ATTACK RADAR MISSION PROFILE

[Music] You'll find a gang of knobs and switches in the front office of the F-111. And you'll spend a lot of time learning which does what. It'll be less confusing if you relax. And remember that it all doesn't happen at once. Each control has its own time and place. For example, take the attack radar. When you first start setting up for radar practice bomb runs with an instructor pilot, the initial concern is CRT intensity, video, and if gain standby gives you 40 seconds for heating up the filaments with the antenna stowed. After this, go to on. The antenna drops out of stow and starts to sector, but it won't be ready to transmit until 5 minutes from turn on. You work CRT, video, and if gain during this delay while you're still in the chocks, CRT to whatever hot or cool setting you like. video on full then back half if gain up till you see noise on the scope. Since you're not transmitting, this has to be system noise. Back this off till it just disappears and you've established a signal to noise threshold. Anything above this threshold has to be signaled and pertinent during the mission. Any radar troubles at this time, you'd call for a fix. But assuming a good radar, you and the IP will press on. He'll call ground control for taxi instructions, at which time he'll get an altimeter reading. The IP will set this in and you'll do the same on the right side. Ground safety pin. Make sure you're in great circle or above. Okay, my heading is 016. Roger. 016. Everything present tolerance. Report when you're ready for tax. Okay. Okay. I'm ready for tax. Heat. [Music] Heat. [Music] Next stop is the arming area. Here you take the usual precautions before the army crew starts the safety checks. Everything checks out so you're ready to launch. Autumn flight number one. Flight clear for takeoff. Winds are calm. Al temperature 2 niner niner 3. Assuming the 5minute delay is over, now's the time to go to transmit when there's no one in close proximity. [Music] Okay, I've got 60 knots now. Rod, disengaged. Coming up 100 knots now. First check. [Music] after joinup. They give each other a safety inspection. Both ships also perform TFR checks at altitude since they'll be running most of the mission at 1,000 ft TFR. If you take a look at the scope now, you won't see anything like the pretty pictures they showed you in class. But if you've done your homework, you'll remember that the APQ113 was designed for optimum presentation at 40,000 ft. Anywhere below that, you're going to get excessive ground return. The lower, the hotter. This is where you go to sensitivity time control. STC biases the closer, more energetic returns, blending them with the weaker distant returns so that you end up with a better balance and even painting on the scope. It's your tool. Use it depending on what you want to see, on what day, at what altitude, with what target. When you drop down for your entry, you'll have to adjust STC again, of course, since you'll be holding at 1,000 ft TFR. As you approach the target, you will face a sighting problem because of the difference between true altitude, necessary for bombing accuracy, and pressure altitude, which is raw input to the NAV computing unit. The difference between the two is DV value. This varies from altitude to altitude, day to day, and at times of extreme weather change from hour to hour. It affects bombing and navigation geometry. In other words, your score, the whole point of the mission. The NAV computer unit in solving for RS, slant range, furnishes one known factor, RG, or ground range. If the NCU were fed true altitude, it could easily derive HG, absolute altitude above a turning point or target. But it's fed pressure altitude, which varies from true altitude with time and place. That variance is D and its value must be determined and fed to the NCU. There are several ways to do this. After first making sure that both the radar and NCU are in computing modes, pick a flat area such as a valley or dry lake where the elevation will remain constant long enough for you to work the problem. Set in terrain elevation to refine the computations based on pressure altitude. Refinement of HG or height above aiming point is accomplished with the altitude test knob in calibrate. If you're at low altitude, the pilot gives you absolute altitude from the radar altimeter. Turn the altitude cal knob until the Nixie counters match the reading he gave. Then return altitude test knob to normal. Highaltitude cal is the same as low altitude except that it uses the attack radar instead of the radar altimeter to derive absolute altitude. Placing the altitude test knob to cal causes an altitude hole to appear on the scope. Run the range cursor out till it reaches the leading edge of the first ground return. That range value will run up on the Nixie counters. Do a little simple math and you have true altitude. Tell the IP so he can then correct his tape readings and you're all set. What you've done is establish the value of D and feed it to the NCU, enabling it to derive HG. Having solved the sighting problem, your crosshairs will remain on the aiming point. We're 8 miles out from your turn point. Okay. Your new heading is 360. Mea 12.5. Uh, it's 360 and 125. [Applause] Okay, your command bars look good. The command bars may be looking good, but if your checkpoint is a complex one, say a water tower or a bridge in the middle of a town, your scope won't be looking good. You'll see a large hot blob, much too gross for precise crosshair placement. The reason is that the energy pulses going out, especially at long