5 ms·

Hi all! I'm the editor of this post. I love traveling, and have always wondered how reservations systems worked. This post explores that. In the future, we're

by dvdhsu 6y ago

Hi all! I'm the editor of this post. I love traveling, and have always wondered how reservations systems worked. This post explores that. In the future, we're hoping to write a piece about how air fare pricing works too. There's a lot of interesting stuff re. fare buckets, forecasting supply + demand, etc. It's also very topical with COVID: https://www.flyertalk.com/forum/united-airlines-mileageplus/2017932-ridiculously-uncompetitive-airfares.html https://www.flyertalk.com/forum/united-airlines-mileageplus/... (If HN has any ideas about what else we should write about, let me know! I'm david AT retool.com)

zan 6y ago
Just the level of airplane nerdery one needs right now. Also probably the best explanation of EDIFACT artifacts I've seen. I just have one remark - how on earth does a 737 fly from SFO to LHR without stopping as in the example?
- raverbashing 6y ago
  It doesn't. Or it has a technical stop. The MAX has a range of 3850 nm, LHR-SFO is 4664 nm So unless it's an empty ferry flight and you've got very favorable winds, you're not doing that without stopping. Hawaiian needed extra tanks to ferry their 717 (or was it MD something) over there (there's a picture around IIRC)
  - Xorlev 6y ago
    That was around the time of the merger with McDonnell-Douglas. The 717 was actually the MD-95, so, you're basically correct either way. :)
  - thunfischbrot 6y ago
    See https://www.avgeekery.com/boeing-717-fly-way-mainland/ https://www.avgeekery.com/boeing-717-fly-way-mainland/ and https://joepriesaviation.net/photoalbum/displayimage.php?album=3&pid=3414 https://joepriesaviation.net/photoalbum/displayimage.php?alb... Seems obvious once you've seen it...
- dvdhsu 6y ago
  Ha, great question. We didn't have access a SABRE system so the lookups are fake. I was just about to go in and change it in to a 388 (my favorite plane!), which I think flies daily between LHR and SFO as BA286. ~Unfortunately, the output is in png format which was generated by carbon.now.sh, so I'll have to type everything out. I'll change it once I have a few minutes...~ Edit: just changed it into BA286, which is an 388. (For fun, I also added in first class fare buckets, which United no longer offers.) For additional accuracy, I also updated the UA equipment to 772s, which IIRC is what they actually fly (as opposed to 77Ws). (If we did this more often, we'd probably actually design it in HTML instead of using Carbon, but an image was much faster, haha.)
tgsovlerkhgsel 6y ago
The article mentions that there is little evidence for prices changing based on cookies. I've seen that happen, reproducibly and in a plausible way: The (third party) site was adding an "agency discount" (name may not be precise, this is from memory, IIRC it was ~$10-30) that turned into a significant (IIRC $50+) "agency surcharge" on your second visit. Clear cookies, discount is back, revisit, surcharge is back, 100% reproducible.
- mehrdadn 6y ago
  Along these lines, I've noticed airlines seem to jack up a ticket price in the subsequent days if you search for a ticket, visit their website, and don't buy the ticket. Though maybe if you wait a couple weeks they might get disappointed and lower it again. Anybody had a similar experience? (From what I can tell, it doesn't tend to happen if you don't actually visit their website.)
  - lotsofpulp 6y ago
    I always buy using the airline’s website and no middleman website, and sometimes it goes up, sometimes it goes down. I use google flight tracker sometimes to track the price, and I can’t find anything to indicate it is targeting me specifically. I presume the price goes up and down based on aggregate searches or reservations for the flight, i.e. supply and demand. I know for hotels, there are programs crawling and searching for competing hotel’s prices and changing pricing based on that as well as changes in inventory and prior year’s data.
    - mehrdadn 6y ago
      I've seen this happen fairly consistently on very low-demand off-peak flights. I don't think it's a supply/demand thing. The coincidence of the timing a day or two after I search and the consistency of the experience is what makes me think they do it deliberately. The normal price variations I do see too (including with Google flight tracker), but they don't seem to correlate nearly as strongly with my searches. Hard to prove it though...
moeffju 6y ago
I was wondering about the time zones mentioned in the article? If SFO/T-7 is 7 hours behind Greenwich Mean Time and LHR is in the (same) GMT time zone, how is that 8 hours ahead of the origin airport?
- vinay427 6y ago
  It's really poorly phrased in the article but I assume what they meant is that LHR is in a time zone that sometimes observes GMT, and otherwise observes BST (British Summer Time) in the summer which is 8 hours ahead. It's not exactly correct that SFO is 7 hours behind GMT because this isn't true for around half the year. It also isn't exactly true that LHR is in GMT. Most of the year, SFO is actually 8 hours behind LHR. A few weeks are off due to different DST dates.
  - PuddleOfSausage 6y ago
    The author/editor has mentioned elsewhere in this thread that he was using dummy data (which contains mistakes). For this dummy December flight LHR would be in GMT (UTC+0) and not BST (UTC+1).
- fraculus 6y ago
  GMT doesn't observe summertime, but LHR does. So LHR (and the rest of Britain) is only in the GMT time zone for half the year.
  - azalemeth 6y ago
    GMT is very nearly the same thing as UTC. Think of it as a reference rather than timezone, but one that happens to be used by a few places half the time. It's just easier to think of yourself in UTC/GMT all the time (known as Zulu time or /Z in the aviation world) and deal with the relative offsets later. Don't forget that US Daylight Saving has different start/end dates to the UK while you're at it too...
gcatalfamo 6y ago
Hi I was wondering - a meta question of sorts - how this topic (which was really interesting) was chosen for the retool blog since it doesn’t seem to be connected in any way.
lowdose 6y ago
If you are going to write more about the pricing of airline tickets I would include a graph of the actual demand and supply curves, plot the corresponding business segments in it. Many people did not study economics and graphs like these are a great visualization of the problem at hand. http://4.bp.blogspot.com/-PDoN9F9YpJo/VjDZxPztmkI/AAAAAAAABng/-XVzzcBmUPI/s1600/buckets.png http://4.bp.blogspot.com/-PDoN9F9YpJo/VjDZxPztmkI/AAAAAAAABn...
dade_ 6y ago
Speaking of XML, don't be shy and advertise your RSS feed! Great story and pictures, thanks for the information.
igrekel 6y ago
Thats was a good read, I wonder where did you get all the information. content and stories from?

