Why has China Southern been Flying a ‘737 MAX’ for Nine Months?

Those who pay close attention to flight tracking apps may have noticed that, what appears to be a China Southern Airlines Boeing 737 MAX, has been flying around in the region since September last year. 

All is not quite as it looks however, because upon closer inspection it seems to be a case of mistaken identity. Since the grounding of the Boeing 737 MAX in March 2019, no airline has been allowed to operate scheduled passenger flights using the type, which is why it was unusual to see one flying around the skies of China every day. 

Wikimedia Commons/N509FZ
Airlines around the world have been prevented from operating scheduled passenger services with the Boeing 737 MAX since its grounding in March 2019. Wikimedia Commons/N509FZ

The aircraft in question is B-1205 (c/n 63253), a two-year-old airframe delivered to China Southern in November 2017.

Flightradar24
As can be seen here, two plots are being displayed for the same aircraft. Flightradar24

What is believed to have happened is that Air Guilin Airbus A320, B-1061 (c/n 8132) has been fitted with a transponder that was previously used by China Southern on its MAX aircraft. Upon installation, the Mode S HEX code may not have been updated and that could be why it is displaying as a Boeing aircraft. 

Flightradar24
The real aircraft in question is this Air Guilin Airbus A320. Registered B-1061 (c/n 8132), the jet has been flying around China with a faulty transponder since September 2019. Flightradar24

Ian Petchenik, director of communications at Flightradar24, commented: “Aircraft transponders broadcast a unique ICAO 24-bit address, but errors in either human programming or the transponder itself can lead to an incorrect value being broadcast by the transponder. These events are generally rare enough that they do attract some attention, like in this instance, or when an American Airlines A330 was broadcasting the address of a Piper PA-28.” 

The case Petchenik is referring to was when American Airlines Airbus A330, N284AY (c/n 1095) flew a transatlantic service from Paris to Philadelphia showing as a Piper PA-28 light aircraft on the flight tracking website. The reason this happened was because the Mode S HEX code for the aircraft was incorrectly entered into the transponder.  

Flightradar24
In May, the '737 MAX' operated 39 services on domestic routes within China. Flightradar24

The difference between that case and the China Southern event, is that two aircraft plots are displaying on the map. 

The Airbus narrowbody has been operating like this since September 2, 2019 when it flew a service between Shenyang/Taoxian and Yangtai/Penglai. 

In May, the European aircraft operated 39 services on domestic routes within China, all of which were shadowed on tracking website Flightradar24 by the rogue Boeing 737 MAX 8 plot. 

While the type remains grounded for commercial passenger flights, some ferry services and Boeing pre-delivery operations have taken place since March 2019.