VOR NDB DME

[wain 879]

Okay just a quickie for the class..

I have been flying the Bus and Phenom and other more commercial stuff a lot so I have decided to freshen up on my Navigational skills...

I was in the A36 Bonanza flying from EGGD to EGWW via a VOR and NDB then capture an ILS to line me up.. all went well except the A36 has no DME..I know you can use the GPS to track distance to nearest VOR etc but it got me thinking.. my flightplan had the distance from the NDB to destination but I was struggling to work out at any given point how far away I would be in an aircraft without the GPS or DME....

Can someone explain in simple terms if there is a formula to work things out like distance..when to descend..what speed to fly and fpm...

I have googled and there is a lot of waffle out there and I prefer my waffles with honey and lemon..

Hope someone can hrlp...

Thanks..

[Corsaire31 419]

During my adventures I like to do a lot of "old school" flying without GPS and of course Plan G not connected.

 

Measuring distances is done with a watch knowing my speed, direction is obviously using the compass ( not forgetting to account for any crosswind ). For descent if I know the distance to the runway it's quite simple to figure out when to start my descent and fpm, knowing my speed. I try to figure it out from the map if I can identify some remarkable features. If I can't I use the "feeling" method. Knowing you can use Papi lights to adjust the descent rate when they exist. On small dirt strips you rely on yourself to feel it...

 

Distance and speed give you the time to the runway. Using this time and your altitude difference to the runway you can easily estimate rate of descent at any point where you decide to start it.

 

As a rule of thumb I usually start my approach at runway altitude + 2000 ft.  At 500 fpm descent takes me 4 minutes which equals to 6 nm at 90 knots approach speed. ( to be adjusted for the real approach speed for each plane )

 

For instance in Australia so far there are a lot of airfields with NDBs on the approach path. Knowing the distance between the NDB and the runway I can estimate how high I should be when flying over the NDB.

Edited July 15, 2016 by Corsaire31

[Tim_A 997]

My suggestion would be to triangulate your position against another VOR. Easy to do on a paper chart - just draw a line to the VOR and read off the radial. Plan-G can draw radials on the map, along with distance rings, and no doubt so can other planning software.

[Corsaire31 419]

I found that in Australia you're already happy when you catch one VOR signal !

[wain 879]

Thanks for the replys so far, I get the bit about planning your descent , Quick posted something somewhere and I cant find it, I think he called it 'the rule of 3' or something similar, however to do this I need to be able to calculate how far I am from airfield when I dont have a DME, for example I was flying at 140kts when I passed the NDB, I was at 4000ft and the Airport was 17nm away, so I would need to slow down and after doing some sums (when I have found said post) I would have a point where I would be (X)nm out and would start to descend. So if that point was 10nm is there a way to work out my distance from Airport with no DME, I get what you are saying Loic but you have not explained how you worked out where to start, is there a calculation to do that would tell me to fly for 4,5,6 minutes or whatever, so then when I pass NDB I start a stopwatch maintain speed for a set time, at that time I descend. I get that but not sure on how the sums work...a+bxc etc, thats where I am stuck....

[wain 879]

right I have found March's post about the math side of things...just need to work out how to calculate when I hit a specific point between last waypoint and airfield...

[Corsaire31 419]

You need to know the airport runway altitude. It's not so important you know you are at 4000 ft, it's important to know how high above the runway you are.

 

I would aim to be over the NDB at runway altitude + 2000 ft. According to my calculation above, I know I will start my 500 fpm descent 6 nm from runway with a 90 knots approach speed. This means I have to fly 11 nm before starting descent. I would aim to be in approach configuration ( flaps on APP and gear down ) over the NDB to have a fixed speed.

 

Let's imagine I am flying 110 knots in this configuration, that's 6 minutes to fly the 11 nm. So I start the stopwatch on my Saitek yoke, and after 6 minutes I start descending at 500 ft/mn lowering flaps in landing position and bring speed to 90 knots. By then I have a clear view on the runway ( admitting there is at least a 6nm visibility... )  and can make necessary adjustments.

 

Calculations have to be done again for different speeds.

 

PS : When flying my usual bush planes on dirt strips or water runways, I usually don't make any sophisticated calculations, I start approaching with my + 2000 ft altitude and start descending at sight when I feel it's the right moment...   That's why I tend to fly many hours in a few planes to get this "feeling".

 

Edited July 15, 2016 by Corsaire31

[wain 879]

thanks Loic, thats clearer I will try this later and over the weekend....

[brett 2,316]

I am horrible at math so one thing I do during the preplanning is create visual waypoints like towers, rivers, mountains, towns and so on, based off measurements from the airport. Got a visual waypoint a certain distance away (based on airport elevation, your cruise altitude and the rule of 3) and I know I can start descending. Try and find visual waypoints that match approach chart distances when possible. 

 

This goes for the whole flight, don't just depend on the VOR/NDB/Airport as a waypoint, sometimes during longer flights the nav signals only go out so far between waypoints, create visual waypoints throughout your flight between the navaids so you know your on the right path and not being blown off.      

[Tim_A 997]

There are lots of rules of thumb in aviation which make life easier.

