Dan Wilson wrote:
The radar site reported this was
a weather balloon launched from Idlewild Airport at about 6:00 p.m., or
79 minutes before the radar-only (no visual) sighting began at 7:19,
when it was tracked at 68,000 ft. Standard meteorological
balloons rise at about 1,000 ft per minute so it is almost an exact
match, or actually an exact match if the round-number launch time of
6:00 was really say 6:11 (my understanding is that target times to
launch met balloons can be off by up to 1/2 hour or even more -- Jan is
the expert on met balloons he can tell you).
During the 10 minutes of the radar tracking the object rose 10,200 ft
or almost exactly the balloon rise rate of 1,000 ft/min (it's 1,020
ft/min, near perfect match). Its horizontal velocity was only 3
miles in 10 minutes or 18 mph, typical wind velocity.
Somethings just do not fit an IFO
evaluation on this case.
No where was there any 18 mph winds.
The winds in this area were given as
5000 feet 29 knots
10,000 feet 33 knots
16,000 feet 47 knots
20,000 feet 43 knots
30,000 feet 61 knots
50,000 feet 59 knots
80,000 feet 28 knots
And was there an IFF signal detected from
The observation was on FPS-20, FPS-6 radars and IFF: UPX-6
The UPX-6 was a function of the
radar itself which received and then enhanced IFF codes being
picked up by the radar. It had three or four frequencies itself
(present day transponders have 7,700 separate codes). The UPX-6
acted pretty much the same way as the raw skin returns work today with
the target blip being brighter and identifiable once the radar set
queried it. When the radar beam struck an aircraft with IFF the usual
signal would (and still does) bloom brighter on the scope. That
way it could be identified as a friendly.
See the following:
Radar Recognition Set
The AN/URX-6 is a receiver transmitter designed to operate with other
IFF (Identification Friend or Foe) or SIF (Selective Identification
Features) equipment as part of an aircraft identification system for an
associated radar set. The Primary function of the equipment is to
transmit and receive coded signals between radar identification
equipment and target aircraft within the range of the IFF/ SIF system.
The receiver and transmitter are tuned by changing operating crystals
and by manual screwdriver adjustments adjacent to these crystals. The
transmitter is factory aligned for 1020 MHz operation,
although its overall tuning range is 990 MHz to 1040 Hz. The receiver
is similarly factory aligned (at 1100 MHz), and may be tuned for any
frequency between 1080 MHz and 1130 MHz. The AN/UPX-6 is compatible
with the following Coder-Decoder Groups: OA-1266, OA-1267, OA-1268,
OA-1269, OA-1271, OP-1272, 0A-2397, OA-2605, AN/GPA-78 or AN/SPA-64.
6 has one tunable channel each for transmission and reception of coded
signals in the IFF/SIF system.
Transmitter - 990-1040 mc
Receiver - 1080-1130 mc
1.5 kW Peak
Voltages and Power Requirements:
105, 117 or 125v ac, 60 or 100
cps, single ph, 250 w
PPI and B indicators of associated radar set
180 to 120 pps (adjusted to conform with pulse repetition
rate of associated radar)
Broad - 8 to 11 mc - 60 db
Narrow - 5 mc - 70 db
Radio Receptor, Inc. (TM 11-487C-1)
analysis seems on the money to me.
to Brad's rough 18mph speed example in comparison with the winds aloft
shown in the report. In fact the horizontal target speed, allowing for
the 3 mile range increment and a 4 degree azimuth change is
closer to about 25 mph or 22 knots during the rise from 68k to 78kft.
Wind at 80k was 28 knots. Nothing is known about the winds below that
until you get down to 50k, so it's quite possible that it averaged 22
knots through the 10k of the observation.
mind that the target coordinates are approximations based on
estimating the centroid of a fuzzy arc on the tube phosophor that
is itself 1/8" wide and also has some depth on the range axis equal to
at least half the pulse length (corresponding to errors in the order
of +/- 1000s and 100s of ft respectively), and then
measuring this position off the scope by eye, then I don't
think the match is bad at all.
thing you can say is that the target heading - from 282 deg @ 40mi to
286 deg @ 43mi - would be roughly NNW, whereas winds at all recorded
heights (230-240 deg) would have taken a balloon NE. But it's a
small hook on which to hang hopes of an exotic unknown. Maybe the wind
direction fluctuated between the data points?
As for the
IFF business, although the UPX-6 is included under "observation by" I
suggest this is only because it was listed as a standard component of
the radar set-up. If there had been an IFF transponder code it would
surely have been explicitly mentioned in the sighting description. The
report only describes a "pip" from a skin return on the surveillance
radar. And I can't imagine that if there was an IFF code
mentioned the compiler of the report would have said there was an
"excellent possibility" that it was the Idlewild weather balloon.
nobody saw anything visually at all. There isn't much here to get