes it is, there's eighty.
16:00:10 CAM-2 Naw, I don't think that's right. Ah, maybe it is.
16:00:21 CAM-1 Hundred and twenty.
16:00:23 CAM-2 I don't know.
16:00:31 CAM-1 V1. Easy, V2.|Transcript|Air Florida Flight 90 Cockpit Voice Recorder
As the plane became briefly airborne, the voice recorder picked up the following from the cockpit, with the sound of the stick-shaker (a device that warns that the plane is in danger of stalling) in the background:

The aircraft traveled almost half a mile (800 m) farther down the runway than is customary before liftoff was accomplished. Survivors of the crash indicated the trip over the runway was extremely rough, with survivor Joe Stiley – a businessman and private pilot – saying that he believed that they would not get airborne and would "fall off the end of the runway".  When the plane became airborne, Stiley told his co-worker (and survivor) Nikki Felch to assume the crash position, with some nearby passengers following their example.
Although the 737 did manage to become airborne, it attained a maximum altitude of just 350 ft before it began losing altitude. Recorders later indicated that the aircraft was airborne for just 30 seconds. At 4:01 pm EST, it crashed into the 14th Street Bridge across the Potomac River, less than a mile from the end of the runway. The plane hit six cars and a truck on the bridge, and tore away the bridge's rail and wall. The aircraft then plunged into the freezing Potomac River. It fell between two of the three spans of the bridge, between the I-395 northbound span (the Rochambeau Bridge) and the HOV north- and southbound spans, about 200 ft offshore. All but the tail section quickly became submerged.
Of the people on board the aircraft:

Four of the crew members (including both pilots) died.
One crew member was seriously injured.
Seventy of the 74 passengers died.
Nineteen occupants were believed to have survived the impact, but their injuries prevented them from escaping.Of the motorists on the bridge involved:

Four sustained fatal injuries
One sustained serious injuries
Three sustained minor injuriesClinging to the tail section of the broken airliner in the ice-choked Potomac River were flight attendant Kelly Duncan and four passengers: Patricia "Nikki" Felch, Joe Stiley, Arland D. Williams Jr. (strapped and tangled in his seat), and Priscilla Tirado. Duncan inflated the only flotation device they could find, and passed it to the severely injured Felch.  Passenger Bert Hamilton, who was floating in the water nearby, was the first to be pulled from the water.


=== Crash response ===
Many federal offices in downtown Washington had closed early that day in response to quickly developing blizzard conditions. Thus,  a massive backup of traffic existed on almost all of the city's roads, making reaching the crash site by ambulances very difficult. The Coast Guard's harbour tugboat Capstan (WYTL 65601)  and its crew were based nearby; their duties include ice breaking and responding to water rescues.  The Capstan was considerably farther downriver on another search-and-rescue mission. Emergency ground response was greatly hampered by ice-covered roads and gridlocked traffic, ambulances dispatched at 4:07 pm took 20 minutes to reach the scene of the crash. Ambulances attempting to reach the scene were even driven down the sidewalk in front of the White House. Rescuers who reached the site were unable to assist survivors in the water because they did not have adequate equipment to reach them. Below-freezing waters and heavy ice made swimming out to them impossible.  Multiple attempts to throw a makeshift lifeline (made out of belts and any other things available that could be tied together) out to the survivors proved ineffective. The rescue attempts by emergency officials and witnesses were recorded and broadcast live by area news reporters, and as the accident occurred in the nation's capital,  large numbers of media personnel were on hand to provide quick and extensive coverage.
Roger Olian, a sheet-metal foreman at St. Elizabeth's Hospital, a Washington psychiatric hospital, was on his way home across the 14th Street Bridge in his truck when he heard a man yelling that  an aircraft was in the water. He was the first to jump into the water to attempt to reach the survivors. At the same time, several military personnel from the Pentagon—Steve Raynes, Aldo De La Cruz, and Steve Bell—ran down to the water's edge to help Olian.

