• ATP = Airline Transport Pilot Certificate. Required to get a job in an airline.
  • R-ATP = Restricted ATP. A restricted ATP certificate does allow a pilot to act as a co-pilot, however you cannot act as pilot-in-command (PIC) until you log the required 1500 hours and get the full (unrestricted) ATP Certification.
  • ATC CTP = ATP Certification Training Program. A training required by both ATP and R-ATP.

Hobbs Time vs Tach Time


  • Hobbs Time measures Flight Time; should be used when logging flight hours.
  • Tach Time measures Engine Time (the number of propeller revolutions); to measure engine hours.s

The Hobbs meter records time as hours and tenths of hours, and it is a true measurement of how long the airplane is being operated. In other words, when an hour passes on your watch, an hour has passed on the Hobbs meter. As a student, pilot or flight instructor, you always want to use Hobbs time when you make entries into your pilot logbook as Hobbs time is a true measure of the time you were flying the aircraft, which is essential when building your flight time for your private pilot’s license and additional pilot certificates and ratings.

Tach time is measured via the tachometer and can be compared to a car’s odometer. However, instead of measuring tire revolutions, the tachometer measures the number of propeller revolutions. The tachometer’s primary use is to measure engine hours, which are recorded in your airplane’s engine logbooks and used to determine when your airplane needs its 50 and 100-hour inspections.


  • FIS-B: Flight Information Service - Broadcast. = weather
  • TIS-B: Traffic Information Services - Broadcast = traffic

Weather: SiriusXM vs ADS-B

  • SiriusXM: satellite based, no altitude restrictions, no geographic coverage limitations, nation wide; montly subscription
  • ADS-B In: ground station based, limited range; free

Carburetors vs Fuel Injector

Both for mixing fuel and air (fuel needs oxygen), ideal fuel:air ratio is 14.7:1

  • Carburetors: cheaper, simpler to maintain, but mostly deprecated
  • Fuel Injector: easier cold start, better fuel efficiency, more consistent transient throttle response, consistent fuel distribution among cylinders. Noted as I in engine names, like Continental IO-550-N used by Cirrus SR22.


  • Above Ground Level, or AGL, describes the literal height above the ground over which you're flying.
  • Mean Sea Level, or MSL, is your true altitude or elevation.


  • Wide Area Augmentation System (WAAS) = ICAO term Satellite-Based Augmentation System (SBAS)
  • Local Area Augmentation System (LAAS) = ICAO term Ground-Based Augmentation System (GBAS)

HF vs VHF vs UHF

  • HF: High Frequency = 3 to 30 MHz
  • VHF: very high frequency = 30 MHz to 300 MHz
  • UHF: Ultra high frequency = 300 MHz to 3 GHz

Used in Aviation:

  • NDB: 190-1750 kHz (North America 190-535 kHz)
  • VOR: VHF 108–118 MHz
  • ATC: VHF 118-137 MHz
  • DME: UHF 960-1215 MHz


  • Visual flight rules (VFR)
  • Instrument flight rules (IFR)


  • The Code of Federal Regulations (CFR) is US Federal Law.
  • The Federal Aviation Regulations (FAR) are included within the CFR under Titles 14 and 49 as federal law.


  • ATIS = Automatic Terminal Information Service. Airports broadcast info, you can listen to the specified frequency to get the info.
  • D-ATIS = Data Link - Automatic Terminal Information Service. An improvement of the voice, ATIS: a digital version that provides the ATIS information directly on the cockpit screens for the pilots to access quickly. D-ATIS is more expensive, only used in some larger airports.


  • CT: control tower frequency. Identified by the letters CT and the frequency appears to the right of the letters.
  • CTAF: Common Traffic Advisory Frequency (without control tower). Identified by C / circle symbol, and the frequency always appears ‘before’ or to the ‘left’ of the circled C.

The Common Traffic Advisory Frequency (CTAF) is a frequency designated for manned aircraft pilots to communicate with each other directly, air-to-air, while operating to or from an airport without an operating control tower.

The CTAF frequency and CT frequency for an airport are often the same.

True North vs Magnetic North

Geographic north (also called “true north”) is the direction towards the fixed point we call the North Pole.

Magnetic north is the direction towards the north magnetic pole, which is a wandering point where the Earth’s magnetic field goes vertically down into the planet.

The Geographic North Pole is static. Magnetic north is slowly chaging.

Most compasses point towards Earth’s north magnetic pole.

Flight School: Part 61 vs Part 141

You may get your training under either Part 61 or Part 141. TL;DR: Part 61 does not offer any structured courses or programs, Flight training is done one-on-one with an instructor of your choice. Part 141 is a much more structured curriculum but has lower hour minimums.


  • Part 61 concerns the requirements for certification for pilots, flight instructors and ground instructors. It regulates several types of licenses as to who is eligible, and it establishes the aeronautical knowledge requirements and flight time requirements.
  • Part 141 is oriented more to the regulation of pilot schools. Part 141 schools are required to use a structured training program and a syllabus. Pilot schools may be certified for a variety of courses for pilots and instructors.


  • Part 61 offers more flexibility. Trainees may attend part-time as their personal schedule permits.
  • Part 141 is more like courses you would take in college. It’s rigorous, and requires full-time attention. The training in Part 141 is more formal and more highly regulated. The curriculum must be approved by the FAA.

Hour Requirements:

  • Part 61 requires 40 hours of Private Pilot License flight time and 250 hours of Commercial Pilot License.
  • Part 141 requires 35 hours for private and 190 hours for commercial.

Job Opportunities (Operations): Part 91 vs 121 vs 135

Three parts of the FAR related to aircraft operations: Part 91, 121, 135.

  • Part 91: general aviation.
  • Part 121: scheduled air carriers.
  • Part 135: commuter operations and on-demand operations (also known as charters). Part 135 only applies to aircraft with 30 or fewer seats or a maximum payload capacity of 7,500 pounds, including commercial helicopter operations. Think of private jets, small turbo-propeller aircraft, and commercial helicopters

When you talk about job opportunities:

  • Part 91: some wealthy people buy private jets and you are hired to operate them.
  • Part 121: you work for the airlines, e.g. mainline (United, Delta, AA), regional (SkyWest, Envoy) and cargo (FedEx or UPS).
  • Part 135: you work for charter companies.


  • part 91 have no legally required rest periods, meaning they can fly their aircraft for days on end without ever taking a break. Under parts 121 and 135, however, this is not the case, and pilots must adhere to strict rest schedules to ensure that they are not fatigued during their operations.
  • Another example is weather minimums. A part 121 or 135 crew cannot legally initiate an approach if the weather is below minimums. Under part 91, however, they are free to do so.
  • One of the most notable distinctions between parts 121 and 135 is the requirement for two pilots on a part 121 operation vs. the allowance for one pilot on a part 135 operation.
  • Passenger identification is not required for domestic flights under part 91. For part 121 or 135 operations, passenger identities need to be verified by the operator, and passengers who are at least 18 years old will be required to provide photo identification.
  • A charter company, for example, may be able to fly their turbo-propeller aircraft under part 91 for a repositioning flight with no passengers, allowing fewer restrictions on that specific flight. Then, when an aspect of part 135 is met (such as a paying passenger onboard), their ops spec for part 135 is enforced.
  • all part 91 restrictions apply to a part 121 operator, but the more restrictive part 121 rules trump their part 91 counterparts.

The FAA’s definition of a scheduled operation is at least “5 round trips per week on at least one route between two or more points according to the published flight schedule.”