History of Flight
On July 29, 2023, about 1034 central daylight time, United Airlines flight 702, a Boeing 767-322 (registration N641UA), experienced substantial damage while landing at George Bush Intercontinental Airport (IAH) in Houston, Texas. The airplane was operating a scheduled domestic passenger flight under Title 14 Code of Federal Regulations Part 121 from Newark Liberty International Airport (EWR) in Newark, New Jersey, to IAH. Onboard were 202 passengers and crew members, none of whom were injured.
The first officer (FO) was the pilot flying, and the captain was the pilot monitoring. The flight crew reported an uneventful departure from EWR and cruise segment. The airplane was cleared for the DOOBI2 arrival to IAH and then the instrument landing system approach to runway 26L. According to the flight crew, the airplane was fully configured for landing, on speed, and in compliance with the company's stable approach criteria. The initial touchdown on the main wheels was normal.
The FO stated that after main landing gear touchdown, he held aft pressure on the control yoke to keep the nosewheel from hitting the runway. However, the nosewheel contacted the runway with "abnormal force." The airplane seemed to bounce, and the FO reacted by pulling the control yoke aft to prevent a second nosewheel impact.
Flight data recorder (FDR) data indicated that control column inputs ranged from about 5° nose high to 5° nose low during the landing. Data also showed that the speedbrakes deployed simultaneously as the thrust reversers transitioned from not deployed to deployed, and the nosewheel bounced a second time. Subsequently, the nosewheel contacted the runway a third time, after which the airplane began to decelerate. The captain then assumed control of the airplane, and the remainder of the landing rollout was normal.
Personnel
The captain was hired by United Airlines in April 2001 as a first officer. At the time of the accident, he was based at EWR and held type ratings in the Airbus 320 and Boeing 737, 757, and 767. His most recently completed training included a proficiency check and emergency drill training on June 12, 2023, crew resource management on April 24, 2023, and initial operating experience on October 23, 2022. His most recent line check was completed on January 21, 2023.
The FO was hired by United Airlines on February 7, 2023. He was based at EWR and held type ratings on several airplanes, including the Boeing 757 and 767. He completed his required training and initial line-oriented evaluation checkride on April 28, 2023, receiving an unsatisfactory performance rating due to deficiencies with takeoffs and aircraft control. During his second checkride, the FO obtained a satisfactory performance rating but received the minimum grade in three areas, one of which was landings, which resulted in a "short cycle." A short cycle allowed the FO to proceed with operating experience but required evaluation in 90 days rather than the normal 9 months. According to the check airman who conducted the second line-oriented evaluation, the short cycle was intended to ensure the FO's proficiency met standards given his previous struggles.
Aircraft Information
The speedbrake on the accident airplane was controlled by a lever located on the control stand. It had three positions: down, armed, and up, identified by demarcation lines. The Boeing 767 Flight Crew Operations Manual stated that the speedbrake lever could be placed in an intermediate position between ARMED and UP. In the ARMED position, when the landing gear was fully on the ground (not tilted) and the thrust levers were at idle, the speedbrake lever was driven aft to the UP position and the spoiler panels fully extended. On the ground, when either thrust lever was moved to the reverse idle detent, the speedbrake lever was driven to the up position and the spoiler panels fully extended, regardless of whether the lever was in the ARMED position.
Meteorological Information
IAH was equipped with an automated surface observing system. Observations from 15 minutes before to 10 minutes after the accident indicated that the wind was from the south-southwest at a speed of 5 knots or less.
Wreckage and Impact Information
A postaccident examination of the airplane revealed damage to the crown of the upper fuselage. The fuselage skin was buckled and fractured, with damage to the underlying stringers and frames.
Additional Information: Similar Occurrences
De-rotation is the lowering of the aircraft's nose gear to the runway following main gear touchdown during landing. A review of National Transportation Safety Board investigations and assisted international investigations identified seven similar de-rotation accidents involving Boeing 757/767 aircraft. These accidents occurred when pilots applied large nose-down control column deflections after main landing gear touchdown, resulting in large nose-down pitch rates and high vertical velocities at the nose gear. The combination of vertical velocity and pitch rate led to compression loads exceeding the design loads of the forward fuselage crown structure.
Flight Recorder Data
FDR data revealed that the airplane touched down on both main wheels with a control column position of about 0.35° and the speedbrake handle in the down (unarmed) position. After initial touchdown, the maximum recorded control column positions during the landing sequence were 5.71° and -4.75°. The data also showed that the airplane rolled to the left, causing the right main landing gear to lift off the runway. Subsequently, the nosewheel impacted the runway with a force equivalent of about 1.4 gravitational force equivalent (G). The thrust reversers were in transit as the speedbrakes deployed, and the nosewheel impacted the runway a second time with a force of about 1.6 G and bounced. A third impact occurred with a force of about 1.6 G.
Operational Guidance
The United Airlines 757-767 Flight Manual, dated June 30, 2023, provided the following landing guidance: "Ensure that the airplane is not allowed to pitch up after touchdown. Fly the nose down to the runway." For a normal landing, the manual stated to plan for touchdown at least 1000 feet from the threshold and hold sufficient back pressure on the control column to keep the pitch attitude constant. It also noted that if the EICAS advisory AUTOBRAKE displayed or if deceleration was not normal, the pilot should brake manually, and the captain should slowly raise the speed brakes to the up position while smoothly lowering the nose to the runway if automatic extension failed.
The Boeing 767 Flight Crew Training Manual provided additional guidance: after main gear touchdown, pilots should fly the nose wheels smoothly onto the runway without delay. If the speedbrakes did not extend automatically, the lever should be moved to the UP position without delay. Control column movement forward of neutral should not be required. The manual advised against holding the nose wheels off the runway, stating that this technique results in high nose gear sink rates and reduced braking effectiveness. It also cautioned against making large nose-down control column movements before the nose wheels are lowered to avoid possible structural damage. For flare and touchdown, the manual recommended initiating the flare when the main gear was approximately 20 to 30 feet above the runway by increasing pitch attitude about 2°–3°, then smoothly retarding thrust levers to idle and making small pitch adjustments.