Private Aviation Glossary

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.

AOC

An Air Operator Certificate is the approval that allows a company to fly passengers or cargo commercially. It names the aircraft the operator may use, the regions it may work in and the type of operation it is approved for, and it is issued by the civil aviation authority of the country the operator is registered in.

It is the document that matters most when checking who is actually flying you. A broker does not hold one. The operator behind the quote does, and the aircraft on your trip has to be listed on it.

FAR

The Federal Aviation Regulations are the body of United States rules governing civil aviation, published as Title 14 of the Code of Federal Regulations. Individual parts cover different activities, which is where the shorthand comes from: FAR Part 91 for general operating rules, FAR Part 135 for on-demand commercial charter.

You will see aircraft described as being on a "Part 91 fleet" or a "Part 135 certificate". That is this system, and it decides what an operator may legally sell you.

IS-BAO

The International Standard for Business Aircraft Operations, a voluntary code built around a working safety management system rather than a checklist. Registration runs in three stages, and an operator at stage three has shown that its safety processes are not only written down but demonstrably used.

It is separate from ARGUS and Wyvern, so an operator can hold one, two or all three. Ask which, rather than accepting a general claim of being fully certified.

SAFA ramp check

Safety Assessment of Foreign Aircraft, the European programme of spot inspections on visiting aircraft. Inspectors examine documents, crew licences, the cabin and the aircraft condition against ICAO standards, usually during a turnaround and without notice.

Findings are graded, and serious ones can ground an aircraft where it stands. It is one of the practical reasons paperwork has to be correct and current on arrival rather than merely obtainable.

N-registered

An aircraft on the United States register carries a tail number beginning with N, and it takes US rules with it wherever it flies. A US-registered aircraft operating in Europe answers to the FAA for airworthiness and crew licensing, while still meeting local rules for entry, permits and airspace.

This matters for permits, customs and inspections: the registry decides which authority owns the aircraft, and the country you land in decides what it requires of the flight.

NBAA

The National Business Aviation Association, the main United States trade body for business aviation. It publishes operational guidance, runs the industry conference where most fleet and product announcements land, and represents operators on regulatory questions.

Its material is a useful independent reference when an operator quotes an industry figure at you.

EBAA

The European Business Aviation Association, the European counterpart to NBAA. Its work concentrates on the issues specific to operating in Europe: airport access, slots, environmental regulation and the patchwork of national rules across the bloc.

ICAO

The International Civil Aviation Organization, the United Nations agency that sets the worldwide standards individual countries then write into their own law. Flight plan formats, airspace classification, aerodrome codes and safety standards all trace back to it.

It does not regulate your flight directly. Its standards are the common language that lets a single trip cross a dozen jurisdictions without being redesigned at each border.

IATA

The International Air Transport Association, the airline trade body. In private aviation its visible legacy is the three-letter airport code (LHR, DXB, TEB) used in booking and passenger-facing material, as against the four-letter ICAO code (EGLL, OMDB, KTEB) that flight planning and permits use.

When an airport has two codes in a guide, that is the difference, and permit paperwork almost always wants the ICAO one.

FAA

The Federal Aviation Administration, the civil aviation authority of the United States. It certifies aircraft and operators, licenses crew, runs the air traffic system in US airspace and publishes the Federal Aviation Regulations.

For an N-registered aircraft the FAA remains the authority for airworthiness and crew licensing anywhere in the world, even on a trip that never touches the United States.

EASA

The European Union Aviation Safety Agency, the authority responsible for civil aviation safety across the EU. It certifies aircraft and operators, and national authorities in member states apply its rules locally.

A trip between Europe and the United States sits under two regimes at once, which is why operators flying both routinely hold approvals on both sides.

GACA

The General Authority of Civil Aviation, the regulator for Saudi Arabia. It issues the landing and overflight approvals required for the Kingdom, and it works through accredited local agents rather than directly with foreign operators.

