[December 2022] United Airlines plane taking off from Maui plunged to within 800 feet of the Pacific Ocean, flight data shows

nbc ^ | 02/13/2023 | Marlene Lenthang

[BenLurkin]

The drop unfolded just 71 seconds after United Airlines Flight UA 1722 took off from Kahului Airport in Maui bound for San Francisco on Dec. 18, according to data from Flight Radar, a flight tracking website. The dive was first reported by The Air Current.

The flight data shows the plane took off at 2:49 p.m. local time and rose to an altitude of 2,200 feet when it suddenly took a dive and dropped to 775 feet over the Pacific Ocean.

The plunge saw the plane dip at a vertical rate of nearly 8,600 feet per minute, according to the data.

The flight recovered and regained an altitude of 2,350 feet shortly after, the dive and recovery making up less than a minute...

[Dave Wright]

This event was similar to an event that happenend to Emerates 231 in December. What they found was that the crew had not entered the correct climb altitude in the flight director (autopilot) during the pretakeoff checklist procedure and had left the setting at 0. Shortly after hand flying the takeoff they switched on the FD and the plane went into a steep decent to 0 altitude as it was commanded. They were able to recover quickly enough and did not reach the ground recorded by the UA 1722 flight. The training was probably a recheck of their preflight procedure to verify the altitude of the FD was properly set before switching it on.

There was turbulence at cruise altitude near Maui on the day of the UA 1722 flight but nothing at the surface. If they had hit a microburst they would have reported it immediately as a warning to other pilots.

[ALPAPilot]

More in depth:

United does two different types of takeoffs: NADP 1, and 2. (NADP - noise abatement departure procedure)

On the runway the power is set to the proper setting (EPR or N1 depending on engine type: Pratt or GE)

Accelerate to rotation speed and lift off. While rotating the plane accelerated to V2+15 knots: V2 is the “takeoff safety speed.

That speed is maintained untill 800 feet AGL (above field ellevation). VNAV (vertical navigation) is then selected. This does two things: reduces power to climb speed and sets clean maneuveing speed as the target airspeed.

There is an indication on the speed tape for each flap retraction. For a short field airport such as Maui a flaps 20 take would be common. Normally the flaps would be retracted from 20 to 5 at the proper airspeed by moving the flap handel to the 5 position. (There is a 15 setting that is normally bypassed on departure retraction). When the airspeed reaches the retraction speed for flaps 1, the handle is then moved to the 1 position. If the airplaine accelrated to that retraction speed before the flaps reach the 5 position, the flaps are position to one and the flaps just head to the 1 posistion. When the plane accelerates to the flaps up speed the handle is moved to the flaps up posistion. The flaps will just continue to the selected position. Even though the handle is moved from 20 to 5 to 1 to up, the flaps may make one continuous move from 20 to 0.

Maui SFo is a relatively short fligh so the airplance was like fairly light.

Thats all NADP2. For an NADP1, flap retraction is delayed until 3000 feet, which is quite common in Europe.

[ALPAPilot]

Yes, could be a lot of other stuff including pilot error.

The article did say they sent the pilots back to training. But that could be because they flew through a thunderstorm when they didn’t have to. Taking off from a field that has a thunderstrom in an engine out procedue track is not permitted. At most airports that means anywhere on the runway extended centerline.