Aviation Terms

Professional airline pilots have their own lingo, and it can be baffling to non-aviators. To help you get a better understanding of the ins and outs of the profession, below is a list of common aviation terms and their meanings. This is by no means an exhaustive list. If you don’t see the aviation term you’re looking for, feel free to contact us and you may see it added to the list.

Aircraft Operations Manual

A manual published by an airline that contains flight and emergency procedures, as well as limitations for a specific aircraft. This publication also includes all pertinent information from the manufacturer's aircraft manual.

Airport Ready Reserve or Standby Reserve

An assignment in which a pilot “stands by” at an airport to be available for a flight that may need a crewmember at short notice.

Block Time or Block to Block

The period of time that begins when an aircraft moves under its own power from the ramp blocks and ends when the aircraft next comes to rest at the ramp blocks, at any station or other point of termination. This is the period during which most pilots receive pay. 

Cancellation Credit Guarantee

A pilot will be guaranteed and credited for pay purposes with a certain percentage of the flight hours awarded on his final bid award, regardless of whether he experiences cancellations in his schedule.


A pilot who is in command of the aircraft and who is responsible for the manipulation of or who manipulates the controls of an aircraft (including takeoff and landing of such aircraft), is properly qualified to serve, and holds current airman’s certificates authorizing him or her to serve as such pilot.


The maximum passenger seating configuration for a particular aircraft type certificated by the Federal Aviation Administration for a particular air carrier.

Check Airman, Check Pilot, or Air Carrier Designated Examiner (ACDE)

A pilot on the pilot seniority list who is designated by the carrier, and approved by the FAA, to examine other pilots to determine pilot proficiency with respect to procedures, technique, and competency to perform pilot duties. 

Check-In Time or Duty-In Time

The time that a pilot is required to report for a duty assignment.

Checkout Time or Duty-Out Time

The time that a pilot is released from duty. A scheduled checkout time may change because of delays in a pilot’s schedule.

Collective Bargaining Agreement (CBA)

The union contract between the airline and the pilots in service of that airline. Among numerous other things, a CBA will outline the pay, work rules, and benefits that a pilot enjoys.


In the airline industry, the practice of living in one city and being domiciled in another. For example, a pilot is based in Chicago but lives in Nashville. That pilot is then responsible for positioning to and from work on his or her own time and without any extra compensation. Pilots will either use the space-available travel privileges on their own airline or the cockpit jumpseat available on all participating airlines.

Company Operations Manual or Flight Operations Manual

The manual provided to pilots by their company that documents the standard operating practices of that airline. This manual is approved by the FAA for that airline and supersedes any FARs or other regulations that a pilot may operate under. This manual also contains the operations specifications (or ops specs) that pertain to pilots at that airline.

Company Seniority

The date used for accredited service with a pilot’s company. It is most often used for fringe benefit purposes including vacation accrual, travel priority, insurance rates, and retirement vesting.

Composite Line

A monthly bid line schedule posted in the monthly bid package that contains a mixture of scheduled flying and reserve days.

Continuous Duty Overnight (CDO) or Stand Up

A scheduled duty period that begins in one calendar day and ends in the next calendar day without interruption by a scheduled on-duty rest period. The pilot’s rest occurs following the return to domicile the next calendar day, although most airlines provide their pilots with hotel rooms during the short break in the middle of the night. 

Contractual Month

The period of time, for pilot scheduling and pay purposes, during which allocated flying and lines of flying will be effective. Contractual months most often exist to even the days in a month and attempt to avoid schedule transitions over holidays.


(required) An FAA term that refers to a pilot or a flight attendant.


A flight leg on which a flightcrew member is transported to an airport where he/she will meet up with a flight he/she is to perform.


A geographical location designated by the company where pilots are stationed.

Duty Day

The period of time during which a pilot has obligations to the company. If he has a trip sequence, his duty day typically begins at his required sign-in and ends at the completion of his post-flight duties. For a pilot who is on reserve, his duty day begins when he becomes obligated to return a phone call from the Crew Scheduling Department and ends when that obligation ends. Current Federal Aviation Regulations do not allow a duty day to exceed 16 consecutive hours.

En Route Inspection

A flight leg that is observed by an FAA examiner for the purpose of ensuring compliance with FAA regulations and company policy. It is similar to a line check except that an FAA examiner performs an en route inspection, rather than a company pilot acting as an FAA “designee.”