Lead times are longer than most of the region and the documentation is specific, so a Saudi trip is usually the one on an itinerary that sets the start date for the paperwork.

AFAC

Agencia Federal de Aviacion Civil, the civil aviation authority of Mexico. It issues the landing authorisations foreign private aircraft need, and its requirements include apostilled documents that cannot be produced at short notice.

The practical consequence is that Mexico rewards early filing far more than most destinations in the Americas.

ECAA

The Egyptian Civil Aviation Authority, which issues the landing and overflight permits required for Egypt. Applications run through a local handling agent and are normally filed several working days before the flight.

KCAA

The Kenya Civil Aviation Authority, the regulator for Kenyan airspace and airports. It issues the permits behind safari and East African operations, including flights into the bush strips served from Nairobi Wilson.

CAAC

The Civil Aviation Administration of China, the authority for Chinese airspace. Its permit process is among the most document-heavy in the world and runs to fixed lead times that do not flex for short-notice trips.

ANAC

The national civil aviation agency in several countries including Brazil and Argentina. As with the rest of South America, permits are issued nationally, so a multi-country itinerary needs a separate approval for each state it enters rather than one regional clearance.

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, bought with a substantial deposit up front 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.

Block time

The time an operator bills for, measured from the moment the aircraft first moves under its own power to the moment it comes to rest at the destination. It therefore includes taxi at both ends, commonly around twelve minutes out and twelve in, where flight time counts only the airborne portion.

Two hourly rates are not comparable until you know which of the two each is billed against. On short sectors the difference is a meaningful share of the trip.

Owner approval

On most charter aircraft the registered owner has to release the aircraft for each individual trip. The operator manages the aircraft and sells the charter, but the owner can decline, and roughly nine requests in ten need this step.

It is the reason a quote is not a confirmation. An experienced desk knows which aircraft in a market will clear owner approval quickly and which routinely will not.

MTOW

Maximum take-off weight, the heaviest an aircraft is certified to be when it begins its take-off roll. It is a fixed limit for the type, and everything loaded competes inside it: fuel, passengers, baggage and the aircraft itself.

It also drives cost on the ground, because landing fees, parking charges and some navigation charges are calculated from it.

Payload and range

The two figures trade against each other on every flight. An aircraft cannot carry full fuel and a full cabin at once, so adding passengers and baggage removes fuel, and removing fuel shortens the distance the aircraft can fly.

This is why a quoted maximum range is a best case rather than a promise, and why a full cabin on a long sector sometimes needs a fuel stop that an emptier one would not.

Nautical mile

The unit distance is measured in throughout aviation, abbreviated NM. One nautical mile is 1,852 metres, about 1.15 statute miles, and it derives from one minute of latitude, which is what makes it convenient for navigation.

Aircraft range figures are quoted in nautical miles, so converting to road miles overstates the distance an aircraft will actually cover.

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.

APU

The auxiliary power unit, a small engine usually in the tail that supplies electrical power and air conditioning while the aircraft is on the ground and the main engines are shut down. It is what keeps the cabin cool and the systems live before departure.

Several airports restrict how long it may run, for noise or emissions, and require ground power instead. Nice is a well-known example. Where a limit applies, the handling agent has to have a GPU ready or the cabin gets warm.

GPU

A ground power unit, the external generator that supplies electrical power to a parked aircraft so the APU can stay off. It is ordered through the handling agent as part of the ground package.

At airports with APU restrictions it is not optional, and its availability is worth confirming rather than assuming, particularly at smaller fields and during busy event weeks.

CIQ

Customs, Immigration and Quarantine, the three clearances a flight crossing a border needs on arrival and, at many airports, on departure. Whether they are available is a question of hours as much as of place.

Plenty of airports are open long after their CIQ desks close, so an aircraft can legally land and the passengers still cannot clear. On an international trip the CIQ hours, not the airport hours, set the workable arrival window.

