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It seems intuitive that the order in which bags reach the carousel should be random, but every time I fly, by the time I reach the luggage claim area, my bag is never there and I have to wait (even though other bags can be).

Aside from a statistical effect (I must've flown >100 times though) the only thing I can think of is that if I fly economy, which I usually do, then my bags are handled later than those in the business and first classes. However since the travelers in business/first class leave the plane earlier too, they should also get to the luggage claim before I do + take their bags, i.e. if those bags already on the carousel belong to these travelers, they should've already been collected.

Allure
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    Do you check in very close to the departure time or do you play it safe? I believe many baggage handling systems operate on a last-in-first-out (LIFO) system so late checkins are sometimes the first to come out except for premium customers. But LIFO is confounded by the use of baggage carts or by cargo units. – RoboKaren Nov 29 '18 at 08:05
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    Note that some airlines also prioritise luggage of frequent flyers with status, though if you have flown > 100 times you should be part of the elite tiers unless those flights were spread out over a very long period or over many different airlines. – jcaron Nov 29 '18 at 09:14
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    I agree with @RoboKaren in that there is "some" LIFO in baggage handling. My family was once the very last to check in on a flight back home from the canary islands (there was no one behind us as we queued for checkin) and the first to have all their bags. Sure, our bags weren't no. 1, 2 and 3 on the belt, but all among the first 10 or so... – Sabine Nov 29 '18 at 09:41
  • @HonoraryWorldCitizen I've removed the comments and copied them into the chatroom, looking forward to continue here. – B.Liu Nov 29 '18 at 11:33
  • I have deleted the now unconnected comments. – Willeke Nov 29 '18 at 11:39
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    "It seems intuitive that the order in which bags reach the carousel should be random" Why? Bags have to be stacked. If you're always somewhere in the middle of the checkin; then why would you expect to be anywhere than somewhere in the middle of the luggage? – UKMonkey Nov 29 '18 at 12:49
  • What are your principal routes and destinations? On larger equipment, bags are put in bins, whereas on smaller aircraft they might sit directly in the hold, which affects how they get offloaded and transported to the terminal. In North America, "priority" tags are almost meaningless aside from the ego massage they give to the passenger, whereas in my experience in East Asia, the ground operation does put in some effort to send the priority bags first (Europe is something of a mix). – choster Nov 29 '18 at 16:04
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    It is all Murphy’s fault. – Hanky Panky Nov 29 '18 at 16:18
  • @jcaron you seem to either be grossly underestimating what it takes to get status or have a very odd definition of "very long period" given the context—since OP didn't include a range, it's almost certainly lifetime total. – Kevin Nov 29 '18 at 18:44
  • When you fly cattle-class on discount jets, late arrivals seem to get their stuff off first, presumably because their stuff is loaded last. I've no good evidence other than anecdote though. – Valorum Nov 29 '18 at 19:29
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    This is observation bias. I always fly economy and sometimes my luggage has come out quickly. I usually only notice when I have to wait for a while though. – CJ Dennis Nov 29 '18 at 23:35
  • @Kevin it probably depends on a number of factors, including the types of flight (short-haul vs long haul), the fare, the airline, and more, but there are many cases when you can get status with a pretty low number of flights. The opposite is also true, in many cases you will need many many flights before you can get status. – jcaron Nov 29 '18 at 23:47
  • The first trip I made after I bought a new bag resulted in my bag being first on the carousel. Never happened since, but I still reminisce about that day. – Laconic Droid Nov 30 '18 at 01:21
  • @UKMonkey exactly. This question is perfect for stats.SE. And philosophy.SE, since CJDennis pointed out, it's observational bias, too. – RonJohn Dec 01 '18 at 09:01

7 Answers7

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The main reasons on why the OP's baggage never arrive one of the first fall under two broad categories - priority baggages and when you check your baggage.

Some baggage get prioritised when getting off the plane

Flight class matters

As the OP has pointed out in the question, the order for a baggage to be loaded on the luggage belt (or their equivalent) may depend on the flight class you are flying on. For example, American Airlines's priority baggage delivery states the following eligibility:

This service applies only to:

First Class and Business Class customers

Virgin Atlantic's introduction to Premium Economy states (emphasis mine):

Skip the queues

With dedicated check in and bag drop, we'll fast track your airport experience. You’ll also enjoy priority boarding and, where possible, your bag will be one of the first off the plane when we arrive.

