The night of the F-16's ▶ Belgium flap ▶ Home ☰

The Belgium flap:

March 31, 1990, the night of the F-16 - one of the F-16 airborne radar records:

Intro

1. How to read data on the Head Up Display (HUD) video frames.
2. The video frames from the HUD video recording.
3. Data set from the HUD video frames.
4. UFO altitude changes versus time.
5. .
6. .

1. How to read data on the Head Up Display (HUD) video frames:

(1)	The radar range. Here it is set to 10 nautical miles. 10 nautical miles in an intercept is when things get serious.
(2)	The radar mode. Here it is set to "Air-to-Air" mode; this AN/APG66(V1) radar has 6 different operation modes. The Air-to-Air mode is designed to eliminate any echo below an altitude of 200 meters above the ground, to filter for example ground clutter.
(3)	The altitude of the target. Here, "05" means 5.000 feet.
(4)	The most recently detected targets are indicated by squares. When locked, the target is indicated by this rhombus symbol seen here. To "lock" a target, the pilot chooses a target picked up by the radar, drags the cursor (the two parallel lines above the "W" here) on its most recent "square" and presses a button. The radar then explicitly shows the target with this symbol and the radar computer displays information about this target.
(5)	Data about the locked-on target are indicated: its heading (270° here), its speed in Knots (780 Knots here, the Knot is a unit of speed, equal to one nautical mile per hour), its relative angular horizontal position to the aircraft (60° at the right of the aircraft here).
(6)	The W symbolizes the aircraft, it shows its pitch in relation to the horizon. Here it shows that the F-16 is turning to the right.
(7)	This line represents the horizon of the Earth. (6) and (7) indicate here that the aircraft maneuvering to close in on the target (the UFO) at its right. The pilot needs to turn at a particular angle for the target not to keep drifting farther away, but he must also keep it away from collision course.
(8)	The heading of the F-16.
(9)	The target's radial closing speed in knots, positive when the F-16 is closing to the target.

2. The video frames from the HUD video recording:

The sequence underneath lasts 7 seconds. I split the video in a high number of frames, 119 frames, so that every event can be seen and commented. This means that the time between two frames is less that 0.0588 seconds less than 1/100th of a second.

