This document summarizes a case study on Air Florida Flight 90, which crashed in 1982 shortly after takeoff from Washington National Airport. The crash was caused by ice buildup on the wings due to the pilots not turning on the engine anti-ice system before takeoff in blizzard conditions with 1/4 mile visibility. The crash killed 74 passengers and crew and highlighted issues with crew resource management, communication, decision making, and training at Air Florida that contributed to the accident. A investigation of the flight data and cockpit voice recorders revealed that anomalies in the engine readings caused by ice led the pilots to believe thrust was higher than it was, resulting in a stall during takeoff.
1. Case Study: Air Florida 90
"Larry-we're going down Larry!".
First Officer-Roger Pettit
Gregory C. Stamp
ASCI 604 Human Factors (Prof. Dr. R. Tyler)
Embry-Riddle Aeronautical University 1
2. AGENDA
Background
Accident Details
“How and Why”
Human Factors Application
Conclusion
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3. Background
Date: January 13, 1982
Bitter winter’s day with blizzard of snow
Temperature Conditions: as low as -5ºC (? ºF)
Limited Visibility: ½ mile in snow showers
Cloud Ceiling: 400ft
Flight Schedule: 2:15 pm Boeing 737
departure (National Airport to Fort Lauderdale, FL)
Aircraft flight hours: ?
Maintenance history: ? www.securiteaerienne.com
Passengers: 74 /
Cock Pit Personnel: ill/air-florida-90-b
Pilot: Captain Larry Wheaton
First Officer: Roger Pettit
Both were fairly young pilots/ new at Air Florida
Airline: Air Florida had rapid growth after Deregulation Act of 1978
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4. Accident Details
Key Events Leading up to Crash
(Timeline):
Just Before 1:40pm
Closed airport to plough instrument runway
Captain requested de-icing and then cancelled after
rejection of departure
2nd de-icing requested after re-opening of airport
At 3:23pm
Palm 90 cleared to depart gate
Captain mis-used reverse thruster to assist in push off
(violation of company policy)
Palm 90 taxied into position behind New York Air
DC-9 to melt snow
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5. Accident Details
At 3:59pm
Palm 90 was cleared for take-off from Runway36-
visibility down to ¼ mile
Within less than a minute after take-off- Palm 90
loss airspeed and started descending and
ploughed in 14th Street (“Rochambeau”) Bridge
Fell into Potomac River with only the tail visible
After Crash- “The Aftermath”:
Rescue team impeded by icy conditions
Only 6 people survived, 4 motorists died
Recovered both the FDR and CVR from the bottom
of the river
Critical in solving the puzzle of Palm 90”.
Discovered captain stated anti-ice switch was off
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6. “How and Why”
‘How:’
Captain Wheaton positioned Palm 90 behind
New York Air DC-9, use exhaust to melt the
ice off fuselage and wings
Counter effect ice melted and blew back over
the wings and re-frozen
Anomalies in engine instrument readings
Investigation concluded:
Failure to use engine anti-ice mechanism
Created large amounts of ice and snow to
gather in the engines without being melted.
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7. “How and Why”
‘Why:’
Exhaust from the DC-9 caused a lower than normal
reading on one of the EPR gauges.
Spectrum analysis of the engine sounds from the CVR
indicated that the anomalies in engines out the takeoff.
Investigators found that the engine de-ice system was
turned off
Ice on the compressor inlet pressure probe would cause a
higher than actual thrust reading on the EPR gauges.
Investigators found that ice build up in the wing
leading edge and slats could cause an abrupt nose up pitch
on takeoff
First Officer Pettit believed that the engines were producing
max thrust
The throttles weren’t advanced to provide more power to
prevent stall 7
8. Human Factors
Application
Decision Making:
Poor decision chain attributed Palm-90 accident
Determine what must be done
Pilot judgment error
Inappropriate procedures
Crew Resource Management:
Accident help initiated training in crew resource
management
Instill professional pilots a positive attitude and skills
Improve flight crew communication.
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9. Human Factors
Application
Communications
Break down in flight crew communication
First Officer Not assertive with communication to Pilot
Ex: “Pettit remarked several times that "that doesn't
seem right!"
Training
Air Florida lacked the necessary infrastructure
Provide adequate training for flight crew
Improper supervision of flight operations.
