Cross country NavEx
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Hello Forum
When flying a route such as the 117NM of A582 to Taegu, how does one count down the miles?
Is it done through the DED ?
Thanks
Bayonet
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Do you really need to know the entire distance? Most navigation goes from point A to point B to point C etc. in BMS mostly (if not all?) are TCNs, so you can see how far you are from the selected TCN station on your HSI.
If you want to know it anyway and your start or endpoint is not a preplanned waypoint, you could make your starting location from where the count needs to start a mark point (ICP “7 mark” until the DED says OFLY and then TMS-up on the stick to mark the GPS locations of the point you are overflying that moment. Hit “0 M-SEL” on the ICP to select the newly made mark point as active waypoint. Then you can read on your HUD and HSI (if in NAV mode) the distance from that waypoint. -
You can direct the distance between Steerpoints in your HUD, though the details of exactly which number refers to this is lost on me at the moment.
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Thank you Focaldesign.
I was intending to fly a 3 or 4 leg trip using “Dead Reckoning” from point A, through B and so on, simply changing course after a particular distance. It is just an experiment to see if I can locate a final destination without using the DME of the TACAN or indeed, the INS.
Thanks again for your useful and detailed advice.Bayonet
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Well if you’re using DR you should be flying timed legs at a set speed. It’s sort of cheating to have the Jet use it’s inertial or GPS systems to tell you the distance. If you’re going to use it for that you might as well use the navigation suite as intended.
These are the basics needed …. the flight computer and plotter isn’t strictly required but it makes life easier.
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using “Dead Reckoning”
Plan your flight path legs at a low level - say 5 thousand feet AGL. Pick sunny weather, and legs that overfly obvious visual cues - towns, mountains, bridges, rivers, anything you can spot reliably from the cockpit.
Use the briefing to determine the length of each leg you aim to fly in the route. Choose a route groundspeed you are comfortable flying at as the baseline speed, and calculate the time you need to fly each leg for at that speed. Check the -1-1 for your turning radius at the route speed. Some basic geometry will tell you that for a 90° turn, you will need to start the turn 1 turn radius before the end of the leg, to end up over the starting point of the new leg. Simple trigonometry will yield distances for angles other than 90°. Calculate the times again, this time for the corrected leg lengths.
Chances are good that when you actually fly the route, you will not fly at exactly the route ground speed that you calculated it at. You need to note the time that you started each leg at, and you need to know at what times you should be overflying certain features along the leg. If you get to a feature before the time you should have, you are going too fast. Work out how early you are, and adjust your speed (by slowing down) to a speed that will hit the turning point at the correct time. If you get to a feature late, you are too slow - you will need to speed up.
If you add wind into the picture, you can find that your heading and your track do not match up anymore. Flying your planned heading with a crosswind will result in a track over the ground which is offset away from the wind. If you get to a feature and find that instead of crossing over it, it is offset to your left or right, you need to correct your ground track back to the correct course. This will mean flying a heading first that intercepts your intended ground track, then turning again to the heading which maintains that ground track.
For these kind of calculations, some simple rules of thumb are helpful. For instance, that 60kts GS is equal to 1 mile per minute over the ground. Similarly 300kts GS is 5 miles per minute. If you are early, then slowing your speed for a set time and correcting back to the intended ground speed will fix that. If you are late, you may be able to correct that by speeding up for a period then slowing back to the intended ground speed. Then there is the ‘1 in 60 rule’ which reckons that at a distance of 60 miles out, 1° is a mile wide - so that if you travel for 60 miles and are off course by 5 miles when you get there, you were flying roughly 5° off course. How to correct that? fly 10° back towards your intended ground track for 60 miles, then back off by 5° to maintain the correct track.
This is all pretty basic stuff. Before pilots get near a fighter jet IRL, they can already hit a precise Time on Target on a low level route in an aircraft which does not HAVE an EGI. All the more reason to learn it in BMS!
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it’s very hard to to Dr in BMS because you need a real good map matching bms world and bms isn’t quite full of landmarks.
it’s possible but not as fun as with a specific flight sim or real lifeIt’s sort of cheating to have the Jet use it’s inertial or GPS systems to tell you the distance.
crap, you meant to say that i’m cheating in real life sometimes
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@Red:
it’s very hard to to Dr in BMS because you need a real good map matching bms world and bms isn’t quite full of landmarks.
it’s possible but not as fun as with a specific flight sim or real lifecrap, you meant to say that i’m cheating in real life sometimes
For a dead reckoning navex - yes.