De-icing and anti-icing

De-icing removes frozen contamination already on the aircraft. Anti-icing applies a thicker fluid that delays new ice forming while the aircraft taxis and waits for departure. Both are done at the stand or a dedicated pad before take-off.

Anti-icing fluid protects only for a defined holdover time that depends on the fluid, the temperature and the precipitation. If the aircraft does not get airborne inside it, the treatment has to be repeated, which is a large part of why winter departures slip.

Hangarage

Indoor parking for an aircraft, as against a ramp position outside. It protects against ice, snow, hail and heat, and at busy fields it is a finite resource booked well in advance.

In winter it is also a scheduling decision: an aircraft that spent the night in a hangar frequently departs without de-icing, while one left outside may not.

Tech stop

A short intermediate landing made for operational reasons rather than for the passengers, most often to take fuel on a sector beyond the aircraft range with the load aboard. Crew changes and customs can also drive one.

A tech stop usually adds between one and two hours door to door. Where a routing shows one, the question worth asking is whether a different aircraft removes it.

PPR

Prior Permission Required. The airport itself must approve the specific movement before the aircraft may use it, separately from any national permit and separately from a slot. It is requested through the handling agent, and it is granted for a named aircraft on a named date and time.

PPR is the single most common reason a perfectly legal flight cannot land where the passenger expected. Business aviation fields in the United Kingdom, the Greek islands, the Alps and much of the Caribbean use it routinely, and at busy fields it can be refused simply because the ramp is full.

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.

ACL

Airport Coordination Limited, the independent body that allocates slots at the United Kingdom coordinated airports including Heathrow, Gatwick and London City. It is separate from the airport operator and separate from PPR.

At a coordinated airport an ACL slot and an airport PPR are two different approvals, and holding one does not give you the other.

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.

AIP

The Aeronautical Information Publication, the official manual each country publishes about its own airspace and airports. It carries operating hours, approach procedures, noise rules, parking limits, customs availability and every local restriction that applies.

It is the primary source behind an airport guide. Where a NOTAM covers what has changed today, the AIP covers what is normally true.

ATC

Air traffic control, the service that separates aircraft in the air and on the manoeuvring area. It issues clearances, routings, levels and departure times, and its instructions override a filed flight plan.

When a departure is delayed for flow reasons rather than for the aircraft, this is where the delay comes from, usually in the form of a CTOT.

FIR

A Flight Information Region, a defined volume of airspace within which one country provides air traffic and flight information services. Every point on a route lies inside one, and crossing from one into the next is what triggers overflight permits and navigation charges.

A routing is planned as a sequence of FIRs, which is why a slightly different track can change both the permits required and the cost of the flight.

Curfew

A ban on movements during defined hours, almost always for noise. Curfews are set locally and vary widely: some are absolute, some allow exemptions for medical or state flights, and some permit arrivals but not departures.

A curfew is the hardest constraint on an itinerary because it cannot be bought around. A late departure upstream can turn a legal arrival into a diversion, so the last usable slot of the evening drives the whole day.

Noise abatement

Procedures that reduce noise over communities near an airport: specified departure tracks, thrust and configuration requirements, restricted runway use at certain hours, and at some airports a limit on which aircraft types may operate at all.

They are mandatory where published, and they can rule out an otherwise suitable aircraft at a specific field.

IFR

Instrument Flight Rules. The aircraft is flown by reference to instruments under a clearance from air traffic control, which provides separation from other traffic. Essentially all business jet operations are conducted this way.

It is what allows a flight to plan through cloud, at night and into weather with confidence, rather than depending on the crew seeing the ground.

VFR

Visual Flight Rules, where the crew navigates by reference to the ground and stays clear of cloud, taking responsibility for their own separation from other traffic. It requires defined minimum visibility and distance from cloud.

It matters most in helicopter work, where many island, coastal and city transfers are flown visually. That is also why those flights are limited by daylight and weather in a way jet operations usually are not.

