Why Do Airlines Switch Airplanes on Flights with One Flight Number? (Ask Cranky)

It’s time for another installment of Ask Cranky. This question is a great one, and I could have sworn I wrote about it before. But my intensive (read: 10 second) search didn’t turn up anything. Even if I have, it’s worth addressing again.

I often take UA 732 from SEA to ORD, “with continuing service to Jacksonville”. Every week, at landing they announce “there will be a plane change for passengers continuing to JAX…” If the plane isn’t the same, how exactly is this a “continuing flight”? Why doesn’t the ORD to JAX flight just have a new number?

Thanks,
Patrick

You guys have probably seen this a million times, because it’s a very common occurrence. In this case, United flight 732 looks like this:
Lv Seattle 6a Arr Chicago 12p
Lv Chicago 126p Arr Jacksonville 451p

You would think that with one flight number, it should be the same airplane the whole way through, right? That’s not the case. In fact, this flight is scheduled with two completely different aircraft types operating each leg. The first is on a 757 and the second on an A319. What gives?

Back in the early days, one flight number would usually have one airplane the whole way. Heck, it was more likely for the airplane to stay the same than the actual airline! (There used to be interchange flights where one airline would take theAsk Cranky airplane part of the way and then they’d turn the airplane over to another airline to go the rest of the way.)

But in the 1980s and 1990s, the airlines started getting (too) smart (for their own good). They realized that in the Global Distribution Systems, nonstop and direct flights (the latter being flights with a stop but no change) received preference. And just like with Google search results today, those flights that showed up first got the most bookings. The airlines wanted more of that so they started designing flight numbers to match those routes with the most demand.

It got out of control quickly as airlines tried to cheat the system. I remember flipping through a timetable when I was young seeing Delta with a ton of high four digit flight numbers that were all assigned to the same flight. So maybe you would see London to Atlanta as one flight, but then they would overlay a bunch of flight numbers so it looked like you could go on a direct flight from London to all the big cities in the US. I don’t remember when that stopped happening, but I assumed it was a government regulation that ended that misleading practice.

But that didn’t mean airlines still couldn’t get creative about how they assigned their flight numbers. It didn’t take long to realize, however, that the flights that were ideal for marketing as direct weren’t the same flights as what would be ideal from an operational perspective. Certain aircraft had to go to maintenance, others just weren’t the right size to operate both legs. So the operational side of the airline started shifting airplanes around regardless of the number attached. That’s where we are today, at least with most airlines.

You still see the old method when you fly Southwest, but that’s the extent of it with large airlines. I don’t know numbers, but I’d imagine it’s less common for one airplane to work multiple legs on a flight than it is or there to be a change in the middle. And that’s because the marketing and operational arms work in different ways. There is now actually a third consideration as well.

Airlines are running out of flight numbers.

With all the codesharing occurring between airline after airline, the big guys are running out of four digit flight numbers. Could they go to five digits? Yeah, right. It would take the industry years to do the programming work required for something like that. Instead, the airlines start cramming more flights on each flight number.

Delta flight 4509 goes from LAX to San Diego and then back to LAX. Clearly nobody is taking both segments of that flight, so why bother lumping them together? Because there just aren’t enough flight numbers to split them apart.

And that’s why you see some goofy things with flight numbers today.

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48 Comments on "Why Do Airlines Switch Airplanes on Flights with One Flight Number? (Ask Cranky)"

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JohnBom
Guest

Delta has a one stopper from SLC to KOA that doesn’t even appear as having the stop at LAX if you don’t look carefully!

XJT DX
Guest

United 872 and 483 have no less than 3 segments each. The city pair? DCA-SFO… How far down in GDS? No.s 6 and 10.

Andrew
Guest

I just think it’s crap that you only get mileage for the beginning/end cities in a direct flight, and not the stop. Two US Airways examples: US449 EWR-CLT-SLC would be 2256 miles if the flight number were different, but you only get 1969 because it’s a “direct” flight. And US700 LAX-PHL-FRA: 6350 actual vs. the 5806 you get from the “direct” flight.

Dan
Guest

TBH, that’s the biggest sin in my book. I kinda sorta get a one-stop with no change of gauge, WN style. But if I’ve got to change planes, that’s a connection. I can live with a connection, ’cause I’d have to on any other flight But then they have the nerve to give me less frequent flyer miles? Unless the ticket was cheaper, that’s just wrong.

James
Guest
Delta still does this regularly. For the longest time DL11 was MCO-ATL with continuing service to LGW, and I know they weren’t taking that crappy 757 all the way to London. I got burned by this once on what I thought was an LAX-MCO non-stop. First I couldn’t find the gate because my boarding pass printed as LAX-MCO and the gate was marked for LAX-MEM. Then, once I got to MEM, they refused to put me on the medallion upgrade list since I was on a “direct” flight and they ended up flying the FC cabin on the MEM-MCO leg… Read more »
David
Guest

My experience with American airlines is that they (unlike United) actually use the same plane if it’s the same flight number.