Frame #1: UFO altitude: 10.000 ft UFO speed: 570 K		The radar eliminates all that is not moving and when it detects a mobile target, it paints a square there on the HUD. The squares slowly fade, the most recent is the most shining. The little squares here are the latest positions of the target; it shows that it was painted at least 6 times already when this recording portion starts. The pilot "locks on" by choosing the most shining by moving a cursor onto it using a joystick and pressing a button when chosen. Here the target was already detected and locked on.
Frame #2: UFO altitude: 10.000 ft UFO speed: 570 K		You will see the squares slowly fading off one after the other in the next displays.
Frame #3: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #4: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #5: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #6: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #7: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #8: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #9: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #10: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #11: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #12: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #13: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #14: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #15: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #16: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #17: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #18: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #19: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #20: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #21: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #22: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #23: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #24: UFO altitude: 10.000 ft UFO speed: 570 K
Frame #25: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #26: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #27: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #28: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #29: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #30: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #31: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #32: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #33: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #34: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #35: UFO altitude: 7.000 ft UFO speed: 770 K
Frame #36: UFO altitude: 6.000 ft UFO speed: 770 K
Frame #37: UFO altitude: 6.000 ft UFO speed: 770 K
Frame #38: UFO altitude: 6.000 ft UFO speed: 770 K
Frame #39: UFO altitude: 6.000 ft UFO speed: 770 K
Frame #40: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #41: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #42: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #43: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #44: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #45: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #46: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #47: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #48: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #49: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #50: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #51: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #52: UFO altitude: 5.000 ft UFO speed: 780 K
Frame #53: UFO altitude: 5.000 ft UFO speed: 780 K
Frame #54: UFO altitude: 5.000 ft UFO speed: 780 K
Frame #55: UFO altitude: 5.000 ft UFO speed: 780 K
Frame #56: UFO altitude: 5.000 ft UFO speed: 780 K
Frame #57: UFO altitude: 5.000 ft UFO speed: 780 K
Frame #58: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #59: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #60: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #61: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #62: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #63: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #64: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #65: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #66: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #67: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #68: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #69: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #70: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #71: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #72: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #73: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #74: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #75: UFO altitude: 5.000 ft UFO speed: 790 K
Frame #76: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #77: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #78: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #79: UFO altitude: 6.000 ft UFO speed: 780 K
Frame #80: UFO altitude: 4.000?? ft UFO speed: ? K		Target is lost.
Frame #81: UFO altitude: 4.000?? ft UFO speed: ? K		Target is lost.
Frame #82: UFO altitude: 4.000?? ft UFO speed: ? K		Target is lost.
Frame #83: UFO altitude: 4.000?? ft UFO speed: ? K		Target is lost.
Frame #84: UFO altitude: 4.000?? ft UFO speed: ? K		Target is lost.
Frame #85: UFO altitude: 4.000? ft UFO speed: ? K		Target is locked on again.
Frame #86: UFO altitude: 4.000? ft UFO speed: ? K
Frame #87: UFO altitude: 4.000? ft UFO speed: ? K
Frame #88: UFO altitude: 4.000? ft UFO speed: ? K
Frame #89: UFO altitude: 4.000? ft UFO speed: ? K
Frame #90: UFO altitude: 4.000? ft UFO speed: ? K
Frame #91: UFO altitude: 3.000? ft UFO speed: ? K		Altitude is computed.
Frame #92: UFO altitude: 3.000? ft UFO speed: ? K
Frame #93: UFO altitude: 3.000? ft UFO speed: ? K
Frame #94: UFO altitude: 3.000? ft UFO speed: ? K
Frame #95: UFO altitude: 3.000? ft UFO speed: ? K
Frame #96: UFO altitude: 3.000? ft UFO speed: ? K
Frame #97: UFO altitude: 3.000? ft UFO speed: ? K
Frame #98: UFO altitude: 3.000? ft UFO speed: ? K
Frame #99: UFO altitude: 3.000? ft UFO speed: ? K
Frame #100: UFO altitude: 3.000? ft UFO speed: ? K
Frame #101: UFO altitude: 3.000? ft UFO speed: ? K
Frame #102: UFO altitude: 3.000 ft UFO speed: 990 K
Frame #103: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #104: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #105: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #106: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #107: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #108: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #109: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #110: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #111: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #112: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #113: UFO altitude: 2.000 ft UFO speed: 990 K
Frame #114: UFO altitude: 1.000 ft UFO speed: 990 K		Altitude is computed.
Frame #115: UFO altitude: 1.000 ft UFO speed: 990 K
Frame #116: UFO altitude: 1.000 ft UFO speed: 990 K
Frame #117: UFO altitude: 1.000 ft UFO speed: 990 K
Frame #118: UFO altitude: 1.000 ft UFO speed: 990 K
Frame #119: UFO altitude: 1.000 ft UFO speed: 990 K

Data set from the HUD video frames:

Frame #:	Time:	UFO altitude:		UFO speed:		UFO position:	UFO heading:	F-16 position:	F-16 heading:	Event:
Frame #:	Time:	Feet	Meters	Knots	Km/h	UFO position:	UFO heading:	F-16 position:	F-16 heading:	Event:
1	0.0000	10.000	3048	570	1056	°	° right	°	° right
2	0.0588	10.000	3048	570	1056	°	° right	°	° right
3	0.1176	10.000	3048	570	1056	°	° right	°	° right
4	0.1765	10.000	3048	570	1056	°	° right	°	° right
5	0.2353	10.000	3048	570	1056	°	° right	°	° right
6	0.2941	10.000	3048	570	1056	°	° right	°	° right
7	0.3529	10.000	3048	570	1056	°	° right	°	° right
8	0.4118	10.000	3048	570	1056	°	° right	°	° right
9	0.4706	10.000	3048	570	1056	°	° right	°	° right
10	0.5294	10.000	3048	570	1056	°	° right	°	° right
11	0.5882	10.000	3048	570	1056	°	° right	°	° right
12	0.6471	10.000	3048	570	1056	°	° right	°	° right
13	0.7059	10.000	3048	570	1056	°	° right	°	° right
14	0.7647	10.000	3048	570	1056	°	° right	°	° right
15	0.8235	10.000	3048	570	1056	°	° right	°	° right
16	0.8824	10.000	3048	570	1056	°	° right	°	° right
17	0.9412	10.000	3048	570	1056	°	° right	°	° right
18	1.0000	10.000	3048	570	1056	°	° right	°	° right
19	1.0588	10.000	3048	570	1056	°	° right	°	° right
20	1.1176	10.000	3048	570	1056	°	° right	°	° right
21	1.1765	10.000	3048	570	1056	°	° right	°	° right
22	1.2353	10.000	3048	570	1056	°	° right	°	° right
23	1.2941	10.000	3048	570	1056	°	° right	°	° right
24	1.3529	10.000	3048	570	1056	°	° right	°	° right
25	1.4118	7.000	2134	770	1426	°	° right	°	° right	Altitude is computed, speed is computed.
26	1.4706	7.000	2134	770	1426	°	° right	°	° right
27	1.5294	7.000	2134	770	1426	°	° right	°	° right
28	1.5882	7.000	2134	770	1426	°	° right	°	° right
29	1.6471	7.000	2134	770	1426	°	° right	°	° right
30	1.7059	7.000	2134	770	1426	°	° right	°	° right
31	1.7647	7.000	2134	770	1426	°	° right	°	° right
32	1.8235	7.000	2134	770	1426	°	° right	°	° right
33	1.8824	7.000	2134	770	1426	°	° right	°	° right
34	1.9412	7.000	2134	770	1426	°	° right	°	° right
35	2.0000	7.000	2134	770	1426	°	° right	°	° right
36	2.0588	6.000	1829	770	1426	°	° right	°	° right	Altitude is computed.
37	2.1176	6.000	1829	770	1426	°	° right	°	° right
38	2.1765	6.000	1829	770	1426	°	° right	°	° right
39	2.2353	6.000	1829	770	1426	°	° right	°	° right
40	2.2941	6.000	1829	780	1445	°	° right	°	° right	Speed is computed.
41	2.3529	6.000	1829	780	1445	°	° right	°	° right
42	2.4118	6.000	1829	780	1445	°	° right	°	° right
43	2.4706	6.000	1829	780	1445	°	° right	°	° right
44	2.5294	6.000	1829	780	1445	°	° right	°	° right
45	2.5882	6.000	1829	780	1445	°	° right	°	° right
46	2.6471	6.000	1829	780	1445	°	° right	°	° right
47	2.7059	6.000	1829	780	1445	°	° right	°	° right
48	2.7647	6.000	1829	780	1445	°	° right	°	° right
49	2.8235	6.000	1829	780	1445	°	° right	°	° right
50	2.8824	6.000	1829	780	1445	°	° right	°	° right
51	2.9412	6.000	1829	780	1445	°	° right	°	° right
52	3.0000	5.000	1524	780	1445	°	° right	°	° right	Altitude is computed.
53	3.0588	5.000	1524	780	1445	°	° right	°	° right
54	3.1176	5.000	1524	780	1445	°	° right	°	° right
55	3.1765	5.000	1524	780	1445	°	° right	°	° right
56	3.2353	5.000	1524	780	1445	°	° right	°	° right
57	3.2941	5.000	1524	780	1445	°	° right	°	° right
58	3.3529	5.000	1524	790	1463	°	° right	°	° right	Speed is computed.
59	3.4118	5.000	1524	790	1463	°	° right	°	° right
60	3.4706	5.000	1524	790	1463	°	° right	°	° right
61	3.5294	5.000	1524	790	1463	°	° right	°	° right
62	3.5882	5.000	1524	790	1463	°	° right	°	° right
63	3.6471	5.000	1524	790	1463	°	° right	°	° right
64	3.7059	5.000	1524	790	1463	°	° right	°	° right
65	3.7647	5.000	1524	790	1463	°	° right	°	° right
66	3.8235	5.000	1524	790	1463	°	° right	°	° right
67	3.8824	5.000	1524	790	1463	°	° right	°	° right
68	3.9412	5.000	1524	790	1463	°	° right	°	° right
69	4.000	5.000	1524	790	1463	°	° right	°	° right
70	4.0588	5.000	1524	790	1463	°	° right	°	° right
71	4.1176	5.000	1524	790	1463	°	° right	°	° right
72	4.1765	5.000	1524	790	1463	°	° right	°	° right
73	4.2353	5.000	1524	790	1463	°	° right	°	° right
74	4.2941	5.000	1524	790	1463	°	° right	°	° right
75	4.3529	5.000	1524	790	1463	°	° right	°	° right
