For most of us, flying is still an inherently mysterious activity.

To shed some light on the world of commercial air travel, Business Insider turned to Patrick Smith, an author and airline pilot, for some answers.

Smith, who is the author of Cockpit Confidential, created a glossary of commonly misunderstood airline jargon that can be found on website, Ask the Pilot.

According to Smith, some of the terminology is highly technology with others are quite humorous and even a bit absurd.

Here is a selection of these entries.

1. Doors to arrival and crosscheck

Used in a sample sentence: "Flight attendants, doors to arrival and crosscheck."

Definition: The announcement, usually made by the lead flight attendant as the plane is approaching the gate, is to verify that the emergency escape slides attached to each door have been disarmed — otherwise the slide will deploy automatically as soon as the door is opened.

2. All-call

Used in a sample sentence: "Flight attendants, doors to arrival, crosscheck and all-call."

Definition: According to Smith, all-call is usually part of the door arming/disarming procedure. "This is a request that each flight attendant report via intercom from his or her station — a sort of flight attendant conference call," he wrote.

3. Holding pattern

Definition: "A racetrack-shaped course flown during weather or traffic delays," Smith wrote.

"Published holding patterns are depicted on aeronautical charts, but one can be improvised almost anywhere."

4. Last minute paperwork

Used in a sample sentence: "We’re just finishing up some last minute paperwork and should be underway shortly…"

Definition: For many of us, this announcement is a precursor to a delay. According to Smith, this "paperwork" is usually a revision of the flight plan, something to do with the plane's weight-and-balance record, or simply waiting for the maintenance staff to get the flight's logbook in order.

5. Ground stop

Used in a sample sentence: "Sorry folks, but there’s a ground stop on all flights headed south from here."

Definition: "The point when departures to one or more destinations are curtailed by air traffic control; usually due to a traffic backlog," Smith wrote.

6. Air pocket

Definition: A colloquial term for a jolt of turbulence.

7. Equipment

Used in a sample sentence: "Due to an equipment change, departure for Heathrow is delayed three hours.”

Definition: The airplane. "Is there not something strange about the refusal to call the focal object of the entire industry by its real name?" Smith wrote.

8. Final approach

Used in a sample sentence: "Ladies and gentlemen, we are now on our final approach into Miami."

Definition: "For pilots, an airplane is on final approach when it has reached the last, straight-in segment of the landing pattern — that is, aligned with the extended centreline of the runway, requiring no additional turns or manoeuvring," Smith wrote. "Flight attendants speak of final approach on their own more general terms, in reference to the latter portion of the descent."

9. Deadhead

Definition: According to Smith, a pilot or flight attendant who is deadheading on board a flight is one that is traveling to a destination to be repositioned as part of an on-duty assignment. "This is not the same as commuting to work or engaging in personal travel," he clarified.

10. Direct flight

Definition: Whether or not a flight is "direct" has nothing to do with how many stops it makes on the way to the destination. Instead, a direct flight is defined as a routing where the flight number does not change.

"This is a carryover from the days when flights between major cities routinely made intermediate stops, sometimes several of them," Smith wrote.

A flight that doesn't make any stops is a non-stop flight.

11. The ramp

Used in a sample sentence: "We’re sorry; your suitcase was crushed by a 747 out on the ramp."

Definition: The ramp is the area closest to the terminal where planes and vehicles are active such as the aircraft parking zones.

Again, this is a relic from the early days of aviation. "In the early days of aviation, many aircraft were amphibious seaplanes or floatplanes. If a plane wasn’t flying, it was either in the water or it was 'on the ramp,'" Smith wrote.

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