Friday, April 15, 2011

Radio Communications in Aviation

Talking on the radio for the first time is intimidating for the new pilot. Understanding some basic rules, formats and conventions helps and with a little experience under your belt radio communications become second nature. Here are some pointers meant for the beginner and the experienced GA pilot.

First, understand that the full, generic format of all initial calls or what is often referred to as initial contact. What does "initial contact" mean?. It's your first call to a controller or the first call to the next controller in flight following (or an IFR flight). Listening to an ATIS at a towered airport you will hear: "...upon initial contact advise you have Tango...".  So when you first contact either ground or tower, let them know you have "Tango".

Initial contact calls have the format:
  1. Who are you
  2. Who am I
  3. Where am I
  4. WaddaIwant
Ok, one at a time. Here is an example of an initial call:
  1. This is who are you addressing. This ensures you are talking to the correct person. How many times have you said "ground, this is N12345" and been on the tower frequency! Because of the message format where you address who you think you are talking to, the mistake is corrected quickly and tower tells you to contact ground on another frequency. The pilot clearly announces to whom he thinks he is talking
  2. The next phrase tells the controller who you are and often starts with the optional "This is...". So using our above example: "Santa Monica Tower, this is Cessna 12345". I like using the optional "this is" because it sets the controller's expectation as to what information follows.
  3. Where am I tells the controller where you are located. If this initial call were made in flight it would also include altitude. E.g., "I am over the SADDE intersection at five thousand, five hundred. This helps the controller identify you on a radar screen and is a sanity check for you because the controller will verify your position and your altitude in case you are not where you think you are or your aircraft's Mode-C transponder or altimeter is lying.
  4. What do I want is easy, but often has to include other information to get what you want. For example: "...I have information Tango and I would like a right shoreline departure".
Ok let's try the whole enchilada using this format:
"Santa Monica ground, this is Cessna 12345. I am at transient parking with information Tango and I would like a right shoreline departure."

Once the controller comes back with "Cessna 12345 this is Santa Monica ground, taxi to runway XX", you know that the connection is good: you are communicating with the ground controller (not someone else). This sounds kind of dumb, but it prevents errors when talking to controllers. Never use your partial tail numbers in an initial contact! It's easy to imagine the confusion that might occur if there were also a Cessna 67345  in the area! If a controller recites an incorrect tail number, now is the time to make corrections.

Often I get question from pilots of the form "the controller said ABC, what did he mean by this?" My answer is see if it is in the Pilot Controller glossary at http://www.faa.gov/air_traffic/publications/ and click on the link "Pilot/Controller Glossary". The PCG creates a concise understanding between the the pilot and the controller. I think of these phrases as handles on a larger, precise meaning. For example, when a controller says "Cessna 12345, you are cleared for the option", the phrase "cleared for the option" has a precise meaning given in the PCG. If the PCG does not show a phrase used by a controller, ask a CFI for advice or talk to someone at a FSDO or phone the tower supervisor. If nonstandard phrases are used by controllers, it may be they are making a mistake or you are dealing with local conventions. Anytime you feel a communication is ambiguous while in flight, get it out in the open immediately with the phrase "unfamiliar with XYZ" where XYZ is whatever phrase the controller used or whatever the controller told you to do. Study up on phrases published in the PCG that you are likely to encounter so you do not have to use "unfamiliar" any more than necessary, especially to a common phrase. My favorite example of a non-published phrase is when approaching a towered airport and ATC says "make a 3 mile right base". I have three definitions of this phrase from different controllers and it is not in the PCG. So, I respond with "unfamiliar with a 3 mile right base" to get expectations out in the open.

A pleasant "I am new to this area and I am unfamiliar with Highway 205" or "I am unfamiliar with a 3 mile right base" will strike a friendly tone and buy you help from the controller. Unfortunately "unfamiliar" is not part of the PCG, but is should be right next to "unable" which is in the glossary. Too often I have seen pilots new to an area not ask for help and end up blundering their way into sharp retorts from the tower. Knowing "unfamiliar" and using it politely will save you a lot of grief. By informal convention, controllers know and respect this phrase.

For those of you whom English isn't your first tongue understand that the set of phrases you are going to hear is limited and if you study these phrases in the PCG and work to listen for them in flight you will eventually understand when you hear them. If you refer to the PCG frequently and understand the format of aviation communications learning to communicate will not be as difficult.

For all pilots, it is important to anticipate. That is, what is the controller likely to say next? This helps speed the learning process. Anticipation promotes safety. Recognize that radio communications start with a pilot calling a controller or a controller calling a pilot. Once the dialog has ended this is when you need to open your ears to catch the next thing you hear on the radio. If it is a controller, the next thing spoken will be a tail number. If the tail number is not yours you can relax. If a pilot initiates a communication, then s/he should start with the name of the control facility (e.g. "SoCal approach", ....). Even a controller initiation starts with a tail number that is not yours, it is good to pay especially when it is a traffic alert to another aircraft of the form: "You have traffic at your 11 o'clock, 4 miles, 4 thousand 500 feet, a Cessna heading west bound) and you happen to be in a Cessna at 4500' and heading west bound because the odds are high that the controller is pointing you out to another pilot. Often the next call is to alert you to the previously called traffic. Ditto in pattern work when the controller tells another aircraft they are behind you in pattern, etc.

I recommend beginners purchase a good active noise reduction (ANR) head set. Noise creates stress which leads to fatigue. The drone of a loud engine isn't conducive to learning. In addition, the ancillary stress of having to ask a controller "what did you say - repeat that" is a waste of time. It's penny wise and dollar foolish not to purchase an ANR headset. You do not need the most expensive, most will do. Ask around early in your training. Also, a good ANR set will have 2 microphones on the mike boom. One is used to analyze background noise and this data is used by a processor to subtract it external sounds which means the controller hears you better. An ANR set will speed up learning and is worth the money.

Make sure you understand that some of phrases you have heard in the movies or on TV were used incorrectly. For example, do you really know the meaning of "roger"? It's in the PCG. It means: "I have received all of your last transmission". I cringe when a pilot is asked a question requiring a yes or no answer and his reply is "roger". "Cessna 12345 do plan to turn left at the freeway?" and the pilot answers "roger"...arghhhh! The pilot was asked for a yes or no answer (affirmative or negative) and instead responds with "I have received all of your last transmission". Pretty stupid reply don't you think? Read the PCG. Your life depends on it and mine does too.


Monday, January 31, 2011

More on Landings - deck angle of the tricycle rigged aircraft during landing

A problem I commonly see in landings is that a pilot pulls on the yoke often reaching a proper landing deck angle soon after the round out. Ok so far, but the next segment of the landing is where things go haywire: the pilot does not maintain this deck angle before the wheels touch and this is a mistake.

What is deck angle? I use it here as slang for the angle of the longitudinal axis of the aircraft from the landing surface, which usually means a runway surface.

To illustrate, assume that the XYZ make and model needs to be landed with a deck angle of 7.5 degrees. Right after the round out, the pilot flares to 7.5 degrees and then freezes - no more pulling on the yoke. What happens to the deck angle? Why? Answers: the deck angle decreases because the effectiveness of the elevator in maintaining pitch decays as the airspeed decays so the nose keeps dropping until a flat landing occurs - simple aerodynamics. In other words, to maintain proper deck angle, the pilot must keep pulling to increase elevator deflection to obtain a constant angle. Instead of a constant landing deck angle, this angle constantly decreases until the wheels touch. This means a poor transfer of weight from wing lift to wheels and it also means a lot more ground speed when the wheels touch. The former is hard on the airframe and the later   unncessarily increases tire wear.

Knowing deck angle in degrees is asking a lot out of most GA pilots and who wants to watch an AI during a landing - not me! There are indices that often work well in the cockpit. For example, for many trainers (not all!), proper deck angle can be acquired by flaring until the front end of the engine cowling is high, but no so high that the runway center line is covered by the cowling. For these aircraft, this means that the nose is really high, but the pilot can always see some center line markings off the very end of the cowling - not a lot, just some. It's my experience this is true for the following aircraft and perhaps more: The C152, PA28-161 & 181, C172(N,S), C182 (all models I have flown). 

Many pilots who do not maintain a proper deck angle are often uncomfortable with a proper landing because they feel the pitch is way to high and looking out at a lot of engine cowling frightens them. Remember - center line is always in sight. I suppose you could verify that you will not have a tail strike if you were to jack up the nose wheel to obtain this deck angle, step outside and verify that the tail is indeed a fair distance from a strike.

Some pilots feel uncomfortable because they feel they do not have the visual references needed for lateral control. This is normally not an issue as long as the center line is in sight over the engine cowling.

The proper amount of deck angle ensures you are reaching and holding the highest possible angle of attack into the touchdown without doing a tail strike. This is important because it tends to minimize runway length requirements for the landing and it is nice to the aircraft because you are milking as much lift out of a very slow aircraft for as long as you can which means nice gentle wheel contact at the lowest possible speed. The proper amount of deck angle is part of what leads to the "greased" landing. A greased landing is nothing more than a landing where the pilot has kept as much lift as possible on the wings until the moment of touch down leading to a smoother transfer of aircraft weight from the wings onto the mains.

Another common problem in landings is concrete legs during cross wind landings. I will save this topic for another time. Meantime, get out there and work on keeping proper deck angle while landing when there is no wind or the wind is down the runway. Be safe and be nice to your airplane - even if you are a renter.