David SF eastbay
Member
I’ve never liked ‘change of gauge’ flights, they were connecting flight no matter what anyone said. Years ago when I worked at TWA, I thought they were the king of ‘COG’, but they didn’t do anything PanAm wasn’t doing either. Back then it would be the phantom flight number say 777 CMH-LHR, but it would really be flight 146 CMH-JFK and flight 700 JFK-LHR so in CMH they would be calling the boarding of flight 146 and 777 for the same aircraft. A bigger city like LAX or SFO could have four flight numbers on that one flight to JFK… Read more »
Ron
Guest
“They realized that in the Global Distribution Systems…” — I thought it was a regulatory issue some time in the mid-80s, possibly prompted by a lawsuit, that caused this change in GDS behavior. I read about it in a book once so I’m not sure about the details, but I think it was at attempt to stop manipulation of search result where an airline would pay a GDS to move its flights higher up. The ruling was, I believe, that direct (same-airplane) flights had to show up first (no provision for non-stop), followed by same-airline connections, followed by everything else.… Read more »
David SF eastbay
Member
Ron your comment reminded me of a funny story from eons ago when I worked for TWA. A woman called up who must have been coached on what to ask for. She said “I want your direct flight from Los Angeles to JFK”. I figured she meant nonstop but had to respond correctly so I said “We don’t have direct flights to JFK. We have four nonstops to JFK, a direct to LaGuardia, and connecting flights throught out the say to all three New York area airports JFK, LaGuardia, and Newark. Could I offer you one of our nonstop flights… Read more »
ICUDoc
Member
My biggest complaint is that you book one flight number and you expect not to have to worry about making a connection. I once booked American Airlines from Montego Bay in Jamaica to JFK as a single flight with a “Stop” in Miami. When my plane was delayed in Montego Bay – I reasoned “No worries” in Miami as they will hold the flight from Miami to JFK since they would “never” have two planes in the air with the same flight number at the same time, right? Wrong. Got to Miami, no flight. So AA had two flights in… Read more »
Nick Barnard
Member

Wow, operationally that scares me. Especially depending on the timing it seems that there might be a large potential for confusion with ground controllers if two flights are in the air with the same flight number…

David SF eastbay
Member

That makes sense. The flight was late out of Jamaica so they must have used an extra plane to still operate the MIA-JFK portion, that happens all the time.

That or it was a change of guage flight two separate flights numbers for each leg and through phantom flight number for the MBJ-JFK listing in the GDS.

Morgan
Guest

One advantage to the customer is that these “direct” flights don’t count as a stopover for the purposes of the fare rules.

For example, many of United’s transcon fares say something to the effect of “2 transfers permitted on the pricing unit.” But if you take a direct flight, the stop doesn’t count as a transfer, so you can effectively get an extra transfer point for free.

That’s not often going to be useful, granted, but it’s something.

Voyager0927
Guest

As a corollary to this point, I believe that a passenger booking a “direct” flight is exempt from Passenger Facility Charges and September 11th Security Fees for the intermediate airport, even if a change of planes is required. This definitely used to be the case — it might still be.

SEAN
Guest

UA recently had a flight 1737 that went PDX-EWR-LAS, while it’t’s companion flew JAX-EWR-PDX.”

NW was notorious for plane changes in MSP with the same flight number. It was easy to note them since the layover was nearly 2-hours rather than the tipical 1-hour.

noahkimmel
Member

I dont think this practice should be legal….As much as I hate all of the airline regulations that have come out lately, and I believe about half are not actually customer friendly, this is deceptive, even to us so-called experts.

IF there is a plane change, there SHOULD be a change of flight number (operational constraints can get an exception).

ICUDoc
Member

I wonder if the count as multiple segments for FF consideration – I have never gone the segment route to status so I don’t look at them.

Darrin
Guest

No they do not. I experienced this last year. MIA to ATL to SDF. Same flight number but a change of planes. Only got credit for one segment. I com

jaybru
Member
I’ve complained about “change-of-guage” flight numbering practices for years, to DOT, at least so there is a record of someone making an official complaint, and directly to UA, my primary carrier, which doesn’t need to wait for DOT to tell them to stop it. I argued to UA, after they had delayed a bag, that “change-of-guage” in all probability had a major part in causing the delay. I wrote that this practice is (1) confusing, (2) frustrating, (3) deceptive, and (4) inadequately described in flight listings. To put it bluntly, this practice is dishonest. These flights are connecting flights, and… Read more »
Nick Barnard
Member

I could care less about LAX->SAN->LAX since no one would book that, and it saves flight numbers. Although, I’m curious for ontime reporting does each leg count as a flight or does just the whole flight number?

Re: Expanding to five digit flight numbers.. I’ve often wondered if airlines could/would just pick up another IATA code to stash their codeshares under… Although that seems like it could be too much of a kluge and cause problems elsewhere in the system..

