NTSB Faults Crew Miscommunication For United’s Altitude Loss Incident


The NTSB says miscommunication between the pilots of a United Boeing 777 caused the aircraft to plunge to under 800 feet over the Pacific Ocean after departing Kahului, Hawaii, on Dec. 18, 2022. The error caused the crew to mismanage the aircraft’s vertical flightpath, airspeed and pitch, the NTSB said.

United Flight 1722 had departed Kahului enroute to San Francisco with 281 passengers and crew aboard. Shortly after departure, it entered heavy rain and IMC and descended rapidly from 2100 feet to about 748 feet above the water before the crew recovered the aircraft, the NTSB said. No injuries or damage occurred and the flight continued to San Francisco.

According to the NTSB, the captain and first officer agreed on a takeoff with flaps 20 and reduced thrust.  During taxi, ground control informed the crew of low-level windshear advisories and the crew revised their takeoff plan to use full thrust. The captain hand-flew the departure with autothrottles engaged.

During climb-out, the 777’s airspeed fluctuated due to turbulence and wind shear and as it accelerated, the captain lowered the pitch and called for flaps five. The first officer, however, thought the command was for flaps 15. The captain then noticed the maximum operating speed indicator shifted to a lower value than expected and to avoid overspeed, he manually reduced power, overriding the autothrottles. He again called for flaps five, which the first officer set.

At this point in the departure, the aircraft’s pitch attitude was decreasing and the airspeed was increasing, causing the rapid descent from low altitude. The descent activated the ground proximity warning system and after initially reducing power to control the airspeed, the captain initiated CFIT recovery, applying full power.

The NTSB said the incident was caused by “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 pilots voluntarily reported the incident to the NTSB. United has reportedly modified its operations training and issued a flightpath awareness notice to pilots.  

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    • Highly unlikely. I don’t know how much automation experience you have but it is my opinion that the one time you shouldn’t try to hand-fly is when things are getting tough. The autopilot would’ve anticipated the airspeed limit and pulled back the power to keep everything within limits and at the same time continue to climb to the preset altitude. Target speed was 200KTS or less and their flap 15 max speed 215, flaps 5 would’ve been 235. This is the time to sit back and monitor rather than overload yourself, which is clearly what happened here. Of course there is a time and place to hand-fly but obviously this wasn’t it. Plenty of reading on this issue in other articles as well.

    • The autopilot system (which is really 3 autopilots working in parallel) is very robust and handles windshear very well.

  1. Priority #1…don’t hit the ground/water.

    Concern over hand flown, automation, mis-configured, bad weather, busting airframe limits/ ATC altitudes…see priority #1.

    By now we’ve all seen the L1011 Everglades video.

  2. Another example of just how precarious flying really is. With all the automation these days we still have incidences like this occurring. I would like to think the F/O had enough experience to question and double-check the flap setting at that point of the flight. Isn’t that what he/she is there for?

  3. I have heard (unconfirmed) that the Captain and First Officer were both very new, and they weren’t getting along very well.
    Choosing to override the autothrottles and reduce thrust in a takeoff climb in (turbulent?) IMC to avoid over speeding the flaps instead of increasing the pitch attitude is absolutely bad airmanship; 999/1000 airline pilots would raise the nose in my experience. A Pilot is setting themselves up for the exact outcome that occurred.
    Glad they recovered from the upset.

    • ^This. 100%. Miscommunication’s happen every day, on every flight. But this is an example of poor airmanship. The captain was behind the airplane and task saturated. Thankfully this event wasn’t worse.

  4. Hate to wag the finger at other pilots when I wasn’t there, but a minor miscommunication like this shouldn’t cause the PF to forget the proper pitch attitude for climb for that aircraft. Yes, there was a distraction, but c’mon.

  5. Once again, the NTSB has issued their opinion, not facts, as to what caused United Flight 1722 to drop from 2,100 to 748 feet unexpectedly on December 18, 2022. Once again, blame it on the pilots, if no other cause can be found. In the report they even noted that there was turbulence in the area. It has wrongly been said that wake turbulence, that air disturbed by one plane in front, could cause wake turbulence which could cause the following plane to drop suddenly, NO! That type of wake turbulence would not cause a plane to drop, it might cause the following plane to experience a rough ride but not drop suddenly and bottom out suddenly, causing injuries to the passengers and crew. Instead, this unexpected drop was caused by the plane flying into a vortex created by a Front and a High Velocity Overhead Jet Stream (HVOJS) of 109 Knots. It should be noted that Hawaiian Airlines Flight 35 encountered the same event, turbulence and dropping earlier that morning, injuring 36 passengers and crew. That same Front was there and the HVOJS was 78 knots at that time. Any time there is a Front and a HVOJS above 58 knots a vortex can be formed. If you read my new book Science About How Tornadoes And Vortexes Form And How They Are Causing Planes To Crash (Including MH370) you will understand.
    Ronald B. Hardwig, Professional Engineer

  6. Somewhat surprised & confused as to the NTSB’s investigative conclusion regarding UAL 1722 – PHOG departure on 12/18/22. Certainly the communication CRM aspect contributed, yet it seems like the Captain was very much task loaded with flying the aircraft.

    A flaps 20 t/o at MAX thrust will result in a time compressed transition to a normal climb profile if you’re not ready for such. Sounds like the Captain failed to appropriately brief the MAX thrust departure to include the non-standard profile and flap retraction. Gotta aviate and get things cleaned up while not forgetting VNAV in the heat of the moment. Important to get to standard CLIMB thrust from MAX.

    I believe the NTSB failed miserably regarding this investigation. Would be interesting to know Boeing’s involvement in the investigation.