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Key Terms

Because the future of aviation has way too many acronyms and initialisms!
Navigating news and technical papers on the future of aviation is daunting enough without acronyms or initialisms. These seemingly nonsense terms add to the frustration from the casually curious and industry players alike. And it’s surprising how tough it is to find decent definitions individually nor collectively.

Because of this, I’ve put together a list of key terms that my teams and I have found immensely helpful over the last few years. If you see something missing, feel free to DM me on
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and I’ll clarify when I get a chance.

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Key Term / Acronym / Initialism
Full Name
Description
1
AAM
Advanced Air Mobility
The superset of emerging aviation modes including: Commercial Inter-city (Longer Range/Thin Haul), Cargo Delivery, Public Services, Private / Recreational Vehicles. Typically intended to include rural and suburban contexts.
2
ADS-B
Automatic Dependent Surveillance –Broadcast
Automatic Dependent Surveillance–Broadcast is a surveillance technology in which an aircraft determines its position via satellite navigation or other sensors and periodically broadcasts it, enabling it to be tracked.
3
AGL
Above Ground Level
Used when referring to altitudes (e.g., 4,000 ft AGL)
4
ASTM
American Society for Testing and Materials
A standard making body that has been key to developing FAA accepted means of compliance for new aircraft (Part 23).
5
ATC
Air Traffic Control
The ground-based personnel and equipment concerned with monitoring and controlling air traffic within a particular area.
6
ATM
Air Traffic Management
Encompasses all systems that assist aircraft to depart from an aerodrome, transit airspace, and land at a destination aerodrome.
7
BMF
Battery Mass Fraction
The percent of the total weight of an aircraft that encompasses all battery packs, thermal management, battery management system.
8
BMS
Battery Management System
An electronic system that manages a rechargeable battery within safe operating conditions.
9
BVLOS
Beyond Visual Line of Sight
Beyond Visual Line of Sight operations are a type of UAS operation in which the unmanned aircraft flies outside the visual range of the pilot and observer.
10
CAA
[New Zealand] Civil Aviation Authority
11
CNEL
Community Noise Equivalent Level
12
CONOP
Concept of Operations
A document describing the characteristics of a system and how it operates.
13
CRM
Common Reference Model
A common model developed for reference analysis and study.
14
CTOL
Conventional Takeoff and Landing
adj. Referring to the way traditional winged aircraft takeoff and land n. also used to describe aircraft that fly in this way
15
DAA
Detect and Avoid
16
dB
Decibel
17
DEP
Distributed Electric Propulsion
18
DL
Disk Loading
A performance metric equal to the powered-lift generated divided by the combined rotor area of all propulsors. Indicative of an aircraft’s aerodynamic efficiency in hover.
19
DNL
Day-Night Average Sound Level
20
DOC
Direct Operating Cost
21
DoD
Department of Defense
An executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national security and the United States Armed Forces.
22
DoD (batteries)
Depth of Discharge
23
EASA
European Union Aviation Safety Agency
24
eCRM
eVTOL Common Reference Model
25
EPNdB
Effective Perceived Noise in Decibels
26
EPNL
Effective Perceived Noise Level
27
eSTOL
Electric Short Takeoff and Landing
28
EVLOS
Extended Visual Line of Sight
Extended Visual Line of Sight operations are a type of UAS operation in which a remote pilot with the help of an observer visual contact with the unmanned aircraft. The aircraft must always be visible to the pilot or observer.
29
eVTOL
Electric Vertical Takeoff and Landing
30
EWF
Empty Weight Fraction
The percent of the total weight inclusive of aircraft structures, propulsion, and equipment, but not inclusive of battery mass or payload (passengers, pilots, and bags).
31
FAA
Federal Aviation Administration
32
FAR
Federal Aviation Regulation
33
FATO
Final Approach and Takeoff Area
34
FBW
Fly By Wire
35
FOQA
Flight Operational Quality Assurance
36
GA
General Aviation
37
GAMA
General Aviation Manufacturers Association
38
GCAS
Ground Collision Avoidance System
39
IATA
International Air Transport Association
40
ICAO
International Civil Aviation Organization
41
IFR
Instrument Flight Rules
42
IMC
Instrument Meteorological Conditions
43
IOC
Indirect Operating Cost
44
L/D
Lift to Drag Ratio
A performance metric equal to the lift generated divided by the drag created by moving through the air. Indicative of an aircraft’s aerodynamic efficiency in cruise.
45
LCC
Life Cycle Cost
The overall cost over the life of a component or system.
46
Leq
Equivalent A-Weighted Sound Level
47
MTOW
Max Takeoff Weight
The maximum weight an aircraft is rated to operate inclusive of payload.
48
NAS
National Airspace System
49
NASA
National Aeronautics and Space Administration
50
ORB
Organic Resupply Bus
51
PAV
Personal Air Vehicle
52
POC
Proof of Concept
53
PSU
Provider of Services for UAM
54
RAM
Regional Air Mobility
55
RDTE / RDT&E
Research, Development, Test, & Evaluation
56
SC-VTOL
Special Conditions VTOL
EASA’s special conditions for the certification and means of compliance for VTOL aircraft
57
SEL
Sound Exposure Level
58
SENEL
Single Event Noise Exposure Level
59
SMS
Safety Management System
60
SoC
State of Charge
61
SPL
Sound Pressure Level
62
STOL
Short Takeoff and Landing
adj. Shorter takeoff and landing compared to CTOL n. also used to describe aircraft that fly in this way
63
sUAS
Small Unmanned Aircraft System
64
SVO
Simplified Vehicle Operation
65
TCAS
Traffic Alert and Collision Avoidance System
66
TFR
Temporary Flight Restriction
67
TLOF
Touchdown Liftoff Area
68
UAM
Urban Air Mobility
69
UAS
Unmanned Aircraft System
70
UAV
Unmanned Aerial Vehicle
71
UML
UAM Maturity Level
72
USAF
US Air Force
73
USS
UAS Service Supplier
74
UTM
Unmanned Traffic Management
75
V/STOL
Vertical / Short Takeoff and Landing
76
V&V
Verification and Validation
77
Vertiport
Vertiport
78
Vertistop
Vertistop
79
VFR
Visual Flight Rules
80
VFS
Vertical Flight Society
81
VHF
Very High Frequency
Used in the context of communications, typically between air and ground.
82
VLOS
Visual Line of Sight
Visual Line of Sight operations are a type of UAS operation in which the remote pilot maintains continuous, unaided visual contact with the unmanned aircraft. The aircraft must always be visible to the pilot.
83
VMC
Visual Meteorological Conditions
84
VTOL
Vertical Takeoff and Landing
adj. Referring to the way helicopters and rotorcraft takeoff and land n. also used to describe aircraft that fly in this way
There are no rows in this table

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