Private aviation runs on a vocabulary that is rarely explained to the people paying for it. This glossary sets out the terms that come up most often when chartering an aircraft or arranging trip support, in plain language, with the practical detail that matters rather than the dictionary definition. Where a term connects to a service we run, the relevant page is linked.
Safety and regulation
Part 135
Part 135 is the section of the US Federal Aviation Regulations that governs on-demand and commuter air carrier operations — in plain terms, commercial charter. An operator must hold a Part 135 certificate to carry passengers for hire, and that certificate brings stricter requirements on crew training, duty limits, maintenance and operational control than private flying does.
Part 91
Part 91 covers general operating and flight rules and applies to private, non-commercial flying, including most corporate flight departments. A Part 91 operator may not sell seats or charge for carriage. The distinction matters when chartering: an aircraft offered for hire should be operating under Part 135, not Part 91.
ARGUS
ARGUS International is an independent auditor that rates charter operators on historical safety data, pilot background checks and on-site audits. Its ratings run Gold, Gold Plus and Platinum. Because operators cannot self-certify, an ARGUS rating is one of the few genuinely independent safety signals available to a charter client. Icarus Jet is ARGUS-registered.
Wyvern
Wyvern is the other widely recognised safety auditing body in business aviation, best known for its Wingman standard. Like ARGUS it verifies operator practices independently rather than relying on self-declaration. Many corporate flight departments will only accept aircraft from operators holding an ARGUS or Wyvern rating.
Continuing airworthiness
Continuing airworthiness is the ongoing responsibility for keeping an aircraft legally and technically fit to fly: tracking the maintenance programme, airworthiness directives and service bulletins, managing records and planning inspections. Owners usually delegate it to a management provider so nothing lapses and the aircraft retains both its value and its availability.
Buying and booking
Charter broker
A charter broker arranges flights on aircraft operated by third parties, rather than owning a fleet. The broker sources suitable aircraft, verifies operator safety credentials, negotiates price and coordinates the trip. The advantage is choice and independence; the risk is that broker quality varies, which is why accreditation and transparent pricing matter.
Empty leg
An empty leg is a repositioning flight with no passengers aboard — for example an aircraft returning to base after a one-way trip. Operators discount these heavily, often 40 to 70 per cent below the normal rate, because the flight is happening anyway. The trade-off is rigid timing and routing, with little flexibility if plans change.
Jet card
A jet card is a prepaid block of flight hours, typically bought with a deposit of $100,000 or more, in exchange for a fixed hourly rate and guaranteed availability. It suits frequent flyers who value certainty. For most travellers flying under roughly 25 hours a year, on-demand charter works out cheaper because there is no capital tied up.
Fractional ownership
Fractional ownership means buying a share of a specific aircraft — commonly a sixteenth or an eighth — which entitles the owner to an allocated number of hours per year. It sits between full ownership and chartering, and carries monthly management fees plus an occupied hourly rate on top of the purchase.
Repositioning flight
A repositioning or ferry flight moves an aircraft without passengers, either to reach the departure airport or to return to base afterwards. On a one-way charter the repositioning time is normally billed, which is why a one-way trip rarely costs half of a return. Where the aircraft is already nearby, the cost falls accordingly.
On the ground
FBO
An FBO, or fixed base operator, is the private terminal at an airport that serves general and business aviation. It provides ramp access, fuel, passenger lounges, crew facilities and often customs handling, separately from the commercial concourse. Departing through an FBO is why a private jet turnaround takes minutes rather than hours.
Handling agent
A handling agent is the company that services an aircraft on the ground: marshalling and parking, baggage and passenger transfer, customs and immigration liaison, refuelling, water and lavatory servicing, catering delivery and crew transport. At many airports the choice of handler determines how smooth — and how expensive — a stop turns out to be.
AOG
AOG stands for “aircraft on ground” — an aircraft that cannot fly until a technical problem is resolved. It is aviation’s highest-priority maintenance status, triggering urgent parts sourcing and engineer dispatch. AOG events are costly because they combine repair expense with a cancelled mission, so success is measured in how fast the aircraft returns to service.
MRO
MRO stands for maintenance, repair and overhaul — the facilities approved to carry out scheduled inspections, defect rectification and major work on an aircraft. Operators build relationships with MROs in the regions they fly, because having an approved facility nearby is what turns a potential AOG into a short delay.
Turnaround
Turnaround is the time between an aircraft arriving and departing again. For a private jet at an FBO a routine turnaround can be twenty to forty minutes, covering refuelling, cleaning, catering and crew paperwork. It stretches when fuel, customs or slot approval have not been arranged in advance.
Planning and operations
Overflight permit
An overflight permit is a country’s authorisation to transit its airspace without landing. A single international mission may need several. Applications require operator and aircraft documents, insurance and a filed schedule, and lead times range from same-day in much of Europe to three business days or more elsewhere.
Landing permit
A landing permit authorises an aircraft to land at a specific airport on specific dates, and is issued by the destination country’s civil aviation authority. It typically requires crew and passenger details, insurance, and a confirmed handling agent. Significant schedule changes after approval usually mean revision or re-application.
Slot
A slot is an allocated window for taking off or landing at a coordinated airport. At busy or capacity-limited airports — and at almost every Mediterranean island in summer — no slot means no flight, regardless of aircraft availability. Parking approval is often tied to the same allocation.
CTOT
A CTOT, or calculated take-off time, is a departure time assigned by air traffic flow management to relieve congestion downstream, most commonly by EUROCONTROL in Europe. It arrives with a narrow tolerance window. Missing it means requesting a new one, which can cascade into delays across the rest of the day’s itinerary.
NOTAM
A NOTAM, or notice to air missions, is an official notice of anything affecting flight operations that is not already on the charts — runway closures, navigation aid outages, airspace restrictions, hazards or temporary flight restrictions. Every flight plan is checked against current NOTAMs for the route and both airports.
Tankering
Tankering is carrying more fuel than a leg requires, uplifted where fuel is cheaper, to avoid buying at an expensive destination. It saves money only when the price gap outweighs the extra fuel burned carrying the weight, so the calculation is run per flight rather than applied as a policy.
Jet A-1
Jet A-1 is the standard kerosene-based aviation turbine fuel used by civil jets outside North America, where the closely related Jet A is common. It is chosen for its high energy density, low freezing point suited to high altitude, and a flash point high enough to make it safer to store and handle than gasoline.
Where these terms apply
Most of the operational vocabulary above — permits, slots, handling, fuel and AOG response — describes work our team does daily. See trip support for permits, handling and flight planning, jet fuel service for uplift and pricing, and aircraft management for continuing airworthiness and AOG. If you are comparing charter options, the charter cost guide explains how the pricing terms above translate into a quote.
Missing a term you need explained? Our operations team answers questions like these every day — get in touch and we will add it.