Transponder emergency transmissions

Code 7700 aircraft transponder signals are normally quite rare, so when there are two in ta week near Geneva we investigate.

Such emergency broadcasts, from an aircraft not too far from Geneva, come every few months, and are noticed by many other spotter sites which list them all over the world. There are three important codes, commonly called Squawk codes: 7500, 7600 and 7700 :-

7500 – Hijack
7600 – Lost Comm (radio failure)
7700 – Emergency

One listed easy way to remember this: 75 taken alive, 76 technical glitch, 77 going to heaven.

On 2 January at 6.45 pm the ARAG transponder message monitor in Geneva registered an emergency 7700 broadcast from a Lufthansa plane. The flightradar24 world-wide service picked this up and reported it as a Lufthansa flight from Munich to Paris, which turned around. Later on, it was announced that there had been a sick passenger on board, so the aircraft was diverted to Zurich.


What was slightly strange was that the aircraft never actually headed towards Paris, but instead came over Basel and the not too far North of Geneva. When it turned around it actually looked to be nearer to Geneva than to Zurich.

Today, 5 January, the old joke about London buses came true: you wait for ages then two come along at once. At 3:45 pm along came another 7700 emergency squawk code. This time it appears to be a Swiss Air Force Falcon F18 fighter plane, flying quite low (5400 feet above sea level). Most probably, this would have been a takeoff somewhere around Payerne, which is on the limits of what the monitor system can detect. Appropriately, the callsign emitted from this FA18 was HAWK42.

Now we start to wonder if the old Swiss adage "jamais deux sans trois" will be validated!

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