Twin-Engine Failure: The Miracle on the Hudson

The case of the Airbus A320 that took off from LaGuardia Airport in New York, Runway 04, on January 15, 2009, only to encounter a large flock of birds- several of which were ingested into the jet engines, rendering them unusable – leading the pilot to complete a landing on the river nearby (creating the moniker of “Miracle on the Hudson”) to save everyone on board is one of the most extraordinary tales of bird strikes and an even more extraordinary case of recovery after a dual-engine failure in aviation. 

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Bird Strike Causes Dual Engine Failure

The flight in question was US Airways Flight 1549, which had the official callsign Cactus 1549. 

The Airbus A320 involved in the miracle was headed for its second flight of the day. It was also the final leg of a four-day rotation for the crew. The entirety of the sequence of US Airways Flight 1549 was captured in the cockpit voice recorder, with the pre-flight checks included. 

Timeline of Hudson River Ditching

The Cockpit Voice recorder revealed that US Airways Flight 1549 had a minor problem with the first officer’s transmission button. Incidentally, despite Jeff Skiles, the first officer being a highly experienced first officer with over 15,000 flight hours, he had clocked less than 50 hours on the A320. A vast reserve of his experience had come from the Fokker 100 and Boeing 737. 

The following table details the timeline of how the US Airways 1549 hit a flock of birds, and had to be ditched into the Hudson:

Category	Details
Takeoff Clearance	Cleared for takeoff to the northeast from LaGuardia Runway 4
Takeoff Time	15:24:56 Eastern Standard Time (20:24:56 UTC)
Initial Climb Report	At 15:25:51, aircraft reported at 700 feet and climbing
Weather Conditions (14:51)	Visibility 10 miles, broken clouds at 3,700 feet, wind 8 knots from 290°
Weather Conditions (Approx. 15:51)	Few clouds at 4,200 feet, wind 9 knots from 310°
Cockpit Observation	At 15:26:37, Captain Sullenberger remarked, “What a view of the Hudson today.”
Initial Flight Direction	Aircraft initially headed north after takeoff
Turn After Departure	Anti-clockwise turn to follow the Hudson River southward
Simulated Alternative Paths	Routes to Teterboro Airport and back toward LaGuardia were modeled
Bird Strike Time	15:27:11
Altitude at Bird Strike	2,818 feet
Location of Bird Strike	Approximately 4.5 miles north-northwest of LaGuardia Airport

Almost two minutes into the flight, Captain Sullenberger shouted the word: “Birds!”, signaling that the aircraft was on a collision course with a flock of of migratory Canada geese, which can weigh as much as twelve pounds. According to Captain Sullenberger: 

“They have five- or six-foot wingspans. They struck the airplane along the leading edges of the wings, the nose, and into the center, the core of both jet engines. Jet engines are turbines. They are finely balanced machinery spinning at tens of thousands of revolutions per minute. Having a ten-pound object or two go through each of them, in the center of the engine core, is incredibly damaging and disruptive.”

One has to note that the Airbus A320 and the CFM56 engines that were a part of it were certified using birds weighing only two to two and a half pounds. 

Investigators found that multiple birds were ingested by both engines following the impact. Some of the other significant happenings included the following:

• In each engine, at least one bird penetrated the core, disrupting internal components

• The ingestion resulted in significant damage to the low-pressure compressors

• Inlet guide vanes in both engines were also compromised

• The mechanical damage caused immediate engine flameouts

• The condition of the engines eliminated the possibility of an in-flight restart

Events After Engine Flameout of US Airways Flight 1549

There was almost no way for the pilots to assess the extent of the damage as it happened. Jeff Skiles words (immediately after the strike) were, “Uh-oh,”, while Captain Sullenberger, “We have one… no, both engines are rolling back.”  This is followed by his words “I’m starting the APU and I have controls.”, just two seconds later. Ten seconds after this, he declared a Mayday (albeit that his Mayday call was partially blocked by another transmission). 

One of the more important details that is pertinent to the crash was revealed by Mentour Pilot:

“At the time, US Airways operated A320s configured both for extended over-water operations and for domestic routes only. Aircraft equipped for over-water use carried life vests for all passengers and had emergency slides that could double as life rafts at both forward and aft exits. By sheer luck, this aircraft was one of those equipped for extended over-water operations, despite not being scheduled to fly over water that day.”

The following table gives us an idea of the tasks carried out by the two captains in the flight.

