An Assessment Of Steve MacKenzie's Account Of the Radar Tracking Of An
Unidentified Object Over Southern New Mexico During Early July, 1947

By C.B. Moore

(Please Note: C.B. Moore's comments in parentheses.)

The Account

On page 5 of the book The Truth About The UFO Crash At Roswell, by Kevin D. Randle and Donald R. Schmitt, the authors give an anecdotal report by a person named Steve MacKenzie who apparently was a member of the Army Air Forces, stationed at Roswell Army Air Field and assigned to the Eighth Air Force in early July, 1947.   In this report, MacKenzie is described as being ordered by Brig. Gen. Martin Scanlon of the Air Defense Command on July 2, 1947 to go to the "radar sites" at White Sands Proving Ground (WSPG) and to monitor the movements of an unidentified flying object, reporting them directly to the general. According to this account, after his arrival at the WSPG radar,

"MacKenzie could not leave the radar room unattended... he set up a system of mirrors so that he could see a warning light even when he had to use the latrine". "... When it (the object) first appeared, radar operators at White Sands had considered the possibility of a malfunction but a check with a second set, as well as coordination with other sites, including those at Roswell and in Albuquerque, established that the target was real and solid ."(??)

"MacKenzie stayed at his post for twenty-four hours straight, but nothing changed (??). The object appeared periodically over southern New Mexico, but usually just 'flitting from one location to another' (even though nothing changed?)" ... "A radar operator stationed at Roswell has confirmed the radar tracks on previous days in early July. On a flight to Albuquerque, they (who are they?) saw a number of disks. When they reported them to the radar facility at Kirtland AAF, they were told they (??) had been tracking disks over New Mexico for several days."

During the next day, MacKenzie returned to Roswell where he continued to monitor the object with the radar there.   Then, on July 4,

"That evening, the situation changed radically. The object, as displayed on the radar, seemed to pulsate, the blip growing larger and brightening before shrinking to its original size and dimming.  This activity kept up for a short time and then the object (more likely, the blip) blossomed into a sunburst and disappeared from the screen at about 11:20 p.m. Because there were three sites tracking the object, the army technicians were able to plot, within vague parameters, the location of the crash or landing."

Although the authors said that "the radar coverage in that section of New Mexico was not as complete as the military would have liked" because of the mountains, "... the army, based on what it had learned while tracking the object at Roswell, knew that the object was down north of town. They just didn't have a precise location."

Assessment of MacKenzie's Account

There are many problems and inconsistencies with this account having to do with the radars available at the time and with how they functioned.  To begin, it is worth considering some official correspondence concerning the disposition of tracking radars in New Mexico during this period.

On June 3, 1947, Headquarters, Eighth Air Force sent a request to the Commanding Officer, White Sands Proving Ground for operation of ground radar equipment for radar countermeasures training.

The first two paragraphs of the request stated:

"1.   The Eighth Air Force is conducting a Radar Countermeasures program as part of its training and is desirous of the cooperation of units which use ground radar equipment in permitting training flights to be scheduled with aircraft equipped with electronic jammers and window" to operate against various types of ground radar sets so that the results and effectiveness of the jamming and training might be observed and made known.

2.   There is a lack of ground radar equipment convenient to Eighth Air Force Bases which are located at Fort Worth, Texas, Tucson, Arizona, and Roswell, New Mexico; and since White Sands is within easy flying distance of all three bases, your cooperation is particularly desirable."

Lt. Col. Harold R. Turner, the Commanding Officer at WSPG, sent this request to the Office of the Chief of Ordnance in Washington with the statement:

"3. The radar equipment currently in use at White Sands Proving Ground is under the control of the Signal Corps Engineering Laboratories of the Office of the Chief Signal Officer.   This equipment is modified SCR-584 designed to operated the AN/APN-55 beacon used in obtaining ballistic information from the missiles fired at this station.   This equipment being of an experimental nature obviously is undergoing modification and extensive testing procedures when not actually in use for a firing.   It would, therefore, preclude any possible use by other agencies for procedures set out in subject request from headquarters Eighth Air Force."

As a result, a letter denying the support of the WSPG radar was sent from the Office of the Chief of Ordnance to the Commanding General, Army Air Forces who, on July 10, 1947, sent a first indorsement to the Commanding General, Air Materiel Command, in Dayton, OH, directing him to have the Commanding Officer, Alamogordo Army Air Base, take care of the needs of the Eighth Air Force on a basis of minimum interference to the guided missile program.

Two major items of information relative to the MacKenzie account are given in this correspondence:

1.   Ground radar equipment capable of tracking aircraft and other aerial objects did not exist at Roswell Army Air Field in June, 1947. The account of tracking the "object" by radar from Roswell on July 4, 1947 is therefore unlikely and probably untrue.

2.   The aircraft tracking radar installed at WSPG was a SCR-584. Its technical characteristics are listed in Table 1.

This equipment was the most successful tracking radar available at the time and it was relatively new;   the manuals on it were published in April, 1946 more than six months after the end of World War II.   The radar was designed, during the war, to locate enemy aircraft and to provide an antiaircraft director with data on the slant range, azimuth and elevation angles to an aircraft.   The SCR-584's maximum range in the search mode was 70,000 yards (39.7 statute miles) and it could track targets, either automatically or manually) if the range to the target was less than 32,000 yards (18.2 miles).

Since the location of the launch pad relative to the radar was known and since the launch time was always specified in advance, a search capability was not required at the Proving Ground; the SCR-584 was dedicated to tracking the V-2s and other rockets being launched at WSPG.

It was never necessary for the operators of a SCR-584 to depend on another radar for help in determining the position of a target because the WSMR radar provided all of the three-dimensional information necessary to locate the target as long as it was within range.   However, since the SCR-584's maximum range was less than 40 miles, it could provide no information whatsoever on objects outside that range.  There was no way that the information from it would be used in conjunction with radars in Albuquerque (if there were any at the 160 mile range) to plot the location of the crash north of Roswell, about 130 miles from the White Sands radar.

MacKenzie's scenario for use of multiple radars to locate an object is ridiculous;  it is not required that the azimuth from one radar be used with that of another radar for the trigonometric location of an object.  The key feature of a radar is that it provides range information on the target; the word "radar" is derived from the phrase "radio detection and ranging".  If one has radar data on a crashing object, the location of the place the object disappeared can immediately be determined from the last azimuth and the slant range from the radar so that a fix is possible from a single radar.   MacKenzie's statement - that the army used three radars "to plot, within vague parameters, the location of the crash" - is ludicrous and further, it is wrong because, according to Headquarters, Eighth Air Force, there was no ground radar equipment at Roswell.

The SCR-584 at WSPG was not in a room; it was built into a trailer from which it was operated during 1947.

The SCR-584 had no "moving target indication" capability and was not equipped with warning lights to indicate the detection of a target.

MacKenzie seems to have confused the video screens of later years with the radar indicator.  On a PPI scope (the Plan-Position Indicator), an echo may become more or less intense than it was on the last scan, about twelve seconds earlier, but one would not see a "sunburst".  The SCR-584 was not equipped with an "A" scope (which displayed a plot of signal intensity versus range) and a "sunburst" would not have been shown on the J scope even if the radar were in the track mode.


The MacKenzie anecdote, in the Randle-Schmitt book, provides an attention-getting opening to the story but... it is clearly incredible.   The "facts" are wrong and the narrator appears not even to have known how a radar works.   He certainly knew nothing about the characteristics of the radar that was in use at White Sands Proving Ground in 1947.

C. B. Moore
September 16, 1995


The Roswell Page
1947 Documents
Return to MAIN PAGE