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March 1961 Radio-Electronics
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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What a difference a
punctuation mark can make, in this case a hyphen. If this 1961
Radio-Electronics magazine article had been titled "Anti-Plane Collision
Radar" rather than "Anti-Plane-Collision Radar," the theme might seem to address
a radar system biased against airplanes and desiring to promote collisions
amongst them, rather than wanting a radar system designed to prevent collisions. In
making his point, editor Hugo Gernsback uses as an example a recent (at the
time)
1960
mid-air collision between a
Douglas DC-8
(4-engine jet) and a
Lockheed Super
Constellation (4-engine propeller) which
occurred over New York City. Another cited was a
1956
mid-air over the Grand Canyon, which also involved a Super Constellation and
this time a Douglas DC-7 (4-engine propeller).
Airborne collision avoidance systems (ACAS)
have been incorporated into airborne radars for many decades, which act
independently of ground-based collision avoidance systems. Mr. Gernsback's call
(and those of many others) was answered.
... Up-to-Date Aircraft Safety Measures Are Needed Urgently
...
 By Hugo Gernsback, Editor
The tragic airplane disaster of Dec. 16, last, in which 134 persons were killed
as a result of the collision of two airliners over New York, points up anew that
present-day safety measures are fundamentally inadequate, particularly near our
large metropolitan air centers.
More than 175 planes are often in the air together within a radius of 50 miles
over New York City. By 1975, there will be over 350, according to a Federal study
recently made.
Modern jets today fly at the rate of 550 miles an hour when cruising at full
speed. Two jets on a collision course can thus approach each other at rates up to
1,100 miles per hour, or over 3 miles in 10 seconds. Even if the pilots see an oncoming
plane, it is doubtful that they can prevent a full head-on or partial collision.
In a few years, jets now on the drawing boards will fly at 1,300 miles cruising
speed. How will they be handled?
Today, jets approaching our airports must fly at a reduced speed of about 230
miles an hour, and are guided to the proper runway by the technicians of Federal
Aviation Agency. The guiding is customarily by radio-phone from ground to plane.
The tower operator literally talks the plane down. In an overcast and thick weather,
the incoming plane also uses its electronic Instrument Landing System (ILS).
But last Dec. 16, when the two doomed planes were on a collision course and were
fully alerted to their danger by ground personnel, one of the planes was some 11
miles off course and completely "blind" in the thick cloud overcast. Hence, even
if the pilot did take evasive measures, he could not possibly have known whether
he was heading out - or into - the danger course in the thick murk.
The obvious answer to this and similar situations is radar. We have commented
on this over the years since 1951.*
After the 1956 two-plane collision over the Grand Canyon that took 128 lives,
we said editorially, in Our May 1956 issue "Airplane Collision Control":
But a plane flies in a three-dimensional medium. Pilots have only a comparatively
small angle within which to make visual observations. They cannot look behind them,
far sideways or above, or below them at a steep angle in a heavy overcast. Hence
the "visual control" is wholly academic and - under certain adverse weather conditions
- absurd.
We also quote from our 1951 editorial (before the practical advent of the transistor):
"It should be possible in the meanwhile, however, to use a six-way modified -
or sweep - radar installation, which need not weigh too much if miniature tubes
and other miniature components are used. In this case, too, there would be several
miniature screens which pilot or copilot could watch and see if another plane was
approaching from any direction. When finally engineered, such a device will prevent
many collisions. Such radar installations will be particularly advantageous during
night flying and while flying in overcast weather when the visibility is extremely
poor or nil."
What was meant here was two specialized steep angle sweep radars, one on top
of the plane, one in the belly. Using two such radars, the pilots are enabled to
see in six directions at once: east, west, north, south, below and above.
Weight and space requirements, once a serious handicap for commercial airplane
radar, are no longer an insurmountable problem today, thanks to transistors and
microminiaturization.
It is quite inexcusable to postpone the adoption of collision radars any longer
- neither the cost nor technical difficulty can be given as valid reasons for delay.
While radar installation on aircraft may not be a 100% solution and insurance against
all collisions, it will certainly do away with a large proportion of midair crashes.
When we speak of radar, we should also mention the fact that not all radars function
on radio waves. There is, for instance, the infrared or heat radar developed during
the past several years by Aerojet-General Corp. It uses a rapidly rotating mirror
which scans the sky for other planes. The mirror is sensitive to infrared heat rays
from a distant airplane engine. It has an automatic warning instrument in the cockpit
to alert the pilot that he is on a collision course. It also gives the range and
bearing of the oncoming plane. Total weight of the new infrared radar is but 30
lb.
How serious the density of our aircraft in the sky is becoming was pointed out
recently in a study made by scientists at the University of Michigan's Institute
of Science and Technology. One of the scientists, Dr. Gustave Rabson said: "Today
more than 109,000 planes use the same air space and many are flying more than 100
miles per hour. By 1975 we can expect aircraft to more than double their present
air mileage .... We must develop a control system to handle incredibly complicated
situations rapidly and safely."
Just what does this mean for the future? It means to us that, by 1975, there
probably will be over 200,000 aircraft, a goodly percentage flying at more than
1,000 miles per hour. Midair collisions are bound to get worse unless we take heroic
electronic measures on the ground and in the air.
As we see it, radar warnings originating in the plane and from the ground can
only be a temporary makeshift - they cannot prevail for long. Man's perception and
his reactions are hopelessly slow and far too sluggish for the air and space age.
The collision radar in the future must be wholly automatic - it must steer the
plane out of its collision course without benefit of pilot. A warning bell or signal
will sound, notifying the pilot that the plane is now under radar control. Likewise,
large airliners will no longer be "talked down" by the tower during overcasts or
at night. The tower operator - not the pilot - will have total electronic control
over the plane during its airport approach and its touchdown. The operation will
be watched by a bank of special TV cameras near the runway, via closed-circuit automated
television receivers in the tower. The rest of the routine landing operation will
be by the pilot. - H.G.
*"Needed Electronic Inventions," Radio-Electronics, May 1951.
Posted June 26, 2023
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