Kris Ziel
Guest

I’ve done flights like that, once did IAD-PHL-IAD, all as the same flight number, doing LAX-PHX-LAX as the same flight number twice later this year. It is nice because in all my looking, they use the same equipment, so even if the inbound is late, you won’t miss the outbound.

jboekhoud
Member

How does your mileage credit with that? 0 miles since the origin and destination are the same?

Demo
Guest

CF – Isn’t it also true that on direct flights with equipment change; should the first leg of the flight be delayed they hold the second from taking off until those passengers make the plane change/connection?

David M
Guest

I remember those “scheduled aircraft change” flights in the back of the Delta timetable. Weren’t they 6000-series flight numbers? I’d stumble across them in the listings too, but never seemed to notice them in real life. Now I know why.

oldiesfan6479
Guest

And then there was “through flight” TW 731 MUC-FRA-JFK-PHX-TUS. A 72S to FRA, then a 747 to JFK, an L10 to PHX, and another 72S to TUS. IIRC, the real flight from FRA-JFK was 701, but it also “carried” flight numbers 711/721/731/741. There were occasions where the PHX-TUS leg departed before the L10 got in from JFK. Couldn’t hold it, or they’d take a crew rest
delay the next day. I think TW in PHX sent their misconnected TUS pax to HP.

toliverjr
Member

I didn’t look today to see if it still applies, but CO had an AUS/IAH/LHR with the same flight number, with a change of a/c in IAH last fall.

stan
Guest

DL 5 (and before that DL 1) was MCO-LHR. there was a plane change at JFK. i took the MCO-JFK portion of it weekly on a junky old 738 (definitely not TATL metal).

this recently changed. now the MCO-JFK has its own flight number DL1221.

noahkimmel
Member

Why not keep the 4 character limit and add in letter into the 4th spot. That would add thousands of additional flight numbers, and regulatory-wise, letters could denote codeshare or something…

jamesgdpollard
Member

What about the longest by distance?

QF 107/108 would be a good chance (SYD-LAX-JFK and vv).

Or multiple flights Europe-Australia / UK-Australia with same flight numbers but stops in SIN/BKK/HKG.

jboekhoud
Member

My guess would be NZ 1 flying LHR-AKL via LAX (11,960 miles).

NZ 38 (LHR-AKL via HKG) is a bit shorter at 11,683 miles.

Sanjeev M
Guest

I was on AA DTW-DFW-BUR and it was the same flight number and aircraft. So AA and WN still do it the old way sometimes.

Hey
Member

Here’s the deal, at least how I understand it:

“Non- stop” = no stops
“direct” = stop(s), but same aircraft
“connecting” = stop(s), change of aircraft

Ron
Guest

In practice, it’s:

“direct” = stop(s), but same flight number
“connecting” = stop(s), change of flight number

toliverjr
Member

Since several legacies have flights with the same number (DL, CO in evidence above), what then would you call a flight with a stop, change of a/c, and the same number?

XJT DX
Guest

Sometimes it may be for the market it serves… Before Emirates came into the scene, Delta had flight 8 From IAH to ATL on an MD then continuing to DXB on a 777. I’m sure it had plenty of Big Energy clients with little to no alternatives.

David SF eastbay
Member

Back in the 90’s WN had a direct flight between Los Angeles and Detroit, but you may not have wanted to take if over a 1-stop and connection like a lot of Southwest flights operate. Why, because the direct flight made 7-stops between LAX and DTW. A slow time at TWA so a coworker and I tried to find the WN flight with the most stops and that flight seemed to be it. You could book it at the same price as a shorter 1-stop/connection flight.

Rich
Guest

It’s very deceptive marketing. I suggest mandating that if an airline misconnects a flight that it disingenously markets as ‘direct’ there should be a mandatory, substantial fine paid to the customer.

Kris Ziel
Guest

When you go to search for tickets, at least on united, it is made very clear that there is a stop at an airport, how long the stop will be, and that there will be an equipment change (where applicable). Hardly deceptive if you ask me, or probably any lawyer.

Gary
Guest

another reason for the same flight/change of guage: the flight can be treated as a “through” instead of a connection for purposes of connecting time (which is typically longer) at the airport. the result is that the total elapsed travel time from point A to C (via B) is shorter on the “through” flight and it therefore shows up earlier on GDS displays for sale.

Allplane
Guest

In Europe, Iberia does it in flights out of Barcelona with connection to America (and plane change) in Madrid. Selling them as one direct flight when they aren’t http://allplane.blogspot.fr/2011/01/when-is-direct-flight-not-direct-flight.html

rerjohnson
Member

docjames, I’d reckon Air NZ’s LHR-HKG-AKL onestop would come high in the distance rankings: BA is down to one routing for LHR-SYD now, via SIN, and Qantas has LHR-SIN-SYD and LHR-SIN-MEL only: Virgin Atlantic is now the only LON-HKG-SYD flight. Last time I looked, Air Austral – yes, the one that is buying 800-plus seater A380s – had a CDG-RUN (Reunion Island)-SYD-NOU (Noumea, New Caledonia) run twice a week, that probably holds some sort of distance record.

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