Calculated Take Off Time (CTOT)

In congested airspaces, Air Navigation Service Providers (ANSPs) have several frameworks which help to manage the air traffic flow across a country or region. European airspace is a primary example of a region that encounters heavily congested traffic conditions. Due to the complexity of European airspace consisting of over 25 individual ANSPs, a set of … Read more

Step Climb

During the pre-flight phase, the flight crew of the aircraft conducts flight planning for the flight. As part of this flight planning, the routing, weather, speeds, and cruise altitude are determined. For a conventional short to medium-haul flight, a cruising altitude is filed as part of the flight plan. In some instances, in which the … Read more

Top of Climb (T/C)

top of climb

What is Top of Climb (T/C)? Top of Climb, commonly abbreviated as T/C or TOC, is the calculated point at which the aircraft reaches its cruising altitude.  At the Top of Climb, the aircraft levels off and is neither descending nor ascending; the climb phase of flight has now been completed.  It is important that … Read more

Top of Descent (T/D) Calculations

What is Top of Descent (T/D)?  In en-route flight management and planning, Top of Descent (T/D) is the calculated point during a flight in which the aircraft begins descent for the arrival airport. Top of Descent (T/D) can be calculated either manually or automatically.  On modern commercial aircraft, T/D calculations are performed automatically by the … Read more

Inertial Navigation System (INS) and Inertial Reference System (IRS) – Differences and Functions

Commercial aircraft navigation systems consist of processes which provide a positioning system to the aircraft. These positioning systems communicate with the onboard navigation systems. This communication allows the exact location of the aircraft to be identified. In order to achieve accurate positioning, aircraft are equipped with Inertial Reference Systems (IRS) or Inertial Navigation Systems (INS). … Read more

Time of Useful Consciousness (TUC) | Aviation Glossary

Time of Useful Consciousness (TUC) refers to the duration of time in which sufficient cognitive function is maintained between loss of standard oxygen levels and the onset of hypoxia.  The higher the altitude levels, the lower the Time of Useful Consciousness will be, thus reducing the response time to counteract the loss of sufficient oxygen … Read more

What is Form Drag? | Aviation Glossary

In aerodynamics, there are various categories of drag used to provide a distinctive classification of different types. Due to the depth and complexity often surrounding the aerodynamics of an airfoil, it is necessary to clarify the enforcing drag types present. Form drag can be defined as the drag created following the departure of airflow (known … Read more

Configuration Deviation List (CDL) | Aviation Glossary


A Configuration Deviation List (CDL) is a list published by the Original Equipment Manufacturer (OEM) of an aircraft design that states external components on an aircraft that are not required for the aircraft to remain airworthy. The external components stated on the CDL are non-critical parts of the aircraft which are not required for the … Read more

Airport Mapping Database (AMDB) – Functions and Features


An Airport Mapping Database, also known as AMDB, is a system which outlines the layout of an airport. The map consists of a detailed and accurate rendering of the exact positioning of airport infrastructure such as runways, taxiways, aircraft gates and terminal facilities.  The primary use of AMDB systems is to provide directional guidance to … Read more

Flaperons | Aviation Glossary


On fixed-wing aircraft, there are numerous aerodynamic devices installed which serve a number of functions. These functions include the generation of lift and drag across the airfoil. Two of the aerodynamic devices found on aircraft are flaps and ailerons. Flaps being lift-generating devices in which the chord of the wing can be changed while also … Read more

Noise Abatement | Aviation Glossary

In areas surrounding most airports, there is typically an initiative undertaken by various stakeholders with the objective of mitigating noise pollution. This noise pollution can be apparent in areas in which aircraft arrive and depart on a frequent basis. Known as Noise Abatement, it is typically delivered through a set of procedures which document and … Read more

What is an Acceptance Flight? | Aviation Glossary

what is an acceptance flight

Outside of commercial operations, aircraft are required to undergo a series of non-revenue test flights to verify particular aspects of airworthiness. The requirement to ensure airworthiness of an aircraft can be sought by different personnel or organizations. A term used to describe such test flights are referred to as an “Acceptance Flight”, in which the … Read more