Lack of experience from both Pilot and Co-pilot
Selection
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Date of Accident: January 13, 1982 Location: Washington National’s Airport (DC) Weather Conditions: Washinton, DC was hit with a large blizzard of snow. Day was describe to be a bitter winter’s day (blizzard like conditions) at Washington’s National Airport Early closing of schools and businesses Travelers swarm the streets trying to get home Airport; Minimal activity Brief closing to clear snow Reopened at 12pm Numerous flights were backed up and dealing with delays
Key Events Leading up to Crash (Timeline): Just Before 1:40pm Closed airport to plough instrument runway Scheduled to reopen 2:30pm Boarding set at 2:30pm Captain requested de-icing and then cancelled after rejection of departure 2 nd de-icing requested after opening of airport After completion of de-icing, report of light dusting of snow on wings (snow still falling and accumulating) At 3:23pm Palm 90 cleared to depart gate Tires spun out of control show snow accumulation Captain mis-used reverse thruster to assit in pushh off (violation of company policy) Reverse thruster failed need two tugs to set free Palm 90 taxied into position behind New York Air DC-9 (last of 16 in line for take-off) Fifteen minutes later NY-Air aircraft was cleared for takeoff, then Palm 90 was instructed to prepare for take-off At 3:59pm Palm 90 was cleared for take-off from Runway36- visibility down to ¼ mile Runway 36 requires: 40 degree left turn shortly after being airborne follow along Potomac River Allows aircraft to avoid flying over the Washington Monument and White House Control Tower lost sight of Palm 90 during roll seuence due to poor visibility Within less than a minute after take-off- Palm 90 loss airspeed and started descending and ploughed in 14 th Street (“ Rochambeau”) Bridge Fell into Potomac River with only the tail visible
After Crash- “The Aftermath”: Rescue team attempted to reach surivors but was stymied by icy conditions Only 6 people survived, 4 motorists died “ Crews were able to recover both the FDR and CVR from the bottom of the river and both devices proved critical in solving the puzzle of Palm 90”. “ Knowing that it had been nearly 50 minutes between the aircraft's de-icing and takeoff, investigators were curious as to what had gone on in the aircraft in that span”. “ Their first clue came when, during the after engine start checklist, the captain replied "off" to the First Officer's call for anti-ice”. “ Though it seems hard to believe that the captain would reply "off" to anti-ice, extensive audio enhancement has given validity to the tape”.
‘ How:’ “ While waiting in line for takeoff, Wheaton positioned the aircraft behind the New York Air DC-9, attempting to use the aircraft's exhaust to melt the ice off Palm 90's fuselage and wings”. “ Though Wheaton thought this a sound practice, in reality the exhaust will just melt the ice and blow it back over the wing, allowing it to re-freeze further back in areas which the aircraft's anti-ice system can not clear”. “ While this information gave evidence of airframe icing, further analysis showed other problems with Palm 90”. “ Shortly before takeoff, the crew have a brief discussion concerning anomalies in the engine instrument readings”. “ Crash investigations concluded that the crew's failure to use the engine anti-ice mechanism caused large amounts of ice and snow to gather in the engines without being melted.”
‘ Why:’ “ Pettit suggested that the hot (less dense) exhaust from the DC-9 ahead was causing a lower than normal reading on one of the EPR gauges.” “ The indications seemed to return to near normal as Palm 90 got closer to takeoff.” “ Just before takeoff, Pettit began the brief, calling out takeoff power as EPR 2.04, V1 as 138kts, Vr as 140kts, and V2 as 144kts.” “ As Palm 90 was cleared for takeoff, Pettit advanced the throttle and immediately remarked at the abnormal indications from the EPR gauges again.” “ Pettit remarked several time that it was "real cold", indicating that the engines indicated the takeoff EPR of 2.04 quickly before the throttles were fully advanced.” “ Spectrum analysis of the engine sounds from the CVR indicated that the engines were actually running at an approximate EPR of 1.70 throughout the takeoff.” “ In studying the engines for signs of the anomaly, investigators found that the engine de-ice system was turned off.” “ In re-creating the conditions, investigators confirmed that ice on the compressor inlet pressure probe would cause a higher than actual thrust reading on the EPR gauges.” “ First Officer Pettit seemed to be aware of the anomaly during takeoff, but did not appear to have any idea what was causing it.” “ Pettit remarked several times that "that doesn't seem right", meaning that the low throttle setting was producing a high EPR reading while the aircraft was not accelerating properly.” Still, 45 seconds into the takeoff roll, Palm 90 reached it's rotation speed and pitched up abruptly, causing Captain Wheaton to exclaim "Easy!" and then, as the stall warning came on, "Forward! Forward!", indicating to Pettit to lower the nose to prevent the stall. Investigators found that ice build up in the wing leading edge and slats could cause an abrupt nose up pitch on takeoff. Pettit apparently believed that the engines were producing max thrust because at no time during the 30 second flight were the throttles advanced to provide more power to prevent stall.
Decision Making: Poor decision chain“The Palm-90 accident was attributed to a poor decision chain as a consequence a failure of Air Florida to give the flight crew adequate training, pilot judgment error, inappropriate procedures, and a break down in flight crew communication.” “ Palm-90 was one of several accidents that led commercial airlines to initiate training in “crew resource management” in order to instill in professional pilots a positive attitude and skills required to improve flight crew communication. But the underlying causes of this accident were clearly organizational in nature.” “ Air Florida, an upstart airline formed after the initial deregulation of the airlines in the 1980’s, had been woefully unprepared to handle interstate Jet flight operations because they lacked the necessary infrastructure to adequately train their flight crews, and did not properly supervise flight operations.”