HDG vs NAV Hold

Hey there,

I'm a bit confused here. I've tried researching this question but people keep going off topic with the answers to the question. So let me explain what I'm trying to do, and then the question.

I'm flying a short route (from EGGL (Bristol) to EGLL (Heathrow)) using the LearJet 45. My flight type is direct GPS so when I'm in the cockpit I set my navigation mode to GPS, set the heading (using HDG hold), speed and altitude. Then, I'm trying to land the aircraft using an ILS approach. Someone told me that when you do an ILS approach, amongst the steps you have to take is to switch from GPS to NAV (which I do) and then switch between HDG and NAV hold (switch to NAV hold). I also enter the frequency and set the heading in the CRS (course) selector. From there you do whatever you need to do to get the aircraft on the ground.

But I saw a tutorial video where the guy does it in the opposite way. He's also flying a direct GPS route - switches to GPS but uses the NAV hold switch. When he does his ILS approach, he switches from NAV hold to HDG hold and using the heading selector to accomplish this. Why?

What is the difference between HDG and NAV hold modes? And which one is the correct way of using it - when performing an ILS landing. Should I fly my entire route in NAV hold mode (with the nav mode set to GPS) and perform my landing using the HDG hold (with the nav mode set to NAV)?

Quick and simple, the HDG (Heading) hold mode will hold the heading you have set on the autopilot's course selector or heading bug, when the autopilot is on. NAV (Navigation) mode lets the autopilot steer from your navigation avionics, the GPS with the GPS/NAV switch in the GPS position, the VORs/ILS when it's in the NAV position.

With those principles in mind, if you're using the GPS for your navigation, then put GPS/NAV switch to GPS and use the AP's NAV mode. If you're navigating by VOR, put the GPS/NAV sitch to NAV position. If you're using the ILS (which is on the NAV radio, just like the VOR is), you also want the GPS/NAV to NAV and, though you may initially use the AP's NAV mode on the ILS, you'll soon want to switch to the APR (Approach) mode on the AP. Once you're established on the localizer, press the ALT (Altitude) button on the AP. When you intercept the glide slope, this will automatically follow the glide slope needle.

As to what YOU should DO, you should use your knowledge of the principles above to decide which way YOU want to do it. It's certainly possible to use HDG hold for all your navigation, but this means you must keep adjusting the heading bug to stay on course. The NAV modes eliminate this step by following the navaid you've set up.

As Skylab would say, aviation is not an exact science -- it takes knowledge and thinking. Learn the principles involved and decide for yourself. Then there'll be no question which way you do it -- your way.

"But I saw a tutorial video where the guy does it in the opposite way. He's also flying a direct GPS route - switches to GPS but uses the NAV hold switch. When he does his ILS approach, he switches from NAV hold to HDG hold and using the heading selector to accomplish this. Why?"

In addition to what Larry said, don't be too concerned with what others do in videos, some know what they are doing, most don't. Check the Learning center in FSX for the basics so you will understand better...

Bottom line is there are various ways to control the aircraft: manually or AP, and different sources for nav info to that AP: GPS (satellite based) and RADIO NAV (land based), not to mention others that FSX doesn't use.

In the Lear 45 some switches/buttons are actually miss-labeled so it adds to the confusion, for example the HEADING button. The description calls it HEADING HOLD but in actuality it's HEADING SELECT, and they are two different functions. If it was a real HOLD it would only track your current heading but in the 45 if you change headings with the knob below it, it will follow whatever you set it too, which is actually heading SELECT mode. Little things like that dont help when trying to learn.

Also, using GPS, if you select an ILS for example using it, you still have to switch to NAV to complete the approach. You use GPS mode to get you to the approach (or HDG or manually), then switch to NAV after dialing in the correct frequency on your NAV 1 radio (be sure you make the freq active,top freq).

If you only select the ILS approach and do not choose a 'transition' (if available) then the GPS will intercept the ILS at the outer marker (OM) which is normally about 5 miles from the runway. It makes for very little time to get the plane ready to land, so you should shoot for a spot around 10 miles out to give yourself enough time to configure for landing.

Lots to learn, dont be shy about asking questions, but wade through the Learning Center first so you have a better idea of what to ask.