range, are too large for individual elements within the target complex. The returns overlap each other. It's as though you were trying to paint delicate figures with a big brush. In a situation like this, switch on fast time constant. This causes the receiver to shape the pulses so that their trailing edges are attenuated. With the leading edges emphasized, only the front of objects within a complex target show on the scope. The picture you get in FTC still seems a little surrealistic, but you know from your target study and your pointer systems just about where in town the tower or the bridge is. And you can crosshair it more easily with FTC on than with it off. I'm going to do an altitude cal on the dry lake. Roger. I'm sitting in a fix point elevation of 5055. Make sure we're flying at 1,000 ft under your radar altimeter. Okay, got it. Let's see. That makes D plus 200. checks with the forecast. Okay. Your command bars are good. Airplane's looking real good. Roger. I'm going to call the range. Autumn flight approaching the IP range 3-4. Anyone working 3-4? Come up on channel 10. Since there's no aircraft working the range, you continue on in. Within 80 miles, you'd be using the big picture, ground auto. We're at VIP now. Roger. Your new heading is 184 Mea 10.9. Roger. You'd have your crosshairs at least on the lake bed. And if you use your controls right, you might even be breaking out the target. You know where you are now and where you're heading. So go to narrow sector. This pairs down the video to the subject at hand, the target, and its immediate vicinity. In ground auto, the target should be marching down the azimuth cursor. Play around with your set. Now's the time to get the best picture you can because you're going to be pretty busy. Switch to ground velocity. Make sure you have target and crosshair synchronized. Make sure that your cursors aren't so hot that they blank out the target. Also, as you move in, your geometry keeps changing with a chance of minor inaccuracies creeping in. For instance, you might be nicely crosshaird and happy as a clam, but stay alert to change. If there seems to be slightly hotter painting either beyond the target or short of it, that means antenna tilt or beta error is present. Adjusting beta with the tilt control puts maximum radar energy right on the target, giving you the best picture. As range to target shortens, you'll want to take a better look. Keep the picture good by using STC video and maybe a little IF gain. On different missions, you tune for hard or soft return. Hard in this case, since radar reflectors are your target from here on in, say the last 30 mi is what it's all about. The mission, putting the bombs on the target. and until you get good. Here's the kind of mistakes that are common, ones you'll study later on from scope photography. STC, too hot near the target. As you close in, target's going to disappear in ground return. Here it's better. Here it's real good. [Music] FTC. What's wrong with this? Crosshairs right on the button. What's wrong? Poor discrimination. Use FTC, right? And that amorphous single blob breaks up into what it really is. Individual reflectors. Cursor intensity. Here, they're too high. They'll swallow up the target. Turn them down and you will get a better picture. Beta angle. This one's looking short. This one's looking long. This man's looking right on. Check your ballistics now. [Music] Check. Recheck your switches. [Music] They're checked. I'm going to trail bomb. [Music] Roger. You've got 120 seconds to release. Got the target. Uh close. Got it. Got to update. Okay. [Music] And I'm updating to the right. [Music] her command bars are doing. Everything's looking real good. The first aircraft goes through all six bomb runs, trail, range, emergency, and so on, while the second ship observes and scores. Then the second aircraft makes its runs with the first observing. Two, take the lead. Roger. Taking the lead. Passing on the left. Roger. All right, I have you in sight. You have the lead. [Music] If you should run into some weather on the way back, say a thunderhead builds up over mountains, you might work out a bit with circular polarization, seeing its effect on video. It goes without saying, however, that you do not carry the experiment through to the point of actually flying into the weather. As you near the base, you apply the usual TAC approach. Actual landing will be a combination of GCA and airborne instrument low approach. GCA has control priority, but you will actually be flying AILA with GCA reacting to AILA input. Ensure that an altitude calibration is complete and this will give the pilot the correct steering commands to hack the approach. Pick up the runway in ground auto and line up the crosshairs with it holding a glide angle of 2.5. Go to ground valve with the approach end of the runway as the target. Since the runway itself is a no-show, tune for the area around it so that you can recognize buildings, taxiways, and other landmarks. Got the reflectors. [Applause] Okay, I've got the runway there. I've got it. Roger. Everything's fine here. Glide slopes are good. [Music] Ro, breaking off the AILA. Now you break off AILA to go visual. And while this was just a clear day rehearsal, you can see how useful it would have been in weather. [Music] A little bit later, you'll be going through the dubious pleasure of seeing how you did, but this is where it's at. A good score doesn't necessarily mean you did everything right, nor does a poor score mean you've done everything wrong. The point is look for your mistakes, correct them and improve. [Music]