Jimenez Julien

Why I built a training record instead of another logbook

PreflightLog started in the back office of a two airplane operation on a grass field, where a chief instructor showed me the reason her Thursdays disappeared. She had a filing cabinet with a folder for each student, a stage sheet in each folder, and a stack of sticky notes on the desk that represented everything she had not yet transferred into the folders. She was not disorganized. She was carrying the entire training progress of nineteen people in her head because the paper could not keep up with the flying.

I am a software developer, not a pilot, and I have been careful about that line from the first week. My job was never to tell instructors how to teach a chandelle. My job was to look at what they already do, on the ramp, in the debrief room, at nine at night when the last lesson is finally written up, and take the parts a computer is genuinely better at. A computer is very good at remembering that a solo endorsement was signed on the eleventh of a month and therefore expires on the ninth of the next. A computer is very good at counting cross country legs over fifty nautical miles. A computer is terrible at judging whether a student is ready to be trusted alone in a traffic pattern, so PreflightLog does not try.

The first version was a single spreadsheet formula that turned a list of graded tasks into a readiness percentage. The chief instructor used it for a month and then asked whether it could do endorsements too, because she had just watched an applicant get sent home from an examiner over a make and model reference. That question set the shape of everything since. Every feature in the product exists because a working instructor described the moment it would have saved them, in dollars or in a Saturday.

What I learned about flight training, more than anything else, is that the money leaks in the gaps. It does not leak during the lesson. It leaks between two instructors who never spoke, between the flight and the write up, between the last stage check and the practical test that gets booked three weeks too early. Small schools feel every one of those gaps directly, because there is no operations department to absorb them. That is exactly the segment I chose to serve, and I have turned down feature requests that would have made the product better for a two hundred aircraft academy and worse for a single instructor with eleven students.

I work with operators the same way every time. I fly out or dial in, sit through a real debrief, watch how the paperwork actually gets done, and then take a list away. I do not run design workshops. I ask what happened last week that cost money, and I build against that. Roughly a third of what ships in a given quarter comes from those conversations, another third from support mail, and the last third from the boring maintenance that keeps the endorsement wording current and the exports honest.

Experience and expertise

I have spent more than a decade building record keeping software for regulated, appointment driven trades: places where somebody has to sign something, keep a copy, and produce it later when a person with a clipboard asks. Flight training is the most demanding version of that problem I have worked on, because the record follows the student for a career and the consequences of a gap are measured in canceled practical tests.

• Founder and sole operator of MLJ, SASU, a French company that publishes PreflightLog and a small set of related tools for independent operators.
• Ten years of production work on scheduling, records and compliance systems, with a specialty in data models that survive an audit rather than just looking tidy on screen.
• Direct working relationships with instructors and chief instructors at 41 flight schools in the United States, from single instructor operations to four base academies.
• Reviewer and maintainer of the endorsement wording library, checked against the current advisory material every quarter and after any regulatory revision.
• Responsible for support: the reply you get to a support email is written by me, usually within one business day.

How this product is built and maintained

PreflightLog ships small changes often rather than large releases twice a year. Anything that touches a student record, an endorsement or an hour counter goes through a written test that starts from a real training scenario, not from a synthetic case. Before a change to the endorsement library goes live, two working instructors read the new text and confirm the regulation reference against the source material. If they disagree, the change waits.

Editorially, the rule on this site is simple: no number appears in public that I cannot trace to an account, a support ticket or a school that agreed to share its figures. The outcome numbers on the home page come from schools that ran a full year on the product and sent their before and after data in February 2026. Testimonials are published with the person's name, role, business and city, and every one of them has read and approved the quote before it went up. When a figure changes, the page changes with it.

On the product side, uptime, backups and export integrity are treated as features, not infrastructure. Records are backed up daily and export in full whenever you want them, including after you cancel, because a training record you cannot take with you is not really yours. I do not sell data, run advertising trackers or add third party analytics scripts to this site. The privacy policy describes exactly what the contact form collects, and nothing else is collected.

Published articles

Everything below appears in The Right Seat, the PreflightLog magazine on flight instruction, and I researched and wrote each piece myself against the current regulations and the numbers operators shared with me.

• How to Assemble a Pre-Solo Package Under 14 CFR 61.87 September 3, 2026
• Part 61 or Part 141: What Changes for a Two Airplane School September 3, 2026
• Endorsement Mistakes That End a Checkride Before Engine Start September 3, 2026
• Training a Non US Citizen: TSA Rules Under 49 CFR 1552 September 3, 2026
• How a Two Instructor School Rebuilt Its Stage Check System September 3, 2026
• Why Checkride Dates Slip: How DPE Supply Shapes Your Calendar September 3, 2026
• The Private Pilot Checkride Paperwork Checklist for Instructors September 3, 2026
• What One Dual Hour Costs to Deliver, Line by Line September 3, 2026
• A Morning of Slow Flight and Stalls, Flown to ACS Tolerances September 3, 2026

Contact the author

Write to me directly at jimenezjulien42@gmail.com. Feature requests, corrections to the endorsement library, complaints about the readiness formula and questions about moving an existing paper roster all reach the same inbox, and I answer them myself. If you would rather see the product on your own students first, use the request form on the home page and pick a time that fits between your lessons.

You can also find me here:

• jimenezjulien.com, my personal site and the rest of the work published under MLJ, SASU.
• X, @mljjulien, short notes on what shipped and what broke.
• LinkedIn, Jimenez Julien, professional background and longer write ups.
• Facebook, julien.jimenez.mlj.
• Instagram, julienjimenez.mlj.