Airline Flight Operations

[Ref. The G lobal A i rline I ndustry Edited By Peter Belobaba, Amedeo Odoni and Cynthia Barnhart © 2009 John Wiley & Sons, L td. ISBN: 978-0-470-74077-4]

Accountability of pilots

  • Airlines’ prioritized goals –  safety, economics and customer service

Airlines Pilots, as the members of flight operations department, are responsible for safe and efficient movement of passengers and/or cargo which ultimately generate the revenue for the airline.

Road to be a pilot

  • Before any flight operations can occur, regulatory requirements must be met for the aircraft as well as flight crew – air crew certification – ensure crew member’s proficiency and currency.

Notes:

Complete (ab initio) training programs are offered by some educational institutions (including airline training departments) which train pilots with limited or no flight experience to a level of proficiency with which they can operate as part of a flight crew, usually at a regional airline.

  • Pilots are required to maintain a minimum health standard which is validated by a licensed medical examiner.

Notes:

However, pilots’ “fit-to-fly” decision for a given flight is based on a self-assessment of their current physical and mental condition and other factors (e.g alcohol consumption, prescription drug use, blood donation and scuba diving)

  • Cockpit crews require licensing by their respective national authorities, including some level of commercial/transport certification (e.g ATPL) as well as individual qualifications in specific aircraft for larger types (type ratings).

Notes:

Before a crew member can conduct unsupervised flight duties, he or she must complete the final phase of flight training, which is usually referred to as Initial Operating Experience (IOE) or Line Operating Experience (LOE). This phase of a pilot’s qualification consists of the first 15 to 25 hours of actual flight time, and is conducted under the supervision of a check pilot who acts as the legal PIC (regardless of whether he or she occupies the left or right seat).

  • In order to maintain a safe, efficient and smoothly functioning operation, airlines and regulators have developed very detailed procedures – including normal, abnormal and emergency conditions, are detailed in the crew members’ operating manuals and backed up through a system of checklists which are cross-checked between flight crew members.

Notes:

The Standard Operating Procedures (SOPs) of an air carrier are detailed in a number of documents including the generalized flight manual (non-fleet-specific operating rules), flight procedures (Jeppesen or other approach and navigation publications), as well as aircraft-specific operating manuals, performance manuals and Minimum Equipment List (MEL, described later in this document).

Checklist is used to ensure completeness and maintaining an acceptable level of standardization.

captain, however, is always ultimately responsible for the safe and efficient conduct of the flight and in extraordinary circumstances may deviate from a procedure or regulation under his or her command authority (i.e., Captain’s Emergency Authority).

  • The simulators can safely replicate a wide variety of environmental, flight and mechanical conditions in order to achieve flight crew proficiency in different procedures, simulation sessions usually occur on a basis of 6, 9, 12 or 24 months (in USA). What about HK?

Roster life of pilots

  • The majority of crew members are assigned to a flight as mentioned in their schedules – “rosters” – A roster describes a crew member’s flight activity for some period (typically a month), and consists of sequences of flight duty and days off.

Flight Crew Activities During a Typical Flight

  1. Flight Crew Sign-in
  2. Operations/Planning (fuel, payload, ALTN, V-speeds)
  3. Pre-flight
  4. Pre-departure
  5. Gate Departure
  6. Taxi-out
  7. Takeoff
  8. Terminal Area Departure
  9. Climb
  10. Cruise
  11. Descent
  12. Terminal Area Arrival
  13. Final Approach
  14. Landing and Rollout
  15. Taxi-in
  16. Parking
  17. Post-flight

Flight Crew Sign-in

crew members are required to sign in (report duty) at the airport flight operations office (normally) 1 – 1.5 hour prior to the departure of the first leg – in order to complete introductions between crew members as well as accommodate administrative responsibilities.

Operations/Planning

Most airlines have a central Airline Operations Control Center (AOCC) staffed by certified flight dispatchers.

flight plan is the means by which the dispatcher communicates the details of a flight to the cockpit crew and is usually available for retrieval via computer terminal approximately 1 hour before departure time.

