United B772 at Kahului on Dec 18th 2022, pilots filed safety report

Last Update: August 10, 2023 / 19:57:51 GMT/Zulu time

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Incident Facts

Date of incident
Dec 18, 2022



Flight number

Aircraft Registration

Aircraft Type
Boeing 777-200

ICAO Type Designator

A United Boeing 777-200, registration N212UA performing flight UA-1722 from Kahului,HI to San Francisco,CA (USA), departed Kahului's runway 02, climbed to initially FL360 and further FL390 and landed on San Francisco's runway 28L about 4:10 hours after departure.

The aircraft remained on the ground in San Francisco for about 2.5 hours, then departed for its next flight.

The FAA reported: "The United Airlines flight crew reported the incident to the FAA as part of a voluntary safety reporting program. The agency reviewed the incident and took appropriate action." but did not elaborate on what incident occurred and also did not comment on a report that had surfaced on Sunday (Feb 12th) whether this report had any merit or not.

The Airline stated:

After landing at SFO, the pilots filed the appropriate safety report. United then closely coordinated with the FAA and ALPA on an investigation that ultimately resulted in the pilots receiving additional training. Safety remains our highest priority.

Additional points:

- The pilots fully cooperated with the investigation and their training program is ongoing

- The two pilots involved have approximately 25,000 hours of flying experience between them

- This was not NTSB reportable.

Again, the airline did not elaborate on what occurrence had happened and did not comment on the story that surfaced on Sunday and is currently going around the world without any further check, assuming these FAA and Airline Statements confirm that narrative.

One radar website claims, the aircraft had reached 2200 feet MSL (according to standard pressure) on Dec 19th 2022 00:50:45Z, then entered a descent passing 1550 feet at 00:50:51Z and reaching 775 feet at 00:50:57Z. The aircraft subsequently climbed again. Taking those data into account, the aircraft would have dropped 1425 feet in 12 seconds maximum which requires about free fall acceleration (9.81m/s/s) without taking into account any drag and airflow around the aircraft still causing residual lift even in the unlikely case that the main wings would have been entirely stalled.

Other radar sites as well as official FAA ASDI data do not show any descent during the climb at all, these data only suggest a slower than normal climb.

Neither recordings show the aircraft turning but rather climb out on a very straight track.

The report that surfaced on Sunday claims that the aircraft experienced an acceleration of about +2.7G during the recovery, which would be beyond structural design limits and would render this occurrence at least a serious incident requiring a NTSB investigation. However, there is no indication that the NTSB opened an investigation (the NTSB so far has not responded to our inquiry) and the airline states: "This was not NTSB reportable." In addition, if indeed 2.7G were encountered, passengers would certainly have reacted and this occurrence would have been all over the media the next day at the very latest. If the FDR indeed had recorded 2.7G, then the aircraft could not have flown within 2.5 hours after landing due to the mandatory structural inspection.

The FAA's point of a "voluntary safety report" by the crew also suggests this was NOT a reportable (serious) incident as the report of Sunday suggests.

We have several inquiries including a Freedom of Information Request open with the FAA, NTSB and United to find out more details about this occurrence, that remains unclear at this point. If and when we receive further information, we shall update our report, of course.

On Feb 14th 2023 the NTSB told The Aviation Herald: "The event you referenced was not required to be reported to the NTSB.", nonetheless, the NTSB have opened an investigation now, a preliminary report can be expected in 2-3 weeks.

On Mar 9th 2023 the FAA responded to our FoIA requests: "The search revealed no records responsive to your request seeking records regarding the incident on December 19, 2022. The records you sought are outside of the Federal Aviation Administration’s (FAA) 45-day record retention period."

On Apr 12th 2023 the NTSB advised: "Some incident investigations bypass the preliminary report phase and go directly to the final report. This was one of those investigations."

From my editorial point of view it is clear however, that the occurrence did not happen along the lines of the report that surfaced on Sunday.

On Aug 10th 2023 the NTSB released their final report and the investigation docket concluding the probable cause of the incident was:

The flight crew’s failure to manage the airplane’s vertical flightpath, airspeed, and pitch attitude following a miscommunication about the captain’s desired flap setting during the initial climb.