Aspect	Captain Chesley “Sully” Sullenberger	First Officer Jeffrey Skiles
Primary Role	Aircraft control and decision-making	Systems management and procedural execution
Immediate Response	Assumed overall command and assessed external options	Immediately began running the engine failure checklist
Initial Focus	Situational awareness and aircraft trajectory	Identification of dual-engine failure and correct checklist
Use of Training	Applied judgment under time pressure	Recent type-rating training aided rapid checklist recall
Interaction with ATC	Communicated directly with air traffic control	No ATC communication; remained task-focused
Runway Assessment	Quickly determined offered runways were not feasible	Continued checklist execution during runway evaluation
Turnback Consideration	Recognised turnback was impractical due to altitude loss	Did not assess flight path options; remained procedural
Teterboro Option	Considered but ruled out due to distance and risk	Checklist-driven, not involved in destination selection
Decision Direction	Early inclination toward Hudson River as safest option	Supported outcome by maintaining aircraft systems discipline
Descent Phase Focus	Flew the aircraft and selected a landing area	Continued checklist despite limitations for low-altitude failure
Checklist Limitations	Recognised procedural mismatch with scenario	Followed checklist designed for high-altitude failures
Crew Coordination	Maintained clear command authority and task division	Maintained strict adherence to assigned role
Final Responsibility	Ensured aircraft control through water landing	Supported flight path by managing systems to the end

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Captain Sully’s Critical Decisions and the Role of the APU in the Ditching

Jeffrey Skiles worked to the best of his abilities to use the checklists to restart at least one of the engines, so that the aircraft could fly again and return to a runway. Two minutes after the aircraft’s engines had given way, Captain Chesley Sullenberger picked up the PA microphone and announced, “This is the captain. Brace for impact.”

The flight attendants might have been taken aback as until this time, there had been no direct communication with the cabin crew about the gravity of the situation. Coupled with this is the fact that an announcement such as “Brace for impact”, which, according to Cabin Safety Investigation Guidelines, helps to “pre-position your body against whatever it is most likely to hit during the crash, and thus avoid the secondary impact which could otherwise take place“. 

The captain also heard flight attendants giving their commands the passengers: “Brace, brace, brace. Heads down, stay down.” Captain Sullenberger had the following multiple warnings that prompted him to ask the passengers to brace for impact:

• TCAS warnings due to rotorcraft traffic over central New York.
• Ground Proximity Warning System alerts

Captain Sulleneberger revealed during the investigation that he felt as of he was was flying at green-dot speed, which has the following properties:

• The Auto Flight System calculates green dot (GD) speed using aircraft weight and pressure altitude.

• Aircraft weight is derived from the Zero Fuel Weight entered into the Flight Management System during preparation.

• The GD formula targets the best lift-to-drag ratio for the aircraft’s weight and altitude.

• This speed applies in a clean configuration with one engine inoperative.

• In certain phases, such as holding, GD is adjusted to minimize drag.

• Reducing drag through GD optimization also lowers fuel consumption.

Roughly two and a half minutes after the dual-engine failure, First Officer Jeff Skiles reaches a critical assessment: restarting the engines was unlikely. About 20 seconds later, Sullenberger requested for flap extension. Skiles reported an airspeed of 170 knots at an altitude of 250 feet. According to Sullenberger, “without engine thrust, we were using gravity to provide forward motion, descending like a hotel elevator at two floors per second“.

Skiles suggested advancing the thrust levers as a final check. He later confirmed whether the aircraft was configured with flaps two and asked whether further extension is required. Sullenberger decides to maintain flaps two, a choice later scrutinized during the investigation.

Sullenberger explained that flaps three would have increased drag at a critical phase, while flaps two offered a more favorable pitch attitude for water contact. Investigators ultimately supported this judgment.

As the aircraft descends toward the Hudson River, Sullenberger begins preparing for the flare maneuver. At this stage, airspeed becomes a major limiting factor.

• Below 200 feet, the aircraft is operating well under ideal margins.

• Airspeed ranges from 15 to as much as 90 knots below the minimum speed associated with a comfortable stall buffer.

• Despite these constraints, the crew maintains control and coordination through the final moments.

The Auxiliary Power Unit Kicks in

The decision of Captain Sullenberger to deploy the APU was pivotal. An Auxiliary Power Unit, commonly known as the APU, enables an aircraft to function independently without the need for external ground-based systems, reports Skybrary. This autonomy removes reliance on equipment such as the following:

• ground power units
• external air-conditioning sources
• high-pressure air start carts

This is especially true of the cases of remote or abnormal operations. The APU is a compact gas turbine engine installed within the aircraft structure. Its placement varies by design.