The flight plan is printed out and its details are examined by the incoming cockpit crew. Agreement is typically indicated by the captain’s signature on the paper or electronic “station copy” of the flight plan.

Notes:

the “cost index” parameter which is the ratio of time-related costs to fuel-related costs and is a major driver of flight plan optimization given that minimum time and minimum fuel trajectories can be quite different.

Fuel

Considerations in determining the fuel load include: vary depending on the type of flight, e.g., over water, destination weather and alternates, off-optimum speed or altitude requirements (which may be driven by marketing or ride conditions), ferrying fuel (tankering) to destinations where it is cost effective and mechanical discrepancies of the aircraft.

  • MEL/CDL fuel
  • Taxi from gate to runway
  • Expected en route (trip fuel) – fuel/time/distance
  • En route reserves required for certain tyes of operations (e.g over-water – 10% of the flight time)
  • Dispatch addition (e.g en route chop)
  • Fuel to get to destination alternate (fuel/time/distance)
  • Holding fuel (e.g 30 mins)
  • Regular reserves (e.g 30 mins)

The fuel load will affect (are affected by) takeoff and landing performance and may influence the payload the aircraft can carry.

Notes:

MEL – Minimum Equipment List

identifies the components which may be inoperative on a given aircraft while still maintaining legality for dispatch as well as the deferral rules.

CDL – Configuration Deviation List

references airframe components that are more structural in nature (e.g., a missing flap track fairing).

 

Takeoff Planning

  1. Fuel – as discussed above
  2. Maximum takeoff weight – Don’t forget the ultimate responsibility of airline pilots are to generate revenue. The ability of a flight to generate revenue is driven by how much payload can be carried. However, the amount of payload that may be accommodated on a given flight is ultimately limited by the maximum takeoff weight consist of:
    1. runway-limited takeoff weight
      • is derived from the most restrictive performance based on runway length, slope, obstacle clearance, brake energy and tire speed.
    2. climb-limited takeoff weight
      • based on the ability of the aircraft to climb at minimum angles with and without all engines operating normally.
    3. structural weight limit of the airframe
      • maximum certified weight based on structural limitations, regardless of phase of flight or ground operations.
    4. the maximum landing weight
      • limited by landing runway length available and/or the ability of the aircraft to execute an aborted landing while still meeting minimum climb gradient requirements.NOTES:
        Flap setting and availability of system or some inoperative system may affect the performance and so the allowed weight of payload might be restricted.
  3. Takeoff performance data also includes significant reference airspeeds (orV-speeds”)
    • V1- is the maximum speed at which an abort can be initiated with adequate runway remaining for stopping the aircraft. Once the aircraft reaches V1, there is sufficient speed that the aircraft can take off with one engine failed and the takeoff must continue. Any problems encountered after V1 are resolved in the air or upon landing
    • Vr – is the airspeed at which the nose of the aircraft is raised for the purpose of lifting off the runway. 
    • V2 – a.k.a takeoff safety speed –the target airspeed that ensures obstacle clearance if an engine fails between V1 and V2.
  4. reduced or “de-rated” thrust
    • to minimize engine wear and noise impacts immediately surrounding the airport
    • Reduce the engine thrust setting (as measured by fan rotation speed (N1) or engine pressure ratio (EPR)) by a calculated amount up to 25% from the maximum available, provided that:
      1. If the balanced field length is less than the actual runway available,
      2. still meeting takeoff safety limits
    • Notes:balanced field length (for a given takeoff weight)is defined as the distance required to accelerate to V1 and safely stop the aircraft on the remaining runway or continue the takeoff so as to reach V2 by 35 feet above the takeoff surface at the end of the runway.Often the decision to use maximum or de-rated engine power is not finalized until reaching the departure runway after taxi-out.
    • however, not always appropriate to perform a de-rated takeoff. It is precluded when there are reports of wind shear, tailwind, anti-icing fluid applied, runway contamination, equipment failures or for certain noise abatement purposes (e.g., when population distributions around an airport mean it is more important to climb as quickly as possible with maximum thrust followed by a thrust reduction when the higher population densities are being overflown further out)
  5. Alternate Airports – contingencies, either weather or traffic may require an alternate destination airport.
    • 4 types of alternate airports
      1. Takeoff alternates
        • whenever the option to return to the departure airfield is in question
        • normally limited to within a certain distance of the departure airfield (i.e., 360nm)
      2. En route alternates
      3. Destination alternates
        • driven by forecast weather conditions at the airport of intended landingIf the weather is forecast to go below certain minimums :- an alternate is stipulated in the flight planning process- require extra fuel to fly from destination to the alternate, plus 30 or 45 minutes of reserve fuel (depending on the type of operation.)
      4. ETOPS alternates