Frequent flyer status also matters

Also as @jcaron pointed out in the comments, it can also depend on one's frequent flyer status. As an example, oneworld Emerald and Sapphire members gets priority baggage according to American Airlines and Cathay Pacific; Star Alliance Gold, and SkyPriority members also get priority baggage handling.

These benefits are usually offered regardless of which class one is flying in. So it is possible for someone travelling in economy to have their luggage delivered first on this basis, despite deplaning after the OP.

The time you check your bag can decide when it gets off

...but it is not a guarantee.

While a common school of thought says baggage operates on a LIFO (last in, first out) system, there is an old discussion on here that questions if it is actually always the case.

In some cases, some operators could use a FIFO (first in, first out) system. This can perhaps be achieved if e.g. the origin airport uses the right cargo door, and the destination airport uses the left cargo door (Boeing 787 do have cargo door on both sides, though I am nowhere near an aviation expert and this is pure speculation).

Lastly as @RoboKaren points out in a comment, "LIFO is confounded by the use of baggage carts or by cargo units." They make the ordering more random, and in this case the first class of reasons will then assume a higher precedence.

A footnote on flight class: It is unfortunate that the OP seemed to have rejected his own proposed reason due to a false premise - while it is true that an average non-economy passenger should arrive at the luggage belt prior to an average economy passenger, not all does so on a regular basis due to a variety of reasons.

As an anecdotal example, I have travelled on a non-economy class for a few times, and every time I got hold up slightly in the immigration queue (as I am subject to immigration control on where I am travelling), and arrived the luggage hall finding mine and a handful of priority luggages going round and hundreds of passengers from the same flight waiting, perhaps impatiently.

Community
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B.Liu
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    Full disclosure: While I fly with some of the airlines/airline alliances mentioned, I do not have an interest in these companies to the extent that I have to actively promote them. – B.Liu Nov 29 '18 at 11:28
  • And sometimes you get lucky; once on a domestic flight from Los Angeles California to D/FW in Texas, USA, on a Labor Day weekend, Monday afternoon, economy class, full flight, our bags were the very first ones to show up on the baggage carousel!

    And side note, American Airlines does put a fluorescent orange PRIORITY tag on my bags when I've flown first class.

     – Mark Stewart Nov 30 '18 at 17:35
  • As Mark alluded to, baggage that is supposed to be handled first is almost always tagged as such, at least in my experience across. It's usually a bright-colored flag that is placed in the bag tag when they stick the two sides together. Similar flags are used for overweight bags and other such purposes. Whether this actually results in the bags coming out first or not, however, is very much hit-or-miss. My experience has been around 50-50 on priority-tagged bags actually coming out first. – reirab Nov 30 '18 at 23:44
  • Re. FIFO/LIFO, If it's either "Last in first out" or "First in first out", all other things being equal (i.e. comparing economy with economy), you'd expect both the first out and last out to be from people on the last leg of connecting flights. First in would be people with long connections (5 hr+, unloaded before check in opened), while last in would be people with short or delayed connections (which might not finish unloading bags until check in closed). – user56reinstatemonica8 Dec 02 '18 at 19:33
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May it be because you come to airport well in advance and submit your luggage promptly?

After I have started coming to airports later and register for flight towards the end of this process, I have noticed that my bags come to conveyor belt much earlier than they used to!

This is a purely anecdotal evidence of course.

alamar
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A couple of problems with the premise of your question:

Is it possible that the baggage carousel has bags from other flights still going round? Also, you tend not to hang around once you have your bag. So you don't really get to see whether your bag was one of the first off the plane or one of the last - it just shows up after what feels like a long time.

This could be a simple case of confirmation bias. You tend to notice when you think you have had to wait a long time at the baggage carousel, sigh and think "oh no, not again". You perhaps tend to not notice when your wait at the baggage carousel is shorter than usual.

Nick
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  • The very fact I have to wait while bags are already there though implies that my bag wasn't one of the first on the carousel - it can't have been bags from another flight, because that would generally use a different carousel (or be displayed on the screen). – Allure Nov 29 '18 at 21:50
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    @Allure: "...another flight... would generally use a different carousel" In my experience, most times I've gone to a baggage carousel, it has been shared with several other recent arrivals. I quite often take a look at the baggage tags of bags already on the carousel to see whether those on my flight have started arriving yet. Of course, there have been some exceptions at particularly quiet airports, where the carousel isn't running yet and only my flight is listed on the screen. – Nick Nov 29 '18 at 22:12
  • @Nick It depends very much on the airport. At the moment, most of my flights are between Heathrow and Minneapolis, both very busy airports. I don't recall having a "shared" carousel at either. – David Richerby Nov 30 '18 at 00:51
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    I had a shared carousel last night at LHR T5. Reclaim 9 serviced my flight (BA238) and an earlier BA flight (BA10, or similar, judging by the tags on bags still on the belt). The monitor was showing both flights. The adjacent monitor for reclaim 10 was showing two, as well, iirc. It's not as uncommon as you think. – MadHatter Nov 30 '18 at 14:30
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Your baggage is not guaranteed not to come first but the odds are stacked against you as described by answers you already got:

  • First and Business class often get preferential treatment.
  • Airline status gives early baggage privileges to those who have it.

There are other things that have an impact too:

  • Baggage on short connections can get prioritized. Sometimes baggage makes it even when the passenger doesn't! On Thai Airways, the last time I flew with less than 30 mins to connect, they added a label to mine saying Hot Connection. Even if not labelled, they probably know.
  • Fragile baggage can get loaded and unloaded by a separate process. Usually loaded last and unloaded first. Sometimes they place it on the carousel at arrivals, sometimes next to it.
Itai
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Math II

This is basically @CactusCake's answer, simplified. I think my intuition was the same as theirs: You often get counterintuitive things happening (see: the Birthday Problem, I won't spoil the answer), so we must first get a general idea of "all things being equal, what is the chance?".

But the answer titled "Math" gets bogged down in hard-to-justify specific details ("Take a Boeing 727!" -- "Why?!"), that lead to ballpark numbers (seat occupancy percentages are competitive info, very selectively given out!), that then anyway don't lead to a numerical or algebraic answer: So there was no reason for those numbers anyway (and the comments didn't like them!).

So. Reformulation: Let's assume we have done N different flights (single flights, not ends of connecting flights) where we've always checked 1 suitcase in, and the other passengers always checked in 99 other suitcases altogether. So, what is the probability after N flights that we've NEVER been first to unload?

Very simple, all these flights are independent occurrences (previous flight doesn't influence next flight), so it's the product of these N identical probabilities (see under: IID, Independent & Identically Distributed). And each flight we've got a 99% (or 99-out-of-a-100, or 0.99, whatever you prefer) probability of disappointment.

So the chance of unbroken disappointment is .99^N (using ^ for "power of"; this clearly goes to zero for large N) for N flights, ... But the real question is, Would you have to be cursed particularly unlucky to be disappointed 100 times in a row??

  • 1 flight: 0.99000000 or 0.990
  • 2 flights: 0.98010000 or 0.980
  • 3 flights: 0.97029900 or 0.970

So I think the OP thought along these lines, "(1- N/100) is a fair approximation, thus after N=100 flights the chance is basically zero", which is just plain wrong (a linear approximation of a power; a nonsensical negative probability past 100; etc). But it's that "tail" past the two most significant digits that grows surprisingly fast!

To save calculating and typing, skip steps by just doubling N so you have the square of the previous: N=2, 4, 8, 16, 32, 64; because A^(2N)= A^(N+N)=A^N * A^N = (A^N)^2. So you must double your flights to halve your chance of unbroken disappointment...

  • 1 flight: .99000000
  • 2 flights: .99000000 * .99000000 = .98010000
  • 4 flights: .98010000 * .98010000 = .96059601
  • 8 flights: .96059601 * .96059601 = .92274469
  • 16 flights: .92274469 * .92274469 = .85145777
  • 32 flights: .85145777 * .85145777 = .72498033
  • 64 flights: .72498033 * .72498033 = .52559648
  • 96 flights = (64 + 32) flights = .72498033 * .52559648 = .38104711 = about 38%

So if three friends each (independently!) take 100 flights each, you expect one of them to have never been first to unload.

Conclusion: You're unlucky (you missed a 2-in-3 chance of at least once being first), but not particularly unlucky.

And you see the same double-flights-to-halve-chance principle holds for any number of suitcases that are checked in: You're plotting points f(x) for x=N of a function f(x)=a^x with the parameter a close to (but less than) 1, so x going to infinity (basically for b suitcases on each flight, a=1-(1/b) = (b-1)/b -- as said, always less than one, and we have large-ish b, say between 50 and 500?

[[Yes yes I know I'm seemingly horribly rounding in that table, repeatedly multiplying 8-digit-precision and keeping 8-digit-precision... But that was for ease of understanding! They were actually calculated with 20-digit precision, and .381 for N=96 is correct. For 100 flights, it's a 0.36603234 or over-one-in-three chance.]]