by dvdhsu 6y ago

zan 6y ago

Just the level of airplane nerdery one needs right now. Also probably the best explanation of EDIFACT artifacts I've seen. I just have one remark - how on earth does a 737 fly from SFO to LHR without stopping as in the example?

raverbashing 6y ago
It doesn't. Or it has a technical stop. The MAX has a range of 3850 nm, LHR-SFO is 4664 nm So unless it's an empty ferry flight and you've got very favorable winds, you're not doing that without stopping. Hawaiian needed extra tanks to ferry their 717 (or was it MD something) over there (there's a picture around IIRC)
- Xorlev 6y ago
  That was around the time of the merger with McDonnell-Douglas. The 717 was actually the MD-95, so, you're basically correct either way. :)
- thunfischbrot 6y ago
  See https://www.avgeekery.com/boeing-717-fly-way-mainland/ https://www.avgeekery.com/boeing-717-fly-way-mainland/ and https://joepriesaviation.net/photoalbum/displayimage.php?album=3&pid=3414 https://joepriesaviation.net/photoalbum/displayimage.php?alb... Seems obvious once you've seen it...
dvdhsu 6y ago
Ha, great question. We didn't have access a SABRE system so the lookups are fake. I was just about to go in and change it in to a 388 (my favorite plane!), which I think flies daily between LHR and SFO as BA286. ~Unfortunately, the output is in png format which was generated by carbon.now.sh, so I'll have to type everything out. I'll change it once I have a few minutes...~ Edit: just changed it into BA286, which is an 388. (For fun, I also added in first class fare buckets, which United no longer offers.) For additional accuracy, I also updated the UA equipment to 772s, which IIRC is what they actually fly (as opposed to 77Ws). (If we did this more often, we'd probably actually design it in HTML instead of using Carbon, but an image was much faster, haha.)