Pre-flight

The crew must determine the airworthiness of the aircraft by coundcting interior and exterior inspections of the aircraft, outlined in checklists.

Once electric power and air are available on the aircraft, interior pre-flight and cockpit “cleanup” checklists are conducted to confirm that each system is operational.

The pre-flight also includes verification that all required manuals and paperwork are on board and complete.

Notes:

APU – auxiliary power unit

  • a small turbine engine which is usually located in the aircraft’s tail cone section
  • meet the electric and pneumatic demands of the aircraft when the main engines are shut down.
  • also provide supplementary air/electric power during abnormal situations such as engine/generator failure or high-altitude operations.

External electric power may be provided to the aircraft either by a cable from the jetbridge, or from an electrical cart.

External low-pressure conditioned air can be provided through a flexible duct to the belly of the aircraft or from a dedicated unit mounted on the jetbridge. External high-pressure air may be provided to the aircraft by one or more “air start” carts for the purpose of starting an engine

Once the exterior/interior inspections and system checks are complete, the crew undertakes the Flight Management System (FMS) and autoflight initialization programming to allow their use during the flight.

The appropriate flight plan information can be entered manually into the FMS via the Control Display Unit (CDU) or some airlines have information systems which allow information required to initialize the autoflight systems to be uploaded automatically via the Aircraft Communication and Reporting System (ACARS) datalink unit.

Notes:

FMS – Flight Management System

  • auto-flight initialization programming allow the use during the flight
  • The appropriate flight plan information can be entered manually into the FMS via the Control Display Unit (CDU) [CDU is both a keypad and multi-line text display that the flight crew uses for input/output to the FMS.]
  • Basically there are three automation levels:
    1. manual control (hand flying)
    2. tactical modes (directly dialing in flight parameters such as heading, altitude, airspeed) and
    3. strategic lateral and vertical navigation modes (in which the aircraft is f lown automatically by the autopilot along a flight path programmed into the FMS)

ACARS – Aircraft Communication and Reporting System

  • ACARS system could be co-located with the FMS as an ACARS page on the CDU,OR as a standalone terminal
  • ACARS by air carriers satisfies the requirement that their aircraft are continuously able to be contacted by dispatch during the entire flight.
  • ACARS typically utilizes a very high-frequency (VHF) datalink and alphanumeric interface to facilitate company-specific communications between the aircraft and AOCC. Two-ways msg:
    1. Downlink
    2. Uplink

Downlink examples:

– OUT time (brakes released, cabin doors closed)

– OFF time (weight off landing gear after takeoff), ON time (weight on landing gear after landing) and 

– IN time (cabin door opened). These time events are automatically sent and are used in determining on-time performance, arrival estimates, crew member compensation, and a number of other statistics.

– engine monitor log

– crew can also downlink weather and position reports, estimated arrival times, holding and diversion notification, delay categories and times, aircraft maintenance requests and virtually any free text message

Uplink examples:

– FMS flight plan routing and performance data during pre-flight

– flight closeout data (final actual payload, fuel and takeoff data) = loadsheet

– messages from dispatch

– arrival gate info

When programming is complete, the crew performs a route check, where one crew member reads the FMS waypoints from the CDU and steps through the map depiction on the navigation display (CDU against ND), while the other compares the waypoints read to the paper copy of the flight plan (CDU against paper FPL).

As the departure time approaches, a fuel slip is provided to the crew by the fueler to corroborate the fuel quantity and distribution (between different fuel tanks) with the flight plan and on-board sensors.

