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After a cancellation and other delays, a Delta 767 took off from JFK this week, only to return hours later, because of a fuel imbalance.

This incident happened on Monday the 25th of July this year. It involved a Delta Air Lines flight, departing from New York’s John F. Kennedy International (KJFK) in the United States. Its destination was Kotoka International Airport (DGAA) in Accra City, Ghana, in west Africa. Originally, this flight should have departed on Sunday the 24th of July, as DL156. Delta performs this service daily, departing JFK at 11:45 pm.

Fuel Imbalance Forces Delta 767 Return To JFK!

Photo: Ramon Kagie

However, Delta had to cancel this flight – but the cancellation had nothing to do with a fuel imbalance. Delta reportedly needed to replace a flight crew member and wasn’t able to do so quickly. This particular aircraft had previously diverted to JFK, likely causing a scheduling upset for Delta’s flight and cabin crews.

So the Delta flight involved in this fuel imbalance issue was DL9923, still heading to Accra. This was the same aircraft that would have flown to Accra as DL156 the day before, according to Flightradar24. It is a Boeing 767-332ER, with registration N195DN. It is just under 25 years old, having entered service with Delta Air Lines (its only operator) in 1997.

Fuel Imbalance Forces Delta 767 Return To JFK!

The incident aircraft. Photo: Pieter van Marion, CC BY-SA 2.0

The flight should have departed at 3:30 pm local time. But more delays meant that it would eventually take off at 5:13 pm (21:13 UTC), using runway 22R. We don’t know how many passengers were on board this flight.

 

Delta 767 Fuel Imbalance, Possible Leak?

The flight crew climbed to FL310. But according to a passenger, a flight crew member emerged from the cockpit and started looking out to one of the wings, about two hours after departure. It appears that the Delta crew had noticed a fuel imbalance. The pilot, possibly a relief crew member for this 10-hour flight, was checking to see if there were visible signs of a fuel leak.

Photo: Franz Harvin Aceituna

It is worth mentioning that a fuel imbalance, such as this Delta crew had to deal with, doesn’t necessarily mean that there is a fuel leak. A recent report on a 2019 incident involving a 767 fuel imbalance, found that on that occasion, the cause of the problem was a centre fuel tank that would only feed one wing tank. So only the engine on that wing would burn this tank’s fuel, creating the problem.

At this point, we don’t know the nature of the fuel imbalance on the Delta flight to Ghana. But at approximately 23:30 UTC, i.e. 2 hours and 17 minutes into the flight, the Delta crew turned back towards JFK. Interestingly, it seems that the pilots elected to descend to FL290 for the return leg. This was likely because they wanted to burn a bit more fuel, in an effort to avoid landing overweight.

PLAY A320neo. Photo: PLAY

This descent suggests that the Delta pilots didn’t believe that a fuel leak was the cause of their fuel imbalance. In another recent incident, the crew of a PLAY Airbus A320neo realized that they would only have 300 kilograms (661 lbs) of fuel on landing. Unable to divert at this stage in the flight, the crew climbed. Their computers then calculated that they would land with 400 kg (882 lbs) of fuel.

 

A Landing And An Airline Statement

It later turned out that the PLAY aircraft had much more fuel than this. But it wasn’t clear if it could get fuel from all its fuel tanks. An investigation is underway. Going back to the Delta fuel imbalance incident, the crew continued to JFK, asking for a priority landing. According to a statement from Delta Air Lines, this is when the flight briefly became an emergency, in order to get landing priority.

Fuel Imbalance Forces Delta 767 Return To JFK!

Photo: Miguel Angel Sanz

A passenger also reported that the captain made an announcement, saying that this would be “a normal landing”. In essence, this means that passengers and cabin crew will not have to brace. The aircraft landed at JFK’s runway 13R, at 01:57 UTC, i.e. nearly two and a half hours after turning around.

Because the cause of this fuel imbalance was unclear, emergency crews approached the Delta 767 before it exited the runway. The aircraft stayed on the runway for approximately five minutes, before continuing to the terminal. The passengers disembarked normally, and the flight was cancelled.

Another Delta statement summed up this fuel imbalance incident:

Delta flight DL9923 on July 25, en route from New York-JFK to Accra, returned to New York-JFK out of an abundance of caution due to operational reasons. The flight landed safely and customers deplaned as normal. The safety and security of Delta’s passengers and crew is Delta’s number one priority. Delta’s customer support teams at JFK were engaged on the ground to assist affected customers and Delta deeply apologizes for the inconvenience and delay of their planned travel.

 

Delta Fuel Imbalance Incident – Some History And… Communication

As we mentioned further up, this particular aircraft had diverted for its previous flight, as well. This was actually a very similar-looking U-turn, back to JFK, to the one the Delta flight made on its way to Ghana, in this fuel imbalance incident. On that occasion, the transatlantic route was further north because the aircraft was flying to Europe.

This was flight DL210 (on the 24th of July) from New York to Prague’s Vaclav Havel Airport, in Czechia. But we don’t know if this Delta diversion was also because of a fuel imbalance. At any rate, a fuel imbalance is something that pilots have to deal with carefully. But it is something that pilots can normally handle safely.

Photo: Jan Rosolino

Even if a leak is serious enough to cause one engine to flame out, the aircraft can fly safely on the remaining engine, also handling the fuel imbalance. Yes, there was Air Transat Flight 236, which actually did run out of fuel. But the aviation industry has learned from that incident, which happened in 2001.

The fact that a Delta pilot was checking the wing for a possible fuel leak in this flight, shows that this crew was aware of this as the possible cause of their imbalance. This incident got some attention thanks to a famous YouTuber, who was a passenger on the flight. His account shows that beyond dealing with the fault itself, flight crews also need to be aware of how the public might interpret their statements – and their actions, if they visit the passenger cabin.

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