Operational Control and Flight Dispatch

Every commercial flight is flown by a crew but controlled by an operator. Operational control is the exercise of authority over the initiation, continuation, diversion or termination of a flight; ICAO adds that it is exercised in the interest of the safety of the aircraft and the regularity and efficiency of the flight. The operator holds this authority by virtue of its air operator certificate and must have a system for exercising it: who decides whether a flight departs, who follows it en route, and who acts when it is late, diverted or missing.

Systems differ. European rules require each operator to describe its method of operational control in its operations manual, but do not require licensed flight dispatchers or a full flight watch system, so the commander usually exercises it in flight with the support of the operator's operations staff. In US airline operations a certificated aircraft dispatcher shares the preflight decisions with the pilot in command and follows each flight throughout. Smaller operators use simpler systems, and some types of flight, such as air taxi and single-engined operations in cloud, raise questions of their own.

What is operational control

The ICAO definition speaks of initiation, continuation, diversion or termination. The FAA's version in 14 CFR 1.1 is shorter: the exercise of authority over initiating, conducting or terminating a flight. Either way the authority belongs to the operator, not to an individual. ICAO allows the operator to delegate it only to the commander and, exceptionally, to a flight operations officer or flight dispatcher where the operator's approved method of supervision requires one (see operational flight plan).

The FAA recognises three systems, matched to the kind of operation (see air operator certification):

Whoever shares the preflight decision, the commander is in command once the flight begins: under Part 121 the pilot in command has full control and authority over the aircraft and crew during flight time, and emergency authority to deviate from rules and procedures as the situation requires. In US rules operational control also settles responsibility under a lease: for a wet lease the FAA determines which party holds it, usually the one that provides the crew, and arrangements that pass it to a party without a certificate are illegal.

Aircraft dispatchers and flight followers

The aircraft dispatcher is the FAA's certificated specialist in flight planning and flight supervision. In Part 121 domestic and flag operations the dispatcher and the pilot in command are jointly responsible for the preflight planning, delay and dispatch release of each flight, and both sign the release. It contains, among other items, the aircraft identification and trip number, the departure, intermediate, destination and alternate airports, the type of operation, the minimum fuel supply and the latest weather reports and forecasts. A flight may be released under IFR only if the reports and forecasts show the destination at or above the authorised minima at the estimated time of arrival.

The dispatcher's duties continue after take-off. Under 14 CFR 121.533 and 121.535 the dispatcher monitors the progress of each flight, issues the information necessary for its safety, and cancels or redispatches it if it cannot operate or continue safely as released. Weather and hazards that develop en route are passed to the crew, today mostly by datalink. Dispatchers take part in dispatcher resource management training, the ground counterpart of crew resource management.

In supplemental operations the release is a flight release, the director of operations shares operational control with the pilot in command, and a flight follower keeps track of each flight under the operator's flight following system.

ICAO's equivalent is the flight operations officer or flight dispatcher, whose licence is set out in Annex 1 and whose duties, in support of the commander before and during the flight, are set out in Annex 6; nothing they do may conflict with the procedures of air traffic control or of the meteorological and communications services. Under the ICAO model operational control is delegated to the commander, and to such staff only where the operator's approved method requires them. European rules do not require them, and an operator that does employ flight operations officers trains them on the basis of Annex 1.

Operations control centres

An operations control centre (OCC), or airline operations control centre, is where an airline runs its day. Typical functions are flight planning and dispatch, flight watch of the airborne fleet, crew control, maintenance control and liaison with ground handling and customer services. The OCC decides on delays, cancellations and aircraft swaps, arranges handling and passenger care after a diversion, and gives the crew weather, runway and technical information when they need it.

The link with the aircraft is datalink, company VHF, satellite voice or HF. Most of the traffic is aeronautical operational control (AOC) messages carried by ACARS: delay reports, weather and NOTAM requests, loadsheets, take-off data, flight plan uplinks and position and fuel reports (see ACARS and aircraft datalink). In a non-normal situation the crew consult the OCC when time allows, but the decision remains the commander's and ATC comes first.

OOOI times and flight tracking

OOOI events (out, off, on, in) mark the four moments of every flight: OUT of the gate, OFF the ground, ON the ground and IN at the gate. The aircraft's systems detect each one, from signals such as the parking brake and the air-ground sensing, and datalink the time to the operator without crew action. The OCC uses them to follow the fleet, plan gates, monitor crew duty time and account for fuel and time.

Block time corresponds closely to flight time as ICAO defines it for crew records: from the moment the aeroplane first moves for the purpose of taking off until it finally comes to rest at the end of the flight. The FAA's definition in 14 CFR 1.1 starts when the aircraft moves under its own power for the purpose of flight (see flight time limitations).