In addition, the captain conducts a briefing with the purser or lead flight attendant – includes standard information covering en route flight time (EET) and destination weather (WX), as well as taxi-out time (in the case of a short taxi, the flight attendants must start the safety video/demonstration as early as practicable), security issues and alerts, ride conditions and turbulence, inoperative cabin components (INOPS), requirement of overwater flight passenger life vest demonstrations, augmented crew, crew meal service and any other relevant safety or operational issues.

The captain may also discuss adherence to the sterile cockpit period in which access to the flight deck is limited to reduce distractions during critical flight phases, generally  anytime the aircraft is below 10 000 feet above mean sea level (MSL).

Pre-departure

Approximately 20 minutes prior to departure, the ATC route clearance is requested, preferably through the ACARS PDC function.

Once the clearance is received, the crew can perform the “before starting engines” checklist. At approximately 10 minutes prior to departure, the captain turns on the “Fasten Seat Belt” sign which signals the flight attendants to ready the cabin for departure and deliver the requisite public address (PA) announcements.

If a hold is issued, the crew must decide on the appropriate action depending on the anticipated length of the delay and specific station requirements. Captain may elect to postpone boarding.

The pilots must account for any potential additional fuel consumption.

If any passengers require removal because of illness or misconduct, or are not on board as the flight nears departure time, all of their checked bags may have to be removed. This can be a time-consuming process if the location of the bag is unknown and/or “buried deep” in the cargo compartment.

In order to prepare the aircraft for movement, the tug is connected to the aircraft via a towbar. 

Typically, the captain communicates to the tug driver (or other ground crew member) through an “interphone” link, while the first officer communicates to ramp control and/or ATC via the VHF radio (for push-back clearance).

Gate Departure

captain acknowledges release of the parking brake and signals the first officer to call ramp control (or ATC, depending on local requirements) for push-back clearance. When received, the aircraft is pushed out of the gate area and engines are started when the cockpit crew is advised by the push-back crew that the area is clear.

In situations where deicing or anti-icing is required, the captain delays the engine start.

Notes:

“holdover time” – the length of time (in minutes) – that the anti-icing fluid is effective and is determined by the flight crew from tables in their flight manuals. The time may vary according to temperature, type and intensity of precipitation, and type and concentration of fluid used.

Deicing fluid is normally a mixture of glycol and hot water.

After the engines are started and the towbar is disconnected, the guide crew member then steps into a position that is visible from the flight deck, presents the nulling pin (used to disable the aircraft’s nosewheel steering system during push-back)

Once clearance is received, the captain begins the taxi-out only after both pilots have visually checked outside and verbally announced “clear left” and “clear right.”

Taxi-out

During the taxi, the load closeout should has been received via ACARS or by VHF radio.

FO uses the updated information to calculate finalized takeoff performance data, either in the CDU or by reference to flight manuals. The FO will also reset the stabilizer trim and set takeoff reference speeds through the bugs on the airspeed indicators. In addition, adjustments may have to be made to the flap and/or power settings.

Once the closeout information is processed, the crew completes the “taxi” and “before takeoff” checklists. At some point, the captain conducts a takeoff briefing.

Again, the captain must ensure that the passenger briefing (video) has been completed, which may be a factor in short taxi-out situations. In addition, the crew needs to verify that minimum fuel requirements remain satisfied and that crew duty time limitations have not been exceeded.

Notes:

“Closeout” = loadsheet

typically includes finalized aircraft and fuel weights, stabilizer trim settings, center of gravity data, passenger count, cargo loading, live animal and security information.

“Takeoff briefing” generally includes which pilot will be making the takeoff, initial heading, altitude and departure procedure requirements, obstacle clearance and noise abatement issues, airport elevation and the normal cleanup altitude (the height where climb pitch is reduced and the aircraft is accelerated). In addition, the briefing must address runway abort considerations, engine-out procedures and associated cleanup altitudes, and emergency contingencies requiring return to the departure point or other proximate landing options.