ILS

The Instrument Landing System, a ground-based approach aid that gives the aircraft precise guidance to the runway in both alignment and descent path. It is the most capable approach available at most airports.

Its category determines how poor the visibility may be before the approach becomes unavailable. An airport without an ILS on the runway in use is materially more likely to be affected by weather, which is a normal reason a guide recommends one field over another nearby.

Low-visibility procedures

The regime an airport moves into when visibility or cloud base drops below defined limits. Aircraft spacing increases, movements on the ground are restricted to protect the approach signals, and the airport accepts fewer aircraft per hour.

The result is delay before it is diversion. Even when your own aircraft and crew are approved for the conditions, the airport is handling less traffic, so the time you are offered moves.

Diversion and alternate

Every instrument flight plan nominates at least one alternate airport, a field the aircraft can reach with the fuel aboard if landing at the destination becomes impossible. A diversion is the act of going there.

The alternate is chosen for weather, runway, hours and handling, not just distance, and the fuel to reach it is loaded before departure. It is why a flight can be delayed by the forecast at an airport it never intends to visit.

Density altitude

The altitude the air actually behaves like, once temperature and pressure are accounted for. Hot air and high ground both thin the air, so an airport at 6,000 feet on a hot afternoon can perform like somewhere far higher.

Thin air reduces engine output, lift and propeller efficiency at the same time, so the aircraft needs more runway and cannot carry as much. At places like Aspen, Bogota or Nairobi this is a real limit on payload, not a technicality, and it is worst in the afternoon.

Crew duty and FDP

Flight duty period is the working day: it starts when the crew reports and ends when the aircraft is parked at the end of the last sector. Limits are set by regulation, they tighten with the number of sectors and with duty starting at night, and they cannot be extended by agreement.

A delay early in the day can therefore make a legal trip illegal later in it. When a desk pushes back on an itinerary that looks achievable on paper, this is usually why.

ETOPS

Extended-range Twin-engine Operations, the approval that lets a twin-engine aircraft fly further than a defined flying time from the nearest suitable diversion airport. The rating is expressed in minutes.

It is what makes direct ocean and polar routings possible rather than long detours tracking the coast, and it applies to the operator and the aircraft together rather than to the aircraft alone.

CPDLC

Controller Pilot Data Link Communications, a text link between the crew and air traffic control used instead of voice for routine clearances. It is mandatory in much of European upper airspace and across oceanic regions.

Aircraft not equipped for it are restricted to lower levels or different routings in the airspace where it is required, which costs time and fuel.

ADS-B

Automatic Dependent Surveillance Broadcast. The aircraft continuously transmits its own position derived from satellite navigation, and both air traffic control and other aircraft receive it. It has largely replaced radar as the primary means of surveillance in many regions.

It is also why private aircraft movements are publicly visible on tracking sites, and the reason privacy programmes exist for owners who want their tail number withheld.

RNP

Required Navigation Performance, a standard that specifies how accurately an aircraft must know and hold its position, with the aircraft itself monitoring whether it is meeting the requirement.

It is what allows precise curved approaches into airports hemmed in by terrain, and it is why some mountain and island fields are accessible to a properly equipped aircraft and not to others.

GPS jamming and spoofing

Jamming drowns out the satellite signal so the aircraft loses its position. Spoofing is the more serious problem: a false but plausible position is transmitted, and the systems on board accept it as real.

Both are now routine near several conflict regions and both have affected business aircraft rather than only airliners. Crews cross-check against inertial and ground-based navigation, so the practical effect is added workload and rerouting rather than immediate danger.

CBP

United States Customs and Border Protection, the agency that clears aircraft, crew and passengers into the United States. An international arrival has to land at an airport with a CBP presence, and the arrival must be notified in advance.

CBP availability, not airport opening hours, decides which US fields an international flight can actually use and when.

