In the first week of August, Delta flight 223 took off from Athens International Airport (ATH)
en route to Hartsfield-Jackson Atlanta International Airport (ATL). However, instead
of making the 11-hour or so journey nonstop, the flight consistently made a stop in Boston Logan
International Airport (BOS). What was the reason for making this seemingly unnecessary stopover?
Since July 2nd, Delta has operated nonstop flights between Atlanta and Athens. Like nearly
every transatlantic route, the flight leaves Atlanta at night and operates as a red-eye,
landing the next morning in Athens. The return flight leaves Athens in the early afternoon
and arrives back in Atlanta in the evening. The route consistently operates with an Airbus A330.
However, consistently, from July 31st through August 3rd,
the airline operated the Athens-Atlanta service with a stopover in Boston. According to Delta,
the reason came down to extreme weather in Athens…
Scorching hot weather had struck the capital city of Greece. This limits Delta’s ability
to operate nonstop flights between Athens and Atlanta, leaving the airline with two
options. Either it could operate a lighter load by offering fewer seats, or it could restrict the
number of bags it could accept for the flight- two options that Delta was looking to avoid.
So, Delta decided to operate Athens to Atlanta with a stopover. The aircraft would refuel in
Boston and then make the onward journey to Hartsfield-Jackson airport. For those
unfamiliar with the scientific side of things, how does hot weather exactly affect flight distance?
While warm weather might attract tourism, extremely hot weather is
a complicated issue for airlines. When it’s too hot, aircraft performance is limited.
Simplifying things, lift is a force required for an aircraft to fly. Without sufficient lift, an
aircraft is not going to take off. As an aircraft accelerates down a runway for takeoff, the wings
splice the air and the shape of the wing, coupled with the flap deployment for takeoff, pushes the
air downward, leading to the generation of lift. Part of this process depends on proper air
density. The density and pressure of the air above the wing is lower than the air below the wing.
The air above the wing is also moving faster than the air below the wing. This works in conjunction
with the shape of the wing directing the flow of air downward which, again, leads to takeoff.
So, when it gets too hot, the density of air decreases. In hot temperatures, the molecules in
the air are moving faster and are not as condensed as in cooler weather. With less dense air,
aircraft performance is limited. A plane will need either a longer runway or the ability to
generate even more speed to take off, assuming the weight of the aircraft is held constant.
However, less dense air means less available oxygen molecules to support combustion, limiting
the amount of thrust an engine can provide to compensate for the lack of available runway.
Delta Air Lines is flying an Airbus A330-300 between Athens and Atlanta.
These planes seat just under 300 passengers..While this plane is
designed to complete transatlantic missions, this particular route has some unique factors at play.
The route routinely takes over 11 hours of flying time, which is starting to hit the
top-end of the A330-300s capabilities with a full load. With a surge in bookings due
to a change in travel restrictions, this full capacity was needed by the airline.
Therefore, Delta wanted to avoid limiting seat count,
leading to the addition of the fuel stop in Boston.
With temperatures having gone down in Athens the following week, the airline went back to operating
flights nonstop. However, with the hot summer season not yet over, we might just see this type
of routing re-emerge as weather changes. Were you aware of this type of operation
as a response to hot weather? Let us know in the comments!