Takeoff

At this time the crew makes final checks of the wind/weather and the presence of runway contamination. If the flight is following the departure of a large aircraft, adequate wake separation requirements must be assured by confirming that an acceptable interval of time has elapsed before commencing the takeoff roll.

Once the takeoff clearance is received, the pilots’ roles of captain/FO change to “Pilot Flying”/“Pilot Monitoring” (PF/PM) in order to accomplish the procedures commensurate with which pilot is flying the leg. However, even if the captain assumes the PM role, at all times he or she is still PIC responsible for the flight and may choose to take over the PF.

PM calls out each V-speed as part of the normal procedure. Should a critical problem occur before the abort decision speed, V1, the takeoff is rejected and the aircraft is stopped on the runway.

An uneventful takeoff is followed by a normal initial climb-out which includes cleaning up the aircraft (gear raised, flaps/slats retracted) while conforming to any noise abatement departure procedure and/or obstacle requirements.

Regardless of the operational status of the Traffic Alert and Collision Avoidance System (TCAS), at least one crew member accomplishes a “traffic watch” (heads up looking outside the aircraft).

Terminal Area Departure

  • The climb flight profile is determined by both ATC/airspace requirements and performance characteristics of the aircraft.
  • the aircraft is accelerated to maximum low-altitude climb speed (normally 250 knots below 10 000 feet MSL in the USA) unless a restriction has been issued by ATC.
  • climb-out the flight typically conforms to a standard Departure Procedure (DP), also commonly called a Standard Instrument Departure (SID).

Notes:

Mode Control Panel (MCP)

  • is an example of tactical automation
  • This interface is used in many flight phases when specific altitude, heading and/or speed target values are required as communicated to the cockpit crew from ATC

Climb

  • during the climb, the cockpit crew checks the FMS and/or performance charts to compare the optimal and maximum cruise altitudes with the planned data and desired cruise Mach.
  • As the aircraft climbs through the transition altitude (18 000 feet MSL in the USA but can be as low as 4000 feet in other parts of the world), the crew resets the altimeter referencing from a local barometric pressure setting to the standard atmospheric pressure reference (1013 mbar or 29.92 in Hg)

NOTES:

requirements of RVSM

Above FL290, eastbound and westbound cruise levels providing for 1000 feet vertical separation are available for those aircraft that meet the equipment requirements of RVSM;

otherwise 2000 feet vertical separations are required.

Cruise

  • As cruise altitude is reached, the power settings/Mach target are established.
  • The crew also performs various administrative duties:
    1. maintain a time/fuel log in order to compare planned time and fuel burn performance with the Actual Time of Arrival (ATA) and Fuel On Board (FOB) over each flight plan waypoint
    2. Other, more routine duties that the crew performs during cruise include monitoring the aircraft flight path and systems, maintaining lateral fuel balance within limits (if not automated), cabin temperature control
    3. step–climb options – as the aircraft weight decreases due to fuel burn, the optimum cruise altitude typically increases due to better engine efficiency at higher altitudes
    4. monitor on frequencies – ATC/AOCC communications requirements – on international flights, transitioning through airspace boundaries – Flight Information Region (FIR) – normally require advance notification via the flight planning process (filed flight plan), and preliminary contact by the aircraft as the flight approaches the boundary. Generally, separate ATC clearances must be issued at each boundary crossing.

NOTES:

  • Aircraft usually equipped with at least two VHF transceivers and, if overwater certified, HF radios. VHF radio management usually requires one tuner to be set to the current ATC frequency, while the other is utilized for company communications OR to maintain a listening watch on the universal emergency channel (121.5MHz).
  • In addition, when out of VHF contact with ground facilities, the crew typically maintains a listening watch on the air-to-air frequency of 123.45MHz.

