Every time you book a flight, you generate personal data that is ripe for harvesting: information like the details on an ID card, your address, your passport information and your travel itinerary, as well as your frequent-flyer number, method of payment and travel preferences (dietary restrictions, mobility restrictions, etc.). All that data becomes part of a registry, in the form of a Passenger Name Record (PNR) – a generic name given to records created by aircraft operators or their authorised agents for each journey booked by or on behalf of any passenger.

When we book a flight or travel itinerary, the travel agent or booking website creates our PNR. Most airlines or travel agents choose to host their PNR databases on a specialised computer reservation system (CRS) or a Global Distribution System (GDS), which coordinates the information from all the travel agents and airlines worldwide, to avoid things like duplicated flight reservations. This means that CRSs/GDSs centralise and store vast amounts of data about travellers. Though we are focusing on air travel here, it is important to note that the PNR is not only flight-related. It can also include other services such as car rentals, hotel reservations and train trips.
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A PNR isn’t necessarily created all at once. If we use the same agency or airline to book our flight and other services, like a hotel, the agency will use the same PNR. Therefore, information from many different sources will be gradually added to our PNR through different channels over time. That means the dataset is much larger than just the flight info: a PNR can contain data as important as our exact whereabouts at specific points in time.

What are the implications of all this for our privacy? The journalist and travel advocate Edward Hasbrouck has been researching and denouncing the PNR’s effects on privacy in the US for decades. In Europe, organisations like European Digital Rights (EDRi) have also criticised PNRs extensively through their advocacy and awareness campaigns. According to Hasbrouck:

PNR data reveals our associations, our activities, and our tastes and preferences. It shows where we went, when, with whom, for how long, and at whose expense. Through departmental and project billing codes, business travel PNR’s reveal confidential internal corporate and other organisation structures and lines of authority and show which people were involved in work together, even if they travelled separately. PNRs typically contain credit card numbers, telephone numbers, email addresses, and IP addresses, allowing them to be easily merged with financial and communications metadata

Your individual PNR also contains a section for free-text “remarks” that can be entered by the airline, the travel agency, a tour operator, a third-party call centre or the staff of the ground-handling contractor. Such texts might include sensitive and private information, like special meal requests and particular medical needs. This may seem innocuous, but information like special meal requests can indicate our religious or political affiliations, especially when it is cross-referenced with other details included in our PNR. Regardless of whether the profile assigned to us is accurate, the repercussions and implications of that profiling are concerning – especially in the absence of public awareness about them.
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In the United States, PNRs are stored in the Automated Targeting System-Passenger (ATS-P), where they become part of an active database for up to five years (after the first six months, they are de-personalised and masked). After five years, the data is transferred to a dormant database for up to ten more years, where it remains available for counter-terrorism purposes for the full duration of its 15-year retention.

According to Edward Hasbrouck, PNRs cannot be deleted: once created, they are archived and retained in the Computer Reservation Data and You and/or Global Distribution Data and You (CRS/GDS), and can still be viewed, even if we never bought a ticket and cancelled our reservations:

“CRS’s retain flown, archived, purged, and deleted PNR’s indefinitely. It doesn’t really matter whether governments store copies of entire PNR’s or only portions of them, whether they filter out certain especially “sensitive” data from their copies of PNR’s, or for how long they retain them. As long as a government agency has the record locator or the airline name, flight number, and date, they can retrieve the complete PNR from the CRS. That’s especially true for the U.S. government, since even PNR’s created by airlines, travel agencies, tour operators, or airline offices in other countries, for flights within and between other countries that don’t touch the USA, are routinely stored in CRS’s based in the USA.
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Under EU regulations, governments can retain PNR data for a maximum of five years, to allow law-enforcement officials to access it if necessary. The regulations state that after six months, the data is masked out or anonymised. But according to research by the EDRi, records are not necessarily anonymised or encrypted, and, in fact, the data can be easily re-personalised.
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PNR is a relatively old system, pre-dating the internet as we know it today. Airlines have built their own systems on top of this, allowing passengers to make adjustments to their reservations using a six-character booking confirmation number or PNR locator. But although the PNR system was originally designed to facilitate the sharing of information rather than the protection of it, in the current digital environment and with the cyber-threats facing our data online, this system needs to be updated to keep up with the existing risks. PNRs are information-rich files are not only of interest for governments; they are also valuable to third parties – whether corporations or adversaries. Potential uses of the data could include anything from marketing research to hacks aimed at obtaining our personal information for financial scams or even doxxing or inflicting harm on activists.

According to Hasbrouck, the controls over who can access PNR data are insufficient, and there are no limitations on how CRS/GDS users (whether governments or travel agents) can access it. Furthermore, there are no records of when a CRS/GDS user has retrieved a PNR, from where they retrieved the record, or for what purpose. This means that any travel agent or any government can retrieve our PNR and access all the data it contains, no questions asked and without leaving a trace.
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Photos of our tickets or luggage tags pose particular risks because of the sensitive information printed on them. In addition to our name and flight information, they also include our PNR locator, though sometimes only inside the barcode. Even if we cannot “see” information in the barcodes or sequences of letters and numbers on our tickets, other people may be able to derive meaning from them.

Source: Booking Flights: Our Data Flies with Us – Our Data Our Selves