Intercept Geometry: Table of Contents
- Part I: Introduction
- Part II: Definitions
- Part III: Target Aspect & Lateral Separation
- Part IV: Modern Gameplans (P-825/17)
- Part V: P-825/17: DT, CT, Timeline
- Part VI: Modern Intercept Demo Videos (P-825/17)
- Part VII: 2000s Intercepts (P-825/02)
- Part VIII: Intercept Progression & Lead Collision (P-825/02)
- Part IX: “Unknown Procedures” & Fleet Conversions p1 (P-825/02)
- Part X: Fleet Conversions p2 & Advanced Intercepts (P-825/02)
- Part XI: A brief look at the past (50s/60s)
- Part XII: In-Depth Timeline (from “Picture” to “Crank”)
- Part XIII: In-Depth Timeline (continuation: FOX 3/1/2)
- Part XIV: Crews’ take on Timelines for DCS
Something spooky this way comes!
The years following the Second World War saw only a marginal evolution of tactics and intercepts. The beginning of the jet era shook things up, but the almost complete reliance on GCI persisted until the introduction of powerful fighter-sized air radars. Until then, Controllers had a broader and more comprehensive perspective of the airspace and could position fighters in the most advantageous position depending on their tasking. The majority of the airborne, fighter-sized radars, such as the MiG-21 or the F-5, were mainly used to provide weapons or close-range guidance. Iconic designs, such as the F-4 Phantom II and later versions of the F-8 Crusader and the English Electric Lightning, were among the first to lead the way towards modern fighter-driven intercepts.
A look at the past. Intercept in the ’50s and ’60s
A while ago I ran into the Youtube Channel of Bruce Gordon, author of Spirit of Attack, a book I have really enjoyed. This fine gentleman recorded an amazing video about Interceptor Tactics back in the days of the Century Series. These tactics may sound outdated by modern standards, but at their core, they are still valid; they are just used slightly differently (besides, these are applicable by Korean / Vietnam-era aircraft in DCS).
This video provides a plethora of valuable information about the pros and cons of different intercepts versus bombers and fighters.
F-8 Crusader
The Vought F-8 Crusader, a single-seater, carrier-operated fighter developed in the mid/late 50s, bridged the gap between the old WW2 conception of fighters, through the modern era dominated (in theory) by radars and missiles.
The tactics used by the F-8 Crusader may appear obsolete, but “the old stuff” is still relevant for several reasons. In primis, DCS allows the player to fly in almost any time frame, so what does not apply to a Viper may be for a Tomcat, a Phantom II or a Sabre. There are always lessons and concepts worth studying and understanding: from a historical perspective to comprehend better the limitations and the features of the aeroplanes of that era. This can be used to explain why tactics evolved in the way they have. From a notional perspective, the more exposure we, desktop pilots and Navs, can get, the better, to grow our understanding and shape our forma mentis.
On a side note, the historical view is useful for creating realistic and appropriate scenarios.
Overview of basic intercept techniques
The following briefly mentions some basic techniques covered by F-8 pilot training.
The F-8, starting with the B, was equipped with one of the first instances of radars useful to intercept a target, rather than simple ranging: the APQ- 83, then 94 and 124.
90° Beam Stern Intercepts
Otherwise, the procedure is quite simple and consists of a turn with lead pursuit starting at 90 Cut to have wings level at 1-3 miles in the rear quarter.
Besides obtaining radar lock at close range ( SR < 3 nm), the common errors highlighted are about the conversion: not leading enough, resulting in a turn too long, or not drifting sufficient, resulting in a turn too tight.
Low Altitude Intercepts
At low altitudes, the turning radius is lower, a solid point to remember even when conducting modern intercepts.
Intercepting a target flying below 2,000ft AGL is challenging, as the radar picture is affected by the proximity of the terrain. For this reason, easing the gain can reduce the maximum contact detection range but allow the pilot to discern clutter and target. Another important suggestion is obtaining a lockon as early as possible: Pulse STT is reliable and effective even at low altitudes, but steep negative antenna elevation angles can induce too much ground clutter. The greater the range instead, the shallower the angle.
135° Beam Stern Intercepts
The execution, suggestions and common errors are similar to the 90° Beam Stern Intercept technique, with variations in the angles.
Pitch-up Intercepts
The pitch angle and the airspeed management are of critical importance. Too steep, and the intercept will fall outside the sustainable envelope. In particular, supersonic, faster-than-transonic is recommended (M1.2) for a 10,000ft pitch-up intercept, but maximum speed is recommended if the altitude difference is greater. The goal is to perform a zoom climb into the missile envelope.
Radar operations require adjustments as well. In particular, it is essential to spotlight the target at the maximum range. As it gets closer, the elevation angle should be set to a greater value, as if the range was 5 nm shorter. This operation will cause the target to fly through the airspace covered by the radar. If radar lock is not acquired within 5nm, the fighter should switch to a boresight acquisition mode and start climb and conversion.
A handy relation to determining the antenna elevation angle is assuming that 1° at 10nm equals 10,000 ft.
An interesting suggestion involves the weapon employment: the steering dot should be moved towards the bottom of the scope if the fighter energy status allows, thus giving the missile more vertical momentum.
Headon Intercepts
A front-quarter engagement situation may occur due to controller or pilot errors, such as insufficient corrections during the geometry computation.
The usage of SEAM (Sidewinder Extended Acquisition Mode) can be beneficial in these scenarios.
Observations
The training-oriented procedures briefly mentioned, and the ones described by Bruce Gordon have commonalities with the techniques seen in the later decades. It is probably a sign that the “building blocks” and the first step of making fighter aircraft crews may still be somewhat similar.
There are a few interesting points observable, among which:
- In primis, the weapon. The first versions of the AIM-9 Sidewinder were incapable or unreliable when employed from the front quarter. This characteristic forced the aircrews to manoeuvre in an advantageous position to maximise the odds of success. As later variants appeared, this issue faded, and IR missiles became reliable no matter the target aspect.
- Controllers are still a fundamental piece in any operation. However, their importance shifted as capable air intercept radars became more powerful and reliable. Fine GCI/AIC control is still possible but, especially in DCS, the fighter’s radar is still the main tool used to intercept a target.
- Due to the introduction of powerful and reliable air intercept radars and other means to provide situational awareness (e.g. Datalink), the intercept range has also changed. Modern techniques see the intercept starting much further than the last 15 nm – 20 nm where, fundamentally, only the conversion and employment occur due to the limited manoeuvring room.
- Moreover, radars are much less demanding operator-wise, and concerns about ground clutter, fine adjustment of the gain, and manual calculation of angles and geometry are minor (or different) concerns nowadays.
- Merging the greater intercept range with the weapon evolution, we see the beginning of the BVR era. Short-range engagements and intercepts, forced by the necessity of, for example, VID the targets, are still a reality, but the fighters have a much longer arm nowadays.
As mentioned, a separate series will cover intercept techniques from similar or later periods concerning the F-4 Phantom II.
FlyAndWire 