76	4.4118	6.000	1829	780	1445	°	° right	°	° right	Altitude is computed, speed is computed.
77	4.4706	6.000	1829	780	1445	°	° right	°	° right
78	4.5294	6.000	1829	780	1445	°	° right	°	° right
79	4.5882	6.000	1829	780	1445	°	° right	°	° right
80	4.6471	(4.000)	(1219)	N/A	N/A	°	° right	°	° right	Target lock is lost.
81	4.7059	(4.000)	(1219)	N/A	N/A	°	° right	°	° right	Target lock is lost.
82	4.7647	(4.000)	(1219)	N/A	N/A	°	° right	°	° right	Target lock is lost.
83	4.8235	(4.000)	(1219)	N/A	N/A	°	° right	°	° right	Target lock is lost.
84	4.8824	(4.000)	(1219)	N/A	N/A	°	° right	°	° right	Target lock is lost.
85	4.9412	4.000	1219	(?)	(?)	°	° right	°	° right	Target is locked again.
86	5.000	4.000	1219	(?)	(?)	°	° right	°	° right	Altitude is computed.
87	5.0588	4.000	1219	(?)	(?)	°	° right	°	° right
88	5.1176	4.000	1219	(?)	(?)	°	° right	°	° right
89	5.1765	4.000	1219	(?)	(?)	°	° right	°	° right
90	5.2353	4.000	1219	(?)	(?)	°	° right	°	° right
91	5.2941	3.000	914	(?)	(?)	°	° right	°	° right	Altitude is computed.
92	5.3529	3.000	914	(?)	(?)	°	° right	°	° right
93	5.4118	3.000	914	(?)	(?)	°	° right	°	° right
94	5.4706	3.000	914	(?)	(?)	°	° right	°	° right
95	5.5294	3.000	914	(?)	(?)	°	° right	°	° right
96	5.5882	3.000	914	(?)	(?)	°	° right	°	° right
97	5.6471	3.000	914	(?)	(?)	°	° right	°	° right
98	5.7059	3.000	914	(?)	(?)	°	° right	°	° right
99	5.7647	3.000	914	(?)	(?)	°	° right	°	° right
100	5.8235	3.000	914	(?)	(?)	°	° right	°	° right
101	5.8824	3.000	914	(?)	(?)	°	° right	°	° right
102	5.9412	3.000	914	990	1834	°	° right	°	° right	Speed is computed.
103	6.0000	2.000	609	990	1834	°	° right	°	° right	Altitude is computed.
104	6.0588	2.000	609	990	1834	°	° right	°	° right
105	6.1176	2.000	609	990	1834	°	° right	°	° right
106	6.1765	2.000	609	990	1834	°	° right	°	° right
107	6.2353	2.000	609	990	1834	°	° right	°	° right
108	6.2941	2.000	609	990	1834	°	° right	°	° right
109	6.3529	2.000	609	990	1834	°	° right	°	° right
110	6.4118	2.000	609	990	1834	°	° right	°	° right
111	6.4706	2.000	609	990	1834	°	° right	°	° right
112	6.5294	2.000	609	990	1834	°	° right	°	° right
113	6.5882	2.000	609	990	1834	°	° right	°	° right
114	6.6471	1.000	305	990	1834	°	° right	°	° right	Altitude is computed, "02" becomes "01".
115	6.7059	1.000	305	990	1834	°	° right	°	° right	You can see that the UFO is now at altitude "01", i.e. at 1000 feet or under 1000 feet. Some authors claimed that the case is "fake" or the UFO "impossible" because, they claim the UFO went "below ground level" but this is silly. The UFO went down to altitude 1000 feet, this is all that can be said, and the ground altitude is lower, at an average between 400 and 500 feet.
116	6.7647	1.000	305	990	1834	°	° right	°	° right	When the UFO is below 1000 feet, it escapes radar detection both from the ground radar sets and the F-16 radar sets.
117	6.8235	1.000	305	990	1834	°	° right	°	° right
118	6.8824	1.000	305	990	1834	°	° right	°	° right
119	6.9412	1.000	305	990	1834	°	° right	°	° right

Data set from the HUD video frames:

From the data set from the HUD video frames, where the duration is sliced in 119 steps, events such as measurements by the F-16's equipment is clearly visible.

The following table shows the measurements of the UFO altitude at each time it was measured, with in addition the initial value and the end value:

Note that there was possibly a measurement between frame 1 and frame 25, with no change in altitude, making that measurement unnoticeable.

Frame #:	Time in seconds:	UFO altitude in meters:
1	0.0000	3048
25	1.4118	2134
36	2.0588	1829
52	3.0000	1524
76	4.4118	1829
86	5.000	1219
91	5.2941	914
103	6.000	609
114	6.6471	305
119	6.9412	305

From the values in the above table, this graph of the UFO altitude versus time is built:

Document history.

Version:	Created/changed by:	Date:	Description:
0.1	Patrick Gross	April 25, 2008	Drafting started.
0.1	Patrick Gross	April 26, 2008	Preview of unfinished draft communicated to 1 ufologist.

Feedback history.

Date:	From:	Content:	Response:
	First publication.
-	-	-	-

This page was last updated on May 28, 2008.