At this point, flight controllers were aware only that the plane had disappeared from radar and did not respond to radio calls, but had no idea of either what had happened or the plane's location.
At approximately 4:20 pm EST, Eagle 1, a United States Park Police Bell 206L-1 Long Ranger helicopter (registry number N22PP), based at the "Eagles Nest" at Anacostia Park in Washington and manned by pilot Donald W. Usher and paramedic Melvin E. Windsor, arrived and began attempting to airlift the survivors to shore. At great risk to themselves, the crew worked close to the water's surface, at one time coming so close to the ice-clogged river that the helicopter's skids dipped beneath the surface.
The helicopter crew lowered a line to survivors to tow them to shore. First to receive the line was Bert Hamilton, who was treading water about 10 ft (3 m) from the plane's floating tail. The pilot pulled him across the ice to shore, while avoiding the sides of the bridge. By then, some fire/rescue personnel had arrived to join the military personnel and civilians who pulled Hamilton (and the next/last three survivors) from the water's edge up to waiting ambulances. The helicopter returned to the aircraft's tail, and this time Arland D. Williams Jr. (sometimes referred to as "the sixth passenger") caught the line. Williams, not able to unstrap himself from the wreckage, passed the line to flight attendant Kelly Duncan, who was towed to shore. On its third trip back to the wreckage, the helicopter lowered two lifelines, fearing that the remaining survivors had only a few minutes before succumbing to hypothermia. Williams, still strapped into the wreckage, passed one line to Joe Stiley, who was holding on to a panic-stricken and blinded (from jet fuel) Priscilla Tirado, who had lost her husband and baby. Stiley's co-worker, Nikki Felch, took the second line. As the helicopter pulled the three through the water and blocks of ice toward shore, both Tirado and Felch lost their grips and fell back into the water.
Priscilla Tirado was too weak to grab the line when the helicopter returned to her. A watching bystander, Congressional Budget Office assistant Lenny Skutnik, stripped off his coat and boots, and in short sleeves, dove into the icy water and swam out to successfully pull her to shore. The helicopter then proceeded to where Felch had fallen, and paramedic Gene Windsor stepped out onto the helicopter skid and grabbed her by the clothing to lift her onto the skid with him, bringing her to shore. When the helicopter crew returned for Williams, the wreckage he was strapped into had rolled slightly, submerging him; according to the coroner Williams was the only passenger to die by drowning. His body and those of the other occupants were later recovered.
While the weather had caused an early start to Washington's rush-hour traffic, frustrating the response time of emergency crews, the early rush hour also meant that trains on the Washington Metro were full when,  just 30 minutes after Flight 90 crashed, the Metro suffered its first fatal crash at Federal Triangle station. This meant that Washington's nearest airport, one of its main bridges in or out of the city, and one of its busiest subway lines were all closed simultaneously, paralyzing much of the metropolitan area.


== NTSB investigation and conclusion ==
The 737 had broken into several large pieces upon impact - the nose and cockpit section, the cabin up to the wing attachment point, the cabin from behind the wings to the rear airstairs, and the empennage. Although actual impact speeds were low and well within survivability limits, the structural breakup of the fuselage and exposure to freezing water nonetheless proved fatal for all persons aboard the plane except those seated in the tail section. The National Transportation Safety Board concluded that the accident was not survivable. Determining the position of the rudder, slats, elevators, and ailerons was not possible due to impact damage and the majority of the flight control system having been destroyed.
The National Transportation Safety Board determined that the probable cause of the crash included the flight crew's failure to enforce a sterile cockpit during the final preflight checklist procedure. The engines' anti-ice heaters were not engaged during the ground operation and takeoff.  The decision to take off with snow/ice on the airfoil surfaces of the aircraft, and the captain's failure to reject the takeoff during the early stage when his attention was called to anomalous engine instrument readings also were erroneous.
The NTSB further stated: