The terms included here are defined/discussed in a non-aviation manner. This is intended to make the reading of the Journal easier for my non-flying friends. Some of the explanations may be over-simplistic for my prop-head friends, but remember the people they are intended for. I will only accept criticism in cases where the definition/explanation blatantly contradicts applicable FARs or is in fact wrong.

This glossary will be updated on a continuing basis. If you have suggestions for terms that should be added, email me at boboggs@aol.com

--- A ---

ADF - Automatic Direction Finder. A radio based navigational aid. The ground station broadcasts a signal in the AM band and the on-board receiver will indicate the bearing from you to the station. More difficult to use than VOR, especially in crosswind. Assume the needle is pointing straight up and you have a crosswind from the right. If you are not at the correct crab angle, the needle will drift to the right as you are blown to the left. Correcting until the needle is up again leaves you still heading towards the station, but at a higher bearing from it. You would need to go more to the right until the needle moved to the left of straight up.

AGL - Above Ground Level.

AOPA - Aircraft Owners and Pilots Association. A blanket organization of aviation enthusiasts currently numbering over 400,000 members. The organization sponsors safety clinics and acts as a clearing house for aviation related issues.

ATIS, AWOS, ASOS - Automated Terminal Information Service, Automated Weather Observing System, Automated Surface Observation System. The current weather and selected other information broadcast from many airports. The lowest level updates hourly and gives only the most important weather parameters. The stations at larger airports update more often when needed and contain additional information regarding operations. Etc.

Audio Panel - An instrument in the "radio stack" which provides for switching headsets and microphones between radios and nav instruments. You may select talk/listen on com2 and listen on com1, etc.

--- B ---

Base (Leg) - See Traffic Pattern

--- C ---

Crab angle - The difference between the heading you are pointing and the direction the plane is actually going due to the effect of a crosswind. Assume heading east (90 degrees) at 100 knots with a crosswind of 20 knots from the south (180 degrees). Your true heading (the direction to point the plane is 101 degrees and your groundspeed over the 90 degree ground track would be 98 knots.

Crosswind (Leg) - See Traffic Pattern

 --- D ---

Density Altitude - A construct that allows pilots an idea of how the airplane will perform in the current conditions. Airplanes become less efficient with altitude and temperature. Even the airlines have troubles at fields like Denver in hot weather. Basically, the number says that this is the altutude your plane perceives regardless of the actual field elevation. Your engine is breathing air which has less oxygen in it. Your prop is beating air with fewer molecules and your wing is trying to make lift from air with fewer molecules.

When the ASOS says 6300' density altitude, it is saying that your airplane will perform as if it were at 6300', the barometer were 29.92 and the temperature was 70. I.e., it will take longer to reach flying speed and it will climb slower. The Mouse has a service ceiling of 11,500', but this assumes a "standard day" (Barometer 29.92 and 70 degrees). In effect, if you subtract the difference between Density altutude and the field elevation from the service ceiling, that is the maximun altitude you can expect to reach today.

Downwind (Leg) - See Traffic Pattern

--- F ---

FBO - Fixed Base Operator. The operation (or operations) which supply services at an airport. Small airports usually have only one. Large airports may have many. Most FBO's sell fuel, do some level maintenance and have some level of lounge and facilities. Those at larger airports have many pilot services: weather computers, flight planning areas, showers and nap rooms etc..

Our experience is that they are nearly all staffed by friendly helpful people and more important, the rest rooms are always clean.

Final (Short Final) - See Traffic Pattern

Flight Following - A service provided by Air Traffic Control. They have you in their system and will provide you with traffic warnings and weather warnings. If anything amiss happens, you can call for help instantly.

Flight Plan - An advisory filed verbally with FSS telling the general parameters of the proposed flight. The flight plan is then held pending until opened by the pilot after takeoff. On opening, the actual takeoff time is adjusted and if the flight plan is not closed within 45 minutes of the estimated time of arrival, search and rescue efforts are initiated.

FSS - Flight Service Station. An operation with regional responsibility for preflight briefings regarding weather, NOTAMs and TFRs. They are also the organization with which you file a flight plan.

--- I ---

IFR - Instrument Flight Rules. The construct that allows a pilot to fly from point to point without being able to see the ground. Contrary to the movie depiction, the plane is not usually landed without the pilot being able to see the runway from a minimum distance at a minimum altitude.

Acquiring an Instrument rating takes many hours of instruction and practice.

--- M ---

MSL - Mean Sea Level. Absolute altitude above the nominal sea level. Altimeters are set to this reading and adjusted for varying barometric pressure.

--- N ---

Nav/Com - the common name for a receiver containing a UHF radio (Com) and a VOR receiver (Nav). Many if not most GA airplanes have 2 nav/coms, usually referred to as com1, nav1 and com2, nav2.

NDB - Non Directional Beacon. See ADF.

NOTAM - NOTice To AirMen. Published notices regarding airport equipment services, runway closings, unlighted towers, terminal area restrictions, etc.

--- O ---

OAT - Outside Air Temperature

--- T ---

TFR - Temporary Flight Restriction. A published restriction on flights within a specified area. As an example, all VFR flight was prohibited and IFR flight severely limited in the New York and Washington, DC area immediately after 9/11.

TPA - Traffic Pattern Altitude. The altitude at which you should enter the traffic pattern. Normally, for small planes, it is 800-1000 AGL.

Traffic Pattern - All airports are based on a "standard" Traffic pattern. This pattern may be visualized as a rectangle with each segment having a name;

• Upwind or Departure leg begins at the start of the runway (based on the direction currently in use). It is normally the runway which is closest to being into the wind, consequently, Upwind leg. For takeoff, it is sometimes referred to Departure.
• Crosswind leg is the connection from the upwind leg to the downwind leg. It's length will vary dependant on the preferred pattern altitude and the type of aircraft.
• Downwind leg is parallel to the runway and from 1/2 to 3/4 mile away.
• Base leg is the connection from downwind to final.
• Final is from the base leg to the beginning of the runway. When less than 1/2 mile from the runway, it becomes "short final".

At most airports, the pattern is a Left Traffic pattern, meaning all turns from downwind to base to final are left turns. At some fields, due to development on one side of the field or conflicts with a parallel runway, the pattern may be Right Traffic on specified runways.

Departure from the airport is normally made from the leg most closely oriented in the desired direction of flight. For example, if the runway is 17 and you are going east, you would depart the pattern on the crosswind leg.

The preferred pattern entry is at about midfield on the downwind leg. You approach from the side opposite the runway at about a 45 degree angle to the downwind direction. This allows you to "ease into" the downwind leg while leaving the crosswind and beginning downwind areas visible to you.

TRSA - Terminal Radar Service Area. The area around larger airports where there is some commercial service, but not the traffic that exists around large cities. DFW is Class B airspace, with the restricted area going from the surface to 11,000'. Longview is a TRSA and it's airspace only goes up to 6000'. Below those altitudes, you muast be under radar control. I.e. go where they tell you.

Transponder - An instrument in the "radio stack" which sends out a numeric code, your type designator and altitude when queried by RADAR. All VFR flights use 1200 as a code unless Flight Following or Approach control are being used. The organization controlling the flight will then assign a code so they can recognize your aircraft among the "targets" they are tracking.

The system is "early" digital. The highest digit recognized is 7 (octal base), so 7777 is the highest number available.

There are some codes that are universally recognized: 7700 is aircraft in emergency. 7600 aircraft with non-functioning radios, etc.

--- U ---

Upwind (Leg) - See Traffic Pattern

--- V ---

VFR - Visual Flight Rules. The construct under which I fly. No flying into cloud cover. I may fly "VFR on Top" over a cloud bank, but cannot descend through clouds at the destination. The operative phrases are "own navigation" (meaning I fly where I want to go including any sightseeing detours), and "no separation services provided" (meaning I am responsible to see and avoid other traffic).

VOR - VHF Omnidirectional Range. A radio navigation aid which broadcasts 2 simultaneous signals. One is a fixed carrier and the other is a narrow beam signal broadcast in 1 degree increments. The pilot tunes the receiver to a specific bearing and the receiver compares the signals received with that bearing to determine whether the plane is right or left of the selected radial.

More simply, VOR gives your bearing from the station as opposed to ADF which tells you the bearing to the station. With VOR in a crosswind situation, you can more easily maintain a constant bearing from the station than with ADF. Keeping the needle centered will keep you on that bearing to the station, regardless of the crosswind effects.