Flight number

[1] For example, QF9 is a Qantas Airways service from Perth, Australia to London Heathrow.

[2] This is distinct from the aircraft's registration number, which identifies a specific airplane.

However, this rule is no longer strictly enforced, as the allocated numbers have become shortage of use.

Still, there are exceptions, as with the case of the aforementioned China Eastern Airlines Flight 5735.

Another example is QF3920, which is a flight from Lima, Peru to Santiago, Chile that is also codeshared with LATAM 523.

This route ceased operation in 2020 due to the COVID-19 pandemic, and British Airways has since announced it will not be restarting the service.

The pool of available flight numbers has been outstripped by demand for them by emergent mega-carriers.

[85] Although 'flight number' is the term used colloquially, the official term as defined in the Standard Schedules Information Manual (SSIM) published annually by the International Air Transport Association (IATA) Schedules Information Standards Committee (SISC), is flight designator.

Officially the term 'flight number' refers to the numeric part (up to four digits) of a flight code.

Space Shuttle missions used numbers with the STS prefix, for example, STS-93.