In your first circuit of the towered airport's traffic pattern, you were cleared to make left closed traffic, and the controller instructed you to “start your crosswind turn when able.” As you were climbing again following your touch and go, you heard the controller clear the aircraft holding short of the runway for “an immediate takeoff,” and to “fly runway heading.”
That series of instructions issued to you and the departing aircraft was not composed of random words or phrases. Depending on the traffic situation being managed, and any potential conflict that could arise, the instructions air traffic control issues to pilots convey very specific expectations—and pilots are expected to know what they are.
How does a pilot know what’s expected? For starters, the Aeronautical Information Manual (AIM) sets forth radio communications phraseology and techniques, and also defines pilot and controller roles and responsibilities. But to glean the intent of specific words or instructions, consult the Pilot Controller Glossary. It is found near the end of the AIM.
Suppose during your session working the pattern you hear the pilot of an arriving aircraft inform ATC of a "minimum fuel" condition. How does that pilot expect the controller to respond? Is the pilot declaring an emergency?
The Pilot/Controller Glossary explains that the term minimum fuel "indicates that an aircraft’s fuel supply has reached a state where, upon reaching the destination, it can accept little or no delay. This is not an emergency situation but merely indicates an emergency situation is possible should any undue delay occur."
The Pilot/Controller Glossary clarifies the difference between the two terms you heard as you made your crosswind turns after your first and second takeoffs. The instruction to turn crosswind "when able" gave you latitude "to delay compliance until a condition or event"—such as reaching a reasonable altitude—has been resolved.
ATC’s use of "immediate" in the takeoff clearance issued to the waiting aircraft was required, the glossary explains, "to avoid an imminent situation"—perhaps the need to cancel the takeoff clearance because of an aircraft on approach to land.
The definitions and examples provided in the Pilot/Controller Glossary are often cited as references in discussions of procedures and interpretations of rules. Test your knowledge of terms and phrases with this Air Safety Institute safety quiz.