Flying added to a pilot's trip after the publication of his final monthly schedule. Extensions occur on days on which the pilot was originally scheduled to fly and are usually limited by the labor agreement.

First Officer

A pilot who is second-in-command and any part of whose duty is to assist or relieve the captain in the manipulation of the controls of an aircraft (including takeoff and landing of such aircraft), is properly qualified to serve as such pilot, and holds current airman’s certificates authorizing him or her to serve as such pilot.

Flight Attendants

Individuals required by the FAA to ensure passenger safety and compliance with rules and procedures. The FAA requires one flight attendant for each 50 passenger seats, regardless of whether all of the seats are occupied.

Flight Leg

A single operation of flying, from block-out at the departure station to block-in at the arrival station.

Flight Log or Maintenance Log

An onboard manual in which pilots record aircraft maintenance discrepancies. Pilots check this manual prior to each flight to ensure that the aircraft is airworthy and does not have any maintenance discrepancies entered from a previous flight crew that have yet to be addressed by mechanics.

Flight Segment

One or more flight legs that operate with the same flight number (e.g., Flight #638 DFW-PIT-TYR).


The removal of a pilot from active duty because of a reduction in force; similar to a “layoff” except that management must return furloughed pilots to employment, in their seniority order, prior to hiring new pilots.


A legal term for a dispute filed by one party to a labor contract when they believe that the other party is in violation of a particular provision of that contract. Grievances that cannot be resolved between the parties are ultimately brought before a neutral arbitrator who decides the case.

Heavy Maintenance Base

A facility where heavy maintenance is performed on aircraft (usually C and D checks). Airlines will often have numerous facilities where routine maintenance may be performed but only a few facilities where major scheduled maintenance can be performed.

International Overnight

An overnight in an international city, most often excluding cities in Mexico, Canada, the Bahamas, and the U.S. Virgin Islands.

Jumpseat or Flight Deck Observer Seat

The extra seat in the flight deck. This seat is installed primarily for purposes of observing pilots during flight by check airmen or FAA examiners. However, when it is not in use, any airline pilot may utilize this seat for commuting or travel purposes.

Junior Manned or Junior Assigned

A pilot assigned a trip sequence, or a portion of a trip sequence, that falls on his days off or is in addition to his normal schedule, and normally results from the lack of availability of reserve pilots to cover the open trip sequence. A junior assignment is normally given to the most junior pilot available that day.

Lateral Bid

A transfer to another domicile without a change of seat position or equipment.

Line Check

A flight leg that is observed by a check airman or check pilot for the purpose of ensuring compliance with FAA regulations and company policy.

Longevity or Classification Seniority

The seniority used for pay purposes. During leaves of absence or furlough, a pilot normally accrues seniority (his place on the seniority list) but not longevity (to determine years of service for pay purposes).

Maintenance Pilot

A pilot on the pilot seniority list who is employed by the company and is qualified for and often domiciled at a heavy maintenance base. Such pilots conduct maintenance flight testing and ferry flights in accordance with FAR Part 91 rules.

Minimum Monthly Guarantee

The monthly pay guarantee as provided for in the collective bargaining agreement. A common minimum monthly guarantee is 70 to 75 hours, depending on the labor agreement.

Monthly Schedule Bid

The period each month where pilots bid for schedules in the following month. Regardless of which scheduling system airlines use, they all incorporate a monthly bid period.

Open Time

Flying not currently awarded or assigned to a specific pilot. Pilots may choose to add open time to their schedule as extra flying. This flying is often compensated at a higher rate than the pilot’s normal hourly rate.


A period of time during which a pilot is relieved from duty away from his domicile.


A pilot’s classification as either captain or first officer.

Preferential Bidding System (PBS)

A way of bidding for monthly schedules that focuses on a pilot’s preference for specific pairings or trips. Pilots input their preferences for pairings, such as days of the week, location of overnights, and start and end times of trips, and the preferential bidding system searches through all of the available flight sequences for the purpose of assembling a monthly schedule that best reflects the pilot’s preferences. This is different from the “hard line” system of bidding whereby the company creates and publishes a full month’s schedule of preassembled trip sequences that pilots review and then bid on. Regardless, both systems are awarded in pilot seniority order resulting in the more senior pilots having a much higher probability of receiving their preference. 

