Flight number

Short description: Airline code for a journey between multiple points

Flight numbers on a split-flap display (Frankfurt airport)

In the aviation industry, a flight number or flight designator is a code for an airline service consisting of two-character airline designator and a 1 to 4 digit number. For example, "BA 222" is a British Airways service from Nashville, Tennessee to London-Heathrow. A service is called "direct" if it is covered by a single flight number, regardless of the number of stops or equipment changes. For example, "WN 417" flies from Jacksonville to Baltimore to Oakland to Los Angeles on Southwest Airlines. A given flight segment may have multiple flight numbers on different airlines under a code-sharing agreement. Strictly speaking, the flight number is just the numerical part, but it is commonly used for the entire flight designator.

The flight designator of the operating carrier of a commercial flight is used as a call sign. This is distinct from the aircraft's registration number, which identifies a specific airplane.

Conventions

A number of conventions have been developed for defining flight numbers, although these vary widely from airline to airline, and are increasingly being modified. Eastbound and northbound flights are traditionally assigned even numbers, while westbound and southbound flights have odd numbers. Other airlines will use an odd number for an outbound flight and use the next even number for the reverse inbound flight. For destinations served by multiple flights per day, numbers tend to increase during the day. Hence, a flight from point A to point B might be flight 101 and the return flight from B to A would be 102, while the next pair of flights on the same route would usually be assigned codes 103 and 104.

Flight numbers of less than three digits are often assigned to long-haul or otherwise premium flights. For example, flight number 1 is often used for an airline's "flagship" service (see below for a 'List of flight number 1 by airlines'). However, for airlines in Mainland China, one-digit and two-digit numbers are only reserved for administrative charters. Furthermore, Cathay Pacific assigns flight numbers which are less than 100 for cargo flights.

Four-digit numbers in the range 3000 to 5999 typically represent regional affiliate flights, while numbers larger than 6000 are generally codeshare numbers for flights operated by different airlines or even railways.

Likewise, flight numbers larger than 9000 usually refer to ferry flights; these carry no passengers and are used to relocate aircraft to or from a maintenance base, or from one air travel market to another in order to start new commercial flights. Flight numbers starting with 8 are often used for charter flights, but it always depends on the commercial carrier's choice.

Codeshare

In a codeshare, airlines share their aircraft with others, resulting in the flight having more than one flight number on the same sector, and either the same or different flight numbers on joined sectors.

As a hypothetical example, flight QQ1234 may fly from airport AAA to BBB to CCC. The AAA-BBB segment may be serviced by airline QQ, and the BBB-CCC segment by airline RR, on a different aircraft. The same flight may also be sold as RR3210, and by a third airline SS as SS2345. Also, the individual flight legs may have multiple flight numbers: AAA-BBB may be QQ12, RR23, and SS45.

For example, Alaska Airlines flight AS61 (As of June 2018) flies from Juneau (JNU) to Yakutat (YAK) to Cordova (CDV) to Anchorage (ANC). A ticket for the Yakutat to Anchorage segment is specified as AS61 YAK-ANC. It is even possible for a given flight number to cover a sequence beginning and ending at the same airport.

List of flight number 1 by airline

Most flights are non-stop from A to B, and few are from A to B then to C (both A-B and B-C have flight number 1). Aircraft type may change due to operation need.

