What is the world's longest over water route with no alternative landing?

Operating a commercial flight is perhaps one of the most rules-driven procedures in the world. From fuel and load calculations to weather considerations and various contingency plans, commercial airliner pilots have plenty to keep in mind during a flight.

Among the various things governing the safety of a flight are diversion airports between the two destinations.

A diversion could be for multiple reasons, but it’s more critical when it involves an engine failure, as finding the nearest landing site becomes important.

And there’s one over water route in particular that offers little choice when it comes to an alternative landing spot.

Hawaii – An outlier

Hawaii is one of the two US states that is not a contiguous part of the mainland—the other is Alaska. Flights to the various airports on the Hawaiian Islands have to cross vast stretches of the Pacific Ocean, and some services from the mainland United States to Hawaii can be longer than those operating to Europe.

For example, a nonstop service from New York JFK Airport to Daniel K. Inouye International Airport (HNL) in Honolulu takes more than 10 hours compared to a JFK-London Heathrow flight that usually lasts a little over six hours.

In fact, Hawaii is so far from the US East Coast that it is slightly faster to fly from Honolulu to Sydney, Australia, than it is to fly from New York to Honolulu.

While destinations on the US West Coast are closer to Hawaii, with flights averaging around 5 hours, these over-water routes have a unique challenge—there are no alternative landing options while crossing the Pacific Ocean for these flights.

Diversion options

Aircraft diversions are not uncommon. They involve the plane either returning to the airport of origin or somewhere midway along the flight path. Two of the most common reasons for flight diversions are onboard medical emergencies and technical issues with the aircraft.

Pilots know the various landing options in case of a diversion, and some routes offer more landing alternatives than others. However, the over-water routes between the US West Coast and the airports on the Hawaiian Islands offer no options for landing along the vast stretches of the Pacific Ocean.

Therefore, it becomes critically important that all aspects of such flights are carefully calculated to prevent anything untoward during the service. Honolulu’s Daniel K. Inouye International Airport is the largest in Hawaii and is more than 2,000 miles away from all major West Coast destinations, including the following:

• Los Angeles
• San Francisco
• San Diego
• Seattle
• Portland

While these aren’t the longest flights in the world, and airlines operate these routes every day safely and without any incidents, extra precautions must be taken because there are no alternative landing spots between the origin and destination airports.

Diversions have become a greater concern when flying over water because of limited options, and flights between the US West Coast and Hawaii offer no options. For example, a flight originating in Hawaii bound for the US Mainland can either turn back to Hawaii or continue toward the West Coast for the nearest landing option based on when an onboard emergency takes place.

In 2016, a United Airlines flight between Hawaii and San Francisco, carrying 263 passengers and 12 crew members, had to turn back because of strong headwinds. The pilots’ decision was made out of caution because the aircraft would otherwise have landed at the destination airport without the legal minimum of fuel. ABC News quoted its aviation expert John Nance as saying,

“When the headwinds are greater than what were expected, and are going to be sustained for four or five hours of flight, you're simply not going to be able to land with your legal minimum of fuel. It doesn't mean you're going to run out, but it means you're not going to be legal. That's when you have to turn around.”

The fuel for a commercial flight is divided into taxi fuel, trip fuel, contingency fuel, alternate fuel, final reserve fuel, additional fuel, and extra fuel. Contingency fuel is the fuel that is uplifted to account for unforeseen circumstances, such as changes in the weather and route changes due to ATC constraints.

Alternate fuel is the fuel required to divert if the pilots fail to land at the destination for some reason. All of these become all the more critical when operating flights to and from Hawaii. Simple Flying has looked at these factors closely in the following article:

In 2011, an experienced ferry pilot ran out of fuel before reaching his intended destination in Hawaii and had to ditch the 300-series Cessna plane in the Pacific Ocean, just 13 miles short of the airport. The 65-year-old man was flying from California to Hawaii and realized he would not have sufficient fuel to reach his destination.

He informed authorities about the situation and the Coast Guard deployed rescue crews to help the pilot, who ditched the plane around 17:23 and then “climbed out of the cockpit onto the wing”, according to the statement released by the Coast Guard.

ETOPS considerations

There was a time when only three or four-engine aircraft, such as the 747s, DC-10s, and L-1011 TriStars, could operate commercial flights to Hawaii. This was before the introduction of ETOPS certifications. The Extended-Range Twin-Engine Operational Performance Standards (ETOPS) really shaped the aviation growth of Hawaii, allowing twin-engine planes such as the Boeing 767 and later smaller single-aisle planes to operate flights.

Before jet engines, when piston engines were unreliable, the FAA had a 60-minute rule, which meant that no aircraft with two or fewer engines would be permitted to fly more than 60 minutes from a diversion airport.

Over the decades, as engine technology improved, the FAA began certifying earlier widebody jets, such as the Boeing 767, with ETOPS 120, meaning that an aircraft could have an engine failure and still be 120 minutes away from a diversion airport.

This opened up several routes for airlines for nonstop flights, but services to Hawaii still required a higher ETOPS rating. An aircraft requires an ETOPS rating of at least 180 to fly to destinations on the Hawaii Islands, and once single-aisle planes were made capable of handling such flights, it really changed how airlines flew to Hawaii.

Evolution of twin-engine flights to Hawaii

Things have come a long way since former FAA Administrator J. Lynn Helms said, "It'll be a cold day in hell before I let twins fly long-haul over-water routes." But that changed over the years as newer-generation airliners had the capability to safely carry out these flights.

In fact, when narrowbody airplanes were allowed to operate flights to Hawaii, their relatively low passenger capacity and operating costs meant they could be used to connect some smaller Hawaiian Island airports like Lihue (LIH). This was when other larger dual-engine planes like the 767 couldn’t operate at such small airports with full loads.

Airplanes like the Boeing 757 revolutionized flying to Hawaii after they received their ETOPS certification. In fact, the 757’s lighter weight compared to other widebodies and powerful engines made it a great option for flights out of some of Hawaii’s smaller airports, enabling airlines to add services on thin routes.

Similarly, the Boeing 737 and the A321 aircraft further allowed airlines to fly to Hawaii with better economics. This happened over time after the FAA extended the Boeing 737 Next Generation's rating from ETOPS 120 to ETOPS 180 in 1999. The A320 was also certified ETOPS 180 in 2004 by the European Union Aviation Safety Agency. Today, both these aircraft families are seen regularly flying from the West Coast to Hawaii.

United Airlines recently performed an ETOPS-proving flight to Hawaii

Getting an ETOPS approval is highly regulated and is not something that is granted to an airline or an operator simply because the aircraft they fly are ETOPS certified. Even established carriers must go through a process whenever they acquire a new aircraft type and deploy it on ETOPS-required routes.

For example, United Airlines, which has a rapidly growing fleet of Airbus A321neo planes, recently performed an ETOPS-proving flight using the type from California to Hawaii and back on a non-commercial flight.

The aircraft, registered N14506, was delivered to the airline in March 2024. On December 10, it departed San Francisco International Airport (SFO) at 12:40 and flew a journey lasting 5 hours and 11 minutes to Honolulu (HNL).

The airline also took delivery of its 25th A321neo in December 2024 amid rapid expansion plans. Last year, the carrier also signed a deal for 40 leased A321neos as it looked for alternatives for the delayed Boeing 737 MAX aircraft. Per ch-aviation, it currently has 29 A321neos.

Indeed, as airlines continue to add new-generation narrowbody planes, we can be sure to continue seeing more of them on long flights with ETOPS mandate.