Between OFF and ON, the operator follows the flight through position reports, ADS-C and ACARS messages. Where coverage is poor, such as over oceans and polar regions, satellite datalink and HF carry the reports. After the disappearance of Malaysia Airlines Flight 370 in 2014, ICAO developed the Global Aeronautical Distress and Safety System. Its aircraft tracking Standards, applicable since November 2018, require operators to establish an aircraft tracking capability, with automated position reports at intervals of 15 minutes or less recommended in all areas and required in oceanic areas for certain categories of aeroplane.

Overdue aircraft procedures

An aircraft is overdue when an expected report, landing message or arrival does not come. The operator's procedures start with its own means: a datalink message, a SELCAL or satellite call, a call on the company frequency, and enquiries to ATC and the aerodromes the aircraft could have diverted to. Most cases end with the aircraft found safe on the ground.

Air traffic services run the formal process, the alerting service described in ICAO Annex 11 (see alerting service and search and rescue):

• the uncertainty phase (INCERFA) begins when no communication has been received within 30 minutes after it should have been, or the aircraft fails to arrive within 30 minutes of its last notified ETA;
• the alert phase (ALERFA) follows if enquiries bring no news, and applies at once to an aircraft cleared to land that has not landed within 5 minutes;
• the distress phase (DETRESFA) is declared when the aircraft is probably in distress or its fuel is considered exhausted.

Under EASA's CAT.GEN.MPA.145 the operator must at all times have available, for immediate communication to rescue coordination centres, lists of the emergency and survival equipment carried on board, such as life rafts, pyrotechnics, medical supplies and portable emergency radios. In the United States, Part 135 operators must have flight locating procedures for flights without an FAA flight plan, including timely notification of the FAA or a search and rescue facility when an aircraft is overdue, and Flight Service starts overdue action if a VFR flight plan is not closed within 30 minutes of the ETA. Under 49 CFR 830.5 an overdue aircraft believed to have been in an accident must be reported to the NTSB immediately, and under 830.15 the operator files a written report if it is still missing after 7 days.

Air taxi and positioning flights

An air taxi operation is non-scheduled, on-demand commercial air transport with a small aircraft, often flown by a single pilot. In the United States it falls under Part 135 as an on-demand operation; in Europe it is commercial air transport under Part-CAT, although air taxi flight time limitations still come from the older EU-OPS and national rules. Operational control in a small company is often concentrated in a few people, sometimes the pilot alone planning and releasing the flight within the operator's procedures.

The hazards are human as much as technical. Single-pilot air taxi lacks a second crew member to challenge a flawed plan, and customer pressure is felt directly. Human performance training therefore recommends building the challenge into the operation: personal minima and go/no-go criteria set in advance, and a briefing to the customer, before the day of the flight, that the weather decides the schedule.

A positioning flight moves an aircraft, without revenue passengers or cargo, to where its next flight begins. It remains under the operator's operational control and needs the same planning as any other flight: a flight plan, fuel and a crew within its limits. Crew members carried as passengers to where they will operate are also said to be positioning; under flight time limitation rules this counts as duty but not as flight time.

Single-engine turbine IMC operations

A single-engined aeroplane cannot continue after an engine failure, so commercial rules traditionally confined it to conditions in which a forced landing can be made safely. Under EU-OPS a single-engined performance class B aeroplane in commercial air transport could not be operated at night, in IMC except under special VFR, or above a cloud layer extending below the minimum safe altitude, and the route had to offer suitable forced landing areas. Pilots plan such routes with glide range circles (see operational flight plan).

Modern turbine engines are far more reliable, and EASA now allows single-engine turbine IMC (SET-IMC) operations, commercial air transport at night or in IMC with single-engined turbine aeroplanes, under a specific approval in Part-SPA. The approval rests on:

• an acceptable level of in-service reliability for the airframe and engine combination, and an engine trend monitoring programme;
• additional equipment, such as two separate electrical generating systems and an area navigation system that can be programmed with the positions of landing sites and guide the crew to them;
• crew training and checking that includes the forced landing procedure flown to touchdown in simulated IMC, with zero thrust set and on emergency electrical power;
• route planning that keeps a landing site within gliding range, with any risk period when none is within reach limited by a risk assessment.

In the United States, Part 135 permits single-engined aircraft to carry passengers under IFR, subject to additional electrical power sources (14 CFR 135.163) and an engine trend monitoring programme (135.421).

Library articles are written for study and exam preparation. They do not replace your aircraft's approved documentation, your operator's procedures or the regulations themselves.