Hey there,

 

I'm a bit confused here. I've tried researching this question but people keep going off topic with the answers to the question. So let me explain what I'm trying to do, and then the question.

 

I'm flying a short route (from EGGL (Bristol) to EGLL (Heathrow)) using the LearJet 45. My flight type is direct GPS so when I'm in the cockpit I set my navigation mode to GPS, set the heading (using HDG hold), speed and altitude. Then, I'm trying to land the aircraft using an ILS approach. Someone told me that when you do an ILS approach, amongst the steps you have to take is to switch from GPS to NAV (which I do) and then switch between HDG and NAV hold (switch to NAV hold). I also enter the frequency and set the heading in the CRS (course) selector. From there you do whatever you need to do to get the aircraft on the ground.

 

But I saw a tutorial video where the guy does it in the opposite way. He's also flying a direct GPS route - switches to GPS but uses the NAV hold switch. When he does his ILS approach, he switches from NAV hold to HDG hold and using the heading selector to accomplish this. Why?

 

What is the difference between HDG and NAV hold modes? And which one is the correct way of using it - when performing an ILS landing. Should I fly my entire route in NAV hold mode (with the nav mode set to GPS) and perform my landing using the HDG hold (with the nav mode set to NAV)?

Hey, I too had issues with ILS landings and learning it was not all that fun but here is something you should do.

1) First know the airport such as altitude/ runway ILS freq. Heading. You can find it on your map once you are at the runway for take off or at the gate.

2) Using the GPS Direct mode is fine and is what I do when planning a flight. Lets say I am going from Salt Lake City (KSLC) to Kansas City Mo. ( KMCI). I will set up an IFR Direct and a screen pops up that shows a map. The red line shows you the direct route. Using the zoom in/out feature go to the airport you want to land at. You should know the runway (KMCI ) Alt 1026 feet , Runway 31L, ILS Freq 110.50.

Now zooming into that airport area take your mouse left click and hold the line to an area just south of runway 31L say over a VOR just outside the runway approach. Using click and hold take that route(red line) to the VOR and release.

You have just created a way-point to help line up your approach !

3) Make sure to set your NAV radios both 1 and 2 to the runway Freq. before you take off (110.50). You know the altitude (1026') this is important because a good rule of thumb is to start an approach line up about 10 to 20 miles away from the airport I will be 2200' above the ground and sometimes 4000' depending on my distance.

4)Once your plane makes that final turn on the GPS way-point you created then set your heading indicator to match and switch to heading and switch the GPS to NAV. Having already put the Freq. (110.50) into your NAV radio, and using the GPS screen as a guide you can use it to line up with the green indicator for the runway.

5) I do not know what aircraft you are flying but I will use the default boeing 737 as the aircraft in question. It is important to know when to use speed adjustments and when to apply flaps. This information is on the checklist for the aircraft and should be noted prior to the flight. In the 737 a good touchdown speed is 135 knots over the runway during flare 5% to 7 %. with full flaps then power down and try to land at a rate of 200' per minute or lower.

As you make that final turn toward the runway there is a button on the radio panel marked NAV1. Press it and it will lite up. A radio beacon will begin to beep once you are close enough to the airport runway and a red marker will appear on your horizon indicator( bottom of the screen) if you are to the left of the runway the red marker will appear to the right of the center line. Looking at the GPS Screen set your heading on an intercept course to that green runway indicator(Note if you do not see the green marker on the GPS, zoom in until it appears) Once the red marker begins to move to the center line Click your NAV Button and the plane will turn on its own toward the runway. DO NOT TURN OFF YOUR ALTITUDE HOLD. A second marker will appear soon( Sometimes both of them will be there) after you set the NAV ( Top right of your screen ) and once you are close enough to intercept the glide slope the red marker at the top right of the screen will move down. Once that maker begins to move down towards center screen hit he APR (Approach) button. Once the red marker reaches center screen position, the ALT HOLD button will automatically turn off and your aircraft will start a controlled decent to the runway.

Last GO TO FLIGHT LESSON 4 on Youtube and the dude known as FSX Genius will show and explain the who, how and most important WHYs

Hope this helps!!

Darrin