Airline	IATA Flight No	ICAO Flight No	From	To	Then to (if applicable)	Aircraft Type
Aeroméxico	AM1	AMX1	Mexico City	Madrid		Boeing 787
Air Canada	AC1	ACA1	Toronto Pearson	Tokyo Haneda		Boeing 777/787
Air Canada Express	QK1	JZA1	Montreal Trudeau	Ottawa		Bombardier CRJ900
Air New Zealand	NZ1	ANZ1	New York JFK	Auckland		Boeing 787-9
Air Tahiti Nui	TN1	THT1	Los Angeles	Papeete		Boeing 787-9
AirAsia X	D71	XAX1	Kuala Lumpur	Osaka Kansai	Honolulu	Airbus A330-300
Alaska Airlines	AS1	ASA1	Washington Reagan	Seattle		Boeing 737-800/Airbus A321neo
All Nippon Airways	NH1	ANA1	Washington Dulles	Tokyo Narita		Boeing 777-300ER
American Airlines	AA1	AAL1	New York JFK	Los Angeles		Airbus A321
American Eagle	CP1	CPZ1	San Francisco	Los Angeles		Embraer 175
Biman Bangladesh Airlines	BG1	BBC001	Dhaka	London Heathrow		Boeing 777-300ER
China Airlines	CI1	CAL1	Honolulu	Taipei Taoyuan		Airbus A350-900
Delta Air Lines	DL1	DAL1	New York JFK	London Heathrow		Airbus A330-200/300/Boeing 767-400ER
DHL Aero Expreso	D51	DAE1	Miami	Panama City		Boeing 757-200PCF
El Al	LY1	ELY1	Tel Aviv	New York JFK		Boeing 787
Emirates	EK1	UAE1	Dubai	London Heathrow		Airbus A380-800
Etihad Airways	EY1	ETD1	Abu Dhabi	Frankfurt		Boeing 777-300ER
FedEx Express	FX1	FDX1	London Stansted	Memphis		Boeing 777F
Finnair	AY1	FIN1	Helsinki	Los Angeles		Airbus A350-900
Hawaiian Airlines	HA1	HAL1	Los Angeles	Honolulu		Airbus A330-200
Japan Airlines	JL1	JAL1	San Francisco	Tokyo Haneda		Boeing 777-300ER
Japan Transocean Air	NU1	JTA1	Osaka Kansai	Naha		Boeing 737-800
JetBlue Airways	B61	JBU1	New York JFK	Fort Lauderdale		Airbus A321-200/Airbus A320-200
Jin Air	LJ1	JNA1	Seoul Incheon	Bangkok Suvarnabhumi		Boeing 737-800
Korean Air Lines	KE1	KAL1	Seoul Incheon	Tokyo Narita	Honolulu	Airbus A330-300
LATAM Chile	LA1	LAN1	Santiago	Puerto Natales		Airbus A320
LOT Polish Airlines	LO1	LOT1	Warsaw	Chicago O'Hare		Boeing 787-8
Lufthansa	LH1	DLH1	Hamburg	Frankfurt		Various (319/320/321)
Malaysia Airlines	MH1	MAS1	London Heathrow	Kuala Lumpur		Airbus A350-900
Peach Aviation	MM1	APJ1	Osaka Kansai	Seoul Incheon		Airbus A320-200
Qantas	QF1	QFA1	Sydney	Singapore	London Heathrow	Airbus A380-800
Qatar Airways	QR1	QTR1	Doha	London Heathrow		Boeing 777-300ER
Scandinavian Airlines	SK1	SAS1	Lulea	Stockholm		Airbus A320neo
Singapore Airlines	SQ1	SIA1	Hong Kong	Singapore		Boeing 777-300ER
Skymark Airlines	BC1	SKY1	Tokyo Haneda	Naha		Boeing 737-800
Southwest Airlines	WN1	SWA1	Dallas Love	Houston Hobby	Corpus Christi	Boeing 737-800
SpiceJet	SG1	SEJ1	Chennai	Colombo		Boeing 737-800
Spirit Airlines	NK1	NKS1	Fort Lauderdale	Chicago O'Hare		Airbus A321
Starlux Airlines	JX1	SJX1	Los Angeles	Taipei–Taoyuan		Airbus A350-900
Turkish Airlines	TK1	THY1	Istanbul	New York JFK		Boeing 777-300ER
United Airlines	UA1	UAL1	San Francisco	Singapore		Boeing 787-9
UPS Airlines	5X1	UPS1	Hong Kong	Cologne/Bonn		Boeing 747-400F or Boeing 747-8F
Virgin Australia	VA1	VOZ1	Sydney	Los Angeles		Boeing 777-300ER
WestJet	WS1	WJA1	Calgary	London Gatwick		Boeing 787-9

A notable former flight number 1 was British Airways flight BA1, operated by the Concorde between London Heathrow and New York's John F. Kennedy airport. After the retirement of Concorde in 2003 the flight number was retired with it, however in 2009 it was given to the all business class A318 flight between London City Airport and New York JFK via Shannon in Ireland. 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.

Flight number changes

Flight numbers are often taken out of use after a crash or a serious incident. For example, following the disappearance of Malaysia Airlines Flight 370, the airline changed the flight number for subsequent flights following the same route to MH 318. Also, American Airlines Flight 77, which regularly flew from Dulles International Airport in Washington, DC, to Los Angeles International Airport, was changed to Flight 149 after it crashed into the Pentagon during the September 11 attacks. After the crash of Air France Flight 447, a regular scheduled flight from Rio de Janeiro to Paris, was changed to Air France Flight 445. On the other hand, other considerations may lead an airline not to change a flight number; for instance, the aforementioned "flagship" American Airlines Flight 1 retains its designation despite a major accident in 1962 and two other accidents in 1941 and 1936. There are at least four instances of the same flight numbers that have suffered two serious accidents: Flight 253 of Linea Aeropostal Venezolana (both in 1956, the first in June, and the second in November), Flight 869 of United Arab Airlines (the first in 1962 and the second in 1963), Flight 800 of TWA (the first in 1964 and the second in 1996), and Flight 383 of American Airlines (the first in 1965 and the second in 2016). As of October 2019 the most recent flight number change due to an accident was from Aeroflot Flight 1492 to Aeroflot Flight 1316.

Flight number conservation

Airline mega mergers, in markets such as the United States, have made it necessary to break conventional flight numbering schemes. Organizations such as IATA, ICAO, ARC, as well as CRS systems and the FAA's ATC systems limit flight numbers to four digits (0001 to 9999). The pool of available flight numbers has been outstripped by demand for them by emergent mega-carriers. As such, some carriers use the same flight number for back-and-forth flights (e.g., DCA-PBI-DCA), or in other cases carriers have assigned a single flight number to a multi-leg flight (e.g., ICT-DAL-HOU-MDW-OMA-DEN-ABQ-LAS-BDL).

Flight designator

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. For example, in the flight codes BA2490 and BA2491A, "2490" and "2491" are flight numbers. Even within the airline and airport industry, it is common to use the colloquial term rather than the official term.

Spacecraft

Flight numbers are also sometimes used for spacecraft, though a flight number for an expendable rocket (say, Ariane 5 Flight 501) might more reasonably be called the serial number of the vehicle used, since an expendable rocket can only be launched once. Space Shuttle missions used numbers with the STS prefix, for example, STS-93. SpaceX uses sequential numbers for flights of reused boosters. As an example, Crew-2 used booster B1061.2 (the second flight of booster B1061).

See also

• Airline call sign
• Codeshare agreement
• Change of gauge (aviation)