Republic Airways Flight RPA3665, Operating on Behalf of United Airlines, Diverts While Flying to Portland and Returns to Land at Newark Liberty International Airport on 23 July: All You Need to Know

Written By: Ananya Dey

Ananya Dey

I amAnanya Dey, a Journalism and Mass Communication postgraduate with a Bachelor's degree in Political Science (Honours). I am passionate about travel, writing, and research, with a strong interest in storytelling and content creation.

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July 23, 2026 11:05 PM

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Republic Airways Flight RPA3665, operating on behalf of United Airlines, diverts while flying to Portland and returns to land at Newark Liberty International Airport on 23 July: all you need to know. Republic Airways Flight RPA3665, operating on behalf of United Airlines, diverts while flying to Portland and returns to land at Newark Liberty International Airport on 23 July: all you need to know. The Embraer E175LR left Newark but turned back before reaching Portland. However, officials have not confirmed the exact cause. Therefore, the explanation is that the crew made an operational return for a reason that remains unknown.

What happened during United Express Flight UA3665?

The supplied flight record shows that the service was scheduled to leave Newark at 07:45 EDT and reach Portland International Jetport at 09:11 EDT, while the Embraer E175LR departed at 08:01 EDT before the journey was recorded as diverted back to EWR. The available tracking history identifies the movement as United Flight UA3665, but it does not provide a separate local return-landing time at Newark or explain what happened after departure, so the scheduled Portland arrival time must not be reported as the aircraft’s return time.

Which aircraft operated the Newark-to-Portland service?

The aircraft carried United States registration N786YX, and the official FAA aircraft registry identifies it as an Embraer ERJ 170-200 LR with Republic Airways listed as its registered owner. This regulatory designation belongs to the Embraer E175 family, commonly displayed in tracking records as E75L or E175LR, while Republic Airways says its wider Embraer fleet operates flights for major airline partners that include United Airlines.

Was the flight operated by United Airlines or Republic Airways?

The ticketed and public-facing service used the United flight number UA3665 and operated within the United Express network, while the aircraft and operating callsign were connected with Republic Airways. This means passengers booked and managed the journey through United, but Republic Airways supplied the regional operation under a partnership arrangement, which is why the flight may appear as UA3665 for customers and RPA3665 in operational tracking information.

Why would the crew return to Newark instead of continuing to Portland?

Returning to Newark can be the safest and most practical choice when an aircraft remains within a manageable distance of its departure airport, because EWR already has airline staff, maintenance support, passenger facilities and replacement-flight options linked to the original service. A crew may turn back because of a technical indication, medical concern, cabin problem, weather issue, air-traffic instruction, fuel consideration or another operational factor, but these remain general possibilities and none has been officially confirmed as the cause of Flight UA3665.

Did poor weather at Portland cause the diversion?

No flight-specific statement reviewed for this report confirms that poor weather caused the return, and official aviation-weather information alone cannot establish why an individual crew discontinued a journey. The National Weather Service provides forecasts and aviation discussions for the Portland region, but it would be inaccurate to blame fog, storms, wind or poor visibility without direct confirmation from United Airlines, Republic Airways, the FAA or another responsible authority.

Did the diversion mean the aircraft faced a serious emergency?

A diversion or return does not automatically prove that passengers or crew faced an immediate or life-threatening danger, because pilots may change their plan whenever continuing would reduce safety margins or make the journey less predictable. Returning to a suitable airport is itself a protective decision, and the aircraft’s landing at Newark shows that the crew selected an airport capable of supporting the aeroplane and its passengers; however, the seriousness of the underlying issue cannot be assessed without a verified explanation.

What happened to the planned journey to Portland?

Because N786YX returned to EWR, the original Newark-to-Portland sector was not completed by that aircraft as scheduled, leaving passengers dependent on United’s revised operating arrangements. The public information reviewed does not confirm whether travellers later continued aboard the same aircraft, transferred to another service, accepted rebooking or ended their journeys in Newark, so any detailed description of the passenger outcome would be speculative.

What should affected passengers check after returning to Newark?

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Travellers should use United’s official flight-status service, mobile application and the official Newark airport flight page for rebooking, revised departure details, baggage instructions and gate information, because third-party tracking services may not display the airline’s final passenger arrangements. United provides separate disruption guidance, while the US Department of Transportation explains that refund rights and airline assistance depend on whether the journey was cancelled or significantly changed, whether alternative transport was accepted and whether the disruption was within the airline’s control.

What is the confirmed conclusion?

The confirmed sequence is clear: United Express Flight UA3665 left Newark for Portland on 23 July 2026 using Republic Airways Embraer E175LR N786YX, but the aircraft did not complete the scheduled sector and instead returned to Newark Liberty International Airport. The reason remains officially unconfirmed, so claims involving a mechanical fault, medical event, severe weather, security concern or another specific cause must remain labelled as speculation until United Airlines, Republic Airways, the FAA or another responsible authority publishes verified information.

Republic Airways Flight RPA3665 departed Newark for Portland on 23 July but did not complete the planned journey. The Embraer E175LR returned and landed at Newark Liberty International Airport. Republic Airways operated the service on behalf of United Airlines. The exact cause remains unconfirmed because neither airline nor an aviation authority has released a flight-specific explanation. A technical issue, medical event, weather problem or air-traffic instruction should not be claimed without evidence. The confirmed answer is clear: the crew discontinued the Portland flight and returned to Newark for an operational reason that has not yet been made public by officials.

Image: United Airlines