The Clearspar blog
Notes on building a Part 135 charter quoting + compliance tool — the hard calls, the tradeoffs, and the things we got wrong and fixed.
How many Part 135 operators are in each state?
A complete count of active FAA Part 135 on-demand charter operators by state — sorted by size, with state-level breakdowns. Alaska leads with 303; the full US total is 1,890.
Why no LLM touches a dollar in our quotes
A language model reads the email. Plain, testable arithmetic does the money and the compliance — so anyone can recompute the number by hand.
We made compliance the moat, not speed
Anyone can quote fast. A correct, defensible compliance gate a Director of Operations will sign off on is the hard part — so that is the product.
Designing software that says no
Most software is built to say yes. Compliance software has to surface UNABLE — with the citation and a legal alternative.
The integration is a forwarding address
Operators will not rip out their stack for a startup. So the whole integration is forwarding an email.
The night prod went down: a Prisma foot-gun
A unique constraint crash-looped a deploy into an overnight outage. The fix was resilience — not the dangerous flag everyone reaches for.
Why we don’t touch the charter payment
It is tempting to take a cut of a six-figure flight. Moving that money is a trap — and a tell. Here is why we stay out.
Audit-ready by default
The compliance log you keep anyway becomes a report a DO — or an underwriter — can use. Honestly framed, no premium promises.
A data flywheel without breaking trust
Every quote teaches us the real market rate on a lane. Capturing that without betraying the operators who created it.
Gray charter: the risk buyers don’t know they have
Flying commercially under Part 91 to dodge 135 is the most expensive mistake in charter — and an educated market is our market.
Pricing a trust product
Per-seat punishes a dispatch desk. Cheap signals “utility.” How we landed on custom, demo-led, unlimited-user pricing.
14 CFR 135.267: what the duty time rules actually say
A plain-language breakdown of the Part 135 duty and rest limits — the 14-hour duty period, the 10-hour rest minimum, cumulative caps, and what “reduced rest” really means.
Charter dispatch software: what to ask before you buy
Most charter dispatch tools handle scheduling. The legal gate is where the real risk lives. Questions that separate compliance tools from calendar apps.
Part 135 crew rest: the 8-hour floor, the 10-hour minimum, and when you can reduce
The FAA gives Part 135 operators one reduced-rest provision per 135.267(d). Here is exactly when you can use it, what the floor is, and what the logbook must show.
What aviation underwriters actually look for in a Part 135 renewal
Underwriters price risk they can quantify and reject what they cannot. Here is the documentation a loss-control-conscious Part 135 operator brings to renewal — and why it moves the conversation.
Loss-control documentation for charter operators: what to keep and how to present it
A pilot logbook and a maintenance log are the floor. The operators getting the best renewal terms bring a pre-dispatch compliance log, a FRAT record, and a corrective-action register.
Part 5 SMS for Part 135 operators: what the four pillars actually require
FAA Part 5 SMS is mandatory for scheduled carriers and recommended for Part 135. Here is what a functioning SMS looks like in an unscheduled charter operation — and what an audit actually checks.
Part 135 instrument currency: the 6-approach rule and what resets the clock
135.297 requires six instrument approaches, holding, and intercepting/tracking in the preceding six calendar months. Here is exactly what counts, what does not, and what an expired currency means for dispatch.
Part 135 medical certificate requirements: class, currency, and what the dispatch gate checks
PIC must hold at least a second-class medical. The expiry windows depend on age and operation type. Here is how the pre-dispatch currency check works and what triggers an UNABLE.
Part 135 MEL dispatch: how to release legally with inoperative equipment
An inoperative item is not automatically a no-go. The MEL tells you when you can fly, what limitations apply, and who has the authority to make the call. Here is how the dispatch gate handles deferred items.
Part 135 operational control: what 135.77 actually means for the dispatch desk
14 CFR 135.77 puts operational control with the certificate holder, not the PIC and not the software. Here is what that means when a compliance gate returns UNABLE and the operator decides to go anyway.
Part 135 IFR dispatch: the checklist before you issue a flight release
An IFR release under Part 135 requires more than a valid IFR flight plan. Here is the full pre-release checklist — weather mins, alternates, fuel, NOTAM review, crew currency, and airworthiness.
Flight risk assessment tool (FRAT) for Part 135: what to score and how to use the result
A FRAT turns subjective risk into a documented band: GREEN, AMBER, or RED. Here is what factors to score, how to calibrate your thresholds, and what the record needs to show for an insurance or FSDO review.
Part 135 vs Part 91: what the difference actually means for charter operators and passengers
Part 91 is private flying. Part 135 is commercial air transportation. The line between them is not always obvious — and crossing it without a certificate is the most serious mistake in on-demand charter.
Part 135 recurrent training requirements: what 135.293 checks and how often
135.293 requires a proficiency check every 12 calendar months. Here is what the check covers, who can give it, what happens when a crew member misses it, and how it interacts with instrument currency.
How to get a Part 135 certificate: the certification process from application to OpSpecs
A Part 135 certificate is issued by the FAA after a five-phase process that takes 90 days minimum and typically runs 6-12 months. Here is what each phase requires and where operators most commonly stall.
Part 135 drug and alcohol testing: what 49 CFR Part 40 and 14 CFR Part 120 require
Drug and alcohol testing is a federal requirement for every Part 135 operator. Here is what the program must include, who is covered, what random testing rates apply, and what a violation triggers.
Charter dispatch software: comparing the options for Part 135 operators
Leon, Q5 Systems, FOS, Avinode Ops — the options for charter dispatch range from scheduling-focused to compliance-first. Here is what each does well and where the compliance gaps are.
Part 135 passenger briefing requirements: what 135.117 requires before every flight
Every Part 135 flight requires a safety briefing before departure. Here is exactly what 135.117 requires, what can be covered by a card, and what must be delivered verbally.
Aviation hazard reporting for small Part 135 operators: building a system that actually works
A hazard reporting system does not need to be complicated. It needs to be used. Here is what a functional reporting system looks like for a 2–10 aircraft charter operation and what auditors check.
Part 135 safety policy: what the document must contain and how to write it
A safety policy is the foundation of Part 5 SMS. Here is exactly what it must include, what the FAA looks for in an audit, and a content template for Part 135 on-demand charter operators.
Corrective action tracking for aviation: what the register must show and how to close items
A corrective action register that collects findings but never closes them is worse than not having one. Here is what the register must contain, how to track closure rate, and what good looks like to an auditor.
Part 135 compliance software: what the category covers and what operators actually need
Compliance software for Part 135 operators ranges from currency trackers to full pre-dispatch gates. Here is what the category covers, what the gaps are, and what to require before buying.
Charter operations software for small Part 135 operators: what actually fits a 1–5 aircraft fleet
Enterprise charter platforms are built for 20-aircraft fleets. A 2-aircraft Part 135 operator needs something lighter. Here is what fits, what is overkill, and where the compliance gaps usually are.