DCS: F/A-18C Hornet | AA Radar Use

Perhaps one of the most complex and confusing aspects of operating the Hornet is correct use of the air-to-air radar. The APG-73 is a mechanically scanned, pulse Doppler radar that is not a magic sensor that detects anything in front of it. Rather, there are several factors that determine what it can detect.

In this video, I’ll go over many of these factors, and in the end, I hope you’ll better understand how to best to use the radar and understand its limitations.

Many of these same principles will also apply to the F-16 radar.

RANGE
It probably goes without saying, but the range setting simply sets the scale of the radar format, it does not affect the actual range at which the radar can detect a contact. If you wish to display a target at 40 nm for instance, you will need to have the scale of the radar set to at least 40 nm.

AZIMUTH
Because the radar searches in front of your aircraft in a cone pattern, with you at the pointy end, contacts left or right of the cone will not be detected. To detect such contacts, you can either increase the azimuth setting of the radar, and thereby increasing your scan volume, or slewing the radar azimuth to the selected location of the contact.

If you increase the azimuth though, recognize that contact updates will be slower. Combined with a low target aging setting, the contact will disappear.

BAR
The bar setting controls the total vertical scan volume of the radar, and this can be 1, 2, 4 and 6 bars in a repeating raster scan. A 1 bar setting provides the fastest contact updates, but the smallest vertical scan volume, whereas a 6 bar setting results in the lowest contact updates but the largest vertical scan volume. Just like the azimuth setting, a large volume can result a dropped contacts when combined with a low target aging selection.

TARGET AGING
If a contact is not detected in the set target ageing time, it will be removed from the radar format. So, if you searching a large volume based on azimuth and bar, contacts can easily disappear from the display because they have aged out.

You may find that 16 or 32 works best for you when searching a large volume.

ELEVATON
Just as with the azimuth setting, the contact will also have to be vertically within the acquisition cone volume of the radar. If a contact is above or below the cone, it would not be detected. To solve this, you can either increase the bar setting to increase vertical scan area or tilt the radar up or down with the elevation control.

PRF
The radar can operate in three pulse repetition frequency, or PRF, modes.

In High mode, the radar is putting out the most energy and is best at detecting closing, high aspect contacts at long range. However, High is greatly limited at detecting low closure contacts that are flying away or perpendicular to you.

Medium mode has less detection range against high closure contacts flying toward you, compared to the High, but it is superior at detecting contacts at low closure rates with lower aspect.
Interleaved alternates High and Medium PRF in each bar of the raster scan and is thus a compromise between the two.

Given this, optimal detection range is based on expected contact aspect / closure rate and then matching that with the best PRF. So, for a likely contact flying at you, select High, for a contact beaming you are away, select Medium, and if you have no idea, go for Interleaved.

NOTCHING
When a contact is below you and flying near-perpendicular to your flight path, there is no Doppler shift difference between the contact and the ground, and the contact can be lost. This is termed the look down Doppler notch.

For optimal detection range and maintaining a track, a look up scenario is your best bet. However, this needs to be balanced with the advantages that a medium to high altitude missile shot affords.

RADAR CROSS SECTION
The Radar Cross Section, or RCS, is the radar return value of the aircraft. These can vary based on shaping, materials, intake shape, and more. For aircraft with no RCS-specific reductions, it often comes down to the general size of the aircraft.

Given this, in general, large aircraft like bombers, tankers, and AWACS, will have a much larger RCS value than a small fighter like an F-16 or MiG-29.

The higher the RCS value of the contact, the further out you’ll be able to detect it.

Datalink
To make things a bit more complicated, let’s also throw datalink into the mix.

When in Latent Track While Scan or Track While Scan modes, the position of friendly, unknown, and hostile contact symbols can also appear on your radar format.

An AWACS datalink contact is indicated as a small diamond that you cannot not lock on to because your radar does not see it.