• Most aircraft house the APU in the tail cone.

• Some configurations position it within an engine nacelle or a wheel well.

• The unit is designed to operate using only onboard electrical power.

Once started from the aircraft batteries, the APU supplies energy to multiple systems.

System Functions Supplied by the APU

According to Mentour Pilot, in the absence of the APU, the A320 that would later land in the Hudson:

“…would have been powered only by the ram air turbine, placing the aircraft in alternate law. In alternate or direct law, the Airbus A320 loses alpha floor protection. In normal law, the aircraft’s computers prevent a stall even if pilots attempt one. Without this protection, the aircraft would have been far more difficult to control at low speed”.

As Sully approached landing on water, he asked his first officer if he had any ideas. Jeff responded that he did not, signifying that the two had realized that they had not overlooked any options and that in whatever little time they had, they had taken every possible action into consideration.

According to Captain Sullenberger, the vast reserves of experience that his first officer was also seminal to miracle landing:

“Had Jeff not also had 20,000 hours of flying time like I did, had he not been a captain before, and had he not been so experienced, he would not have known either to do that or how to do that. He made important suggestions at several points in the flight. He was silently supporting me as I made each decision, ready to intervene or check my performance if he thought I was making an error.”

Final Approach and Water Impact

During the final descent, Captain Sullenberger initiated the flare maneuver. However, the aircraft’s low airspeed, combined with alpha floor protection, limited the pitch response.

Despite full aft sidestick input, the aircraft did not achieve the intended nose-up attitude and struck the water with significant force. The final cockpit voice recorder entry captured the captain instructing the crew to brace for impact.

Impact Forces and Structural Damage

The aircraft contacted the Hudson River at loads exceeding its certified ditching limits. Structural damage was concentrated toward the aft section.

Despite the severity of the impact, the aircraft remained largely intact and came to rest on the water surface.

Damage to the rear fuselage allowed water to enter the cabin, causing the aft section to begin sinking. Although the Airbus A320 was designed to remain afloat long enough to support a full evacuation, the progressive flooding required immediate action by the cabin crew.

Evacuation Dynamics

Evacuation over the wings progressed more slowly than a standard water evacuation.

• Cabin crew redirected passengers away from the aft cabin.

• Evacuation efforts focused on the overwing exits and forward slides.

• Passengers in the rear were guided forward where possible.

• Many passengers remained standing on the wings instead of entering the river.

• Forward slide rafts were used by passengers who moved ahead from the rear cabin.

• Space on the wings and rafts was sufficient for all occupants.

All 150 passengers and five crew members were accommodated without overcrowding.

Rescue and External Response

Air traffic control rapidly coordinated with the Port Authority, initiating waterborne rescue operations within minutes of the ditching.

• Multiple vessels reached the aircraft shortly after impact.

• Cold water temperatures increased the urgency of rescue efforts.

• Proximity of ferries and boats was critical in preventing hypothermia-related fatalities.

The rapid response significantly reduced the risk of loss of life.

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Crew Actions After Evacuation

The flight crew remained uninjured throughout the event. After the aircraft stabilized, Captain Sullenberger and First Officer Skiles conducted a final cabin inspection to confirm that all passengers and cabin crew had evacuated. Only after verifying the aircraft was empty did the pilots exit through the forward doors.

The following points highlighted by the FAA report on the findings of the US Airways Flight 1549, which has been immortalized as the “Miracle in the Hudson”, shows the extraordinary skills of the pilot and how despite the twin-engine failure, Captain Sully, has been so highly revered:

• Despite being unable to complete the Engine Dual Failure checklist, the captain started the auxiliary power unit (APU), which improved the ditching outcome by ensuring continued electrical power and maintaining normal flight control law with envelope protections.

• The captain’s decision to ditch the aircraft in the Hudson River rather than attempt a return to an airport provided the highest probability of survivability.

• During the final approach, the captain experienced difficulty maintaining the intended airspeed, resulting in high angles of attack, challenges during the flare, a high descent rate at touchdown, and contributing fuselage damage.

• The difficulty in maintaining airspeed was attributed in part to high workload, stress, and task saturation.

• The captain’s decision to configure the aircraft with flaps 2 for the ditching was reasonable and consistent with the limited civilian and military guidance available for powerless forced landings.