tgsovlerkhgsel 6y ago

The article mentions that there is little evidence for prices changing based on cookies. I've seen that happen, reproducibly and in a plausible way: The (third party) site was adding an "agency discount" (name may not be precise, this is from memory, IIRC it was ~$10-30) that turned into a significant (IIRC $50+) "agency surcharge" on your second visit. Clear cookies, discount is back, revisit, surcharge is back, 100% reproducible.

mehrdadn 6y ago
Along these lines, I've noticed airlines seem to jack up a ticket price in the subsequent days if you search for a ticket, visit their website, and don't buy the ticket. Though maybe if you wait a couple weeks they might get disappointed and lower it again. Anybody had a similar experience? (From what I can tell, it doesn't tend to happen if you don't actually visit their website.)
- lotsofpulp 6y ago
  I always buy using the airline’s website and no middleman website, and sometimes it goes up, sometimes it goes down. I use google flight tracker sometimes to track the price, and I can’t find anything to indicate it is targeting me specifically. I presume the price goes up and down based on aggregate searches or reservations for the flight, i.e. supply and demand. I know for hotels, there are programs crawling and searching for competing hotel’s prices and changing pricing based on that as well as changes in inventory and prior year’s data.
  - mehrdadn 6y ago
    I've seen this happen fairly consistently on very low-demand off-peak flights. I don't think it's a supply/demand thing. The coincidence of the timing a day or two after I search and the consistency of the experience is what makes me think they do it deliberately. The normal price variations I do see too (including with Google flight tracker), but they don't seem to correlate nearly as strongly with my searches. Hard to prove it though...

moeffju 6y ago

I was wondering about the time zones mentioned in the article? If SFO/T-7 is 7 hours behind Greenwich Mean Time and LHR is in the (same) GMT time zone, how is that 8 hours ahead of the origin airport?

vinay427 6y ago
It's really poorly phrased in the article but I assume what they meant is that LHR is in a time zone that sometimes observes GMT, and otherwise observes BST (British Summer Time) in the summer which is 8 hours ahead. It's not exactly correct that SFO is 7 hours behind GMT because this isn't true for around half the year. It also isn't exactly true that LHR is in GMT. Most of the year, SFO is actually 8 hours behind LHR. A few weeks are off due to different DST dates.
- PuddleOfSausage 6y ago
  The author/editor has mentioned elsewhere in this thread that he was using dummy data (which contains mistakes). For this dummy December flight LHR would be in GMT (UTC+0) and not BST (UTC+1).
fraculus 6y ago
GMT doesn't observe summertime, but LHR does. So LHR (and the rest of Britain) is only in the GMT time zone for half the year.
- azalemeth 6y ago
  GMT is very nearly the same thing as UTC. Think of it as a reference rather than timezone, but one that happens to be used by a few places half the time. It's just easier to think of yourself in UTC/GMT all the time (known as Zulu time or /Z in the aviation world) and deal with the relative offsets later. Don't forget that US Daylight Saving has different start/end dates to the UK while you're at it too...

gcatalfamo 6y ago

Hi I was wondering - a meta question of sorts - how this topic (which was really interesting) was chosen for the retool blog since it doesn’t seem to be connected in any way.

lowdose 6y ago

If you are going to write more about the pricing of airline tickets I would include a graph of the actual demand and supply curves, plot the corresponding business segments in it. Many people did not study economics and graphs like these are a great visualization of the problem at hand. http://4.bp.blogspot.com/-PDoN9F9YpJo/VjDZxPztmkI/AAAAAAAABng/-XVzzcBmUPI/s1600/buckets.png http://4.bp.blogspot.com/-PDoN9F9YpJo/VjDZxPztmkI/AAAAAAAABn...

dade_ 6y ago

Speaking of XML, don't be shy and advertise your RSS feed! Great story and pictures, thanks for the information.

igrekel 6y ago

Thats was a good read, I wonder where did you get all the information. content and stories from?