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This clearance had been received by the company radio operator from the Atlanta Airway Traffic Control office and was relayed to the pilot. Trip 21 acknowledged receipt of the message. At 11:38 p.m., Trip 21 called the company radio operator at Atlanta and reported "Passing over Stone Mountain, Georgia, ... descending." The EAL radio operator at Atlanta acknowledged receipt of this message and in turn gave Trip 21 a Kollsman altimeter[1] reading of 28.94 and the following weather report: "Ceiling 300 ... visibility one mile, light rain, light fog, ceiling variable from 200 to 500 feet. Trip 19[2] reported it 300."[3] Trip 21 repeated the Kollsman reading and acknowledged receipt of the message. Trip 21 then called the Atlanta airport control tower[4] and transmitted the following message: "EAL Trip 21 to Atlanta Tower - over Stone Mountain 11.37 p.m. making approach.[5] Will give you a call over range station." The Atlanta control tower acknowledged receipt of the message and transmitted the surface wind as "Surface northeast 10." Trip 21 acknowledged receipt of
- ↑ The Civil Air Regulations (sec. 04.532(d)) require that all air carrier aircraft be equipped with two altimeters of the sensitive type. Eastern uses an instrument known as Kollsman. On Eastern aircraft barometric pressure of one altimeter is kept at sea level pressure which allows the pilot to fly at indicated altitudes above sea level. Prior to landing the barometric scale of the other altimeter is set to correspond with a duplicate instrument on the airport which is kept set to show zero elevation. This allows the pilot to land to a zero reading at that particular airport.
- ↑ Trip 19 had landed a few minutes prior to Trip 21's arrival over the Stone Mountain fan marker.
- ↑ Weather minimums prescribed in accordance with the Civil Air Regulations in competency letters issued to Eastern by the Civil Aeronautic Administration authorized weather minimums for landing down through at Candler Field, Atlanta, Georgia, as ceiling 300 feet, one mile visibility, day or night.
- ↑ Airport control towers are erected and maintained by municipalities at various municipal airports for the purpose of regulating the flow of traffic in the vicinity of the airport in order to eliminate the possibility of collision between aircraft. These towers are normally equipped with radio receivers tuned to air carrier company frequencies as well as to frequencies used by military and privately owned aircraft. They usually are also equipped with a transmitter which operates on 278 kilocycles.
- ↑ See sketch of Eastern's instrument approach procedure which is incorporated in the company operations manual.