Probationary Pilot

A newly hired pilot who has not been employed long enough to move into an “active” status. Most airlines require one year of service before a pilot will be removed from probation. Probationary pilots have full access to their labor agreement and all the rights of active pilots, except that they are restricted in their use of the grievance/arbitration process in the event of termination.

Proffer to Displace or Stand in Stead

An option by which a more senior pilot may request to be displaced out of a particular status instead of a more junior pilot who would otherwise be involuntarily displaced from that same status.

Proficiency Check or Proficiency Checkride

The maneuvers and procedures required by the FAA for the purpose of initial qualification or maintaining qualification in an aircraft type.

Ramp Check

A crewmember and aircraft “spot” inspection by an FAA aviation safety inspector. Inspectors will often check the status of pilot manual revisions, pilot certificates, and aircraft airworthiness.

Regular Line of Flying or Regular Line of Time

A monthly schedule consisting of flying made available to pilots for bid.

Relief Line of Flying or Relief Line of Time

A monthly schedule built from known open time resulting from trip sequences removed from other pilots due to month-to-month transition schedule conflicts that is awarded to pilots as part of or immediately following the normal awarding of monthly schedules. Relief schedules do not usually include reserve duty days.

Reroute or Reassignment

A trip sequence that has been changed because of the deletion of, modification of, or the addition of flight legs to the original trip sequence.

Reserve Day

a duty day on which a pilot is available to crew flying that comes open. Reserve pilots are usually permitted to “sit reserve” at home, so long as they can be at the airport within a certain amount of time, typically ranging from 2 to 4 hours for “short call” reserve and 12 to 24 hours for “long call” reserve.

Reserve Line or Reserve Line of Time

A monthly schedule consisting of days of reserve availability and days off, but no published flight sequences.

Reserve Pilot

A captain or first officer who is awarded a reserve line or assigned reserve duty.


A pilot's flight assignment as reflected on the monthly bid award.


Refers to the scope of the labor agreement. For example, a scope clause might say, “All flying performed on the XYZ Airlines code must be performed by pilots on the XYZ Airlines pilot seniority list.” As a result of that clause, the scope of that particular labor agreement would cover the pilots on the XYZ Airlines pilot seniority list and all flying that XYZ Airlines performed on the XYZ code. Regional or feed carriers most often exist because there is an exception in a mainline labor agreement that permits pilots at another airline to perform feed flying in smaller gauge aircraft.

Seniority or Occupational Seniority

The date used to place a pilot on the pilot seniority list and is most often used for bidding seniority.


A term used in radio communications asking the other person to wait for further instructions. It can also indicate that a pilot or passenger is on a waiting list; if there are any no-shows or open seats available, that person may then travel on a flight without a prior reservation.


The combination of position (captain or first officer), equipment (767, CRJ-700, etc.), and domicile (Denver, LaGuardia). For example, a pilot’s status may be 767 captain, Denver.

Supervisory Pilot or Chief Pilot

A pilot on the pilot seniority list who has been designated by the company to be responsible for management functions within the flight department operation and to administer flight department and company policy as it relates to the pilot workforce.

Surplus Bid

A pilot who has been placed into a particular status where he is not needed, due to his failure to achieve a new status as a result of a medical or training issue. As a result, surplus bid pilots are often placed at the bottom of the seniority list for that particular status for the purpose of schedule bidding, until such time as they are able to obtain a new status.

System Board

An arbitration that uses a board consisting of one representative from each party plus a neutral arbitrator.

Transition Period

The period in the beginning of a contractual or calendar month, where schedules may be adjusted to resolve conflicts between the awarded bid of the previous month and that of the current month.

Trip Hour(s)

The period of time that starts when a pilot checks in at his domicile and ends when a pilot checks out at his domicile.

Trip Sequence or Trip Pairing

A published pairing of flying and/or deadheading, consisting of two or more flight legs, and that, at most airlines, originates and terminates at the same domicile.

Trip Selection

Any monthly regular, relief, reserve, or composite line of flying.

Value of the Day or VOD

The value of a day for purposes of pay when a pilot is removed from duty and there is no flying assignment or has a reserve obligation on that day.

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