High and hot: the extreme conditions for which the Emirates Dubai-Bogota flight makes a stopover in Miami
Looking at Ethiopian Airlines' schedule reveals a curious thing: all flights operated by the African airline to [...]
Ethiopian Airlines
Emirates
Star Alliance
MIA
United States of America
United Arab Emirates
Looking at the schedule of Ethiopian Airlines a curious thing is discovered: All flights operated by the African airline to North America make a stopover in Europe or West Africa, while all those in the opposite direction operate those same routes nonstop. (Photo BriYYZ CC BY-SA 2.0)
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The reason may lie in the fact that westward flights last longer on average, also aided by winds blowing across the Atlantic in the opposite direction. But while issues related to aircraft range might apply to flights to the West Coast of the U.S., certainly the East Coast is largely within the reach of the range of the Boeing 777-8, 787-9, 777-200LR, 777-300ER and Airbus A350 that Ethiopian uses across the Atlantic.
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The proof? Kenya Airways quietly flies nonstop from Nairobi to New York in both directions with its 787-8s on a route that is at least an hour longer than the route from Addis Ababa to New York. Perhaps that Ethiopian wants to pick up some passengers 'along the way' to increase load factor? Hardly credible, since it then flies from the U.S. and Canada directly to Ethiopian on its return.
No, the reason for those layovers on flights out of Addis Ababa is In the characteristics of Ethiopian's hub, specifically. In the altitude at which Bole International Airport is located: 2,334 meters above sea level. Add to this the fact that despite the altitude, Between March and November, temperatures in Addis Ababa average high and you get what is referred to in the jargon as the 'high and hot conditions', conditions of heat and high ground. (Photo Vob08 CC BY 3.0, https://commons.wikimedia.org)
The combination of those two factors is among the most detrimental to aircraft engine performance, because both altitude and high temperatures have the effect of reducing atmospheric pressure. The latter, Adversely affects the performance of jet turbines, which drop conspicuously, Increasing the length of the takeoff run required for aircraft to lift off from the ground.
This factor can only be counterbalanced in one way: Reducing the weight of the aircraft, i.e., its passenger or cargo load. But this would have a negative effect on the economic performance of flights. So Ethiopian, like many other airlines that are used to operating in 'hot and high conditions,' in order to reduce the weight of aircraft departing from Addis Ababa prefers to reduce the amount of fuel embarked.
Which, however, inevitably impacts the range of the aircraft. Which, like this, Are forced to make a stopover on some of the routes operated by the company departing from its hub, refuel and then depart for the final destination.
On the return trip, departing from airports such as Los Angeles, San Francisco, Chicago, New York, or Toronto (to name a few), which are at sea level or otherwise at modest altitudes, Ethiopian airline planes can refuel, flying safely nonstop to Addis Ababa.
Emirates' recently announced flight from Dubai to Bogota also falls into this category, while considering that in this case the distance between the two cities is still very close to what the Boeing 777-300ER that will be used on the route from June 3 is capable of flying nonstop.
In order not to run into operational problems in the event of adverse winds, the Emirates carrier thought of Introduce along the flight a stopover in Miami both on the outward and return legs, also because the Colombian capital's El Dorado International Airport is located at an even higher altitude than Addis Ababa, at 2,548 meters above sea level.
Admittedly, the two-and-a-half-hour layover in Miami, required for refueling and for passengers to safely pass through U.S. immigration, is not exactly enticing for those planning to fly from Dubai to Bogota or in the reverse direction. But Emirates has compensated for the flight's relative appeal by getting the fifth freedom rights between Miami and Bogota and back.
In addition to Addis Ababa and Bogota, other major airports that operate year-round or even just in the summer season in 'high and hot' conditions are Denver (at 1,656 meters altitude), Johannesburg, (at 1,694 meters), Las Vegas (at 'only 665 meters altitude, but with summer temperatures easily bypassing 50 degrees celsius) and Mexico City (at 2,230 meters). The record for the world's highest airport, however, among those that regularly receive international flights, belongs to the airport in La Paz, Bolivia, located at an altitude of 4,061 meters. Not for nothing is it called El Alto International Airport...