The private aviation glossary
104 terms explained in plain English — from ACMI to wet lease.
A
AOC (Air Operator Certificate) regulation
An Air Operator Certificate is the licence a national aviation authority issues to a company allowed to carry passengers or cargo for hire. Outside the United States it is the equivalent of a Part 135 certificate: an EASA AOC in Europe, a UK CAA AOC, a GCAA AOC in the UAE, a CAAC certificate in China and so on. The AOC lists the aircraft the operator may use commercially and the types of operation approved. Any legitimate charter quote should identify the operator and its AOC, and you can ask for a copy or check the regulator's public register. An aircraft that is not on an AOC cannot legally be chartered, however impressive its cabin.
C
Cabotage regulation
Cabotage rules restrict foreign-registered aircraft or foreign operators from carrying paying passengers between two points inside another country. A US-registered charter jet may fly New York to Paris, but it generally cannot then sell a Paris–Nice sector; likewise an EU operator cannot pick up a paying passenger in Miami and fly them to Aspen. Some countries grant exemptions with prior approval, and private (non-revenue) flights with the same passengers are usually allowed. Cabotage matters when you plan a multi-city trip abroad: the operator may need to use a local aircraft for domestic legs, or price the whole itinerary as one international journey with the same passengers throughout.
E
EASA regulation
The European Union Aviation Safety Agency writes the common safety rules for the EU member states plus Norway, Iceland, Switzerland and Liechtenstein, covering aircraft certification, maintenance, pilot licensing and commercial operations. National authorities such as Germany's LBA or France's DGAC issue AOCs under EASA rules. For a charter customer, an EASA AOC signals a regime broadly comparable to FAA Part 135, with its own crew duty limits and a mandatory safety management system. Since Brexit the UK CAA runs a separate but very similar rulebook, so a UK operator flying into Europe and an EU operator flying into Britain each need permissions from the other side.
I
ICAO registration marks (N-reg, M-reg, VP-C) regulation
Every civil aircraft carries a registration prefix identifying its state of registry, such as N for the United States, G for the UK, D for Germany, M- for the Isle of Man, VP-C for the Cayman Islands, T7 for San Marino and 9H for Malta. The registry determines which authority certifies the aircraft and its crew, which tax and mortgage rules apply and whether the aircraft can be used commercially. N-registration is popular worldwide because of the depth of the US market and the fact that non-US owners can register through a trust. Offshore registries like Isle of Man and Cayman are used by private owners for neutrality and resale value; they generally do not allow charter, so aircraft moving onto an AOC must be re-registered.
Illegal charter / grey charter regulation
Illegal or grey charter is carriage for hire on an aircraft or by an operator not certificated to do it, typically a privately operated Part 91 or non-AOC jet whose owner or a middleman takes money for flights. It is often dressed up as a dry lease, a cost-sharing arrangement or membership of a 'club'. The danger is not only legal: the pilots may not be trained to commercial standards, the maintenance programme may be lighter, and the insurance will usually be void for a commercial flight, leaving passengers with no cover in an accident. Protect yourself by asking for the operator's certificate number and confirming the tail number is on it.
L
Landing permit regulation
A landing permit is state-level permission for a foreign aircraft to land in a country, separate from the airport's own slot or PPR. Countries such as India, Indonesia, Nigeria, Saudi Arabia and Russia require them for most private and charter flights, and they usually demand passenger and crew details, the sponsor or purpose of the visit, and aircraft documents. Lead times range from 24 hours to ten working days, and a change of date or tail number can invalidate the permit. Charter operators build permit fees and lead times into international quotes, which is why a quick trip to a permit-heavy country is rarely as quick as it sounds.
O
Overflight permit regulation
An overflight permit is the authorisation a state grants for a foreign aircraft to transit its airspace without landing. Most of Europe and North America require none for private flights, but much of Africa, the Middle East, Central and South Asia and parts of Latin America do, and processing can take from a few hours to more than a week. Permits are tied to a specific aircraft registration, route, date window and sometimes crew, and each carries a fee. Trip-support companies handle them for operators. For travellers, permit lead time is one reason a last-minute charter from Europe to Lagos or Islamabad is harder to arrange than one to Nice.
P
Part 135 regulation
Part 135 is the US regulation for on-demand commercial operations, including nearly all private jet charter. An operator must hold an FAA-issued certificate, name each aircraft on it, train and check pilots to commercial standards, observe flight and duty limits, keep maintenance programmes approved by the FAA, and meet stricter weather and runway rules than private Part 91 flights. When you charter a jet in the United States, your flight should be operated by a Part 135 certificate holder, and you can verify the certificate number on the FAA website. Brokers do not hold certificates; they arrange flights on certificated operators' aircraft, and a good broker will tell you which operator is flying you.
Part 380 (public charter) regulation
Part 380 is a US Department of Transportation rule that lets a 'public charter operator' buy whole flights from a Part 135 operator and resell individual seats to the public. It underpins the semi-private carriers such as JSX, Aero and XO's shared flights, and the seat-sharing marketplaces that let you buy one seat on a jet. The arrangement has been controversial because it allows scheduled-looking service under charter rules; the FAA and TSA tightened it in 2025 with mandatory passenger screening. For a traveller it means a cheaper, airline-like experience from a private terminal, with the trade-offs of fixed schedules and less privacy than a private charter.
Part 91 regulation
Part 91 is the section of the US Federal Aviation Regulations covering private, non-commercial flying. An owner flying their own jet, a company flying its executives, or a fractional programme operating under Subpart K all fly under Part 91. Its rules are lighter than the commercial rules: no operating certificate, less prescriptive crew rest and training requirements, and more freedom over airports and weather minimums. Crucially, Part 91 flights cannot be sold to the public; if money changes hands for carriage, the flight generally must be Part 135. Many countries mirror the split, with a private category for owners and a commercial category requiring an air operator certificate.
T
TSA waiver regulation
A TSA waiver is a US Transportation Security Administration authorisation that lets a private or charter aircraft do something normally restricted: enter certain flight-restricted airspace such as the Washington DC area, land at Reagan National under the DASSP gateway programme, or carry foreign nationals on some international flights. Waivers require advance submission of crew and passenger details, and vetting can take several days. For travellers the practical effect is that flying privately into Washington DC, near a presidential visit or a major sporting event needs extra notice and paperwork, and a last-minute passenger change may not be possible.
Twelve-Five program regulation
The Twelve-Five Standard Security Program (TFSSP) is the TSA security regime for US charter operators flying aircraft with a maximum take-off weight above 12,500 lb, which covers most jets. Operators must check passengers against watch lists, verify identity, control access to the aircraft and follow written security procedures, but until 2025 they were not required to screen passengers or bags. Since July 2025 flights sold by the seat under Part 380 must screen passengers and carry-ons with TSA-approved equipment, which brought liquid limits and screening lanes to semi-private terminals. Conventional whole-aircraft charters still typically walk straight from the FBO lounge to the jet.