The breakdown that befell a pilot of the Spanish airline Air Europa on Wednesday evening before taking off at Amsterdam Airport had far-reaching consequences: When the captain entered a four-digit transponder code, he must have confused numbers: the 7500 numbers triggered a major alarm – They stand for hijacking.
The code 7500 is feared, because it is a distress signal that is automatically sent to the air traffic control and triggers an alarm. Student students remember the signal with the donkey bridge: seven-five – man with knife.
The warning at Amsterdam's Schiphol Airport caused heavily armed police forces to evacuate part of the airport. In addition, emergency services were disengaged and dozens of flights were delayed.
In the course of the evening, however, there was an all-clear. Air Europa said via Twitter that the warning had been triggered in error and apologized for the glitch. Apparently the pilot had not noticed his mistake at first.
Entering an “oblique number”
The individual transponder code is assigned to the pilot before each flight by the air traffic controllers, who enter the four-digit number sequence manually in the cockpit via rotary buttons. During the flight, this code serves to uniquely identify the aircraft on the radar screens.
In addition, the transponder has another function: An emergency situation can be reported via the coding. Various codes are commonly used internationally to report an emergency at ground stations:
- 7500 – Kidnapping, hijacking: “seven-five – man with a knife”
- 7600 – Radio failure, radio failure: “seven-six – hear nothing”
- 7700 – Air emergency, emergency: “seven-seven – going to heaven”
Only very rarely does it happen that pilots dodge when entering. For the aviation expert Heinrich Großbongardt the incident on Wednesday evening in Amsterdam is “an odd number”, as he talks to the star explained.
More than 4 hours late
The code is entered in two steps: First, the pilot sets the value. In a second step he activates the code, after he has convinced himself of the correctness. A precise verification of the input should therefore not be done.
“The mistake happened when the machine's captain explained the function of each button to a pilot in training,” a spokeswoman for Air Europa said a day later. He apparently accidentally submitted the code “7500” to the flight control.
All passengers of the Air Europa flight with the code UX1094 to Madrid had to leave the plane on Wednesday evening. Instead of 19.10 clock could start the Airbus A330-300 until 23.40 clock with several hours late.
Only a little over a year ago, a pilot of a machine reported that the Bundeswehr was ready to fly on the emergency code 7600, a technical problem. On the flight from Berlin to Buenos Aires, the communication system with the ground had failed on the Airbus A340-300. Due to the code for radio failure, the government airline was given preferential treatment by air traffic control and was allowed to land unscheduled in Cologne / Bonn.
On board was Chancellor Angela Merkel, who the next day had to fly via Madrid with a line machine of Iberia for G20 meeting in Argentina.