APIS

The Advance Passenger Information System, the electronic manifest of crew and passengers filed with United States authorities before an international flight departs. Details have to match travel documents exactly.

It is filed both inbound and outbound, and a late or incorrect submission is one of the most common causes of a delay on a US border crossing.

GAR

The General Aviation Report, the United Kingdom notification filed for flights arriving from or departing to another country. It is submitted through the official service, typically between two and forty eight hours before the flight.

It applies even on routes that feel domestic, and it is required whether or not anyone meets the aircraft.

Gendec

The General Declaration, the standard ICAO form listing the flight, the crew and the passengers on board. Many countries require copies on arrival and departure, and some still want them stamped and signed on paper.

It is routine paperwork that becomes a delay when it is wrong, because customs and immigration check it against the passengers actually on the aircraft.

ESTA

The Electronic System for Travel Authorization, the pre-clearance that visa waiver nationals need before travelling to the United States. It is applied for online and tied to the passport.

Private aircraft are not exempt. A passenger without a valid ESTA or visa is not carried, however the flight was arranged.

ETIAS

The European Travel Information and Authorisation System, the pre-travel authorisation for visa-exempt nationals entering the Schengen area. It is the European counterpart to ESTA.

It is worth checking early on a trip that mixes Schengen and non-Schengen stops, because the requirement follows the passenger rather than the aircraft.

EES

The Entry/Exit System, the European Union border system that records the entry and exit of non-EU nationals biometrically in place of stamping passports.

The practical effect at a private terminal is that first-time registration takes longer than a stamp did, so arrival timings at a busy border post are worth building in.

TSA

The Transportation Security Administration, responsible for civil aviation security in the United States. In private aviation its most visible programme governs larger aircraft and international private operations rather than every charter flight.

Security screening at an FBO is normally handled by the operator and the terminal rather than by a public checkpoint, which is most of why the ground time is short.

Cabotage

Carrying passengers or cargo between two points inside a country on an aircraft registered elsewhere. Most states prohibit it, protecting domestic traffic for domestic operators.

It is a live constraint on multi-leg itineraries. A foreign-registered aircraft may fly you into a country and out of it, but a leg between two domestic airports may be off limits or need specific approval.

VAT on charter

Value added tax treatment varies by country, by route and by whether the flight is treated as domestic or international. Within Europe some domestic legs attract VAT where an international departure from the same airport does not.

It is one of the reasons two similar-looking itineraries price differently, and it is worth asking how a quote treats it rather than assuming the figure is final.

Reimbursable Services Program

A United States arrangement under which an airport or operator pays for customs officers to be available outside normal hours or at a location that would not otherwise be staffed.

It is what allows an international arrival at some business aviation fields at times CBP would not normally cover. The service has to be arranged in advance, so it is a planning item rather than something available on the day.

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.

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.

AVGAS

Aviation gasoline, the fuel used by piston-engined aircraft. It is a different product from the jet fuel used by turbine aircraft, and the common grade still contains a lead additive.

Availability is patchy and shrinking at larger airports. It matters when a trip involves a piston aircraft on a leg, because an airport that has jet fuel does not necessarily have AVGAS.

SAF

Sustainable aviation fuel, made from waste oils, agricultural residue or captured carbon rather than crude. It is certified to blend with conventional jet fuel and burns in existing engines with no modification to the aircraft.

It reduces emissions at the point of use rather than paying for a reduction elsewhere, which is why it is treated differently from offsetting. It remains a small fraction of what aviation burns, and the constraint is production volume rather than willingness to buy.

Carbon credit and offsetting

A carbon credit represents one tonne of carbon dioxide either avoided or removed by a funded project. Buying credits equal to a flight calculated emissions is what a carbon neutral charter means in practice.

Offsetting does not remove the emission from your flight. It funds a reduction somewhere else, so the registry and the standard behind the credit decide whether the claim holds. If offsets are added to a charter, ask which, rather than only the price per tonne.