Descent

  • In the present system, the descent profile is determined by both ATC limitations and optimal aircraft performance
  • operating at typical cruise altitudes (FL310–410) will nominally initiate the descent at 100 to 130 nautical miles from the destination airport, the initial descent takes place with about 30 to 40 minutes remaining in the flight
  • “In Range” message is often transmitted to the destination airport station either through ACARS or by VHF radio. This message includes the latest touchdown estimate, special passenger requests (wheelchairs/connections) and, if not already transmitted, any maintenance discrepancies
  • During the descent, ATC may issue crossing restrictions which can be part of a published standard arrival procedure (such as a Standard Terminal Arrival Route (STAR)
  • The FMS is the primary resource available to the crew for descent planning as restrictions can be programmed directly via the CDU and a profile calculated ; The “3 to 1” rule is still used by most pilots to back up the FMS solution – 3 miles are required for every 1000 feet of altitude loss, e.g., 30 000 feet would require 90 miles
  • captain’s descent PA announcement usually includes updates of arrival estimates and weather conditions
  • As the aircraft descends below the transition level (FL180 in the USA) the altimeters are reset to the local barometric setting
  • PM works on completing the “descent” checklist -includes monitoring the pressurization, correcting any accumulated fuel imbalance, and calculating and/or reviewing landing data (approach speeds, runway limits)

NOTES:

precision approach procedures – require lateral and vertical path information to be continuously available include GPS autoland, GPS LNAV/VNAV and CATI,II and III ILS approaches

Non-precision approaches – vertical guidance is received through barometric referencing or other means not directly associated with the specific runway ground-based NAVAIDs, and usually have higher minimum values

Terminal Area Arrival

  • Terminal area maneuvering generally begins when the aircraft descends below 10 000 feet, usually about 30 to 40 miles from the destination airport
  • captain alerts the cabin crew (by chime or PA) that the sterile cockpit period is in effect and that the final cabin preparations for landing should be completed
  • The flight path is usually defined by the STAR and/or radar vectors from ATC.
  • As the flight nears the position where it will commence the approach, the crew may be issued additional real-time landing information or instructions – e.g Braking action reports

NOTES:

Radar vectors – consist of heading directives and are used by ATC for the sequencing and/or spacing of air traffic

Final Approach

  • At some point during the vectoring, the flight will be “cleared for the approach.” An approach clearance by ATC authorizes the crew to start execution of the approach procedures as published
  • The aircraft operated by most air carriers are usually equipped to satisfy the navigation requirements of a variety of approach procedures – e.g ILS to provide guidance to aircraft, lateral and vertical elements called the localizer and glide slope respectively
  • Most authorities designate a specific location in the procedure where the current weather must be at or above weather minimums in order for the aircraft to continue the approach

NOTES:

In the USA, Non-precision approaches : final approach fix, while 

precision approaches : glide slope intercept (at a “normal” intercept altitude) is the requirement

Other countries may utilize the outer marker or specific altitudes

  • In the event that the requirements for completing the approach and landing are not satisfied, a “go-around” is executed – the standardized missed approach procedure and/or ATC instructions must be followed

Landing and Rollout

  • After touching down on the runway, the PF uses a combination of reverse thrust, ground spoilers and wheel braking to decelerate to taxi speed and vacate the runway

NOTES:

Reverse thrust may not be allowed at some airports and at some times of the day for noise abatement reasons

  • As the aircraft slows to turnoff speed, the captain and FO assume the taxi and communications tasks as per normal ground operations.
  • FO contacts ground control for taxi-in instructions, completes the “after landing taxi” checklist

Taxi-in

  • during taxi-in, the captain determines the necessity of starting the APU. In the interest of fuel conservation, an engine may be shut down which may require utilizing the APU, depending on the aircraft type
  • The marshallers utilize lighted wands to signal clearance to taxi to the stop point adjacent to the jetbridge (and Some stations utilize automatic parking systems)

Parking

  • In most cases, setting the parking brake and opening a cabin door trigger the “IN” event
  • crew completes the “engine shutdown” checklist
  • The flight crew secures the cockpit and cabin before departing the aircraft

Post-flight

cockpit crew accomplishes any required debriefing reports – declared emergency or ATC violation, significant mechanical failures (e.g., engine shutdown), fuel dumping, illness, injury or death of a passenger or crew member, passenger misconduct/smoking, overweight landing, HAZMAT issues, diversions, high-speed aborts, lightning strikes, near midair collisions and a number of other situations involving non-standard operations or issues – review everything

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