The NTSB analysed:

United flight 1722 lost altitude about 1 minute after departure while in instrument meteorological conditions, which included heavy rain. The airplane descended from 2,100 ft to about 748 ft above the water before the crew recovered from the descent. No injuries were reported, and the airplane was not damaged. The NTSB was not originally notified of the event, since it did not meet the requirements of Title 49 Code of Federal Regulations Part 830.5. However, the NTSB learned of the event about 2 months later and chose to open an investigation. By that time, both the cockpit voice and flight data recorder durations had been exceeded. The investigation utilized flight crew statements and other records as information sources.

The captain (who was the pilot flying) reported that he and the first officer had initially planned for a flaps-20 takeoff (flap setting of 20°) with a reduced-thrust setting, based on performance calculations. However, during taxi, the ground controller advised them that low-level windshear advisories were in effect. Based on this information, the captain chose a flaps-20 maximum thrust takeoff instead. He hand-flew the takeoff, with the auto throttles engaged. During the takeoff, the rotation and initial climb were normal; however, as the airplane continued to climb, the flight crew noted airspeed fluctuations as the airplane encountered turbulence. When the airplane reached the acceleration altitude, the captain reduced the pitch attitude slightly and called for the flap setting to be reduced to flaps 5. According to the first officer, he thought that he heard the captain announce flaps 15, which the first officer selected before contacting the departure controller and discussing the weather conditions. The captain noticed that the maximum operating speed indicator moved to a lower value than expected, and the airspeed began to accelerate rapidly.

The captain reduced the engine thrust manually, overriding the auto throttle servos, to avoid a flap overspeed and began to diagnose the flap condition. He noticed that the flap indicator was showing 15°, and he again called for flaps 5, and he confirmed that the first officer moved the flap handle to the 5° position.

The first officer stated that he “knew the captain was having difficulty with airspeed control”, and he queried the captain about it as he considered if his own (right side) instrumentation may have been in error. He did not receive an immediate response from the captain. Both pilots recalled that, about this time, the airplane’s pitch attitude was decreasing, and the airspeed was increasing. The first officer recalled that that the captain asked for flaps 1 soon after he had called for flaps 5, and when the first officer set the flaps to 1°, he then noticed the airspeed had increased further, and the control column moved forward.

Both pilots recalled hearing the initial warnings from the ground proximity warning system (GPWS), and the first officer recalled announcing “pull up pull up” along with those initial GPWS warnings. The captain then pulled aft on the control column, initially reduced power to reduce airspeed, and then applied full power to “begin the full CFIT [controlled flight into terrain] recovery.” The first officer recalled that, as the captain was performing the recovery, the GPWS alerted again as the descent began to reverse trend; data showed this occurred about 748 ft above the water. After noting a positive rate of climb, the captain lowered the nose to resume a normal profile, ensured that the flaps and speed brakes were fully retracted, and engaged the autopilot. The remainder of the flight was uneventful.

According to the docket the airline submitted flight information to the NTSB in e-mail amongst other details stating:

14:50:51– Vertical speed and pitch attitude continued a negative downward trend to reach a maximum of -8,536 feet per minute and -16.74 degrees respectively while at 1,386 feet (radio altitude)

14:50:52 – Maximum roll attitude measured at -4.83 degrees; this is a left wing down condition

14:50:57– GPWS “Too Low Terrain” aural
1. Latitude: 20 degrees 57’48.83” N / Longitude: 156 degrees 23’24.18
2. Magnetic heading 18.5 degrees
3. The lowest radio altitude during the undesired aircraft state was 748 feet; this occurred approximately 5.06 miles after the location that the aircraft rotated from the runway.
4. Vertical acceleration recorded was 2.66g

14:51:01 – Maximum pitch attitude was recorded at +23.42 degrees at an altitude of 1,020 Feet (radio altitude)
Aircraft Registration Data
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Incident Facts

Date of incident
Dec 18, 2022



Flight number

Aircraft Registration

Aircraft Type
Boeing 777-200

ICAO Type Designator

This article is published under license from Avherald.com. © of text by Avherald.com.
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