Reference

Aircraft Ownership Glossary

Name: Wingbase
Author: Wingbase

Plain-language definitions of terms you'll encounter as an aircraft owner, co-owner, or partnership member. From Hobbs time to TBO to wet rates.

1

100-Hour Inspection: Under 14 CFR 91.409(b), and subject to its exceptions, the 100-hour requirement applies when an aircraft carries a person other than a crewmember for hire, or when a person gives flight instruction for hire in an aircraft that person provides. The aircraft must have received an annual or 100-hour inspection within the preceding 100 hours of time in service and been approved for return to service. An annual inspection may take the place of a required 100-hour inspection, but a 100-hour inspection does not take the place of the annual inspection requirement.

A

Annual Inspection: Under 14 CFR 91.409, most U.S.-registered aircraft must be inspected every 12 calendar months to remain airworthy. Return to service may be approved by an FAA-certificated A&P mechanic holding an Inspection Authorization (IA), an appropriately rated repair station, or the manufacturer. Aircraft operating under an approved progressive inspection program or other FAA-authorized inspection program may follow a different schedule. Wingbase lets you track the due date, log the completed inspection, and receive advance reminders.
Airworthiness Directive (AD): A regulatory notice issued by the FAA that requires mandatory corrective action on aircraft, engines, propellers, or appliances found to have an unsafe condition. ADs can be one-time actions or recurring at specific intervals. Owners are legally responsible for complying with all applicable ADs.
Aircraft Partnership: A shared ownership arrangement in which two or more individuals co-own an aircraft. Partnerships split the fixed costs of ownership (insurance, hangar, annual inspection) while sharing access. Managing an aircraft partnership requires clear records of who flew, for how long, and how costs are allocated — which is what Wingbase is built to handle.

C

Cost Per Hour: The effective hourly cost of operating or using an aircraft, usually combining fixed costs such as hangar, insurance, subscriptions, and annual inspection reserves with variable costs such as fuel, oil, maintenance reserves, and engine reserves. Aircraft owners and partnerships use cost-per-hour estimates to set wet or dry rates and understand true ownership economics.

D

Dry Rate: A cost-per-hour rate for using an aircraft that does not include the cost of fuel. Pilots pay for fuel separately. Dry rates are common in flying clubs and leaseback arrangements where fuel costs vary by mission.

F

Flight Time: The time from when an aircraft first moves under its own power for the purpose of flight until it comes to rest at the end of the flight. Flight time is what pilots log in their pilot logbooks for regulatory currency purposes. Not to be confused with Hobbs time or engine time.
Flying Club: A membership organization that collectively owns or leases one or more aircraft. Members pay monthly dues plus an hourly rate when they fly. Flying clubs provide access to aircraft at lower cost than individual ownership. Wingbase supports aircraft partnerships and clubs with shared scheduling, multi-user accounts, and unified flight records.
FBO (Fixed-Base Operator): A business at an airport that provides aviation services such as fueling, aircraft parking, maintenance, pilot supplies, and sometimes aircraft rentals or charter services. Many FBOs manage fleets of aircraft that require tracking software for scheduling, maintenance, and billing.

H

Hobbs Time: Elapsed time recorded by a Hobbs meter. Meter activation varies by installation: it may run while the engine is running or only while the aircraft is airborne. Hobbs time may differ from flight time as defined in 14 CFR 1.1 for pilot logbooks; use the flight-time definition rather than assuming meter time is loggable. Hobbs time is commonly used to calculate cost-per-hour billing in flying clubs and aircraft partnerships. Wingbase's AI can read your Hobbs meter value directly from a photo of your instrument panel.
Hobbs Meter: An instrument installed in aircraft that measures and displays elapsed engine or flight time in hours and tenths of hours. Hobbs meters are used to track when maintenance is due and to calculate hourly operating costs. Wingbase's AI photo logging reads the Hobbs meter display from a smartphone photo.

L

Leaseback: An arrangement where an aircraft owner places their aircraft with an FBO or flight school to generate revenue from rentals or flight instruction while retaining ownership. The owner receives a portion of the rental revenue; the FBO handles scheduling, maintenance oversight, and insurance. The aircraft's usage must be carefully tracked.

M

METAR: Aviation Routine Weather Report. A standardized format for reporting current surface weather conditions at airports. METARs are issued hourly (or more frequently when conditions change significantly) and include wind, visibility, cloud cover, temperature, dew point, and altimeter setting. Wingbase displays METARs from NOAA for airports relevant to your flights.

N

N-Number: The registration number assigned to a U.S.-registered aircraft by the FAA. All U.S. civil aircraft have an N-number displayed on the fuselage. Wingbase uses your aircraft's N-number to identify your aircraft in FlightAware data and automatically create draft flight logs when your aircraft flies.
NOTAM (Notice to Air Missions): A notice filed with an aviation authority to alert pilots about hazards, temporary flight restrictions, airspace changes, or other conditions relevant to flight. NOTAMs are checked during preflight planning.

P

PIREP (Pilot Report): A report from a pilot describing actual in-flight conditions — turbulence, icing, visibility, cloud tops, and other hazards encountered. PIREPs are valuable because they describe real-time conditions rather than forecasts. Wingbase integrates NOAA PIREPs for weather briefing.

T

Tach Time: Engine time measured by a tachometer (tach meter), calibrated so that it accumulates one tach hour per clock hour at a reference RPM — typically cruise power. Below that RPM, during taxi, descent, and idle, it accumulates more slowly; above it, more quickly. Because a typical flight spends part of its time below the reference RPM, tach time usually reads less than the engine-running clock time, which is why it serves as a proxy for engine wear rather than a record of flight time. Wingbase's AI can read tach meter values from instrument panel photos.
Tach Meter: An instrument that displays engine RPM and counts elapsed time, calibrated so that one tach hour equals one hour of flight at a reference RPM (typically cruise power). Used to track engine life and schedule time-limited maintenance items.
TAF (Terminal Aerodrome Forecast): A weather forecast for conditions at a specific airport, typically covering a 24-30 hour period. TAFs are issued by the National Weather Service and updated every 6 hours. They use the same coded format as METARs and include expected wind, visibility, cloud ceilings, and significant weather changes.
TBO (Time Between Overhaul): The manufacturer-recommended maximum number of hours an aircraft engine should be operated before undergoing a complete overhaul. TBO is not legally mandatory for piston aircraft operated under FAR Part 91 (private use), but it is a common maintenance benchmark. Operators frequently track hours-to-TBO to plan for the significant cost of an engine overhaul.
Total Time: The cumulative number of hours an aircraft or engine has accumulated since new. A major engine overhaul starts a separate time-since-major-overhaul (SMOH) measure; it does not reset engine total time. Total airframe time and total engine time are key factors in determining an aircraft's value and upcoming maintenance needs.

W

Wet Rate: A cost-per-hour rate for using an aircraft that includes the cost of fuel. Wet rates make cost accounting simpler — the pilot or club member pays one fixed hourly rate and doesn't separately track fuel costs. Most flying clubs and partnerships use wet rates to keep billing straightforward.

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