• 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.


  • IATA: generally supports the airline industry, while the ICAO.
  • ICAO: provides global standards for air transport operations, not limited to airlines.

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.

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

  • VLF: Very Low Frequency = 0.003 MHz to 0.03 MHz
  • LF: Low Frequency = 0.03 MHz to 0.3 MHz
  • MF: Medium Frequency = 0.3 MHz to 3 MHz
  • HF: High Frequency = 3 MHz to 30 MHz
  • VHF: very high frequency = 30 MHz to 300 MHz
  • UHF: Ultra high frequency = 300 MHz to 3 GHz

Used in Aviation:

  • (AM Radio: 530 and 1710 kHz, 10 kHz wide channels)
  • NDB: 190-1750 kHz (North America 190-535 kHz)
  • (FM Radio: VHF 87.5 to 108.0 MHz)
  • VOR: VHF 108–117.975 MHz
  • ATC: VHF 118-136.975 MHz: 25 KHz wide channel, (137-118)/0.025 = 760 channels
  • 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.

Part 61 vs 91

  • Part 61 deals with training and licensing.
  • Part 91 of the FARs contains a set of operating and flight rules that civil aircraft pilots must follow. These are the guidelines you must adhere to when flying.

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 91 Subpart K: Fractional Ownership Operations, e.g. PlaneSense.
  • 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.”

carburetor vs fuel injector:

carburetor mixes air and fuel in advance of intake into the cylinder fuel injector squirts fuel into the cylinder

normally aspirated vs forced induction:

  • normally aspirated: intake air comes from outside the engine and matches that density
  • forced induction: use of a turbocharger or supercharger to increase density of intake air


  • too rich: too much fuel, not all the fuel burns, engine runs cooler, less than optimal power
  • too lean: not enough fuel, not be enough explosion to push up the cylinder, engine could quit

High Performance vs Complex

  • high performance > 200hp (not including 200 hp) e.g. 182 has 230 hp, 172 has 180 hp, SR22 310 hp
  • complex:
    • retractable landing gear
    • adjustable pitch propeller
    • has flaps

longerons vs stringers

Longerons often carry larger loads than stringers and also help to transfer skin loads to internal structure. Longerons nearly always attach to frames or ribs. Stringers often are not attached to anything but the skin, where they carry a portion of the fuselage bending moment through axial loading.


RNP is more advanced and more accurate, does not require ground monitoring.

Part 23 vs 25

  • Part 23 aircraft: normal, utility, acrobatic, and commuter category airplanes; standards for airplanes weighing 19,000 pounds or less and with 19 or fewer passenger seats.
  • Part 25 defines transport category airplanes.


  • Part 27: utility helicopters.
  • Part 29: transport helicopters.

Alternator vs Generator

much older airplanes used a generator rather than an alternator to perform essentially the same function. Alternators are lighter than generators; they run at greatly reduced speeds, which means less wear and tear on the unit; and they are more dependable.

the battery provides all electrical power to the aircraft and the alternator’s primary role is to recharge the battery.

Vx vs Vy

Vx is your best angle of climb speed. you have the most excess force (thrust) The amount of power you have available to climb is the difference between the thrust line (blue) and the drag; climb the most for the least distance travelled over the ground. (minimize the distance)

Vy is your best rate of climb speed. you have the most excess power (horsepower). Get to altitude in the least amount of time. (minimize the time)

Thrust vs Power

“Thrust” is the force that moves an airplane forward in flight. Power is the rate of change in that force, or to put it another way, its the rate of change in FORWARD energy. Thrust is produced by power.

Power is work done per unit of time.

Power Required = Thrust Required X Airspeed

P= F v

thrust in terms of pounds. On a reciprocating engine aircraft, we measure power in "horsepower."

Vy is the speed where you have the biggest difference between power required and power available.

Comm: 10w vs 16w

10 watts is plenty, unless you fly in the flight levels.

The higher power is nice, makes for a nice clear radio transmission.

If you are going to cross the north Atlantic Ocean get a 16w, otherwise the 10w that most everyone else uses is just fine.s

Runway: Asphalt vs Concrete

Asphalt runways are cheaper, easier, and quicker to build. Concrete runways are much more durable and last a lot longer. For a small airport that handles mostly small, light aircraft and is not very busy, asphalt is fine.

