The residents of Alcalá de Henares have been hearing a strange noise of unknown origin for several nights this week: first the Alcalá de Henares City Council and later the Air and Space Force responded to citizens’ concerns about this nighttime noise.
The council, which contacted the Torrejón Air Base, explained in a statement on social media that “it comes from tests of the new fuel being carried out on a Eurofighter aircraft.” The tests also had to be carried out at night “because sunlight could contaminate the infrared measurements,” as explained to the administration.
Another aggravating factor that made the noise even more noticeable was the fact that the engine tests were carried out outdoors, outside the hangars where they are usually carried out, as they are not large enough to accommodate this model of aircraft.
As confirmed by the Alcalá City Council and the Air and Space Force, the tests—and therefore the associated nighttime noise—came to an end on the night of Wednesday, February 11.
The reason for the tests and infrared measurements
The Air and Space Force has stated that the purpose of these fuel tests is to “verify whether the use of SAF [Sustainable Aviation Fuel] biofuel emits less infrared radiation than conventional fuel.” The reason why the noise has been audible in recent days has to do with the conditions under which these tests must be carried out.
“The tests must be carried out at night, thus avoiding solar radiation, and in the open air, which, combined with certain weather conditions, means that the noise produced may be audible from some neighboring population centers, “ according to the Ministry of Defense.