So, further confounding factors: (1) Have you actually checked stuff in on all (or vast majority of) hundred flights? (2) Have you actually never been first? Because (2a) if yours appears first but you have poor positioning at luggage belt, you still won't retrieve yours first; and first class/priority have best chance for good positioning, and (2b) on international flights if you don't have "retina scan"/Privium/... fast checking, you may have arrived at the belt with the luggagge already there, exactly the time you were first, natch! Also, (3) practically each flight the first 5items on the belt are pushchairs and child car seats, as they were collected at the gate (after loading checked luggagge, so unloaded first); this may mislead your observations?

With that as a given, on the flights I take you have to pay to check in (always for 'budget' companies, the last 2--3years for more medium like BritishAirways in my case -- the complimentary gin&tonic is a receding memory on shorter flights!!); so I check in only when I'm on a significant trip, say 10+days or 7days in a cold/wet destination; or sports/elegant dinners thus extra clothes. 5-day academic conference = handluggage only. "Significant trips" tends to be further, so larger plane, so 100+ checked in suitcases seems reasonable to me and the 1-in-3 chance (all else being equal) stands: Redo for 50 if you feel 100 suitcases is not justified.

So this is all a priori reasoning, with the other answers (economy = bottom of unloading priority; economy = checkin on intercontinental closes before business checkin; LIFO to an extent; maybe you have a habit of checking in early; ... ) being strong factors on top.

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    But the question says "never one of the first to unload" and that changes the probabilities dramatically. As I pointed out in a comment to "Math", if you take 100 flights, you only have about a 1-in-40000 chance of never being among the first 10% of bags to hit the carousel, and only about 1-in-30 for never being among the first 3%. That's hugely different from your 1-in-about-3. – David Richerby Nov 30 '18 at 00:56
  • I suggest asking on the math SE site for a better probability analysis. – Fattie Dec 02 '18 at 02:50
  • @DavidRicherby Hm... I think I make that 1-in-22 chance of "never being among the first 3%". Because "first 3%" that would be a plane with 33 checked bags and yours coming out first, so (32/33)^100= 0.046. That's still only the size of a sports team on the road: I'd call it an unusual but not rare occurrence. – user3445853 Dec 03 '18 at 16:58
  • My favourite flight statistic is that at any moment of the day, there's a million people in the air --- a good-sized city. It would contain a good many that never unloaded first... – user3445853 Dec 03 '18 at 17:00
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Math

In addition to the existing, quite valid answers provided regarding flyer status, ticket class, and loading/unloading methods used by the airlines to prioritize baggage handling, the problem you experience could simply be ascribed to randomness.

You say you've flown 100+ times, but how many times exactly in excess of 100 flights have you checked bags? Consider that the most passenger airliners have seats for around 200 - 500 passengers. If we assume most of them sell 90% of their seats and then 50% of those seats are associated with one or more checked bags (I'm just guessing numbers here but trying to stay conservative), then a small aircraft would still have about 45 passengers checking bags. A more averaged sized aircraft might have 100-200 passengers checking bags (and many more - almost every passenger - on any transcontinental flights), some of whom will check more than one bag.

If you exclusively took small planes, and baggage handling was purely random, then you might expect to see your bag be first out on the carousel about once in every 50 flights. But we're pretty sure it's not purely random. And it's probably also safe to assume you're not exclusively travelling on small aircraft. Maybe your bag's turn to be first off just hasn't come around yet. Or maybe it has and you just didn't get to the carousel immediately when it happened. Or maybe your bags just have a hideous design that the baggage handlers don't want to go near.