On the other hand, concrete is more environmentally friendly due to asphalt's petroleum-based binder.


  • LAX the outer runways (24R, 25L) are Asphalt, inner runways (24L, 25R) are Concrete
  • SFO all 4 runways are Asphalt
  • SEA all concrete (x3)

heading vs bearing vs course vs track

  • Heading: where the nose points, relative to north.
  • Course: the intended path of travel.
  • Track: the actual path of travel.
  • Bearing:
    • relative bearing: between heading and the location.
    • magnetic bearing: between magnetic north and the object.


  • CAT I: ceiling >= 200 ft, visibility >= 550 m
  • CAT II: ceiling >= 100 ft, visibility >= 350 m
  • CAT IIIa: ceiling >= 50 ft, visibility >= 200 m
  • CAT IIIb: no min ceiling, visibility >= 50 m
  • CAT IIIc: no min ceiling, no min visibility

Installing and maintaining CAT II/III ILS equipment at an airport is very expensive, not all airports have it.


Performance-based navigation (PBN) = RNP or RNAV

The fundamental difference between RNP and RNAV is that RNP requires on-board performance monitoring and alerting capability. Think of this as a computer system that's constantly self-assessing and ensuring the reliability of navigation signals and position information.

You won't fly RNP procedures unless you're flying airline or corporate aircraft.

While GPS doesn't automatically equal RNAV, it's the most common system found in cockpits around the world, especially for piston aircraft.

"performance-based": the spec is defined by performance (accuracy, integrity, availability, continuity, and functionality required for the proposed operations), not by a specific sensor/system (e.g. VOR). Technology can evolve over time without requiring the operation itself to be revisited as long as the requisite performance is provided by the RNAV or RNP system.


Variation vs Deviation

  • Magnetic variation: the angular difference between true north (geographic north) and magnetic north.
  • Magnetic (Compass) deviation: the difference between the (inaccurate) magnetic heading indicated by the compass and the actual magnetic heading of the aircraft.

inclination倾角 vs declination赤纬

  • Magnetic inclination is the angle between the earth’s surface and the magnetic field lines.
  • Magnetic declination is the angle between the magnetic north of the compass and the true north. The declination can be measured using a compass, the direct measurement method, and a map.

constant speed propeller vs fixed pitch

A FP propeller is lighter, less complex, easier to maintain, and costs less than a Constant Speed (CS) propeller. The downside to a FP propeller is you can’t adjust it in flight.

In a fixed-pitch propeller, the engine and propeller are working in tandem, but in the constant speed world, the engine can produce significantly more power, while the RPM’s remain constant, i.e. we cannot tell the power from the RPM, instead we need to check the manifold pressure gauge.

the manifold pressure gauge reads the barometric pressure when the engine is turned off. (because when the engine isn’t turning, there’s not a vacuum being created. It’ll just read the outside pressure because it’s nothing more than a pressure gauge. )


NDB's are non directional and VOR's are omnidirectional.

both broadcast in all directions.

Think of the signal from a VOR as a collection of beams radiating out from the transmitter. Each beam carries data: it is encoded with the azimuth from the station.

With a NDB, we also have beams radiating in all directions from a transmitter, but all the beams are the same. That's why you can only get a relative bearing from a NDB.

Slip vs Skid

  • A slip is caused by too slow a rate of turn for the bank angle. The nose of the aircraft yaws to the outside of the turn, and the aircraft's banked too much for the rate of turn.
  • A skid is caused by too fast a rate of turn for the bank angle.

A skid turn is more dangerous.

Audio panel vs intercom

IFR flight depended on multiple radios, VORs, DME, NDBs, Inner & Outer markers, all with unique audio identifiers and notification signals. Since the pilot was required to confirm via audio identifier each if the navigational aids, the Audio Panel allowed the pilot to selectively activate/deactivate the audio portion of these multiple inputs from a single control panel.

Audio panels are "nice" but not required.

However, for most VFR and some IFR panels, marker beacons are not required, and only a single comm is required or a dual comm can be handled with an external switch. Multiple audio sources can be managed with individual volume controls on the instruments.

With the exception of the marker beacon receiver, it's quite possible to eliminate the function of the legacy audio panel, even in an IFR machine.