ZAA

Eastern Air Transport's energetic publicity department last week made copy of the letters "ZAA." The letters are a radio signal, not new but not previously publicized. Flashed by an E. A. T. copilot to his ground station it means the opposite of SOS: "m at proper position, flying on schedule, nothing to report."

Aircraft radio is slowly producing a lexicon of abbreviations which some day may be as familiar as nautical signals. The U. S. public hears little about them because all domestic transport lines, Eastern Air excepted, use radiophone (voice) transmission. E. A. T. planes are equipped with radiophone for short distances, the more penetrating dot-dash radio telegraph for long range. Pan American Airways, whose ground stations are far spaced through tropical latitudes where static is frequently bad, uses code telegraph exclusively. Phone-users may, if reception is poor, whistle their messages in dots & dashes.

All radio telegraph-equipped airlines use the International Morse Code, with special aeronautical signals, among them: QAA--When do you expect to arrive? QAE--Have you news of (certain air-craft)? QAJ--Must I look for another aircraft in my neighborhood? QAL--I shall land at -- QAO--Give me latest information concerning upper wind.

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