CactusCake
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    I dispute your claim that "most passenger airliners have seats for around 200-500 passengers". The article you link includes the Boeing 727 in its list of "popular airliners" but the 727 went out of production 35 years ago and almost all of them are now out of service. Further, if you go sit at an airport in the US, the majority of flights taking off and landing are regional jets carrying between 50 and 100 passengers. Most of the rest, and most of what you'll see in Europe, will be B737s and A320s, most of which are configured with around 175 seats. – David Richerby Nov 29 '18 at 16:38
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    Also, you haven't actually presented any math. Suppose you ride only on 300-seat planes where every passenger checks a bag (basically, the worst realistic case). If bags are unloaded in uniformly random order, the probability of taking 100 flights and never being in the first 30 bags off the plane is 0.9^100, which is about one in 40000. The probability of never being in the first ten is about one in 30, which is still pretty unlikely. – David Richerby Nov 29 '18 at 16:43
  • @DavidRicherby I think CactusCake has taken the question asking "the first" instead of "one of the first" in the question. Using your example, the probability of not being the first bag in 100 flights will come up as (299/300)^100 = 0.7161..., which then fits their argument. The maths is valid, but the assumption that starts the maths is perhaps not the best fit to the question we have. – B.Liu Nov 29 '18 at 16:47
  • (According to Wikipedia, there were only two 727s in passenger service, as of July this year, both in Iran.) – David Richerby Nov 29 '18 at 16:48
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    @B.Liu Sure but, as you say, the question explicitly says "one of the first". – David Richerby Nov 29 '18 at 16:51
  • @DavidRicherby Nowhere disagreeing! – B.Liu Nov 29 '18 at 16:51
  • What does "one of the first" mean anyway? one of the first 10%? 20%? 50%? – CactusCake Nov 29 '18 at 16:52
  • @CactusCake Only the OP can define in this case ;) – B.Liu Nov 29 '18 at 16:53
  • @CactusCake Well, I already ran the numbers for first ~3% and first 10%. I don't think anyone would object to saying that the tenth bag out of 300 is "one of the first". – David Richerby Nov 29 '18 at 16:55
  • This is back of the envelope stuff anyway. I don't know what the true average number of seats is, but I'm pretty sure it's more than 100. Last flight I took with Southwest was on a 737 - it has 143 seats, 13 were unsold. The previous flight, same aircraft, completely sold out. In this scenario I would expect my bags to be one of the first, say 10, about once in every 30 flights, and that is probably about what my experience has actually been. They are a nice airline to use as a case study because they have fewer "classes". – CactusCake Nov 29 '18 at 17:10
  • @CactusCake OK but Southwest fly exclusively 737s and "my last flight" isn't a good indication of what the average is. And I would expect my bag to be in the first ten bags one flight in 14.3 if there are 143 bags on the plane. In any case, the average doesn't necessarily tell you much: rather, we need the probabilities of being far from the average, which is what I calculated above. – David Richerby Nov 29 '18 at 20:53
  • Right, but we can't know the real numbers of checked bags. You have to start somewhere. I did say "I'm guessing numbers here". The spirit of this answer was to indicate that in any situation involving probabilities there is always a chance that you might simply be (un)lucky. The numbers given above make a rough attempt to determine how unlucky OP is. This isn't MathOverflow but if you really want that kind of answer, see the one from @user3445853 (who also had to just pick a random number - 100 checked bags in that case). – CactusCake Nov 30 '18 at 15:42
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To add onto some of the other answers in here: it's pretty much impossible to increase the chance that your bags will be one of the first on the carousel, because there are multiple times where bag order effectively gets randomized:

  1. The order at which passengers arrive at the airport is random, so you might be among the first, in the middle of the pack, or among the last.
  2. there are often multiple check-in counters, so your bag tends to get mixed up among other bags for your flight and other flights.
  3. Once the bag enters the luggage maze beneath the airport, there are a number of things that could happen to it and other bags that change the order in which bags are handled:
    • security checks;
    • problems with reading the label;
    • your bag somehow getting lost in the maze;
    • technical or human errors;
  4. The bags then end up on carts and get pulled to the airplane. The order in which these bags end up on the carts is also random, and airport employees often are under a lot of pressure to get these bags loaded efficiently. To do this, they're going to fit as many bags on a cart as possible, trying to squeeze them in and generally putting on the bags quite randomly.
  5. At the plane itself, the bags again get unloaded randomly and loaded into the hold randomly. Same rules apply: they're just going to put these bags in the most optimal way to save time, so randomly and tightly fitting.
  6. Once the plane lands, the luggage gets unloaded. It might be through a different cargo door, and again the focus is on getting everything out of the hold and into the luggage maze as fast as possible.
  7. The bag then gets unloaded onto the caroussel, again in a random fashion. It could even again go through another luggage sorting system, with the same isues as in point 3.

I haven't flown in I think 7 years by now, but before that I tended to take 2 flights a year, more or less in some years. I think I've had 1 time in those 40 or so times I've flown that I had one of my 4 bags be among the first 5 or so bags to end up on the carousel, and the other 3 bags I checked in didn't arrive until 10 or 15 minutes later. It's effectively random.

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