 

One "thumb" (from tip to 1st knuckle) is 10nm on a half-mil chart or sectional.

 

The 1-in-60 rule: At 60kts, travelling 1nm takes 1 minute (so at 120kts, 1nm takes half a minute and so on)

By the same rule, a 1 degree course deviation results in being 1 nm wide of track after 60nm.

 

Again by the same rule, estimate your distance from a VOR by flying 90 degrees to a radial. The time it takes to travel 10 degrees (full scale deflection to full scale deflection) in seconds divided by 10 is the time in minutes it'll take you to fly to the VOR at your current speed.

[wain 879]

thenks Brett / Tim very helpful....I have set up a few flightplans and will be trying things out....

[Captain Coffee 2,030]

All that stuff above is why I never pursued flying as a career despite wanting to fly more than anything. I hate math, don't trust my manipulation of numbers...and seeing USAF pilots walking into the cockpits while I was finishing whatever I was doing with their flight instruments (Instrument Specialist was my job), decked out with bags full of charts, slide rules, compasses and calculators...scared me right out of aviation.

 

I do all my approaches Seat of Pants in every aircraft. I have never calculated TOD...or descent rate. I tend to overshoot occasionally :D...naturally, but Half the time when I actually pay attention to ATC they want me to fly past the place anyhow before I land...so I call it No Harm/No Foul when I miss my insane approaches .

 

I fly an approach the same way I bring my boat into a marina entrance while crossing a fast tide. I visually keep the height of the airfield consistent above my dash (similar to keeping a fixed sight line on the marina entrance and a point past it for reference), and adjust speed and Rate of Descent to keep it there. (In a boat I'd adjust speed and Angle of Approach). This is how I learned my Netflix Approach...I pushed that to the limits and learned how to Stall some of my aircraft nearly down to the runway.

 

BTW...I don't recommend doing this, it's probably a good way to die in real life...but in the simulator, it's fun as hell and saves a lot of time.

[Corsaire31 419]

I've learned navigation on racing sailboats in my home region where tides are the world's second highest after Fundy Bay in Canada ( we have up to 13 m height difference between low and high tide and typical 3 to 5 knots tidal streams which can go one way or the other depending on the time of the day or even 100 m away at the same time. We also have many rocks all over the bay )  This was of course way before we even heard about GPS or electronic depth sounders !  So I had to learn how to do a few simple calculations with water height, wind and current drifts, etc...

 

When I moved to the south of France and did some racing in the Mediterranean, there were no tides, no currents, no rocks and the sea was 50m deep 100 m from the shore. At that time we also had Loran Cs and later GPS giving coordinates, then high precision GPS maps which you could interface with the autopilot. Man, was it boring !

 

In fact with FSX I  also fly bush planes by the "seat of pants" ...  I don't do calculations everytime, I have done once a printed Excel sheet with different speeds, distances and descent rates and it's sitting on the desk with my checklists if I ever need a quick solution.

 

I'm pretty sure you're going to tell me " what is a checklist anyway ?"

Edited July 16, 2016 by Corsaire31

[brett 2,316]

Well Loic, I do know what a checklist is but I'm sure everyone here wouldn't mind a peek at your Excel spreadsheet.

[Corsaire31 419]

2 hours ago, brett said:

Well Loic, I do know what a checklist is but I'm sure everyone here wouldn't mind a peek at your Excel spreadsheet.

 

Nothing fancy, the rows are approach speeds in knots, the columns are descent rates in fpm and when I cross both I have the distance at which I need to start descent for an approach at runway altitude + 2000 ft on the recto and at + 3000 ft on the verso. ( most of the time on IFR flights the FSX ATC tends to guide me on a + 2000 ft approach )

 

I don't use it most of the time but I like the idea to have it lying around, would I need a quick glimpse if my aging brain is too busy on the approach to crunch numbers. ( like at night with a good crosswind, bad visibility, and some traffic around the airport for instance ... )

 

Of course this being a flight sim I could hit the "Pause" key and do my calculations without stress, but I would consider it as "cheating" as I try to have the same work load as irl. ( I mouse-click all the buttons and switches, I always start cold and dark , I stop on the designated parking with all shutdown steps, I even dial the radio frequencies when requested and I ask for clearances for departing, crossing airspaces and landing. Must be a little nuts ? )

 

 

[wain 879]

Loic I think in some eyes we may all be consider 'a little nuts', however we all enjoy this for our own reasons, sometimes I will do a flight and everything by the book, using all the procedures etc, other times I just need a quick buzz and will just use my Xbox controller wont use ATC and fly here there and everywhere by hand and have some fun....thats the important word 'FUN' whether its proper or a whizz around......

 

I think people who go and run every night are a 'little nuts' but they enjoy it, I only run if theres someone chasing me or the coffe shops about to close.....

[Corsaire31 419]

I understand what you mean, I also often plug in my joystick and fire up " Rise of Flight " or " Wings over Flanders Fields " for a patrol mission in the WW1 skies !  

 

I can also fire up " Total War  Warhammer " and continue my Dwarf campaign against Greenskins, have a fun special football game in " Blood Bowl 2 " or try to save the world from aliens in " XCom 2"

Edited July 17, 2016 by Corsaire31