How do I find the registration or serial number for the aircraft I flew on specific trips in the past?

Question

I understand that there are various paid subscription services that allow me to search back up to a year in the past for the IDs of any flight and the histories of any aircraft.

Is there a free (or one-time fee) service or API for identifying the aircraft I've flown on specific dates and flights in the (up to several years) past?

Answer 1

I've asked one of my customers who works in the field, and he pointed me to this:

https://opensky-network.org/

I've never used it myself (I didn't know of it's existence 'till like half an hour ago), so I can grant for it. Let us know if it worked!

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And while we are here, a small explanation 'bout why it's quite difficult to find those data for free.

The basic problem are:

1. Flights data are complex to retrieve, as there is not a single, central, shared information system where everybody connects to store and retrieve data, so entities interested in this kind of information must house-build a system that connect to a plethora of different companies/organizations/servers/API. This is obviously really expensive, so they need costly licenses to get their money back.
2. After you retrieve the data as per point 1 you need to "translate" them to a common format which works well for you and then store the results. There are on average 100.000 commercial, passengers flights everyday, which means that when you are going to store each flight basic data (flight codes, airports involved, time of departure and landing, textual data, and so on) plus their real flight path data, you begin to have to store a lot of data, so you need lot of money for the storage infrastructure too, and that add to the costs for the data retrieval infrastructure too.

So, in conclusion, it takes a lot of money to build a service like that.