Communication and Situational Awareness: United Airlines Flight 1722 Incident

Table of Contents

1. Introduction
2. The Weather Conditions
3. The Pilots
4. The Aircraft
5. The Pre-Flight Briefing
6. The Performance Calculations
7. The Takeoff
8. The Flap Overspeed
9. The Recovery
10. The Investigation

The United Airlines Flight 1722 Incident: A Lesson in Communication and Situational Awareness

On December 18th, 2022, United Airlines Flight 1722 was scheduled to depart from Kahului Airport in Maui, Hawaii, and fly to San Francisco. However, what should have been a routine flight turned into a terrifying ordeal for the passengers and crew on board. Just a minute after takeoff, the Boeing 777-222 suddenly started diving towards the sea below. The pilots managed to recover the aircraft, but the incident raised many questions about what had caused the sudden dive.

The Weather Conditions

The Hawaiian Islands were in the grip of a severe winter storm on the day of the incident. The storm was moving up from the southwest, carrying with it heavy thunderstorms, gusty winds, and intense hail. During these kinds of conditions, the job of pilots and air traffic controllers quickly becomes very complicated, as loads of aircraft generally will be forced to abandon their normal arrival and departure route to avoid flying through storm cells. Even outside of these worst cells, moderate to sometimes severe turbulence can be experienced, which makes flying quite unpleasant.

The Pilots

The two pilots of United Airlines Flight 1722 were well-rested and in a good mood. The captain, who was 55 years old, had over 19,600 hours of total time, and 5,000 of those had been flown on the Boeing 777. The co-pilot was also quite experienced, with around 5,300 hours of total time, but he was very new on this particular Type, with only 120 hours on it. This likely also meant that he was relatively new in the company.

The Aircraft

The aircraft that the pilots were going to fly was a 22-year old Boeing 777-222. It had no open technical malfunctions recorded, and it was arriving into Maui at the same time as these two pilots were now getting closer to the airport. On board the inbound flight were the eight cabin crew members, who were then going to fly with these pilots back again to San Francisco on their Second flight of the day.

The Pre-Flight Briefing

As the pilots were sitting in their shuttle bus, they thought that they should use the time and started going through their pre-flight briefing. The captain got into contact with a United Airlines dispatcher, who advised him about the very challenging weather around the Hawaiian Islands. Together, they then decided on a new alternate routing that should bring them away from the most severe parts of the storm. The two pilots also looked at the technical status of the aircraft, which was fine, and the NOTAMs but everything looked reasonably okay. The departure weather was definitely the biggest problem.

The Performance Calculations

When it came time for the performance calculations, the first officer tried to take the ATIS, but it didn't work for some reason, so he had to call the tower up to get that info instead. The tower advised them that the winds were reasonably light at the moment, from a southerly direction at around 10 knots. And, at the moment, they were using Runway 20 for departure. The first officer who had extensive previous experience flying in between the Hawaiian Islands commented on the fact that it was very unusual that Runway 20 was being used, but thought that it likely had to do with the complicated weather affecting arrivals. In any case, because the winds were reasonably light, their performance software, Sabre, suggested that flaps 20 and a derated thrust should be used for departure.

The Takeoff

The pilots finished their pushback and engine start and then went into their FMC and changed over all of their planning to the new runway. They, again, selected flaps 20 as the departure flap setting but this time, they would use full thrust instead. They also manually re-entered V1, rotation, and V2 speeds but they used the speeds associated with the derated takeoff, as that was both allowed according to the United SOP and would be more conservative. The aircraft accelerated rapidly down the runway, due to the higher than normal thrust setting, but the rotation was completely normal, followed by the gear being retracted, and an initial climb attitude around 12 to 15 degrees. The aircraft gained altitude fast and soon began experiencing moderate turbulence which caused the speed to start fluctuating.

The Flap Overspeed

As the speed was accelerating, the captain called for flaps five to be selected. He then looked down onto his speed tape and saw that the maximum speed for his Current flap setting was fast approaching. The first officer thought that he had heard the captain call for flaps 15 and since that was the next flap step, he didn't think about questioning that at all. At the same time as the captain called for this new flap setting, the tower controller also called them up and asked them to switch over to Honolulu Control. The first officer responded to this call, switched over to the departure frequency, and then selected flaps 15, as he called the new controller up. He was immediately cleared to Continue to climb to 16,000 feet, and the controller also advised him that there were extreme precipitation in all quadrants and that they were clear to avoid weather at their own discretion.

The Recovery

The captain's Attention now turned to what was happening to the flaps. In his mind, the flaps should have been moving to flaps five and since that was not happening, he was now anticipating some kind of flap malfunction and started looking at the EICAS to see if there was any emergency procedure that needed to be done, and since there was nothing there, and no chimes had been heard, he called flaps five again, twice, and then looked at the first officer to verify that he indeed was selecting flaps five. But as this caused him to divert his attention away from his primary flight display for around 10 seconds to try and figure this out, the captain had not noticed that the downward pitch motion of the nose had continued and it had now moved to around zero degrees pitch and was still moving.

The Investigation

The outcome of the investigation led to United Airlines modifying one of their pilot-training modules, as well as releasing an inter-company awareness campaign, describing what had happened, and what could be learned from it. The incident was caused by a miscommunication between the pilots which led to a failure to manage the aircraft's vertical flight path, air speed, and pitch attitude. This incident serves as a reminder of the importance of communication and situational awareness in aviation.